Source/WebKit2/UIProcess/ios/ViewGestureControllerIOS.mm - WebKit - Git at Google

 /*
  * Copyright (C) 2013, 2014 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 "ViewGestureController.h"

 #if PLATFORM(IOS)

 #import "DrawingAreaProxy.h"
 #import "UIKitSPI.h"
 #import "ViewGestureControllerMessages.h"
 #import "ViewGestureGeometryCollectorMessages.h"
 #import "ViewSnapshotStore.h"
 #import "WKBackForwardListItemInternal.h"
 #import "WKWebViewInternal.h"
 #import "WeakObjCPtr.h"
 #import "WebBackForwardList.h"
 #import "WebPageGroup.h"
 #import "WebPageMessages.h"
 #import "WebPageProxy.h"
 #import "WebProcessProxy.h"
 #import <UIKit/UIScreenEdgePanGestureRecognizer.h>
 #import <WebCore/IOSurface.h>
 #import <WebCore/QuartzCoreSPI.h>

 using namespace WebCore;

 @interface WKSwipeTransitionController : NSObject <_UINavigationInteractiveTransitionBaseDelegate>
 - (instancetype)initWithViewGestureController:(WebKit::ViewGestureController*)gestureController gestureRecognizerView:(UIView *)gestureRecognizerView;
 - (void)invalidate;
 @end

 @interface _UIViewControllerTransitionContext (WKDetails)
 @property (nonatomic, copy, setter=_setInteractiveUpdateHandler:)  void (^_interactiveUpdateHandler)(BOOL interactionIsOver, CGFloat percentComplete, BOOL transitionCompleted, _UIViewControllerTransitionContext *);
 @end

 @implementation WKSwipeTransitionController
 {
     WebKit::ViewGestureController *_gestureController;
     RetainPtr<_UINavigationInteractiveTransitionBase> _backTransitionController;
     RetainPtr<_UINavigationInteractiveTransitionBase> _forwardTransitionController;
     WebKit::WeakObjCPtr<UIView> _gestureRecognizerView;
 }

 static const float swipeSnapshotRemovalRenderTreeSizeTargetFraction = 0.5;

 - (instancetype)initWithViewGestureController:(WebKit::ViewGestureController*)gestureController gestureRecognizerView:(UIView *)gestureRecognizerView
 {
     self = [super init];
     if (self) {
         _gestureController = gestureController;
         _gestureRecognizerView = gestureRecognizerView;

         _backTransitionController = adoptNS([_UINavigationInteractiveTransitionBase alloc]);
         _backTransitionController = [_backTransitionController initWithGestureRecognizerView:gestureRecognizerView animator:nil delegate:self];

         _forwardTransitionController = adoptNS([_UINavigationInteractiveTransitionBase alloc]);
         _forwardTransitionController = [_forwardTransitionController initWithGestureRecognizerView:gestureRecognizerView animator:nil delegate:self];
         [_forwardTransitionController setShouldReverseTranslation:YES];
     }
     return self;
 }

 - (void)invalidate
 {
     _gestureController = nullptr;
 }

 - (WebKit::ViewGestureController::SwipeDirection)directionForTransition:(_UINavigationInteractiveTransitionBase *)transition
 {
     return transition == _backTransitionController ? WebKit::ViewGestureController::SwipeDirection::Back : WebKit::ViewGestureController::SwipeDirection::Forward;
 }

 - (void)startInteractiveTransition:(_UINavigationInteractiveTransitionBase *)transition
 {
     _gestureController->beginSwipeGesture(transition, [self directionForTransition:transition]);
 }

 - (BOOL)shouldBeginInteractiveTransition:(_UINavigationInteractiveTransitionBase *)transition
 {
     return _gestureController->canSwipeInDirection([self directionForTransition:transition]);
 }

 - (BOOL)interactiveTransition:(_UINavigationInteractiveTransitionBase *)transition gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
 {
     return [otherGestureRecognizer isKindOfClass:[UITapGestureRecognizer class]];
 }

 - (BOOL)interactiveTransition:(_UINavigationInteractiveTransitionBase *)transition gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
 {
     return YES;
 }

 - (UIPanGestureRