Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm

/*
 * Copyright (C) 2014, 2015 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#import "config.h"
#import "WKWebViewInternal.h"

#if WK_API_ENABLED

#import "APIFormClient.h"
#import "APIPageConfiguration.h"
#import "APISerializedScriptValue.h"
#import "CompletionHandlerCallChecker.h"
#import "DiagnosticLoggingClient.h"
#import "FindClient.h"
#import "LegacySessionStateCoding.h"
#import "NavigationState.h"
#import "ObjCObjectGraph.h"
#import "RemoteLayerTreeScrollingPerformanceData.h"
#import "RemoteLayerTreeTransaction.h"
#import "RemoteObjectRegistry.h"
#import "RemoteObjectRegistryMessages.h"
#import "UIDelegate.h"
#import "ViewGestureController.h"
#import "ViewSnapshotStore.h"
#import "WKBackForwardListInternal.h"
#import "WKBackForwardListItemInternal.h"
#import "WKBrowsingContextHandleInternal.h"
#import "WKErrorInternal.h"
#import "WKHistoryDelegatePrivate.h"
#import "WKLayoutMode.h"
#import "WKNSData.h"
#import "WKNSURLExtras.h"
#import "WKNavigationDelegate.h"
#import "WKNavigationInternal.h"
#import "WKPreferencesInternal.h"
#import "WKProcessPoolInternal.h"
#import "WKSharedAPICast.h"
#import "WKUIDelegate.h"
#import "WKUIDelegatePrivate.h"
#import "WKUserContentControllerInternal.h"
#import "WKWebViewConfigurationInternal.h"
#import "WKWebViewContentProvider.h"
#import "WKWebsiteDataStoreInternal.h"
#import "WebBackForwardList.h"
#import "WebCertificateInfo.h"
#import "WebFormSubmissionListenerProxy.h"
#import "WebKitSystemInterface.h"
#import "WebPageGroup.h"
#import "WebPageProxy.h"
#import "WebPreferencesKeys.h"
#import "WebProcessPool.h"
#import "WebProcessProxy.h"
#import "_WKDiagnosticLoggingDelegate.h"
#import "_WKFindDelegate.h"
#import "_WKFormDelegate.h"
#import "_WKInputDelegate.h"
#import "_WKRemoteObjectRegistryInternal.h"
#import "_WKSessionStateInternal.h"
#import "_WKVisitedLinkStoreInternal.h"
#import <WebCore/IOSurface.h>
#import <WebCore/JSDOMBinding.h>
#import <wtf/HashMap.h>
#import <wtf/MathExtras.h>
#import <wtf/NeverDestroyed.h>
#import <wtf/Optional.h>
#import <wtf/RetainPtr.h>
#import <wtf/TemporaryChange.h>

#if PLATFORM(IOS)
#import "_WKFrameHandleInternal.h"
#import "_WKWebViewPrintFormatter.h"
#import "PrintInfo.h"
#import "ProcessThrottler.h"
#import "RemoteLayerTreeDrawingAreaProxy.h"
#import "RemoteScrollingCoordinatorProxy.h"
#import "UIKitSPI.h"
#import "WKContentViewInteraction.h"
#import "WKPDFView.h"
#import "WKScrollView.h"
#import "WKWebViewContentProviderRegistry.h"
#import "WebPageMessages.h"
#import "WebVideoFullscreenManagerProxy.h"
#import <UIKit/UIApplication.h>
#import <WebCore/CoreGraphicsSPI.h>
#import <WebCore/DynamicLinkerSPI.h>
#import <WebCore/FrameLoaderTypes.h>
#import <WebCore/InspectorOverlay.h>
#import <WebCore/QuartzCoreSPI.h>

@interface UIScrollView (UIScrollViewInternal)
- (void)_adjustForAutomaticKeyboardInfo:(NSDictionary*)info animated:(BOOL)animated lastAdjustment:(CGFloat*)lastAdjustment;
- (BOOL)_isScrollingToTop;
- (BOOL)_isInterruptingDeceleration;
- (CGPoint)_animatedTargetOffset;
@end

@interface UIPeripheralHost(UIKitInternal)
- (CGFloat)getVerticalOverlapForView:(UIView *)view usingKeyboardInfo:(NSDictionary *)info;
@end

@interface UIView (UIViewInternal)
- (UIViewController *)_viewControllerForAncestor;
@end

@interface UIWindow (UIWindowInternal)
- (BOOL)_isHostedInAnotherProcess;
@end

@interface UIViewController (UIViewControllerInternal)
- (UIViewController *)_rootAncestorViewController;
- (UIViewController *)_viewControllerForSupportedInterfaceOrientations;
@end

enum class DynamicViewportUpdateMode {
    NotResizing,
    ResizingWithAnimation,
    ResizingWithDocumentHidden,
};

#endif

#if PLATFORM(MAC)
#import "WKViewInternal.h"
#import <WebCore/ColorMac.h>
#endif

static HashMap<WebKit::WebPageProxy*, WKWebView *>& pageToViewMap()
{
    static NeverDestroyed<HashMap<WebKit::WebPageProxy*, WKWebView *>> map;
    return map;
}

WKWebView* fromWebPageProxy(WebKit::WebPageProxy& page)
{
    return pageToViewMap().get(&page);
}

@implementation WKWebView {
    std::unique_ptr<WebKit::NavigationState> _navigationState;
    std::unique_ptr<WebKit::UIDelegate> _uiDelegate;

    RetainPtr<_WKRemoteObjectRegistry> _remoteObjectRegistry;
    _WKRenderingProgressEvents _observedRenderingProgressEvents;

    WebKit::WeakObjCPtr<id <_WKInputDelegate>> _inputDelegate;

#if PLATFORM(IOS)
    RetainPtr<WKScrollView> _scrollView;
    RetainPtr<WKContentView> _contentView;

    BOOL _overridesMinimumLayoutSize;
    CGSize _minimumLayoutSizeOverride;
    BOOL _overridesMaximumUnobscuredSize;
    CGSize _maximumUnobscuredSizeOverride;
    CGRect _inputViewBounds;
    CGFloat _viewportMetaTagWidth;
    CGFloat _initialScaleFactor;
    BOOL _fastClickingIsDisabled;

    BOOL _allowsLinkPreview;

    UIEdgeInsets _obscuredInsets;
    BOOL _haveSetObscuredInsets;
    BOOL _isChangingObscuredInsetsInteractively;

    UIInterfaceOrientation _interfaceOrientationOverride;
    BOOL _overridesInterfaceOrientation;

    BOOL _hasCommittedLoadForMainFrame;
    BOOL _needsResetViewStateAfterCommitLoadForMainFrame;
    uint64_t _firstPaintAfterCommitLoadTransactionID;
    DynamicViewportUpdateMode _dynamicViewportUpdateMode;
    CATransform3D _resizeAnimationTransformAdjustments;
    uint64_t _resizeAnimationTransformTransactionID;
    RetainPtr<UIView> _resizeAnimationView;
    CGFloat _lastAdjustmentForScroller;
    Optional<CGRect> _frozenVisibleContentRect;
    Optional<CGRect> _frozenUnobscuredContentRect;

    BOOL _needsToRestoreExposedRect;
    WebCore::FloatRect _exposedRectToRestore;
    BOOL _needsToRestoreUnobscuredCenter;
    WebCore::FloatPoint _unobscuredCenterToRestore;
    uint64_t _firstTransactionIDAfterPageRestore;
    double _scaleToRestore;

    std::unique_ptr<WebKit::ViewGestureController> _gestureController;
    BOOL _allowsBackForwardNavigationGestures;

    RetainPtr<UIView <WKWebViewContentProvider>> _customContentView;
    RetainPtr<UIView> _customContentFixedOverlayView;

    WebCore::Color _scrollViewBackgroundColor;

    // This value tracks the current adjustment added to the bottom inset due to the keyboard sliding out from the bottom
    // when computing obscured content insets. This is used when updating the visible content rects where we should not
    // include this adjustment.
    CGFloat _totalScrollViewBottomInsetAdjustmentForKeyboard;
    BOOL _currentlyAdjustingScrollViewInsetsForKeyboard;

    BOOL _delayUpdateVisibleContentRects;
    BOOL _hadDelayedUpdateVisibleContentRects;

    BOOL _pageIsPrintingToPDF;
    RetainPtr<CGPDFDocumentRef> _printedDocument;
    Vector<std::function<void ()>> _snapshotsDeferredDuringResize;
#endif
#if PLATFORM(MAC)
    RetainPtr<WKView> _wkView;
    CGSize _intrinsicContentSize;
#endif
}

- (instancetype)initWithFrame:(CGRect)frame
{
    return [self initWithFrame:frame configuration:adoptNS([[WKWebViewConfiguration alloc] init]).get()];
}

#if PLATFORM(IOS)
static int32_t deviceOrientationForUIInterfaceOrientation(UIInterfaceOrientation orientation)
{
    switch (orientation) {
    case UIInterfaceOrientationUnknown:
    case UIInterfaceOrientationPortrait:
        return 0;
    case UIInterfaceOrientationPortraitUpsideDown:
        return 180;
    case UIInterfaceOrientationLandscapeLeft:
        return -90;
    case UIInterfaceOrientationLandscapeRight:
        return 90;
    }
}

static int32_t deviceOrientation()
{
    return deviceOrientationForUIInterfaceOrientation([[UIApplication sharedApplication] statusBarOrientation]);
}

- (BOOL)_isShowingVideoPictureInPicture
{
    if (!_page || !_page->videoFullscreenManager())
        return false;
    
    return _page->videoFullscreenManager()->hasMode(WebCore::HTMLMediaElementEnums::VideoFullscreenModePictureInPicture);
}

- (BOOL)_mayAutomaticallyShowVideoPictureInPicture
{
#if !HAVE(AVKIT)
    return false;
#else
    if (!_page || !_page->videoFullscreenManager())
        return false;

    return _page->videoFullscreenManager()->mayAutomaticallyShowVideoPictureInPicture();
#endif
}

static bool shouldAllowPictureInPictureMediaPlayback()
{
    static bool shouldAllowPictureInPictureMediaPlayback = dyld_get_program_sdk_version() >= DYLD_IOS_VERSION_9_0;
    return shouldAllowPictureInPictureMediaPlayback;
}

#endif

- (instancetype)initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration *)configuration
{
    if (!(self = [super initWithFrame:frame]))
        return nil;

    if (!configuration)
        [NSException raise:NSInvalidArgumentException format:@"Configuration cannot be nil"];

    _configuration = adoptNS([configuration copy]);

    if (WKWebView *relatedWebView = [_configuration _relatedWebView]) {
        WKProcessPool *processPool = [_configuration processPool];
        WKProcessPool *relatedWebViewProcessPool = [relatedWebView->_configuration processPool];
        if (processPool && processPool != relatedWebViewProcessPool)
            [NSException raise:NSInvalidArgumentException format:@"Related web view %@ has process pool %@ but configuration specifies a different process pool %@", relatedWebView, relatedWebViewProcessPool, configuration.processPool];

        [_configuration setProcessPool:relatedWebViewProcessPool];
    }

    [_configuration _validate];

    CGRect bounds = self.bounds;

    WebKit::WebProcessPool& processPool = *[_configuration processPool]->_processPool;
    
    auto pageConfiguration = API::PageConfiguration::create();

    pageConfiguration->setProcessPool(&processPool);
    pageConfiguration->setPreferences([_configuration preferences]->_preferences.get());
    if (WKWebView *relatedWebView = [_configuration _relatedWebView])
        pageConfiguration->setRelatedPage(relatedWebView->_page.get());

    pageConfiguration->setUserContentController([_configuration userContentController]->_userContentControllerProxy.get());
    pageConfiguration->setVisitedLinkStore([_configuration _visitedLinkStore]->_visitedLinkStore.get());
    pageConfiguration->setWebsiteDataStore([_configuration websiteDataStore]->_websiteDataStore.get());
    pageConfiguration->setTreatsSHA1SignedCertificatesAsInsecure([_configuration _treatsSHA1SignedCertificatesAsInsecure]);

    RefPtr<WebKit::WebPageGroup> pageGroup;
    NSString *groupIdentifier = configuration._groupIdentifier;
    if (groupIdentifier.length) {
        pageGroup = WebKit::WebPageGroup::create(configuration._groupIdentifier);
        pageConfiguration->setPageGroup(pageGroup.get());
    }

    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::suppressesIncrementalRenderingKey(), WebKit::WebPreferencesStore::Value(!![_configuration suppressesIncrementalRendering]));

#if PLATFORM(IOS)
    pageConfiguration->setAlwaysRunsAtForegroundPriority([_configuration _alwaysRunsAtForegroundPriority]);

    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::allowsInlineMediaPlaybackKey(), WebKit::WebPreferencesStore::Value(!![_configuration allowsInlineMediaPlayback]));
    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::inlineMediaPlaybackRequiresPlaysInlineAttributeKey(), WebKit::WebPreferencesStore::Value(!![_configuration _inlineMediaPlaybackRequiresPlaysInlineAttribute]));
    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::allowsPictureInPictureMediaPlaybackKey(), WebKit::WebPreferencesStore::Value(!![_configuration allowsPictureInPictureMediaPlayback] && shouldAllowPictureInPictureMediaPlayback()));
    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::requiresUserGestureForMediaPlaybackKey(), WebKit::WebPreferencesStore::Value(!![_configuration requiresUserActionForMediaPlayback]));
    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::mediaDataLoadsAutomaticallyKey(), WebKit::WebPreferencesStore::Value(!![_configuration _mediaDataLoadsAutomatically]));
#endif
#if ENABLE(WIRELESS_PLAYBACK_TARGET)
    pageConfiguration->preferenceValues().set(WebKit::WebPreferencesKey::allowsAirPlayForMediaPlaybackKey(), WebKit::WebPreferencesStore::Value(!![_configuration allowsAirPlayForMediaPlayback]));
#endif

#if PLATFORM(IOS)
    _scrollView = adoptNS([[WKScrollView alloc] initWithFrame:bounds]);
    [_scrollView setInternalDelegate:self];
    [_scrollView setBouncesZoom:YES];

    [self addSubview:_scrollView.get()];

    _contentView = adoptNS([[WKContentView alloc] initWithFrame:bounds processPool:processPool configuration:WTF::move(pageConfiguration) webView:self]);

    _page = [_contentView page];
    _page->setDeviceOrientation(deviceOrientation());

    [_contentView layer].anchorPoint = CGPointZero;
    [_contentView setFrame:bounds];
    [_scrollView addSubview:_contentView.get()];
    [_scrollView addSubview:[_contentView unscaledView]];
    [self _updateScrollViewBackground];

    _viewportMetaTagWidth = WebCore::ViewportArguments::ValueAuto;
    _initialScaleFactor = 1;
    _fastClickingIsDisabled = [[NSUserDefaults standardUserDefaults] boolForKey:@"WebKitFastClickingDisabled"];

    [self _frameOrBoundsChanged];

    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
    [center addObserver:self selector:@selector(_keyboardWillChangeFrame:) name:UIKeyboardWillChangeFrameNotification object:nil];
    [center addObserver:self selector:@selector(_keyboardDidChangeFrame:) name:UIKeyboardDidChangeFrameNotification object:nil];
    [center addObserver:self selector:@selector(_keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    [center addObserver:self selector:@selector(_keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
    [center addObserver:self selector:@selector(_windowDidRotate:) name:UIWindowDidRotateNotification object:nil];
    [center addObserver:self selector:@selector(_contentSizeCategoryDidChange:) name:UIContentSizeCategoryDidChangeNotification object:nil];
    _page->contentSizeCategoryDidChange([self _contentSizeCategory]);

    [[_configuration _contentProviderRegistry] addPage:*_page];
#endif

#if PLATFORM(MAC)
    _wkView = adoptNS([[WKView alloc] initWithFrame:bounds processPool:processPool configuration:WTF::move(pageConfiguration) webView:self]);
    [self addSubview:_wkView.get()];
    _page = WebKit::toImpl([_wkView pageRef]);

    _intrinsicContentSize = CGSizeMake(NSViewNoInstrinsicMetric, NSViewNoInstrinsicMetric);

#if __MAC_OS_X_VERSION_MIN_REQUIRED >= 101000
    [_wkView _setAutomaticallyAdjustsContentInsets:YES];
#endif
#endif

    _page->setBackgroundExtendsBeyondPage(true);

    if (NSString *applicationNameForUserAgent = configuration.applicationNameForUserAgent)
        _page->setApplicationNameForUserAgent(applicationNameForUserAgent);

    _navigationState = std::make_unique<WebKit::NavigationState>(self);
    _uiDelegate = std::make_unique<WebKit::UIDelegate>(self);
    _page->setFindClient(std::make_unique<WebKit::FindClient>(self));
    _page->setDiagnosticLoggingClient(std::make_unique<WebKit::DiagnosticLoggingClient>(self));

    pageToViewMap().add(_page.get(), self);

    return self;
}

- (instancetype)initWithCoder:(NSCoder *)coder
{
    [self release];
    return nil;
}

- (void)dealloc
{
    if (_remoteObjectRegistry)
        _page->process().processPool().removeMessageReceiver(Messages::RemoteObjectRegistry::messageReceiverName(), _page->pageID());

    _page->close();

    [_remoteObjectRegistry _invalidate];
#if PLATFORM(IOS)
    [[_configuration _contentProviderRegistry] removePage:*_page];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [_scrollView setInternalDelegate:nil];
#endif

    pageToViewMap().remove(_page.get());

    [super dealloc];
}

- (WKWebViewConfiguration *)configuration
{
    return [[_configuration copy] autorelease];
}

- (WKBackForwardList *)backForwardList
{
    return wrapper(_page->backForwardList());
}

- (id <WKNavigationDelegate>)navigationDelegate
{
    return _navigationState->navigationDelegate().autorelease();
}

- (void)setNavigationDelegate:(id <WKNavigationDelegate>)navigationDelegate
{
    _page->setNavigationClient(_navigationState->createNavigationClient());
    _navigationState->setNavigationDelegate(navigationDelegate);
}

- (id <WKUIDelegate>)UIDelegate
{
    return _uiDelegate->delegate().autorelease();
}

- (void)setUIDelegate:(id<WKUIDelegate>)UIDelegate
{
#if ENABLE(CONTEXT_MENUS)
    _page->setContextMenuClient(_uiDelegate->createContextMenuClient());
#endif
    _page->setUIClient(_uiDelegate->createUIClient());
    _uiDelegate->setDelegate(UIDelegate);
}

- (WKNavigation *)loadRequest:(NSURLRequest *)request
{
    auto navigation = _page->loadRequest(request);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (WKNavigation *)loadFileURL:(NSURL *)URL allowingReadAccessToURL:(NSURL *)readAccessURL
{
    if (![URL isFileURL])
        [NSException raise:NSInvalidArgumentException format:@"%@ is not a file URL", URL];

    if (![readAccessURL isFileURL])
        [NSException raise:NSInvalidArgumentException format:@"%@ is not a file URL", readAccessURL];

    auto navigation = _page->loadFile([URL _web_originalDataAsWTFString], [readAccessURL _web_originalDataAsWTFString]);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (WKNavigation *)loadHTMLString:(NSString *)string baseURL:(NSURL *)baseURL
{
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];

    return [self loadData:data MIMEType:@"text/html" characterEncodingName:@"UTF-8" baseURL:baseURL];
}

- (WKNavigation *)loadData:(NSData *)data MIMEType:(NSString *)MIMEType characterEncodingName:(NSString *)characterEncodingName baseURL:(NSURL *)baseURL
{
    auto navigation = _page->loadData(API::Data::createWithoutCopying(data).ptr(), MIMEType, characterEncodingName, baseURL.absoluteString);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (WKNavigation *)goToBackForwardListItem:(WKBackForwardListItem *)item
{
    auto navigation = _page->goToBackForwardItem(&item._item);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (NSString *)title
{
    return _page->pageLoadState().title();
}

- (NSURL *)URL
{
    return [NSURL _web_URLWithWTFString:_page->pageLoadState().activeURL()];
}

- (BOOL)isLoading
{
    return _page->pageLoadState().isLoading();
}

- (double)estimatedProgress
{
    return _page->pageLoadState().estimatedProgress();
}

- (BOOL)hasOnlySecureContent
{
    return _page->pageLoadState().hasOnlySecureContent();
}

- (NSArray *)certificateChain
{
    auto certificateInfo = _page->pageLoadState().certificateInfo();
    if (!certificateInfo)
        return @[ ];

    return (NSArray *)certificateInfo->certificateInfo().certificateChain() ?: @[ ];
}

- (BOOL)canGoBack
{
    return _page->pageLoadState().canGoBack();
}

- (BOOL)canGoForward
{
    return _page->pageLoadState().canGoForward();
}

- (WKNavigation *)goBack
{
    auto navigation = _page->goBack();
    if (!navigation)
        return nil;
 
    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (WKNavigation *)goForward
{
    auto navigation = _page->goForward();
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (WKNavigation *)reload
{
    const bool reloadFromOrigin = false;
    const bool contentBlockersEnabled = true;
    auto navigation = _page->reload(reloadFromOrigin, contentBlockersEnabled);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (WKNavigation *)reloadFromOrigin
{
    const bool reloadFromOrigin = true;
    const bool contentBlockersEnabled = true;
    auto navigation = _page->reload(reloadFromOrigin, contentBlockersEnabled);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (void)stopLoading
{
    _page->stopLoading();
}

static WKErrorCode callbackErrorCode(WebKit::CallbackBase::Error error)
{
    switch (error) {
    case WebKit::CallbackBase::Error::None:
        ASSERT_NOT_REACHED();
        return WKErrorUnknown;

    case WebKit::CallbackBase::Error::Unknown:
        return WKErrorUnknown;

    case WebKit::CallbackBase::Error::ProcessExited:
        return WKErrorWebContentProcessTerminated;

    case WebKit::CallbackBase::Error::OwnerWasInvalidated:
        return WKErrorWebViewInvalidated;
    }
}

- (void)evaluateJavaScript:(NSString *)javaScriptString completionHandler:(void (^)(id, NSError *))completionHandler
{
    auto handler = adoptNS([completionHandler copy]);

    _page->runJavaScriptInMainFrame(javaScriptString, [handler](API::SerializedScriptValue* serializedScriptValue, bool hadException, const WebCore::ExceptionDetails& details, WebKit::ScriptValueCallback::Error errorCode) {
        if (!handler)
            return;

        if (errorCode != WebKit::ScriptValueCallback::Error::None) {
            auto error = createNSError(callbackErrorCode(errorCode));
            if (errorCode == WebKit::ScriptValueCallback::Error::OwnerWasInvalidated) {
                // The OwnerWasInvalidated callback is synchronous. We don't want to call the block from within it
                // because that can trigger re-entrancy bugs in WebKit.
                // FIXME: It would be even better if GenericCallback did this for us.
                dispatch_async(dispatch_get_main_queue(), [handler, error] {
                    auto rawHandler = (void (^)(id, NSError *))handler.get();
                    rawHandler(nil, error.get());
                });
                return;
            }

            auto rawHandler = (void (^)(id, NSError *))handler.get();
            rawHandler(nil, error.get());
            return;
        }

        auto rawHandler = (void (^)(id, NSError *))handler.get();
        if (hadException) {
            ASSERT(!serializedScriptValue);

            RetainPtr<NSMutableDictionary> userInfo = adoptNS([[NSMutableDictionary alloc] init]);

            [userInfo setObject:localizedDescriptionForErrorCode(WKErrorJavaScriptExceptionOccurred) forKey:NSLocalizedDescriptionKey];
            [userInfo setObject:static_cast<NSString *>(details.message) forKey:_WKJavaScriptExceptionMessageErrorKey];
            [userInfo setObject:@(details.lineNumber) forKey:_WKJavaScriptExceptionLineNumberErrorKey];
            [userInfo setObject:@(details.columnNumber) forKey:_WKJavaScriptExceptionColumnNumberErrorKey];

            if (!details.sourceURL.isEmpty())
                [userInfo setObject:[NSURL _web_URLWithWTFString:details.sourceURL] forKey:_WKJavaScriptExceptionSourceURLErrorKey];

            rawHandler(nil, adoptNS([[NSError alloc] initWithDomain:WKErrorDomain code:WKErrorJavaScriptExceptionOccurred userInfo:userInfo.get()]).get());
            return;
        }

        if (!serializedScriptValue) {
            rawHandler(nil, createNSError(WKErrorJavaScriptResultTypeIsUnsupported).get());
            return;
        }

        id body = API::SerializedScriptValue::deserialize(*serializedScriptValue->internalRepresentation(), 0);
        rawHandler(body, nil);
    });
}

- (NSString *)customUserAgent
{
    return _page->customUserAgent();
}

- (void)setCustomUserAgent:(NSString *)customUserAgent
{
    _page->setCustomUserAgent(customUserAgent);
}

- (WKPageRef)_pageForTesting
{
    return toAPI(_page.get());
}

- (BOOL)allowsLinkPreview
{
#if PLATFORM(MAC)
    return [_wkView allowsLinkPreview];
#elif PLATFORM(IOS)
    return _allowsLinkPreview;
#endif
}

- (void)setAllowsLinkPreview:(BOOL)allowsLinkPreview
{
#if PLATFORM(MAC)
    [_wkView setAllowsLinkPreview:allowsLinkPreview];
    return;
#elif PLATFORM(IOS)
    if (_allowsLinkPreview == allowsLinkPreview)
        return;

    _allowsLinkPreview = allowsLinkPreview;

#if HAVE(LINK_PREVIEW)
    if (_allowsLinkPreview)
        [_contentView _registerPreview];
    else
        [_contentView _unregisterPreview];
#endif // HAVE(LINK_PREVIEW)
#endif // PLATFORM(IOS)
}

#pragma mark iOS-specific methods

#if PLATFORM(IOS)
- (void)setFrame:(CGRect)frame
{
    CGRect oldFrame = self.frame;
    [super setFrame:frame];

    if (!CGSizeEqualToSize(oldFrame.size, frame.size))
        [self _frameOrBoundsChanged];
}

- (void)setBounds:(CGRect)bounds
{
    CGRect oldBounds = self.bounds;
    [super setBounds:bounds];
    [_customContentFixedOverlayView setFrame:self.bounds];

    if (!CGSizeEqualToSize(oldBounds.size, bounds.size))
        [self _frameOrBoundsChanged];
}

- (UIScrollView *)scrollView
{
    return _scrollView.get();
}

- (WKBrowsingContextController *)browsingContextController
{
    return [_contentView browsingContextController];
}

- (BOOL)becomeFirstResponder
{
    return [_contentView becomeFirstResponder] || [super becomeFirstResponder];
}

static inline CGFloat floorToDevicePixel(CGFloat input, float deviceScaleFactor)
{
    return CGFloor(input * deviceScaleFactor) / deviceScaleFactor;
}

static inline bool pointsEqualInDevicePixels(CGPoint a, CGPoint b, float deviceScaleFactor)
{
    return fabs(a.x * deviceScaleFactor - b.x * deviceScaleFactor) < std::numeric_limits<float>::epsilon()
        && fabs(a.y * deviceScaleFactor - b.y * deviceScaleFactor) < std::numeric_limits<float>::epsilon();
}

static CGSize roundScrollViewContentSize(const WebKit::WebPageProxy& page, CGSize contentSize)
{
    float deviceScaleFactor = page.deviceScaleFactor();
    return CGSizeMake(floorToDevicePixel(contentSize.width, deviceScaleFactor), floorToDevicePixel(contentSize.height, deviceScaleFactor));
}

- (UIView *)_currentContentView
{
    return _customContentView ? _customContentView.get() : _contentView.get();
}

- (void)_setHasCustomContentView:(BOOL)pageHasCustomContentView loadedMIMEType:(const WTF::String&)mimeType
{
    if (pageHasCustomContentView) {
        [_customContentView removeFromSuperview];
        [_customContentFixedOverlayView removeFromSuperview];

        Class representationClass = [[_configuration _contentProviderRegistry] providerForMIMEType:mimeType];
        ASSERT(representationClass);
        _customContentView = adoptNS([[representationClass alloc] web_initWithFrame:self.bounds webView:self]);
        _customContentFixedOverlayView = adoptNS([[UIView alloc] initWithFrame:self.bounds]);
        [_customContentFixedOverlayView setUserInteractionEnabled:NO];

        [[_contentView unscaledView] removeFromSuperview];
        [_contentView removeFromSuperview];
        [_scrollView addSubview:_customContentView.get()];
        [self addSubview:_customContentFixedOverlayView.get()];

        [_customContentView web_setMinimumSize:self.bounds.size];
        [_customContentView web_setFixedOverlayView:_customContentFixedOverlayView.get()];
    } else if (_customContentView) {
        [_customContentView removeFromSuperview];
        _customContentView = nullptr;

        [_customContentFixedOverlayView removeFromSuperview];
        _customContentFixedOverlayView = nullptr;

        [_scrollView addSubview:_contentView.get()];
        [_scrollView addSubview:[_contentView unscaledView]];
        [_scrollView setContentSize:roundScrollViewContentSize(*_page, [_contentView frame].size)];

        [_customContentFixedOverlayView setFrame:self.bounds];
        [self addSubview:_customContentFixedOverlayView.get()];
    }
}

- (void)_didFinishLoadingDataForCustomContentProviderWithSuggestedFilename:(const String&)suggestedFilename data:(NSData *)data
{
    ASSERT(_customContentView);
    [_customContentView web_setContentProviderData:data suggestedFilename:suggestedFilename];

    // FIXME: It may make more sense for custom content providers to invoke this when they're ready,
    // because there's no guarantee that all custom content providers will lay out synchronously.
    _page->didLayoutForCustomContentProvider();
}

- (void)_willInvokeUIScrollViewDelegateCallback
{
    _delayUpdateVisibleContentRects = YES;
}

- (void)_didInvokeUIScrollViewDelegateCallback
{
    _delayUpdateVisibleContentRects = NO;
    if (_hadDelayedUpdateVisibleContentRects) {
        _hadDelayedUpdateVisibleContentRects = NO;
        [self _updateVisibleContentRects];
    }
}

static CGFloat contentZoomScale(WKWebView *webView)
{
    CGFloat scale = webView._currentContentView.layer.affineTransform.a;
    ASSERT(scale == [webView->_scrollView zoomScale]);
    return scale;
}

static WebCore::Color baseScrollViewBackgroundColor(WKWebView *webView)
{
    if (webView->_customContentView)
        return [webView->_customContentView backgroundColor].CGColor;

    if (webView->_gestureController) {
        WebCore::Color color = webView->_gestureController->backgroundColorForCurrentSnapshot();
        if (color.isValid())
            return color;
    }

    return webView->_page->pageExtendedBackgroundColor();
}

static WebCore::Color scrollViewBackgroundColor(WKWebView *webView)
{
    if (!webView.opaque)
        return WebCore::Color::transparent;

    WebCore::Color color = baseScrollViewBackgroundColor(webView);

    if (!color.isValid())
        color = WebCore::Color::white;

    CGFloat zoomScale = contentZoomScale(webView);
    CGFloat minimumZoomScale = [webView->_scrollView minimumZoomScale];
    if (zoomScale < minimumZoomScale) {
        CGFloat slope = 12;
        CGFloat opacity = std::max<CGFloat>(1 - slope * (minimumZoomScale - zoomScale), 0);
        color = WebCore::colorWithOverrideAlpha(color.rgb(), opacity);
    }

    return color;
}

- (void)_updateScrollViewBackground
{
    WebCore::Color color = scrollViewBackgroundColor(self);

    if (_scrollViewBackgroundColor == color)
        return;

    _scrollViewBackgroundColor = color;

    auto uiBackgroundColor = adoptNS([[UIColor alloc] initWithCGColor:cachedCGColor(color, WebCore::ColorSpaceDeviceRGB)]);
    [_scrollView setBackgroundColor:uiBackgroundColor.get()];

    // Update the indicator style based on the lightness/darkness of the background color.
    double hue, saturation, lightness;
    color.getHSL(hue, saturation, lightness);
    if (lightness <= .5 && color.alpha() > 0)
        [_scrollView setIndicatorStyle:UIScrollViewIndicatorStyleWhite];
    else
        [_scrollView setIndicatorStyle:UIScrollViewIndicatorStyleDefault];
}

- (CGPoint)_adjustedContentOffset:(CGPoint)point
{
    CGPoint result = point;
    UIEdgeInsets contentInset = [self _computedContentInset];

    result.x -= contentInset.left;
    result.y -= contentInset.top;

    return result;
}

- (UIEdgeInsets)_computedContentInset
{
    if (_haveSetObscuredInsets)
        return _obscuredInsets;

    return [_scrollView contentInset];
}

- (void)_processDidExit
{
    if (!_customContentView && _dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing) {
        NSUInteger indexOfResizeAnimationView = [[_scrollView subviews] indexOfObject:_resizeAnimationView.get()];
        [_scrollView insertSubview:_contentView.get() atIndex:indexOfResizeAnimationView];
        [_scrollView insertSubview:[_contentView unscaledView] atIndex:indexOfResizeAnimationView + 1];
        [_resizeAnimationView removeFromSuperview];
        _resizeAnimationView = nil;

        _resizeAnimationTransformAdjustments = CATransform3DIdentity;
    }
    [_contentView setFrame:self.bounds];
    [_scrollView setBackgroundColor:[UIColor whiteColor]];
    [_scrollView setContentOffset:[self _adjustedContentOffset:CGPointZero]];
    [_scrollView setZoomScale:1];

    _viewportMetaTagWidth = WebCore::ViewportArguments::ValueAuto;
    _initialScaleFactor = 1;
    _hasCommittedLoadForMainFrame = NO;
    _needsResetViewStateAfterCommitLoadForMainFrame = NO;
    _dynamicViewportUpdateMode = DynamicViewportUpdateMode::NotResizing;
    [_contentView setHidden:NO];
    _needsToRestoreExposedRect = NO;
    _needsToRestoreUnobscuredCenter = NO;
    _scrollViewBackgroundColor = WebCore::Color();
    _delayUpdateVisibleContentRects = NO;
    _hadDelayedUpdateVisibleContentRects = NO;
}

- (void)_didCommitLoadForMainFrame
{
    _firstPaintAfterCommitLoadTransactionID = downcast<WebKit::RemoteLayerTreeDrawingAreaProxy>(*_page->drawingArea()).nextLayerTreeTransactionID();

    _hasCommittedLoadForMainFrame = YES;
    _needsResetViewStateAfterCommitLoadForMainFrame = YES;
}

static CGPoint contentOffsetBoundedInValidRange(UIScrollView *scrollView, CGPoint contentOffset)
{
    UIEdgeInsets contentInsets = scrollView.contentInset;
    CGSize contentSize = scrollView.contentSize;
    CGSize scrollViewSize = scrollView.bounds.size;

    CGFloat maxHorizontalOffset = contentSize.width + contentInsets.right - scrollViewSize.width;
    contentOffset.x = std::min(maxHorizontalOffset, contentOffset.x);
    contentOffset.x = std::max(-contentInsets.left, contentOffset.x);

    CGFloat maxVerticalOffset = contentSize.height + contentInsets.bottom - scrollViewSize.height;
    contentOffset.y = std::min(maxVerticalOffset, contentOffset.y);
    contentOffset.y = std::max(-contentInsets.top, contentOffset.y);
    return contentOffset;
}

static void changeContentOffsetBoundedInValidRange(UIScrollView *scrollView, WebCore::FloatPoint contentOffset)
{
    scrollView.contentOffset = contentOffsetBoundedInValidRange(scrollView, contentOffset);
}

- (WebCore::FloatRect)visibleRectInViewCoordinates
{
    WebCore::FloatRect bounds = self.bounds;
    bounds.moveBy([_scrollView contentOffset]);
    WebCore::FloatRect contentViewBounds = [_contentView bounds];
    bounds.intersect(contentViewBounds);
    return bounds;
}

// WebCore stores the page scale factor as float instead of double. When we get a scale from WebCore,
// we need to ignore differences that are within a small rounding error on floats.
static inline bool areEssentiallyEqualAsFloat(float a, float b)
{
    return WTF::areEssentiallyEqual(a, b);
}

- (void)_didCommitLayerTree:(const WebKit::RemoteLayerTreeTransaction&)layerTreeTransaction
{
    if (_customContentView)
        return;

    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing) {
        if (layerTreeTransaction.transactionID() >= _resizeAnimationTransformTransactionID) {
            [_resizeAnimationView layer].sublayerTransform = _resizeAnimationTransformAdjustments;
            if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::ResizingWithDocumentHidden) {
                [_contentView setHidden:NO];
                [self _endAnimatedResize];
            }
        }
        return;
    }

    CGSize newContentSize = roundScrollViewContentSize(*_page, [_contentView frame].size);
    [_scrollView _setContentSizePreservingContentOffsetDuringRubberband:newContentSize];

    [_scrollView setMinimumZoomScale:layerTreeTransaction.minimumScaleFactor()];
    [_scrollView setMaximumZoomScale:layerTreeTransaction.maximumScaleFactor()];
    [_scrollView setZoomEnabled:layerTreeTransaction.allowsUserScaling()];
    if (!layerTreeTransaction.scaleWasSetByUIProcess() && ![_scrollView isZooming] && ![_scrollView isZoomBouncing] && ![_scrollView _isAnimatingZoom])
        [_scrollView setZoomScale:layerTreeTransaction.pageScaleFactor()];

    _viewportMetaTagWidth = layerTreeTransaction.viewportMetaTagWidth();
    _initialScaleFactor = layerTreeTransaction.initialScaleFactor();
    if (![_contentView _mayDisableDoubleTapGesturesDuringSingleTap])
        [_contentView _setDoubleTapGesturesEnabled:self._allowsDoubleTapGestures];

    [self _updateScrollViewBackground];

    if (_gestureController)
        _gestureController->setRenderTreeSize(layerTreeTransaction.renderTreeSize());

    if (_needsResetViewStateAfterCommitLoadForMainFrame && layerTreeTransaction.transactionID() >= _firstPaintAfterCommitLoadTransactionID) {
        _needsResetViewStateAfterCommitLoadForMainFrame = NO;
        [_scrollView setContentOffset:[self _adjustedContentOffset:CGPointZero]];
        [self _updateVisibleContentRects];
        if (_observedRenderingProgressEvents & _WKRenderingProgressEventFirstPaint)
            _navigationState->didFirstPaint();
    }

    bool isTransactionAfterPageRestore = layerTreeTransaction.transactionID() >= _firstTransactionIDAfterPageRestore;

    if (_needsToRestoreExposedRect && isTransactionAfterPageRestore) {
        _needsToRestoreExposedRect = NO;

        if (areEssentiallyEqualAsFloat(contentZoomScale(self), _scaleToRestore)) {
            WebCore::FloatPoint exposedPosition = _exposedRectToRestore.location();
            exposedPosition.scale(_scaleToRestore, _scaleToRestore);

            changeContentOffsetBoundedInValidRange(_scrollView.get(), exposedPosition);
            if (_gestureController)
                _gestureController->didRestoreScrollPosition();
        }
        [self _updateVisibleContentRects];
    }

    if (_needsToRestoreUnobscuredCenter && isTransactionAfterPageRestore) {
        _needsToRestoreUnobscuredCenter = NO;

        if (areEssentiallyEqualAsFloat(contentZoomScale(self), _scaleToRestore)) {
            CGRect unobscuredRect = UIEdgeInsetsInsetRect(self.bounds, _obscuredInsets);
            WebCore::FloatSize unobscuredContentSizeAtNewScale(unobscuredRect.size.width / _scaleToRestore, unobscuredRect.size.height / _scaleToRestore);
            WebCore::FloatPoint topLeftInDocumentCoordinates(_unobscuredCenterToRestore.x() - unobscuredContentSizeAtNewScale.width() / 2, _unobscuredCenterToRestore.y() - unobscuredContentSizeAtNewScale.height() / 2);

            topLeftInDocumentCoordinates.scale(_scaleToRestore, _scaleToRestore);
            topLeftInDocumentCoordinates.moveBy(WebCore::FloatPoint(-_obscuredInsets.left, -_obscuredInsets.top));

            changeContentOffsetBoundedInValidRange(_scrollView.get(), topLeftInDocumentCoordinates);
            if (_gestureController)
                _gestureController->didRestoreScrollPosition();
        }
        [self _updateVisibleContentRects];
    }
    
    if (WebKit::RemoteLayerTreeScrollingPerformanceData* scrollPerfData = _page->scrollingPerformanceData())
        scrollPerfData->didCommitLayerTree([self visibleRectInViewCoordinates]);
}

- (void)_dynamicViewportUpdateChangedTargetToScale:(double)newScale position:(CGPoint)newScrollPosition nextValidLayerTreeTransactionID:(uint64_t)nextValidLayerTreeTransactionID
{
    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing) {
        CGFloat animatingScaleTarget = [[_resizeAnimationView layer] transform].m11;
        double currentTargetScale = animatingScaleTarget * [[_contentView layer] transform].m11;
        double scale = newScale / currentTargetScale;
        _resizeAnimationTransformAdjustments = CATransform3DMakeScale(scale, scale, 1);

        CGPoint newContentOffset = [self _adjustedContentOffset:CGPointMake(newScrollPosition.x * newScale, newScrollPosition.y * newScale)];
        CGPoint currentContentOffset = [_scrollView contentOffset];

        _resizeAnimationTransformAdjustments.m41 = (currentContentOffset.x - newContentOffset.x) / animatingScaleTarget;
        _resizeAnimationTransformAdjustments.m42 = (currentContentOffset.y - newContentOffset.y) / animatingScaleTarget;
        _resizeAnimationTransformTransactionID = nextValidLayerTreeTransactionID;
    }
}

- (void)_couldNotRestorePageState
{
    // The gestureController may be waiting for the scroll position to be restored
    // in order to remove the swipe snapshot. Since the scroll position could not be
    // restored, tell the gestureController it was restored so that it no longer waits
    // for it.
    if (_gestureController)
        _gestureController->didRestoreScrollPosition();
}

- (void)_restorePageStateToExposedRect:(WebCore::FloatRect)exposedRect scale:(double)scale
{
    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing)
        return;

    if (_customContentView)
        return;

    _needsToRestoreUnobscuredCenter = NO;
    _needsToRestoreExposedRect = YES;
    _firstTransactionIDAfterPageRestore = downcast<WebKit::RemoteLayerTreeDrawingAreaProxy>(*_page->drawingArea()).nextLayerTreeTransactionID();
    _exposedRectToRestore = exposedRect;
    _scaleToRestore = scale;
}

- (void)_restorePageStateToUnobscuredCenter:(WebCore::FloatPoint)center scale:(double)scale
{
    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing)
        return;

    if (_customContentView)
        return;

    _needsToRestoreExposedRect = NO;
    _needsToRestoreUnobscuredCenter = YES;
    _firstTransactionIDAfterPageRestore = downcast<WebKit::RemoteLayerTreeDrawingAreaProxy>(*_page->drawingArea()).nextLayerTreeTransactionID();
    _unobscuredCenterToRestore = center;
    _scaleToRestore = scale;
}

- (PassRefPtr<WebKit::ViewSnapshot>)_takeViewSnapshot
{
    float deviceScale = WebCore::screenScaleFactor();
    WebCore::FloatSize snapshotSize(self.bounds.size);
    snapshotSize.scale(deviceScale, deviceScale);

    CATransform3D transform = CATransform3DMakeScale(deviceScale, deviceScale, 1);

#if USE(IOSURFACE)
    auto surface = WebCore::IOSurface::create(WebCore::expandedIntSize(snapshotSize), WebCore::ColorSpaceDeviceRGB);
    CARenderServerRenderLayerWithTransform(MACH_PORT_NULL, self.layer.context.contextId, reinterpret_cast<uint64_t>(self.layer), surface->surface(), 0, 0, &transform);

    RefPtr<WebKit::ViewSnapshot> viewSnapshot = WebKit::ViewSnapshot::create(nullptr);
    WebCore::IOSurface::convertToFormat(WTF::move(surface), WebCore::IOSurface::Format::YUV422, [viewSnapshot](std::unique_ptr<WebCore::IOSurface> convertedSurface) {
        viewSnapshot->setSurface(WTF::move(convertedSurface));
    });

    return viewSnapshot;
#else
    uint32_t slotID = [WebKit::ViewSnapshotStore::snapshottingContext() createImageSlot:snapshotSize hasAlpha:YES];

    if (!slotID)
        return nullptr;

    CARenderServerCaptureLayerWithTransform(MACH_PORT_NULL, self.layer.context.contextId, (uint64_t)self.layer, slotID, 0, 0, &transform);
    WebCore::IntSize imageSize = WebCore::expandedIntSize(WebCore::FloatSize(snapshotSize));
    return WebKit::ViewSnapshot::create(slotID, imageSize, imageSize.width() * imageSize.height() * 4);
#endif
}

- (void)_zoomToPoint:(WebCore::FloatPoint)point atScale:(double)scale animated:(BOOL)animated
{
    CFTimeInterval duration = 0;
    CGFloat zoomScale = contentZoomScale(self);

    if (animated) {
        const double maximumZoomDuration = 0.4;
        const double minimumZoomDuration = 0.1;
        const double zoomDurationFactor = 0.3;

        duration = std::min(fabs(log(zoomScale) - log(scale)) * zoomDurationFactor + minimumZoomDuration, maximumZoomDuration);
    }

    if (scale != zoomScale)
        _page->willStartUserTriggeredZooming();

    [_scrollView _zoomToCenter:point scale:scale duration:duration];
}

- (void)_zoomToRect:(WebCore::FloatRect)targetRect atScale:(double)scale origin:(WebCore::FloatPoint)origin animated:(BOOL)animated
{
    // FIXME: Some of this could be shared with _scrollToRect.
    const double visibleRectScaleChange = contentZoomScale(self) / scale;
    const WebCore::FloatRect visibleRect([self convertRect:self.bounds toView:self._currentContentView]);
    const WebCore::FloatRect unobscuredRect([self _contentRectForUserInteraction]);

    const WebCore::FloatSize topLeftObscuredInsetAfterZoom((unobscuredRect.minXMinYCorner() - visibleRect.minXMinYCorner()) * visibleRectScaleChange);
    const WebCore::FloatSize bottomRightObscuredInsetAfterZoom((visibleRect.maxXMaxYCorner() - unobscuredRect.maxXMaxYCorner()) * visibleRectScaleChange);

    const WebCore::FloatSize unobscuredRectSizeAfterZoom(unobscuredRect.size() * visibleRectScaleChange);

    // Center to the target rect.
    WebCore::FloatPoint unobscuredRectLocationAfterZoom = targetRect.location() - (unobscuredRectSizeAfterZoom - targetRect.size()) * 0.5;

    // Center to the tap point instead in case the target rect won't fit in a direction.
    if (targetRect.width() > unobscuredRectSizeAfterZoom.width())
        unobscuredRectLocationAfterZoom.setX(origin.x() - unobscuredRectSizeAfterZoom.width() / 2);
    if (targetRect.height() > unobscuredRectSizeAfterZoom.height())
        unobscuredRectLocationAfterZoom.setY(origin.y() - unobscuredRectSizeAfterZoom.height() / 2);

    // We have computed where we want the unobscured rect to be. Now adjust for the obscuring insets.
    WebCore::FloatRect visibleRectAfterZoom(unobscuredRectLocationAfterZoom, unobscuredRectSizeAfterZoom);
    visibleRectAfterZoom.move(-topLeftObscuredInsetAfterZoom);
    visibleRectAfterZoom.expand(topLeftObscuredInsetAfterZoom + bottomRightObscuredInsetAfterZoom);

    [self _zoomToPoint:visibleRectAfterZoom.center() atScale:scale animated:animated];
}

static WebCore::FloatPoint constrainContentOffset(WebCore::FloatPoint contentOffset, WebCore::FloatSize contentSize, WebCore::FloatSize unobscuredContentSize)
{
    WebCore::FloatSize maximumContentOffset = contentSize - unobscuredContentSize;
    contentOffset = contentOffset.shrunkTo(WebCore::FloatPoint(maximumContentOffset.width(), maximumContentOffset.height()));
    contentOffset = contentOffset.expandedTo(WebCore::FloatPoint());
    return contentOffset;
}

- (void)_scrollToContentOffset:(WebCore::FloatPoint)contentOffsetInPageCoordinates scrollOrigin:(WebCore::IntPoint)scrollOrigin
{
    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing)
        return;

    WebCore::FloatPoint contentOffsetRespectingOrigin = scrollOrigin + toFloatSize(contentOffsetInPageCoordinates);

    WebCore::FloatPoint scaledOffset = contentOffsetRespectingOrigin;
    CGFloat zoomScale = contentZoomScale(self);
    scaledOffset.scale(zoomScale, zoomScale);

    CGPoint contentOffsetInScrollViewCoordinates = [self _adjustedContentOffset:scaledOffset];
    contentOffsetInScrollViewCoordinates = contentOffsetBoundedInValidRange(_scrollView.get(), contentOffsetInScrollViewCoordinates);

    [_scrollView _stopScrollingAndZoomingAnimations];

    if (!CGPointEqualToPoint(contentOffsetInScrollViewCoordinates, [_scrollView contentOffset]))
        [_scrollView setContentOffset:contentOffsetInScrollViewCoordinates];
    else {
        // If we haven't changed anything, there would not be any VisibleContentRect update sent to the content.
        // The WebProcess would keep the invalid contentOffset as its scroll position.
        // To synchronize the WebProcess with what is on screen, we send the VisibleContentRect again.
        _page->resendLastVisibleContentRects();
    }
}

- (BOOL)_scrollToRect:(WebCore::FloatRect)targetRect origin:(WebCore::FloatPoint)origin minimumScrollDistance:(float)minimumScrollDistance
{
    WebCore::FloatRect unobscuredContentRect([self _contentRectForUserInteraction]);
    WebCore::FloatPoint unobscuredContentOffset = unobscuredContentRect.location();
    WebCore::FloatSize contentSize([self._currentContentView bounds].size);

    // Center the target rect in the scroll view.
    // If the target doesn't fit in the scroll view, center on the gesture location instead.
    WebCore::FloatPoint newUnobscuredContentOffset;
    if (targetRect.width() <= unobscuredContentRect.width())
        newUnobscuredContentOffset.setX(targetRect.x() - (unobscuredContentRect.width() - targetRect.width()) / 2);
    else
        newUnobscuredContentOffset.setX(origin.x() - unobscuredContentRect.width() / 2);
    if (targetRect.height() <= unobscuredContentRect.height())
        newUnobscuredContentOffset.setY(targetRect.y() - (unobscuredContentRect.height() - targetRect.height()) / 2);
    else
        newUnobscuredContentOffset.setY(origin.y() - unobscuredContentRect.height() / 2);
    newUnobscuredContentOffset = constrainContentOffset(newUnobscuredContentOffset, contentSize, unobscuredContentRect.size());

    if (unobscuredContentOffset == newUnobscuredContentOffset) {
        if (targetRect.width() > unobscuredContentRect.width())
            newUnobscuredContentOffset.setX(origin.x() - unobscuredContentRect.width() / 2);
        if (targetRect.height() > unobscuredContentRect.height())
            newUnobscuredContentOffset.setY(origin.y() - unobscuredContentRect.height() / 2);
        newUnobscuredContentOffset = constrainContentOffset(newUnobscuredContentOffset, contentSize, unobscuredContentRect.size());
    }

    WebCore::FloatSize scrollViewOffsetDelta = newUnobscuredContentOffset - unobscuredContentOffset;
    scrollViewOffsetDelta.scale(contentZoomScale(self));

    float scrollDistance = scrollViewOffsetDelta.diagonalLength();
    if (scrollDistance < minimumScrollDistance)
        return false;

    [_contentView willStartZoomOrScroll];

    [_scrollView setContentOffset:([_scrollView contentOffset] + scrollViewOffsetDelta) animated:YES];
    return true;
}

- (void)_scrollByOffset:(WebCore::FloatPoint)offset
{
    CGPoint currentOffset = ([_scrollView _isAnimatingScroll]) ? [_scrollView _animatedTargetOffset] : [_scrollView contentOffset];

    CGPoint boundedOffset = contentOffsetBoundedInValidRange(_scrollView.get(), currentOffset + offset);
    
    if (CGPointEqualToPoint(boundedOffset, currentOffset))
        return;
    [_contentView willStartZoomOrScroll];
    [_scrollView setContentOffset:boundedOffset animated:YES];
}

- (void)_zoomOutWithOrigin:(WebCore::FloatPoint)origin animated:(BOOL)animated
{
    [self _zoomToPoint:origin atScale:[_scrollView minimumZoomScale] animated:animated];
}

- (void)_zoomToInitialScaleWithOrigin:(WebCore::FloatPoint)origin animated:(BOOL)animated
{
    ASSERT(_initialScaleFactor > 0);
    [self _zoomToPoint:origin atScale:_initialScaleFactor animated:animated];
}

// focusedElementRect and selectionRect are both in document coordinates.
- (void)_zoomToFocusRect:(WebCore::FloatRect)focusedElementRectInDocumentCoordinates selectionRect:(WebCore::FloatRect)selectionRectInDocumentCoordinates fontSize:(float)fontSize minimumScale:(double)minimumScale maximumScale:(double)maximumScale allowScaling:(BOOL)allowScaling forceScroll:(BOOL)forceScroll
{
    const double WKWebViewStandardFontSize = 16;
    const double kMinimumHeightToShowContentAboveKeyboard = 106;
    const CFTimeInterval UIWebFormAnimationDuration = 0.25;
    const double CaretOffsetFromWindowEdge = 20;

    // Zoom around the element's bounding frame. We use a "standard" size to determine the proper frame.
    double scale = allowScaling ? std::min(std::max(WKWebViewStandardFontSize / fontSize, minimumScale), maximumScale) : contentZoomScale(self);
    CGFloat documentWidth = [_contentView bounds].size.width;
    scale = CGRound(documentWidth * scale) / documentWidth;

    UIWindow *window = [_scrollView window];

    WebCore::FloatRect focusedElementRectInNewScale = focusedElementRectInDocumentCoordinates;
    focusedElementRectInNewScale.scale(scale);
    focusedElementRectInNewScale.moveBy([_contentView frame].origin);

    // Find the portion of the view that is visible on the screen.
    UIViewController *topViewController = [[[_scrollView _viewControllerForAncestor] _rootAncestorViewController] _viewControllerForSupportedInterfaceOrientations];
    UIView *fullScreenView = topViewController.view;
    if (!fullScreenView)
        fullScreenView = window;

    CGRect unobscuredScrollViewRectInWebViewCoordinates = UIEdgeInsetsInsetRect([self bounds], _obscuredInsets);
    CGRect visibleScrollViewBoundsInWebViewCoordinates = CGRectIntersection(unobscuredScrollViewRectInWebViewCoordinates, [fullScreenView convertRect:[fullScreenView bounds] toView:self]);
    CGRect formAssistantFrameInWebViewCoordinates = [window convertRect:_inputViewBounds toView:self];
    CGRect intersectionBetweenScrollViewAndFormAssistant = CGRectIntersection(visibleScrollViewBoundsInWebViewCoordinates, formAssistantFrameInWebViewCoordinates);
    CGSize visibleSize = visibleScrollViewBoundsInWebViewCoordinates.size;

    CGFloat visibleOffsetFromTop = 0;
    if (!CGRectIsEmpty(intersectionBetweenScrollViewAndFormAssistant)) {
        CGFloat heightVisibleAboveFormAssistant = CGRectGetMinY(intersectionBetweenScrollViewAndFormAssistant) - CGRectGetMinY(visibleScrollViewBoundsInWebViewCoordinates);
        CGFloat heightVisibleBelowFormAssistant = CGRectGetMaxY(visibleScrollViewBoundsInWebViewCoordinates) - CGRectGetMaxY(intersectionBetweenScrollViewAndFormAssistant);

        if (heightVisibleAboveFormAssistant >= kMinimumHeightToShowContentAboveKeyboard || heightVisibleBelowFormAssistant < heightVisibleAboveFormAssistant)
            visibleSize.height = heightVisibleAboveFormAssistant;
        else {
            visibleSize.height = heightVisibleBelowFormAssistant;
            visibleOffsetFromTop = CGRectGetMaxY(intersectionBetweenScrollViewAndFormAssistant) - CGRectGetMinY(visibleScrollViewBoundsInWebViewCoordinates);
        }
    }

    BOOL selectionRectIsNotNull = !selectionRectInDocumentCoordinates.isZero();
    if (!forceScroll) {
        CGRect currentlyVisibleRegionInWebViewCoordinates;
        currentlyVisibleRegionInWebViewCoordinates.origin = unobscuredScrollViewRectInWebViewCoordinates.origin;
        currentlyVisibleRegionInWebViewCoordinates.origin.y += visibleOffsetFromTop;
        currentlyVisibleRegionInWebViewCoordinates.size = visibleSize;

        // Don't bother scrolling if the entire node is already visible, whether or not we got a selectionRect.
        if (CGRectContainsRect(currentlyVisibleRegionInWebViewCoordinates, [self convertRect:focusedElementRectInDocumentCoordinates fromView:_contentView.get()]))
            return;

        // Don't bother scrolling if we have a valid selectionRect and it is already visible.
        if (selectionRectIsNotNull && CGRectContainsRect(currentlyVisibleRegionInWebViewCoordinates, [self convertRect:selectionRectInDocumentCoordinates fromView:_contentView.get()]))
            return;
    }

    // We want to zoom to the left/top corner of the DOM node, with as much spacing on all sides as we
    // can get based on the visible area after zooming (workingFrame).  The spacing in either dimension is half the
    // difference between the size of the DOM node and the size of the visible frame.
    CGFloat horizontalSpaceInWebViewCoordinates = std::max((visibleSize.width - focusedElementRectInNewScale.width()) / 2.0, 0.0);
    CGFloat verticalSpaceInWebViewCoordinates = std::max((visibleSize.height - focusedElementRectInNewScale.height()) / 2.0, 0.0);

    CGPoint topLeft;
    topLeft.x = focusedElementRectInNewScale.x() - horizontalSpaceInWebViewCoordinates;
    topLeft.y = focusedElementRectInNewScale.y() - verticalSpaceInWebViewCoordinates - visibleOffsetFromTop;

    CGFloat minimumAllowableHorizontalOffsetInWebViewCoordinates = -INFINITY;
    CGFloat minimumAllowableVerticalOffsetInWebViewCoordinates = -INFINITY;
    if (selectionRectIsNotNull) {
        WebCore::FloatRect selectionRectInNewScale = selectionRectInDocumentCoordinates;
        selectionRectInNewScale.scale(scale);
        selectionRectInNewScale.moveBy([_contentView frame].origin);
        minimumAllowableHorizontalOffsetInWebViewCoordinates = CGRectGetMaxX(selectionRectInNewScale) + CaretOffsetFromWindowEdge - visibleSize.width;
        minimumAllowableVerticalOffsetInWebViewCoordinates = CGRectGetMaxY(selectionRectInNewScale) + CaretOffsetFromWindowEdge - visibleSize.height - visibleOffsetFromTop;
    }

    WebCore::FloatRect documentBoundsInNewScale = [_contentView bounds];
    documentBoundsInNewScale.scale(scale);
    documentBoundsInNewScale.moveBy([_contentView frame].origin);

    // Constrain the left edge in document coordinates so that:
    //  - it isn't so small that the scrollVisibleRect isn't visible on the screen
    //  - it isn't so great that the document's right edge is less than the right edge of the screen
    if (selectionRectIsNotNull && topLeft.x < minimumAllowableHorizontalOffsetInWebViewCoordinates)
        topLeft.x = minimumAllowableHorizontalOffsetInWebViewCoordinates;
    else {
        CGFloat maximumAllowableHorizontalOffset = CGRectGetMaxX(documentBoundsInNewScale) - visibleSize.width;
        if (topLeft.x > maximumAllowableHorizontalOffset)
            topLeft.x = maximumAllowableHorizontalOffset;
    }

    // Constrain the top edge in document coordinates so that:
    //  - it isn't so small that the scrollVisibleRect isn't visible on the screen
    //  - it isn't so great that the document's bottom edge is higher than the top of the form assistant
    if (selectionRectIsNotNull && topLeft.y < minimumAllowableVerticalOffsetInWebViewCoordinates)
        topLeft.y = minimumAllowableVerticalOffsetInWebViewCoordinates;
    else {
        CGFloat maximumAllowableVerticalOffset = CGRectGetMaxY(documentBoundsInNewScale) - visibleSize.height;
        if (topLeft.y > maximumAllowableVerticalOffset)
            topLeft.y = maximumAllowableVerticalOffset;
    }

    WebCore::FloatPoint newCenter = CGPointMake(topLeft.x + unobscuredScrollViewRectInWebViewCoordinates.size.width / 2.0, topLeft.y + unobscuredScrollViewRectInWebViewCoordinates.size.height / 2.0);

    if (scale != contentZoomScale(self))
        _page->willStartUserTriggeredZooming();

    // The newCenter has been computed in the new scale, but _zoomToCenter expected the center to be in the original scale.
    newCenter.scale(1 / scale, 1 / scale);
    [_scrollView _zoomToCenter:newCenter
                        scale:scale
                     duration:UIWebFormAnimationDuration
                        force:YES];
}

- (CGFloat)_targetContentZoomScaleForRect:(const WebCore::FloatRect&)targetRect currentScale:(double)currentScale fitEntireRect:(BOOL)fitEntireRect minimumScale:(double)minimumScale maximumScale:(double)maximumScale
{
    WebCore::FloatSize unobscuredContentSize([self _contentRectForUserInteraction].size);
    double horizontalScale = unobscuredContentSize.width() * currentScale / targetRect.width();
    double verticalScale = unobscuredContentSize.height() * currentScale / targetRect.height();

    horizontalScale = std::min(std::max(horizontalScale, minimumScale), maximumScale);
    verticalScale = std::min(std::max(verticalScale, minimumScale), maximumScale);

    return fitEntireRect ? std::min(horizontalScale, verticalScale) : horizontalScale;
}

- (BOOL)_zoomToRect:(WebCore::FloatRect)targetRect withOrigin:(WebCore::FloatPoint)origin fitEntireRect:(BOOL)fitEntireRect minimumScale:(double)minimumScale maximumScale:(double)maximumScale minimumScrollDistance:(float)minimumScrollDistance
{
    const float maximumScaleFactorDeltaForPanScroll = 0.02;

    double currentScale = contentZoomScale(self);
    double targetScale = [self _targetContentZoomScaleForRect:targetRect currentScale:currentScale fitEntireRect:fitEntireRect minimumScale:minimumScale maximumScale:maximumScale];

    if (fabs(targetScale - currentScale) < maximumScaleFactorDeltaForPanScroll) {
        if ([self _scrollToRect:targetRect origin:origin minimumScrollDistance:minimumScrollDistance])
            return true;
    } else if (targetScale != currentScale) {
        [self _zoomToRect:targetRect atScale:targetScale origin:origin animated:YES];
        return true;
    }
    
    return false;
}

- (void)didMoveToWindow
{
    _page->viewStateDidChange(WebCore::ViewState::AllFlags);
}

- (void)setOpaque:(BOOL)opaque
{
    BOOL oldOpaque = self.opaque;

    [super setOpaque:opaque];
    [_contentView setOpaque:opaque];

    if (oldOpaque == opaque)
        return;

    _page->setDrawsBackground(opaque);
    [self _updateScrollViewBackground];
}

- (void)setBackgroundColor:(UIColor *)backgroundColor
{
    [super setBackgroundColor:backgroundColor];
    [_contentView setBackgroundColor:backgroundColor];
}

#pragma mark - UIScrollViewDelegate

- (BOOL)usesStandardContentView
{
    return !_customContentView;
}

- (CGSize)scrollView:(UIScrollView*)scrollView contentSizeForZoomScale:(CGFloat)scale withProposedSize:(CGSize)proposedSize
{
    return roundScrollViewContentSize(*_page, proposedSize);
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    ASSERT(_scrollView == scrollView);

    if (_customContentView)
        return _customContentView.get();

    return _contentView.get();
}

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
    if (![self usesStandardContentView])
        return;

    if (scrollView.pinchGestureRecognizer.state == UIGestureRecognizerStateBegan) {
        _page->willStartUserTriggeredZooming();
        [_contentView scrollViewWillStartPanOrPinchGesture];
    }
    [_contentView willStartZoomOrScroll];
}

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    if (![self usesStandardContentView])
        return;

    if (scrollView.panGestureRecognizer.state == UIGestureRecognizerStateBegan)
        [_contentView scrollViewWillStartPanOrPinchGesture];

    [_contentView willStartZoomOrScroll];
#if ENABLE(CSS_SCROLL_SNAP) && ENABLE(ASYNC_SCROLLING)
    // FIXME: We will want to detect whether snapping will occur before beginning to drag. See WebPageProxy::didCommitLayerTree.
    WebKit::RemoteScrollingCoordinatorProxy* coordinator = _page->scrollingCoordinatorProxy();
    ASSERT(scrollView == _scrollView.get());
    CGFloat scrollDecelerationFactor = (coordinator && coordinator->shouldSetScrollViewDecelerationRateFast()) ? UIScrollViewDecelerationRateFast : [_scrollView preferredScrollDecelerationFactor];
    scrollView.horizontalScrollDecelerationFactor = scrollDecelerationFactor;
    scrollView.verticalScrollDecelerationFactor = scrollDecelerationFactor;
#endif
}

- (void)_didFinishScrolling
{
    if (![self usesStandardContentView])
        return;

    [self _updateVisibleContentRects];
    [_contentView didFinishScrolling];
}

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
    // Work around <rdar://problem/16374753> by avoiding deceleration while
    // zooming. We'll animate to the right place once the zoom finishes.
    if ([scrollView isZooming])
        *targetContentOffset = [scrollView contentOffset];
#if ENABLE(CSS_SCROLL_SNAP) && ENABLE(ASYNC_SCROLLING)
    if (WebKit::RemoteScrollingCoordinatorProxy* coordinator = _page->scrollingCoordinatorProxy()) {
        // FIXME: Here, I'm finding the maximum horizontal/vertical scroll offsets. There's probably a better way to do this.
        CGSize maxScrollOffsets = CGSizeMake(scrollView.contentSize.width - scrollView.bounds.size.width, scrollView.contentSize.height - scrollView.bounds.size.height);
        
        CGRect fullViewRect = self.bounds;

        UIEdgeInsets contentInset;

        id<WKUIDelegatePrivate> uiDelegatePrivate = static_cast<id <WKUIDelegatePrivate>>([self UIDelegate]);
        if ([uiDelegatePrivate respondsToSelector:@selector(_webView:finalObscuredInsetsForScrollView:withVelocity:targetContentOffset:)])
            contentInset = [uiDelegatePrivate _webView:self finalObscuredInsetsForScrollView:scrollView withVelocity:velocity targetContentOffset:targetContentOffset];
        else
            contentInset = [self _computedContentInset];

        CGRect unobscuredRect = UIEdgeInsetsInsetRect(fullViewRect, contentInset);
        
        coordinator->adjustTargetContentOffsetForSnapping(maxScrollOffsets, velocity, unobscuredRect.origin.y, targetContentOffset);
    }
#endif
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
    // If we're decelerating, scroll offset will be updated when scrollViewDidFinishDecelerating: is called.
    if (!decelerate)
        [self _didFinishScrolling];
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    [self _didFinishScrolling];
}

- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView
{
    [self _didFinishScrolling];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    if (![self usesStandardContentView])
        [_customContentView scrollViewDidScroll:(UIScrollView *)scrollView];

    [self _updateVisibleContentRects];
    
    if (WebKit::RemoteLayerTreeScrollingPerformanceData* scrollPerfData = _page->scrollingPerformanceData())
        scrollPerfData->didScroll([self visibleRectInViewCoordinates]);
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    [self _updateScrollViewBackground];
    [self _updateVisibleContentRects];
}

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
    ASSERT(scrollView == _scrollView);
    [self _updateVisibleContentRects];
    [_contentView didZoomToScale:scale];
}

- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
{
    [self _didFinishScrolling];
}

- (void)_scrollViewDidInterruptDecelerating:(UIScrollView *)scrollView
{
    if (![self usesStandardContentView])
        return;

    [_contentView didInterruptScrolling];
    [self _updateVisibleContentRects];
}

- (void)_frameOrBoundsChanged
{
    CGRect bounds = self.bounds;
    [_scrollView setFrame:bounds];

    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::NotResizing) {
        if (!_overridesMinimumLayoutSize)
            _page->setViewportConfigurationMinimumLayoutSize(WebCore::FloatSize(bounds.size));
        if (!_overridesMaximumUnobscuredSize)
            _page->setMaximumUnobscuredSize(WebCore::FloatSize(bounds.size));
        if (WebKit::DrawingAreaProxy* drawingArea = _page->drawingArea())
            drawingArea->setSize(WebCore::IntSize(bounds.size), WebCore::IntSize(), WebCore::IntSize());
    }

    [_customContentView web_setMinimumSize:bounds.size];
    [self _updateVisibleContentRects];
}

// Unobscured content rect where the user can interact. When the keyboard is up, this should be the area above or below the keyboard, wherever there is enough space.
- (CGRect)_contentRectForUserInteraction
{
    // FIXME: handle split keyboard.
    UIEdgeInsets obscuredInsets = _obscuredInsets;
    obscuredInsets.bottom = std::max(_obscuredInsets.bottom, _inputViewBounds.size.height);
    CGRect unobscuredRect = UIEdgeInsetsInsetRect(self.bounds, obscuredInsets);
    return [self convertRect:unobscuredRect toView:self._currentContentView];
}

// Ideally UIScrollView would expose this for us: <rdar://problem/21394567>.
- (BOOL)_scrollViewIsRubberBanding
{
    float deviceScaleFactor = _page->deviceScaleFactor();

    CGPoint contentOffset = [_scrollView contentOffset];
    CGPoint boundedOffset = contentOffsetBoundedInValidRange(_scrollView.get(), contentOffset);
    return !pointsEqualInDevicePixels(contentOffset, boundedOffset, deviceScaleFactor);
}

- (void)_updateVisibleContentRects
{
    if (![self usesStandardContentView]) {
        [_customContentView web_computedContentInsetDidChange];
        return;
    }

    if (_delayUpdateVisibleContentRects) {
        _hadDelayedUpdateVisibleContentRects = YES;
        return;
    }

    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing
        || _needsResetViewStateAfterCommitLoadForMainFrame
        || [_scrollView isZoomBouncing]
        || _currentlyAdjustingScrollViewInsetsForKeyboard)
        return;

    CGRect fullViewRect = self.bounds;
    CGRect visibleRectInContentCoordinates = _frozenVisibleContentRect ? _frozenVisibleContentRect.value() : [self convertRect:fullViewRect toView:_contentView.get()];

    UIEdgeInsets computedContentInsetUnadjustedForKeyboard = [self _computedContentInset];
    if (!_haveSetObscuredInsets)
        computedContentInsetUnadjustedForKeyboard.bottom -= _totalScrollViewBottomInsetAdjustmentForKeyboard;

    CGRect unobscuredRect = UIEdgeInsetsInsetRect(fullViewRect, computedContentInsetUnadjustedForKeyboard);
    CGRect unobscuredRectInContentCoordinates = _frozenUnobscuredContentRect ? _frozenUnobscuredContentRect.value() : [self convertRect:unobscuredRect toView:_contentView.get()];

    CGFloat scaleFactor = contentZoomScale(self);

    BOOL isStableState = !(_isChangingObscuredInsetsInteractively || [_scrollView isDragging] || [_scrollView isDecelerating] || [_scrollView isZooming] || [_scrollView _isAnimatingZoom] || [_scrollView _isScrollingToTop] || [self _scrollViewIsRubberBanding]);

    // FIXME: this can be made static after we stop supporting iOS 8.x.
    if (isStableState && [_scrollView respondsToSelector:@selector(_isInterruptingDeceleration)])
        isStableState = ![_scrollView performSelector:@selector(_isInterruptingDeceleration)];

#if ENABLE(CSS_SCROLL_SNAP) && ENABLE(ASYNC_SCROLLING)
    if (isStableState) {
        WebKit::RemoteScrollingCoordinatorProxy* coordinator = _page->scrollingCoordinatorProxy();
        if (coordinator && coordinator->hasActiveSnapPoint()) {
            CGRect fullViewRect = self.bounds;
            CGRect unobscuredRect = UIEdgeInsetsInsetRect(fullViewRect, computedContentInsetUnadjustedForKeyboard);
            
            CGPoint currentPoint = [_scrollView contentOffset];
            CGPoint activePoint = coordinator->nearestActiveContentInsetAdjustedSnapPoint(unobscuredRect.origin.y, currentPoint);

            if (!CGPointEqualToPoint(activePoint, currentPoint)) {
                RetainPtr<WKScrollView> strongScrollView = _scrollView;
                dispatch_async(dispatch_get_main_queue(), [strongScrollView, activePoint] {
                    [strongScrollView setContentOffset:activePoint animated:NO];
                });
            }
        }
    }
#endif
    
    [_contentView didUpdateVisibleRect:visibleRectInContentCoordinates
        unobscuredRect:unobscuredRectInContentCoordinates
        unobscuredRectInScrollViewCoordinates:unobscuredRect
        scale:scaleFactor minimumScale:[_scrollView minimumZoomScale]
        inStableState:isStableState isChangingObscuredInsetsInteractively:_isChangingObscuredInsetsInteractively];
}

- (void)_didFinishLoadForMainFrame
{
    if (_gestureController)
        _gestureController->didFinishLoadForMainFrame();
}

- (void)_didFailLoadForMainFrame
{
    if (_gestureController)
        _gestureController->didFailLoadForMainFrame();
}

- (void)_didSameDocumentNavigationForMainFrame:(WebKit::SameDocumentNavigationType)navigationType
{
    [_customContentView web_didSameDocumentNavigation:toAPI(navigationType)];

    if (_gestureController)
        _gestureController->didSameDocumentNavigationForMainFrame(navigationType);
}

- (void)_keyboardChangedWithInfo:(NSDictionary *)keyboardInfo adjustScrollView:(BOOL)adjustScrollView
{
    NSValue *endFrameValue = [keyboardInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
    if (!endFrameValue)
        return;

    // The keyboard rect is always in screen coordinates. In the view services case the window does not
    // have the interface orientation rotation transformation; its host does. So, it makes no sense to
    // clip the keyboard rect against its screen.
    if ([[self window] _isHostedInAnotherProcess])
        _inputViewBounds = [self.window convertRect:[endFrameValue CGRectValue] fromWindow:nil];
    else
        _inputViewBounds = [self.window convertRect:CGRectIntersection([endFrameValue CGRectValue], self.window.screen.bounds) fromWindow:nil];

    if (adjustScrollView) {
        CGFloat bottomInsetBeforeAdjustment = [_scrollView contentInset].bottom;
        TemporaryChange<BOOL> insetAdjustmentGuard(_currentlyAdjustingScrollViewInsetsForKeyboard, YES);
        [_scrollView _adjustForAutomaticKeyboardInfo:keyboardInfo animated:YES lastAdjustment:&_lastAdjustmentForScroller];
        CGFloat bottomInsetAfterAdjustment = [_scrollView contentInset].bottom;
        if (bottomInsetBeforeAdjustment != bottomInsetAfterAdjustment)
            _totalScrollViewBottomInsetAdjustmentForKeyboard += bottomInsetAfterAdjustment - bottomInsetBeforeAdjustment;
    }

    [self _updateVisibleContentRects];
}

- (BOOL)_shouldUpdateKeyboardWithInfo:(NSDictionary *)keyboardInfo
{
    if ([_contentView isAssistingNode])
        return YES;

    NSNumber *isLocalKeyboard = [keyboardInfo valueForKey:UIKeyboardIsLocalUserInfoKey];
    return isLocalKeyboard && !isLocalKeyboard.boolValue;
}

- (void)_keyboardWillChangeFrame:(NSNotification *)notification
{
    if ([self _shouldUpdateKeyboardWithInfo:notification.userInfo])
        [self _keyboardChangedWithInfo:notification.userInfo adjustScrollView:YES];
}

- (void)_keyboardDidChangeFrame:(NSNotification *)notification
{
    [self _keyboardChangedWithInfo:notification.userInfo adjustScrollView:NO];
}

- (void)_keyboardWillShow:(NSNotification *)notification
{
    if ([self _shouldUpdateKeyboardWithInfo:notification.userInfo])
        [self _keyboardChangedWithInfo:notification.userInfo adjustScrollView:YES];
}

- (void)_keyboardWillHide:(NSNotification *)notification
{
    // Ignore keyboard will hide notifications sent during rotation. They're just there for
    // backwards compatibility reasons and processing the will hide notification would
    // temporarily screw up the the unobscured view area.
    if ([[UIPeripheralHost sharedInstance] rotationState])
        return;

    [self _keyboardChangedWithInfo:notification.userInfo adjustScrollView:YES];
}

- (void)_windowDidRotate:(NSNotification *)notification
{
    if (!_overridesInterfaceOrientation)
        _page->setDeviceOrientation(deviceOrientation());
}

- (void)_contentSizeCategoryDidChange:(NSNotification *)notification
{
    _page->contentSizeCategoryDidChange([self _contentSizeCategory]);
}

- (NSString *)_contentSizeCategory
{
    return [[UIApplication sharedApplication] preferredContentSizeCategory];
}

- (void)setAllowsBackForwardNavigationGestures:(BOOL)allowsBackForwardNavigationGestures
{
    if (_allowsBackForwardNavigationGestures == allowsBackForwardNavigationGestures)
        return;

    _allowsBackForwardNavigationGestures = allowsBackForwardNavigationGestures;

    if (allowsBackForwardNavigationGestures) {
        if (!_gestureController) {
            _gestureController = std::make_unique<WebKit::ViewGestureController>(*_page);
            _gestureController->installSwipeHandler(self, [self scrollView]);
            _gestureController->setAlternateBackForwardListSourceView([_configuration _alternateWebViewForNavigationGestures]);
        }
    } else
        _gestureController = nullptr;

    _page->setShouldRecordNavigationSnapshots(allowsBackForwardNavigationGestures);
}

- (BOOL)allowsBackForwardNavigationGestures
{
    return _allowsBackForwardNavigationGestures;
}

- (void)_navigationGestureDidBegin
{
    // During a back/forward swipe, there's a view interposed between this view and the content view that has
    // an offset and animation on it, which results in computing incorrect rectangles. Work around by using
    // frozen rects during swipes.
    CGRect fullViewRect = self.bounds;
    CGRect unobscuredRect = UIEdgeInsetsInsetRect(fullViewRect, [self _computedContentInset]);

    _frozenVisibleContentRect = [self convertRect:fullViewRect toView:_contentView.get()];
    _frozenUnobscuredContentRect = [self convertRect:unobscuredRect toView:_contentView.get()];
}

- (void)_navigationGestureDidEnd
{
    _frozenVisibleContentRect = Nullopt;
    _frozenUnobscuredContentRect = Nullopt;
}

#endif // PLATFORM(IOS)

#pragma mark OS X-specific methods

#if PLATFORM(MAC)

- (BOOL)becomeFirstResponder
{
    return [[self window] makeFirstResponder: _wkView.get()];
}

- (BOOL)acceptsFirstResponder
{
    return [_wkView acceptsFirstResponder];
}

- (void)resizeSubviewsWithOldSize:(NSSize)oldSize
{
    [_wkView setFrame:self.bounds];
}

- (void)setAllowsBackForwardNavigationGestures:(BOOL)allowsBackForwardNavigationGestures
{
    [_wkView setAllowsBackForwardNavigationGestures:allowsBackForwardNavigationGestures];
}

- (BOOL)allowsBackForwardNavigationGestures
{
    return [_wkView allowsBackForwardNavigationGestures];
}

- (void)setAllowsMagnification:(BOOL)allowsMagnification
{
    [_wkView setAllowsMagnification:allowsMagnification];
}

- (BOOL)allowsMagnification
{
    return [_wkView allowsMagnification];
}

- (void)setMagnification:(CGFloat)magnification
{
    [_wkView setMagnification:magnification];
}

- (CGFloat)magnification
{
    return [_wkView magnification];
}

- (void)setMagnification:(CGFloat)magnification centeredAtPoint:(CGPoint)point
{
    [_wkView setMagnification:magnification centeredAtPoint:NSPointFromCGPoint(point)];
}

- (BOOL)_ignoresNonWheelEvents
{
    return [_wkView _ignoresNonWheelEvents];
}

- (void)_setIgnoresNonWheelEvents:(BOOL)ignoresNonWheelEvents
{
    [_wkView _setIgnoresNonWheelEvents:ignoresNonWheelEvents];
}

- (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender
{
    return [_wkView draggingEntered:sender];
}

- (NSDragOperation)draggingUpdated:(id <NSDraggingInfo>)sender
{
    return [_wkView draggingUpdated:sender];
}

- (void)draggingExited:(id <NSDraggingInfo>)sender
{
    [_wkView draggingExited:sender];
}

- (BOOL)prepareForDragOperation:(id <NSDraggingInfo>)sender
{
    return [_wkView prepareForDragOperation:sender];
}

- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender
{
    return [_wkView performDragOperation:sender];
}

- (CGSize)intrinsicContentSize
{
    return _intrinsicContentSize;
}

- (void)_setIntrinsicContentSize:(CGSize)intrinsicContentSize
{
    // If the intrinsic content size is less than the minimum layout width, the content flowed to fit,
    // so we can report that that dimension is flexible. If not, we need to report our intrinsic width
    // so that autolayout will know to provide space for us.

    CGSize intrinsicContentSizeAcknowledgingFlexibleWidth = intrinsicContentSize;
    if (intrinsicContentSize.width < _page->minimumLayoutSize().width())
        intrinsicContentSizeAcknowledgingFlexibleWidth.width = NSViewNoInstrinsicMetric;

    _intrinsicContentSize = intrinsicContentSizeAcknowledgingFlexibleWidth;
    [self invalidateIntrinsicContentSize];
}

#endif // PLATFORM(MAC)

@end

@implementation WKWebView (WKPrivate)

- (BOOL)_isEditable
{
    return _page->isEditable();
}

- (void)_setEditable:(BOOL)editable
{
    _page->setEditable(editable);
#if !PLATFORM(IOS)
    [_wkView _addFontPanelObserver];
#endif
}

- (_WKRemoteObjectRegistry *)_remoteObjectRegistry
{
    if (!_remoteObjectRegistry) {
        _remoteObjectRegistry = adoptNS([[_WKRemoteObjectRegistry alloc] _initWithMessageSender:*_page]);
        _page->process().processPool().addMessageReceiver(Messages::RemoteObjectRegistry::messageReceiverName(), _page->pageID(), [_remoteObjectRegistry remoteObjectRegistry]);
    }

    return _remoteObjectRegistry.get();
}

- (WKBrowsingContextHandle *)_handle
{
    return [[[WKBrowsingContextHandle alloc] _initWithPageID:_page->pageID()] autorelease];
}

- (_WKRenderingProgressEvents)_observedRenderingProgressEvents
{
    return _observedRenderingProgressEvents;
}

- (id <WKHistoryDelegatePrivate>)_historyDelegate
{
    return _navigationState->historyDelegate().autorelease();
}

- (void)_setHistoryDelegate:(id <WKHistoryDelegatePrivate>)historyDelegate
{
    _page->setHistoryClient(_navigationState->createHistoryClient());
    _navigationState->setHistoryDelegate(historyDelegate);
}

- (NSURL *)_unreachableURL
{
    return [NSURL _web_URLWithWTFString:_page->pageLoadState().unreachableURL()];
}

- (void)_loadAlternateHTMLString:(NSString *)string baseURL:(NSURL *)baseURL forUnreachableURL:(NSURL *)unreachableURL
{
    _page->loadAlternateHTMLString(string, [baseURL _web_originalDataAsWTFString], [unreachableURL _web_originalDataAsWTFString]);
}

- (WKNavigation *)_loadData:(NSData *)data MIMEType:(NSString *)MIMEType characterEncodingName:(NSString *)characterEncodingName baseURL:(NSURL *)baseURL userData:(id)userData
{
    auto navigation = _page->loadData(API::Data::createWithoutCopying(data).ptr(), MIMEType, characterEncodingName, baseURL.absoluteString, WebKit::ObjCObjectGraph::create(userData).ptr());
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (NSArray *)_certificateChain
{
    if (WebKit::WebFrameProxy* mainFrame = _page->mainFrame())
        return mainFrame->certificateInfo() ? (NSArray *)mainFrame->certificateInfo()->certificateInfo().certificateChain() : nil;

    return nil;
}

- (NSURL *)_committedURL
{
    return [NSURL _web_URLWithWTFString:_page->pageLoadState().url()];
}

- (NSString *)_MIMEType
{
    if (_page->mainFrame())
        return _page->mainFrame()->mimeType();

    return nil;
}

- (NSString *)_userAgent
{
    return _page->userAgent();
}

- (NSString *)_applicationNameForUserAgent
{
    return _page->applicationNameForUserAgent();
}

- (void)_setApplicationNameForUserAgent:(NSString *)applicationNameForUserAgent
{
    _page->setApplicationNameForUserAgent(applicationNameForUserAgent);
}

- (NSString *)_customUserAgent
{
    return self.customUserAgent;
}

- (void)_setCustomUserAgent:(NSString *)customUserAgent
{
    self.customUserAgent = customUserAgent;
}

- (void)_setUserContentExtensionsEnabled:(BOOL)userContentExtensionsEnabled
{
    // This is kept for binary compatibility with iOS 9.
}

- (BOOL)_userContentExtensionsEnabled
{
    // This is kept for binary compatibility with iOS 9.
    return true;
}

- (pid_t)_webProcessIdentifier
{
    return _page->isValid() ? _page->processIdentifier() : 0;
}

- (void)_killWebContentProcess
{
    if (!_page->isValid())
        return;

    _page->process().terminate();
}

- (WKNavigation *)_reloadWithoutContentBlockers
{
    const bool reloadFromOrigin = false;
    const bool contentBlockersEnabled = false;
    auto navigation = _page->reload(reloadFromOrigin, contentBlockersEnabled);
    if (!navigation)
        return nil;
    
    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (void)_killWebContentProcessAndResetState
{
    _page->terminateProcess();
}

#if PLATFORM(IOS)
static WebCore::FloatSize activeMinimumLayoutSize(WKWebView *webView, const CGRect& bounds)
{
    return WebCore::FloatSize(webView->_overridesMinimumLayoutSize ? webView->_minimumLayoutSizeOverride : bounds.size);
}

static WebCore::FloatSize activeMaximumUnobscuredSize(WKWebView *webView, const CGRect& bounds)
{
    return WebCore::FloatSize(webView->_overridesMaximumUnobscuredSize ? webView->_maximumUnobscuredSizeOverride : bounds.size);
}

static int32_t activeOrientation(WKWebView *webView)
{
    return webView->_overridesInterfaceOrientation ? deviceOrientationForUIInterfaceOrientation(webView->_interfaceOrientationOverride) : webView->_page->deviceOrientation();
}

- (void (^)(void))_retainActiveFocusedState
{
    ++_activeFocusedStateRetainCount;

    // FIXME: Use something like CompletionHandlerCallChecker to ensure that the returned block is called before it's released.
    return [[[self] {
        --_activeFocusedStateRetainCount;
    } copy] autorelease];
}

- (void)_becomeFirstResponderWithSelectionMovingForward:(BOOL)selectingForward completionHandler:(void (^)(BOOL didBecomeFirstResponder))completionHandler
{
    typeof(completionHandler) completionHandlerCopy = nil;
    if (completionHandler)
        completionHandlerCopy = Block_copy(completionHandler);

    [_contentView _becomeFirstResponderWithSelectionMovingForward:selectingForward completionHandler:[completionHandlerCopy](BOOL didBecomeFirstResponder) {
        if (!completionHandlerCopy)
            return;

        completionHandlerCopy(didBecomeFirstResponder);
        Block_release(completionHandlerCopy);
    }];
}

- (id)_snapshotLayerContentsForBackForwardListItem:(WKBackForwardListItem *)item
{
    if (_page->backForwardList().currentItem() == &item._item)
        _page->recordNavigationSnapshot(*_page->backForwardList().currentItem());

    if (auto* viewSnapshot = item._item.snapshot())
        return viewSnapshot->asLayerContents();

    return nil;
}

#endif

- (void)_didRelaunchProcess
{
#if PLATFORM(IOS)
    CGRect bounds = self.bounds;
    WebCore::FloatSize minimalLayoutSize = activeMinimumLayoutSize(self, bounds);
    _page->setViewportConfigurationMinimumLayoutSize(minimalLayoutSize);
    _page->setMaximumUnobscuredSize(activeMaximumUnobscuredSize(self, bounds));
#endif
}

- (NSData *)_sessionStateData
{
    WebKit::SessionState sessionState = _page->sessionState();

    // FIXME: This should not use the legacy session state encoder.
    return [wrapper(*WebKit::encodeLegacySessionState(sessionState).release().leakRef()) autorelease];
}

- (_WKSessionState *)_sessionState
{
    return adoptNS([[_WKSessionState alloc] _initWithSessionState:_page->sessionState()]).autorelease();
}

- (void)_restoreFromSessionStateData:(NSData *)sessionStateData
{
    // FIXME: This should not use the legacy session state decoder.
    WebKit::SessionState sessionState;
    if (!WebKit::decodeLegacySessionState(static_cast<const uint8_t*>(sessionStateData.bytes), sessionStateData.length, sessionState))
        return;

    _page->restoreFromSessionState(WTF::move(sessionState), true);
}

- (WKNavigation *)_restoreSessionState:(_WKSessionState *)sessionState andNavigate:(BOOL)navigate
{
    auto navigation = _page->restoreFromSessionState(sessionState->_sessionState, navigate);
    if (!navigation)
        return nil;

    return [wrapper(*navigation.release().leakRef()) autorelease];
}

- (void)_close
{
    _page->close();
}

- (BOOL)_allowsRemoteInspection
{
#if ENABLE(REMOTE_INSPECTOR)
    return _page->allowsRemoteInspection();
#else
    return NO;
#endif
}

- (void)_setAllowsRemoteInspection:(BOOL)allow
{
#if ENABLE(REMOTE_INSPECTOR)
    _page->setAllowsRemoteInspection(allow);
#endif
}

- (BOOL)_addsVisitedLinks
{
    return _page->addsVisitedLinks();
}

- (void)_setAddsVisitedLinks:(BOOL)addsVisitedLinks
{
    _page->setAddsVisitedLinks(addsVisitedLinks);
}

- (BOOL)_networkRequestsInProgress
{
    return _page->pageLoadState().networkRequestsInProgress();
}

static inline WebCore::LayoutMilestones layoutMilestones(_WKRenderingProgressEvents events)
{
    WebCore::LayoutMilestones milestones = 0;

    if (events & _WKRenderingProgressEventFirstLayout)
        milestones |= WebCore::DidFirstLayout;

    if (events & _WKRenderingProgressEventFirstVisuallyNonEmptyLayout)
        milestones |= WebCore::DidFirstVisuallyNonEmptyLayout;

    if (events & _WKRenderingProgressEventFirstPaintWithSignificantArea)
        milestones |= WebCore::DidHitRelevantRepaintedObjectsAreaThreshold;

    if (events & _WKRenderingProgressEventReachedSessionRestorationRenderTreeSizeThreshold)
        milestones |= WebCore::ReachedSessionRestorationRenderTreeSizeThreshold;

    if (events & _WKRenderingProgressEventFirstLayoutAfterSuppressedIncrementalRendering)
        milestones |= WebCore::DidFirstLayoutAfterSuppressedIncrementalRendering;

    if (events & _WKRenderingProgressEventFirstPaintAfterSuppressedIncrementalRendering)
        milestones |= WebCore::DidFirstPaintAfterSuppressedIncrementalRendering;

    return milestones;
}

- (void)_setObservedRenderingProgressEvents:(_WKRenderingProgressEvents)observedRenderingProgressEvents
{
    _observedRenderingProgressEvents = observedRenderingProgressEvents;
    _page->listenForLayoutMilestones(layoutMilestones(observedRenderingProgressEvents));
}

- (void)_getMainResourceDataWithCompletionHandler:(void (^)(NSData *, NSError *))completionHandler
{
    auto handler = adoptNS([completionHandler copy]);

    _page->getMainResourceDataOfFrame(_page->mainFrame(), [handler](API::Data* data, WebKit::CallbackBase::Error error) {
        void (^completionHandlerBlock)(NSData *, NSError *) = (void (^)(NSData *, NSError *))handler.get();
        if (error != WebKit::CallbackBase::Error::None) {
            // FIXME: Pipe a proper error in from the WebPageProxy.
            RetainPtr<NSError> error = adoptNS([[NSError alloc] init]);
            completionHandlerBlock(nil, error.get());
        } else
            completionHandlerBlock(wrapper(*data), nil);
    });
}

- (void)_getWebArchiveDataWithCompletionHandler:(void (^)(NSData *, NSError *))completionHandler
{
    auto handler = adoptNS([completionHandler copy]);

    _page->getWebArchiveOfFrame(_page->mainFrame(), [handler](API::Data* data, WebKit::CallbackBase::Error error) {
        void (^completionHandlerBlock)(NSData *, NSError *) = (void (^)(NSData *, NSError *))handler.get();
        if (error != WebKit::CallbackBase::Error::None) {
            // FIXME: Pipe a proper error in from the WebPageProxy.
            RetainPtr<NSError> error = adoptNS([[NSError alloc] init]);
            completionHandlerBlock(nil, error.get());
        } else
            completionHandlerBlock(wrapper(*data), nil);
    });
}

- (_WKPaginationMode)_paginationMode
{
    switch (_page->paginationMode()) {
    case WebCore::Pagination::Unpaginated:
        return _WKPaginationModeUnpaginated;
    case WebCore::Pagination::LeftToRightPaginated:
        return _WKPaginationModeLeftToRight;
    case WebCore::Pagination::RightToLeftPaginated:
        return _WKPaginationModeRightToLeft;
    case WebCore::Pagination::TopToBottomPaginated:
        return _WKPaginationModeTopToBottom;
    case WebCore::Pagination::BottomToTopPaginated:
        return _WKPaginationModeBottomToTop;
    }

    ASSERT_NOT_REACHED();
    return _WKPaginationModeUnpaginated;
}

- (void)_setPaginationMode:(_WKPaginationMode)paginationMode
{
    WebCore::Pagination::Mode mode;
    switch (paginationMode) {
    case _WKPaginationModeUnpaginated:
        mode = WebCore::Pagination::Unpaginated;
        break;
    case _WKPaginationModeLeftToRight:
        mode = WebCore::Pagination::LeftToRightPaginated;
        break;
    case _WKPaginationModeRightToLeft:
        mode = WebCore::Pagination::RightToLeftPaginated;
        break;
    case _WKPaginationModeTopToBottom:
        mode = WebCore::Pagination::TopToBottomPaginated;
        break;
    case _WKPaginationModeBottomToTop:
        mode = WebCore::Pagination::BottomToTopPaginated;
        break;
    default:
        return;
    }

    _page->setPaginationMode(mode);
}

- (BOOL)_paginationBehavesLikeColumns
{
    return _page->paginationBehavesLikeColumns();
}

- (void)_setPaginationBehavesLikeColumns:(BOOL)behavesLikeColumns
{
    _page->setPaginationBehavesLikeColumns(behavesLikeColumns);
}

- (CGFloat)_pageLength
{
    return _page->pageLength();
}

- (void)_setPageLength:(CGFloat)pageLength
{
    _page->setPageLength(pageLength);
}

- (CGFloat)_gapBetweenPages
{
    return _page->gapBetweenPages();
}

- (void)_setGapBetweenPages:(CGFloat)gapBetweenPages
{
    _page->setGapBetweenPages(gapBetweenPages);
}

- (NSUInteger)_pageCount
{
    return _page->pageCount();
}

- (BOOL)_supportsTextZoom
{
    return _page->supportsTextZoom();
}

- (double)_textZoomFactor
{
    return _page->textZoomFactor();
}

- (void)_setTextZoomFactor:(double)zoomFactor
{
    _page->setTextZoomFactor(zoomFactor);
}

- (double)_pageZoomFactor
{
    return _page->pageZoomFactor();
}

- (void)_setPageZoomFactor:(double)zoomFactor
{
    _page->setPageZoomFactor(zoomFactor);
}

- (id <_WKDiagnosticLoggingDelegate>)_diagnosticLoggingDelegate
{
    return [static_cast<WebKit::DiagnosticLoggingClient&>(_page->diagnosticLoggingClient()).delegate().leakRef() autorelease];
}

- (void)_setDiagnosticLoggingDelegate:(id<_WKDiagnosticLoggingDelegate>)diagnosticLoggingDelegate
{
    static_cast<WebKit::DiagnosticLoggingClient&>(_page->diagnosticLoggingClient()).setDelegate(diagnosticLoggingDelegate);
}

- (id <_WKFindDelegate>)_findDelegate
{
    return [static_cast<WebKit::FindClient&>(_page->findClient()).delegate().leakRef() autorelease];
}

- (void)_setFindDelegate:(id<_WKFindDelegate>)findDelegate
{
    static_cast<WebKit::FindClient&>(_page->findClient()).setDelegate(findDelegate);
}

static inline WebKit::FindOptions toFindOptions(_WKFindOptions wkFindOptions)
{
    unsigned findOptions = 0;

    if (wkFindOptions & _WKFindOptionsCaseInsensitive)
        findOptions |= WebKit::FindOptionsCaseInsensitive;
    if (wkFindOptions & _WKFindOptionsAtWordStarts)
        findOptions |= WebKit::FindOptionsAtWordStarts;
    if (wkFindOptions & _WKFindOptionsTreatMedialCapitalAsWordStart)
        findOptions |= WebKit::FindOptionsTreatMedialCapitalAsWordStart;
    if (wkFindOptions & _WKFindOptionsBackwards)
        findOptions |= WebKit::FindOptionsBackwards;
    if (wkFindOptions & _WKFindOptionsWrapAround)
        findOptions |= WebKit::FindOptionsWrapAround;
    if (wkFindOptions & _WKFindOptionsShowOverlay)
        findOptions |= WebKit::FindOptionsShowOverlay;
    if (wkFindOptions & _WKFindOptionsShowFindIndicator)
        findOptions |= WebKit::FindOptionsShowFindIndicator;
    if (wkFindOptions & _WKFindOptionsShowHighlight)
        findOptions |= WebKit::FindOptionsShowHighlight;
    if (wkFindOptions & _WKFindOptionsDetermineMatchIndex)
        findOptions |= WebKit::FindOptionsDetermineMatchIndex;

    return static_cast<WebKit::FindOptions>(findOptions);
}

- (void)_countStringMatches:(NSString *)string options:(_WKFindOptions)options maxCount:(NSUInteger)maxCount
{
#if PLATFORM(IOS)
    if (_customContentView) {
        [_customContentView web_countStringMatches:string options:options maxCount:maxCount];
        return;
    }
#endif
    _page->countStringMatches(string, toFindOptions(options), maxCount);
}

- (void)_findString:(NSString *)string options:(_WKFindOptions)options maxCount:(NSUInteger)maxCount
{
#if PLATFORM(IOS)
    if (_customContentView) {
        [_customContentView web_findString:string options:options maxCount:maxCount];
        return;
    }
#endif
    _page->findString(string, toFindOptions(options), maxCount);
}

- (void)_hideFindUI
{
#if PLATFORM(IOS)
    if (_customContentView) {
        [_customContentView web_hideFindUI];
        return;
    }
#endif
    _page->hideFindUI();
}

- (void)_saveBackForwardSnapshotForItem:(WKBackForwardListItem *)item
{
    _page->recordNavigationSnapshot(item._item);
}

- (id <_WKInputDelegate>)_inputDelegate
{
    return _inputDelegate.getAutoreleased();
}

- (id <_WKFormDelegate>)_formDelegate
{
    return (id <_WKFormDelegate>)[self _inputDelegate];
}

- (void)_setInputDelegate:(id <_WKInputDelegate>)inputDelegate
{
    _inputDelegate = inputDelegate;

    class FormClient : public API::FormClient {
    public:
        explicit FormClient(WKWebView *webView)
            : m_webView(webView)
        {
        }

        virtual ~FormClient() { }

        virtual void willSubmitForm(WebKit::WebPageProxy&, WebKit::WebFrameProxy&, WebKit::WebFrameProxy& sourceFrame, const Vector<std::pair<WTF::String, WTF::String>>& textFieldValues, API::Object* userData, Ref<WebKit::WebFormSubmissionListenerProxy>&& listener) override
        {
            if (userData && userData->type() != API::Object::Type::Data) {
                ASSERT(!userData || userData->type() == API::Object::Type::Data);
                m_webView->_page->process().connection()->markCurrentlyDispatchedMessageAsInvalid();
                listener->continueSubmission();
                return;
            }

            auto inputDelegate = m_webView->_inputDelegate.get();

            if (![inputDelegate respondsToSelector:@selector(_webView:willSubmitFormValues:userObject:submissionHandler:)]) {
                listener->continueSubmission();
                return;
            }

            auto valueMap = adoptNS([[NSMutableDictionary alloc] initWithCapacity:textFieldValues.size()]);
            for (const auto& pair : textFieldValues)
                [valueMap setObject:pair.second forKey:pair.first];

            NSObject <NSSecureCoding> *userObject = nil;
            if (API::Data* data = static_cast<API::Data*>(userData)) {
                auto nsData = adoptNS([[NSData alloc] initWithBytesNoCopy:const_cast<void*>(static_cast<const void*>(data->bytes())) length:data->size() freeWhenDone:NO]);
                auto unarchiver = adoptNS([[NSKeyedUnarchiver alloc] initForReadingWithData:nsData.get()]);
                [unarchiver setRequiresSecureCoding:YES];
                @try {
                    userObject = [unarchiver decodeObjectOfClass:[NSObject class] forKey:@"userObject"];
                } @catch (NSException *exception) {
                    LOG_ERROR("Failed to decode user data: %@", exception);
                }
            }

            RefPtr<WebKit::WebFormSubmissionListenerProxy> localListener = WTF::move(listener);
            RefPtr<WebKit::CompletionHandlerCallChecker> checker = WebKit::CompletionHandlerCallChecker::create(inputDelegate.get(), @selector(_webView:willSubmitFormValues:userObject:submissionHandler:));
            [inputDelegate _webView:m_webView willSubmitFormValues:valueMap.get() userObject:userObject submissionHandler:[localListener, checker] {
                checker->didCallCompletionHandler();
                localListener->continueSubmission();
            }];
        }

    private:
        WKWebView *m_webView;
    };

    if (inputDelegate)
        _page->setFormClient(std::make_unique<FormClient>(self));
    else
        _page->setFormClient(nullptr);
}

- (void)_setFormDelegate:(id <_WKFormDelegate>)formDelegate
{
    [self _setInputDelegate:(id <_WKInputDelegate>)formDelegate];
}

- (BOOL)_isDisplayingStandaloneImageDocument
{
    if (auto* mainFrame = _page->mainFrame())
        return mainFrame->isDisplayingStandaloneImageDocument();
    return NO;
}

- (BOOL)_isDisplayingStandaloneMediaDocument
{
    if (auto* mainFrame = _page->mainFrame())
        return mainFrame->isDisplayingStandaloneMediaDocument();
    return NO;
}

- (BOOL)_isShowingNavigationGestureSnapshot
{
    return _page->isShowingNavigationGestureSnapshot();
}

- (_WKLayoutMode)_layoutMode
{
#if PLATFORM(MAC)
    switch ([_wkView _layoutMode]) {
    case kWKLayoutModeFixedSize:
        return _WKLayoutModeFixedSize;
    case kWKLayoutModeDynamicSizeComputedFromViewScale:
        return _WKLayoutModeDynamicSizeComputedFromViewScale;
    case kWKLayoutModeDynamicSizeComputedFromMinimumDocumentSize:
        return _WKLayoutModeDynamicSizeComputedFromMinimumDocumentSize;
    case kWKLayoutModeViewSize:
    default:
        return _WKLayoutModeViewSize;
    }
#else
    return _page->useFixedLayout() ? _WKLayoutModeFixedSize : _WKLayoutModeViewSize;
#endif
}

- (void)_setLayoutMode:(_WKLayoutMode)layoutMode
{
#if PLATFORM(MAC)
    WKLayoutMode wkViewLayoutMode;
    switch (layoutMode) {
    case _WKLayoutModeFixedSize:
        wkViewLayoutMode = kWKLayoutModeFixedSize;
        break;
    case _WKLayoutModeDynamicSizeComputedFromViewScale:
        wkViewLayoutMode = kWKLayoutModeDynamicSizeComputedFromViewScale;
        break;
    case _WKLayoutModeDynamicSizeComputedFromMinimumDocumentSize:
        wkViewLayoutMode = kWKLayoutModeDynamicSizeComputedFromMinimumDocumentSize;
        break;
    case _WKLayoutModeViewSize:
    default:
        wkViewLayoutMode = kWKLayoutModeViewSize;
        break;
    }
    [_wkView _setLayoutMode:wkViewLayoutMode];
#else
    _page->setUseFixedLayout(layoutMode == _WKLayoutModeFixedSize || layoutMode == _WKLayoutModeDynamicSizeComputedFromViewScale);
#endif
}

- (CGSize)_fixedLayoutSize
{
    return _page->fixedLayoutSize();
}

- (void)_setFixedLayoutSize:(CGSize)fixedLayoutSize
{
    _page->setFixedLayoutSize(WebCore::expandedIntSize(WebCore::FloatSize(fixedLayoutSize)));
}

- (CGFloat)_viewScale
{
    return _page->viewScaleFactor();
}

- (void)_setViewScale:(CGFloat)viewScale
{
#if PLATFORM(MAC)
    [_wkView _setViewScale:viewScale];
#else
    if (viewScale <= 0 || isnan(viewScale) || isinf(viewScale))
        [NSException raise:NSInvalidArgumentException format:@"View scale should be a positive number"];

    _page->scaleView(viewScale);
#endif
}

#pragma mark scrollperf methods

- (void)_setScrollPerformanceDataCollectionEnabled:(BOOL)enabled
{
    _page->setScrollPerformanceDataCollectionEnabled(enabled);
}

- (BOOL)_scrollPerformanceDataCollectionEnabled
{
    return _page->scrollPerformanceDataCollectionEnabled();
}

- (NSArray *)_scrollPerformanceData
{
#if PLATFORM(IOS)
    if (WebKit::RemoteLayerTreeScrollingPerformanceData* scrollPerfData = _page->scrollingPerformanceData())
        return scrollPerfData->data();
#endif
    return nil;
}

#pragma mark media playback restrictions

- (BOOL)_allowsMediaDocumentInlinePlayback
{
#if PLATFORM(IOS)
    return _page->allowsMediaDocumentInlinePlayback();
#else
    return NO;
#endif
}

- (void)_setAllowsMediaDocumentInlinePlayback:(BOOL)flag
{
#if PLATFORM(IOS)
    _page->setAllowsMediaDocumentInlinePlayback(flag);
#endif
}

#pragma mark iOS-specific methods

#if PLATFORM(IOS)

- (CGSize)_minimumLayoutSizeOverride
{
    ASSERT(_overridesMinimumLayoutSize);
    return _minimumLayoutSizeOverride;
}

- (void)_setMinimumLayoutSizeOverride:(CGSize)minimumLayoutSizeOverride
{
    _overridesMinimumLayoutSize = YES;
    if (CGSizeEqualToSize(_minimumLayoutSizeOverride, minimumLayoutSizeOverride))
        return;

    _minimumLayoutSizeOverride = minimumLayoutSizeOverride;
    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::NotResizing)
        _page->setViewportConfigurationMinimumLayoutSize(WebCore::FloatSize(minimumLayoutSizeOverride));
}

- (UIEdgeInsets)_obscuredInsets
{
    return _obscuredInsets;
}

- (void)_setObscuredInsets:(UIEdgeInsets)obscuredInsets
{
    ASSERT(obscuredInsets.top >= 0);
    ASSERT(obscuredInsets.left >= 0);
    ASSERT(obscuredInsets.bottom >= 0);
    ASSERT(obscuredInsets.right >= 0);
    
    _haveSetObscuredInsets = YES;

    if (UIEdgeInsetsEqualToEdgeInsets(_obscuredInsets, obscuredInsets))
        return;

    _obscuredInsets = obscuredInsets;

    [self _updateVisibleContentRects];
}

- (void)_setInterfaceOrientationOverride:(UIInterfaceOrientation)interfaceOrientation
{
    if (!_overridesInterfaceOrientation)
        [[NSNotificationCenter defaultCenter] removeObserver:self name:UIWindowDidRotateNotification object:nil];

    _overridesInterfaceOrientation = YES;

    if (interfaceOrientation == _interfaceOrientationOverride)
        return;

    _interfaceOrientationOverride = interfaceOrientation;

    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::NotResizing)
        _page->setDeviceOrientation(deviceOrientationForUIInterfaceOrientation(_interfaceOrientationOverride));
}

- (UIInterfaceOrientation)_interfaceOrientationOverride
{
    ASSERT(_overridesInterfaceOrientation);
    return _interfaceOrientationOverride;
}

- (CGSize)_maximumUnobscuredSizeOverride
{
    ASSERT(_overridesMaximumUnobscuredSize);
    return _maximumUnobscuredSizeOverride;
}

- (void)_setMaximumUnobscuredSizeOverride:(CGSize)size
{
    ASSERT(size.width <= self.bounds.size.width && size.height <= self.bounds.size.height);
    _overridesMaximumUnobscuredSize = YES;
    if (CGSizeEqualToSize(_maximumUnobscuredSizeOverride, size))
        return;

    _maximumUnobscuredSizeOverride = size;
    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::NotResizing)
        _page->setMaximumUnobscuredSize(WebCore::FloatSize(size));
}

- (void)_setBackgroundExtendsBeyondPage:(BOOL)backgroundExtends
{
    _page->setBackgroundExtendsBeyondPage(backgroundExtends);
}

- (BOOL)_backgroundExtendsBeyondPage
{
    return _page->backgroundExtendsBeyondPage();
}

- (void)_beginInteractiveObscuredInsetsChange
{
    ASSERT(!_isChangingObscuredInsetsInteractively);
    _isChangingObscuredInsetsInteractively = YES;
}

- (void)_endInteractiveObscuredInsetsChange
{
    ASSERT(_isChangingObscuredInsetsInteractively);
    _isChangingObscuredInsetsInteractively = NO;
    [self _updateVisibleContentRects];
}

- (void)_hideContentUntilNextUpdate
{
    if (auto* area = _page->drawingArea())
        area->hideContentUntilAnyUpdate();
}

- (void)_beginAnimatedResizeWithUpdates:(void (^)(void))updateBlock
{
    CGRect oldBounds = self.bounds;
    WebCore::FloatRect oldUnobscuredContentRect = _page->unobscuredContentRect();

    if (_customContentView || !_hasCommittedLoadForMainFrame || CGRectIsEmpty(oldBounds) || oldUnobscuredContentRect.isEmpty()) {
        updateBlock();
        return;
    }

    _dynamicViewportUpdateMode = DynamicViewportUpdateMode::ResizingWithAnimation;

    WebCore::FloatSize oldMinimumLayoutSize = activeMinimumLayoutSize(self, oldBounds);
    WebCore::FloatSize oldMaximumUnobscuredSize = activeMaximumUnobscuredSize(self, oldBounds);
    int32_t oldOrientation = activeOrientation(self);
    UIEdgeInsets oldObscuredInsets = _obscuredInsets;

    updateBlock();

    CGRect newBounds = self.bounds;
    WebCore::FloatSize newMinimumLayoutSize = activeMinimumLayoutSize(self, newBounds);
    WebCore::FloatSize newMaximumUnobscuredSize = activeMaximumUnobscuredSize(self, newBounds);
    int32_t newOrientation = activeOrientation(self);
    UIEdgeInsets newObscuredInsets = _obscuredInsets;
    CGRect futureUnobscuredRectInSelfCoordinates = UIEdgeInsetsInsetRect(newBounds, _obscuredInsets);
    CGRect contentViewBounds = [_contentView bounds];

    ASSERT_WITH_MESSAGE(!(_overridesMinimumLayoutSize && newMinimumLayoutSize.isEmpty()), "Clients controlling the layout size should maintain a valid layout size to minimize layouts.");
    if (CGRectIsEmpty(newBounds) || newMinimumLayoutSize.isEmpty() || CGRectIsEmpty(futureUnobscuredRectInSelfCoordinates) || CGRectIsEmpty(contentViewBounds)) {
        _dynamicViewportUpdateMode = DynamicViewportUpdateMode::NotResizing;
        [self _frameOrBoundsChanged];
        if (_overridesMinimumLayoutSize)
            _page->setViewportConfigurationMinimumLayoutSize(WebCore::FloatSize(newMinimumLayoutSize));
        if (_overridesMaximumUnobscuredSize)
            _page->setMaximumUnobscuredSize(WebCore::FloatSize(newMaximumUnobscuredSize));
        if (_overridesInterfaceOrientation)
            _page->setDeviceOrientation(newOrientation);
        [self _updateVisibleContentRects];
        return;
    }

    if (CGRectEqualToRect(oldBounds, newBounds)
        && oldMinimumLayoutSize == newMinimumLayoutSize
        && oldMaximumUnobscuredSize == newMaximumUnobscuredSize
        && oldOrientation == newOrientation
        && UIEdgeInsetsEqualToEdgeInsets(oldObscuredInsets, newObscuredInsets)) {
        _dynamicViewportUpdateMode = DynamicViewportUpdateMode::NotResizing;
        [self _updateVisibleContentRects];
        return;
    }

    _resizeAnimationTransformAdjustments = CATransform3DIdentity;

    NSUInteger indexOfContentView = [[_scrollView subviews] indexOfObject:_contentView.get()];
    _resizeAnimationView = adoptNS([[UIView alloc] init]);
    [_scrollView insertSubview:_resizeAnimationView.get() atIndex:indexOfContentView];
    [_resizeAnimationView addSubview:_contentView.get()];
    [_resizeAnimationView addSubview:[_contentView unscaledView]];

    CGSize contentSizeInContentViewCoordinates = contentViewBounds.size;
    [_scrollView setMinimumZoomScale:std::min(newMinimumLayoutSize.width() / contentSizeInContentViewCoordinates.width, [_scrollView minimumZoomScale])];
    [_scrollView setMaximumZoomScale:std::max(newMinimumLayoutSize.width() / contentSizeInContentViewCoordinates.width, [_scrollView maximumZoomScale])];

    // Compute the new scale to keep the current content width in the scrollview.
    CGFloat oldWebViewWidthInContentViewCoordinates = oldUnobscuredContentRect.width();
    CGFloat visibleContentViewWidthInContentCoordinates = std::min(contentSizeInContentViewCoordinates.width, oldWebViewWidthInContentViewCoordinates);
    CGFloat targetScale = newMinimumLayoutSize.width() / visibleContentViewWidthInContentCoordinates;
    CGFloat resizeAnimationViewAnimationScale = targetScale / contentZoomScale(self);
    [_resizeAnimationView setTransform:CGAffineTransformMakeScale(resizeAnimationViewAnimationScale, resizeAnimationViewAnimationScale)];

    // Compute a new position to keep the content centered.
    CGPoint originalContentCenter = oldUnobscuredContentRect.center();
    CGPoint originalContentCenterInSelfCoordinates = [self convertPoint:originalContentCenter fromView:_contentView.get()];
    CGPoint futureUnobscuredRectCenterInSelfCoordinates = CGPointMake(futureUnobscuredRectInSelfCoordinates.origin.x + futureUnobscuredRectInSelfCoordinates.size.width / 2, futureUnobscuredRectInSelfCoordinates.origin.y + futureUnobscuredRectInSelfCoordinates.size.height / 2);

    CGPoint originalContentOffset = [_scrollView contentOffset];
    CGPoint contentOffset = originalContentOffset;
    contentOffset.x += (originalContentCenterInSelfCoordinates.x - futureUnobscuredRectCenterInSelfCoordinates.x);
    contentOffset.y += (originalContentCenterInSelfCoordinates.y - futureUnobscuredRectCenterInSelfCoordinates.y);

    // Limit the new offset within the scrollview, we do not want to rubber band programmatically.
    CGSize futureContentSizeInSelfCoordinates = CGSizeMake(contentSizeInContentViewCoordinates.width * targetScale, contentSizeInContentViewCoordinates.height * targetScale);
    CGFloat maxHorizontalOffset = futureContentSizeInSelfCoordinates.width - newBounds.size.width + _obscuredInsets.right;
    contentOffset.x = std::min(contentOffset.x, maxHorizontalOffset);
    CGFloat maxVerticalOffset = futureContentSizeInSelfCoordinates.height - newBounds.size.height + _obscuredInsets.bottom;
    contentOffset.y = std::min(contentOffset.y, maxVerticalOffset);

    contentOffset.x = std::max(contentOffset.x, -_obscuredInsets.left);
    contentOffset.y = std::max(contentOffset.y, -_obscuredInsets.top);

    // Make the top/bottom edges "sticky" within 1 pixel.
    if (oldUnobscuredContentRect.maxY() > contentSizeInContentViewCoordinates.height - 1)
        contentOffset.y = maxVerticalOffset;
    if (oldUnobscuredContentRect.y() < 1)
        contentOffset.y = -_obscuredInsets.top;

    // FIXME: if we have content centered after double tap to zoom, we should also try to keep that rect in view.
    [_scrollView setContentSize:roundScrollViewContentSize(*_page, futureContentSizeInSelfCoordinates)];
    [_scrollView setContentOffset:contentOffset];

    CGRect visibleRectInContentCoordinates = [self convertRect:newBounds toView:_contentView.get()];
    CGRect unobscuredRectInContentCoordinates = [self convertRect:futureUnobscuredRectInSelfCoordinates toView:_contentView.get()];

    _page->dynamicViewportSizeUpdate(newMinimumLayoutSize, newMaximumUnobscuredSize, visibleRectInContentCoordinates, unobscuredRectInContentCoordinates, futureUnobscuredRectInSelfCoordinates, targetScale, newOrientation);
    if (WebKit::DrawingAreaProxy* drawingArea = _page->drawingArea())
        drawingArea->setSize(WebCore::IntSize(newBounds.size), WebCore::IntSize(), WebCore::IntSize());
}

- (void)_endAnimatedResize
{
    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::NotResizing)
        return;

    _page->synchronizeDynamicViewportUpdate();

    NSUInteger indexOfResizeAnimationView = [[_scrollView subviews] indexOfObject:_resizeAnimationView.get()];
    [_scrollView insertSubview:_contentView.get() atIndex:indexOfResizeAnimationView];
    [_scrollView insertSubview:[_contentView unscaledView] atIndex:indexOfResizeAnimationView + 1];

    CALayer *contentViewLayer = [_contentView layer];
    CGFloat adjustmentScale = _resizeAnimationTransformAdjustments.m11;
    contentViewLayer.sublayerTransform = CATransform3DIdentity;

    CGFloat animatingScaleTarget = [[_resizeAnimationView layer] transform].m11;
    CALayer *contentLayer = [_contentView layer];
    CATransform3D contentLayerTransform = contentLayer.transform;
    CGFloat currentScale = [[_resizeAnimationView layer] transform].m11 * contentLayerTransform.m11;

    // We cannot use [UIScrollView setZoomScale:] directly because the UIScrollView delegate would get a callback with
    // an invalid contentOffset. The real content offset is only set below.
    // Since there is no public API for setting both the zoomScale and the contentOffset, we set the zoomScale manually
    // on the zoom layer and then only change the contentOffset.
    CGFloat adjustedScale = adjustmentScale * currentScale;
    contentLayerTransform.m11 = adjustedScale;
    contentLayerTransform.m22 = adjustedScale;
    contentLayer.transform = contentLayerTransform;

    CGPoint currentScrollOffset = [_scrollView contentOffset];
    double horizontalScrollAdjustement = _resizeAnimationTransformAdjustments.m41 * animatingScaleTarget;
    double verticalScrollAdjustment = _resizeAnimationTransformAdjustments.m42 * animatingScaleTarget;

    [_scrollView setContentSize:roundScrollViewContentSize(*_page, [_contentView frame].size)];
    [_scrollView setContentOffset:CGPointMake(currentScrollOffset.x - horizontalScrollAdjustement, currentScrollOffset.y - verticalScrollAdjustment)];

    [_resizeAnimationView removeFromSuperview];
    _resizeAnimationView = nil;
    _resizeAnimationTransformAdjustments = CATransform3DIdentity;

    _dynamicViewportUpdateMode = DynamicViewportUpdateMode::NotResizing;
    [_contentView setHidden:NO];
    [self _updateVisibleContentRects];

    while (!_snapshotsDeferredDuringResize.isEmpty())
        _snapshotsDeferredDuringResize.takeLast()();
}

- (void)_resizeWhileHidingContentWithUpdates:(void (^)(void))updateBlock
{
    [self _beginAnimatedResizeWithUpdates:updateBlock];
    if (_dynamicViewportUpdateMode == DynamicViewportUpdateMode::ResizingWithAnimation) {
        [_contentView setHidden:YES];
        _dynamicViewportUpdateMode = DynamicViewportUpdateMode::ResizingWithDocumentHidden;
    }
}

- (void)_setOverlaidAccessoryViewsInset:(CGSize)inset
{
    [_customContentView web_setOverlaidAccessoryViewsInset:inset];
}

- (void)_snapshotRect:(CGRect)rectInViewCoordinates intoImageOfWidth:(CGFloat)imageWidth completionHandler:(void(^)(CGImageRef))completionHandler
{
    if (_dynamicViewportUpdateMode != DynamicViewportUpdateMode::NotResizing) {
        // Defer snapshotting until after the current resize completes.
        void (^copiedCompletionHandler)(CGImageRef) = [completionHandler copy];
        RetainPtr<WKWebView> retainedSelf = self;
        _snapshotsDeferredDuringResize.append([retainedSelf, rectInViewCoordinates, imageWidth, copiedCompletionHandler] {
            [retainedSelf _snapshotRect:rectInViewCoordinates intoImageOfWidth:imageWidth completionHandler:copiedCompletionHandler];
            [copiedCompletionHandler release];
        });
        return;
    }

    CGRect snapshotRectInContentCoordinates = [self convertRect:rectInViewCoordinates toView:self._currentContentView];
    CGFloat imageScale = imageWidth / snapshotRectInContentCoordinates.size.width;
    CGFloat imageHeight = imageScale * snapshotRectInContentCoordinates.size.height;
    CGSize imageSize = CGSizeMake(imageWidth, imageHeight);

#if USE(IOSURFACE)
    // If we are parented and thus won't incur a significant penalty from paging in tiles, snapshot the view hierarchy directly.
    if (CADisplay *display = self.window.screen._display) {
        auto surface = WebCore::IOSurface::create(WebCore::expandedIntSize(WebCore::FloatSize(imageSize)), WebCore::ColorSpaceDeviceRGB);
        CGFloat imageScaleInViewCoordinates = imageWidth / rectInViewCoordinates.size.width;
        CATransform3D transform = CATransform3DMakeScale(imageScaleInViewCoordinates, imageScaleInViewCoordinates, 1);
        transform = CATransform3DTranslate(transform, -rectInViewCoordinates.origin.x, -rectInViewCoordinates.origin.y, 0);
        CARenderServerRenderDisplayLayerWithTransformAndTimeOffset(MACH_PORT_NULL, (CFStringRef)display.name, self.layer.context.contextId, reinterpret_cast<uint64_t>(self.layer), surface->surface(), 0, 0, &transform, 0);
        completionHandler(surface->createImage().get());
        return;
    }
#endif
    
    if (_customContentView) {
        UIGraphicsBeginImageContextWithOptions(imageSize, YES, 1);

        UIView *customContentView = _customContentView.get();
        [customContentView.backgroundColor set];
        UIRectFill(CGRectMake(0, 0, imageWidth, imageHeight));

        CGContextRef context = UIGraphicsGetCurrentContext();
        CGContextTranslateCTM(context, -snapshotRectInContentCoordinates.origin.x * imageScale, -snapshotRectInContentCoordinates.origin.y * imageScale);
        CGContextScaleCTM(context, imageScale, imageScale);
        [customContentView.layer renderInContext:context];

        completionHandler([UIGraphicsGetImageFromCurrentImageContext() CGImage]);

        UIGraphicsEndImageContext();
        return;
    }

    void(^copiedCompletionHandler)(CGImageRef) = [completionHandler copy];
    _page->takeSnapshot(WebCore::enclosingIntRect(snapshotRectInContentCoordinates), WebCore::expandedIntSize(WebCore::FloatSize(imageSize)), WebKit::SnapshotOptionsExcludeDeviceScaleFactor, [=](const WebKit::ShareableBitmap::Handle& imageHandle, WebKit::CallbackBase::Error) {
        if (imageHandle.isNull()) {
            copiedCompletionHandler(nullptr);
            [copiedCompletionHandler release];
            return;
        }

        RefPtr<WebKit::ShareableBitmap> bitmap = WebKit::ShareableBitmap::create(imageHandle, WebKit::SharedMemory::Protection::ReadOnly);

        if (!bitmap) {
            copiedCompletionHandler(nullptr);
            [copiedCompletionHandler release];
            return;
        }

        RetainPtr<CGImageRef> cgImage;
        cgImage = bitmap->makeCGImage();
        copiedCompletionHandler(cgImage.get());
        [copiedCompletionHandler release];
    });
}

- (void)_overrideLayoutParametersWithMinimumLayoutSize:(CGSize)minimumLayoutSize minimumLayoutSizeForMinimalUI:(CGSize)minimumLayoutSizeForMinimalUI maximumUnobscuredSizeOverride:(CGSize)maximumUnobscuredSizeOverride
{
    UNUSED_PARAM(minimumLayoutSizeForMinimalUI);
    [self _overrideLayoutParametersWithMinimumLayoutSize:minimumLayoutSize maximumUnobscuredSizeOverride:maximumUnobscuredSizeOverride];
}

- (void)_overrideLayoutParametersWithMinimumLayoutSize:(CGSize)minimumLayoutSize maximumUnobscuredSizeOverride:(CGSize)maximumUnobscuredSizeOverride
{
    [self _setMinimumLayoutSizeOverride:minimumLayoutSize];
    [self _setMaximumUnobscuredSizeOverride:maximumUnobscuredSizeOverride];
}

- (UIView *)_viewForFindUI
{
    return [self viewForZoomingInScrollView:[self scrollView]];
}

- (BOOL)_isDisplayingPDF
{
    return [_customContentView isKindOfClass:[WKPDFView class]];
}

- (NSData *)_dataForDisplayedPDF
{
    if (![self _isDisplayingPDF])
        return nil;
    CGPDFDocumentRef pdfDocument = [(WKPDFView *)_customContentView pdfDocument];
    return [(NSData *)CGDataProviderCopyData(CGPDFDocumentGetDataProvider(pdfDocument)) autorelease];
}

- (NSString *)_suggestedFilenameForDisplayedPDF
{
    if (![self _isDisplayingPDF])
        return nil;
    return [(WKPDFView *)_customContentView.get() suggestedFilename];
}

- (BOOL)_allowsDoubleTapGestures
{
    if (_fastClickingIsDisabled)
        return YES;

    // If the page is not user scalable, we don't allow double tap gestures.
    if (![_scrollView isZoomEnabled] || [_scrollView minimumZoomScale] >= [_scrollView maximumZoomScale])
        return NO;

    // For scalable viewports, only disable double tap gestures if the viewport width is device width.
    if (_viewportMetaTagWidth != WebCore::ViewportArguments::ValueDeviceWidth)
        return YES;

    return !areEssentiallyEqualAsFloat(contentZoomScale(self), _initialScaleFactor);
}

- (_WKWebViewPrintFormatter *)_webViewPrintFormatter
{
    UIViewPrintFormatter *viewPrintFormatter = self.viewPrintFormatter;
    ASSERT([viewPrintFormatter isKindOfClass:[_WKWebViewPrintFormatter class]]);
    return (_WKWebViewPrintFormatter *)viewPrintFormatter;
}

#else // #if PLATFORM(IOS)

#pragma mark - OS X-specific methods

- (NSColor *)_pageExtendedBackgroundColor
{
    WebCore::Color color = _page->pageExtendedBackgroundColor();
    if (!color.isValid())
        return nil;

    return nsColor(color);
}

- (BOOL)_drawsTransparentBackground
{
    return _page->drawsTransparentBackground();
}

- (void)_setDrawsTransparentBackground:(BOOL)drawsTransparentBackground
{
    _page->setDrawsTransparentBackground(drawsTransparentBackground);
}

- (void)_setOverrideDeviceScaleFactor:(CGFloat)deviceScaleFactor
{
    [_wkView _setOverrideDeviceScaleFactor:deviceScaleFactor];
}

- (CGFloat)_overrideDeviceScaleFactor
{
    return [_wkView _overrideDeviceScaleFactor];
}

- (id)_immediateActionAnimationControllerForHitTestResult:(_WKHitTestResult *)hitTestResult withType:(_WKImmediateActionType)type userData:(id<NSSecureCoding>)userData
{
    return nil;
}

- (void)_setTopContentInset:(CGFloat)contentInset
{
    [_wkView _setTopContentInset:contentInset];
}

- (CGFloat)_topContentInset
{
    return [_wkView _topContentInset];
}

- (BOOL)_windowOcclusionDetectionEnabled
{
    return [_wkView windowOcclusionDetectionEnabled];
}

- (void)_setWindowOcclusionDetectionEnabled:(BOOL)flag
{
    [_wkView setWindowOcclusionDetectionEnabled:flag];
}

#if __MAC_OS_X_VERSION_MIN_REQUIRED >= 101000

- (void)_setAutomaticallyAdjustsContentInsets:(BOOL)automaticallyAdjustsContentInsets
{
    [_wkView _setAutomaticallyAdjustsContentInsets:automaticallyAdjustsContentInsets];
}

- (BOOL)_automaticallyAdjustsContentInsets
{
    return [_wkView _automaticallyAdjustsContentInsets];
}

#endif // __MAC_OS_X_VERSION_MIN_REQUIRED >= 101000

- (CGFloat)_minimumLayoutWidth
{
    return _page->minimumLayoutSize().width();
}

- (void)_setMinimumLayoutWidth:(CGFloat)width
{
    BOOL expandsToFit = width > 0;

    _page->setMinimumLayoutSize(WebCore::IntSize(width, 0));
    _page->setMainFrameIsScrollable(!expandsToFit);

    [_wkView setShouldClipToVisibleRect:expandsToFit];
}

#endif

@end


@implementation WKWebView (WKTesting)

#if PLATFORM(IOS)

- (CGRect)_contentVisibleRect
{
    return [self convertRect:[self bounds] toView:self._currentContentView];
}

- (CGPoint)_convertPointFromContentsToView:(CGPoint)point
{
    return [self convertPoint:point fromView:self._currentContentView];
}

- (CGPoint)_convertPointFromViewToContents:(CGPoint)point
{
    return [self convertPoint:point toView:self._currentContentView];
}

#endif // PLATFORM(IOS)

// Execute the supplied block after the next transaction from the WebProcess.
- (void)_doAfterNextPresentationUpdate:(void (^)(void))updateBlock
{
    void (^updateBlockCopy)(void) = nil;
    if (updateBlock)
        updateBlockCopy = Block_copy(updateBlock);

    _page->callAfterNextPresentationUpdate([updateBlockCopy](WebKit::CallbackBase::Error error) {
        if (updateBlockCopy) {
            updateBlockCopy();
            Block_release(updateBlockCopy);
        }
    });
}

@end


#if PLATFORM(MAC)

@implementation WKWebView (WKIBActions)

- (BOOL)validateUserInterfaceItem:(id <NSValidatedUserInterfaceItem>)item
{
    SEL action = item.action;

    if (action == @selector(goBack:))
        return !!_page->backForwardList().backItem();

    if (action == @selector(goForward:))
        return !!_page->backForwardList().forwardItem();

    if (action == @selector(stopLoading:)) {
        // FIXME: Return no if we're stopped.
        return YES;
    }

    if (action == @selector(reload:) || action == @selector(reloadFromOrigin:)) {
        // FIXME: Return no if we're loading.
        return YES;
    }

    return NO;
}

- (IBAction)goBack:(id)sender
{
    [self goBack];
}

- (IBAction)goForward:(id)sender
{
    [self goForward];
}

- (IBAction)reload:(id)sender
{
    [self reload];
}

- (IBAction)reloadFromOrigin:(id)sender
{
    [self reloadFromOrigin];
}

- (IBAction)stopLoading:(id)sender
{
    _page->stopLoading();
}

@end

#endif // PLATFORM(MAC)

#if PLATFORM(IOS)
@implementation WKWebView (_WKWebViewPrintFormatter)

- (Class)_printFormatterClass
{
    return [_WKWebViewPrintFormatter class];
}

- (NSInteger)_computePageCountAndStartDrawingToPDFForFrame:(_WKFrameHandle *)frame printInfo:(const WebKit::PrintInfo&)printInfo firstPage:(uint32_t)firstPage computedTotalScaleFactor:(double&)totalScaleFactor
{
    if ([self _isDisplayingPDF])
        return CGPDFDocumentGetNumberOfPages([(WKPDFView *)_customContentView pdfDocument]);

    _pageIsPrintingToPDF = YES;
    Vector<WebCore::IntRect> pageRects;
    uint64_t frameID = frame ? frame._frameID : _page->mainFrame()->frameID();
    if (!_page->sendSync(Messages::WebPage::ComputePagesForPrintingAndStartDrawingToPDF(frameID, printInfo, firstPage), Messages::WebPage::ComputePagesForPrintingAndStartDrawingToPDF::Reply(pageRects, totalScaleFactor)))
        return 0;
    return pageRects.size();
}

- (void)_endPrinting
{
    _pageIsPrintingToPDF = NO;
    _printedDocument = nullptr;
    _page->send(Messages::WebPage::EndPrinting());
}

// FIXME: milliseconds::max() overflows when converted to nanoseconds, causing condition_variable::wait_for() to believe
// a timeout occurred on any spurious wakeup. Use nanoseconds::max() (converted to ms) to avoid this. We should perhaps
// change waitForAndDispatchImmediately() to take nanoseconds to avoid this issue.
static constexpr std::chrono::milliseconds didFinishLoadingTimeout = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::nanoseconds::max());

- (CGPDFDocumentRef)_printedDocument
{
    if ([self _isDisplayingPDF]) {
        ASSERT(!_pageIsPrintingToPDF);
        return [(WKPDFView *)_customContentView pdfDocument];
    }

    if (_pageIsPrintingToPDF) {
        if (!_page->process().connection()->waitForAndDispatchImmediately<Messages::WebPageProxy::DidFinishDrawingPagesToPDF>(_page->pageID(), didFinishLoadingTimeout)) {
            ASSERT_NOT_REACHED();
            return nullptr;
        }
        ASSERT(!_pageIsPrintingToPDF);
    }
    return _printedDocument.get();
}

- (void)_setPrintedDocument:(CGPDFDocumentRef)printedDocument
{
    if (!_pageIsPrintingToPDF)
        return;
    ASSERT(![self _isDisplayingPDF]);
    _printedDocument = printedDocument;
    _pageIsPrintingToPDF = NO;
}

@end
#endif

#endif // WK_API_ENABLED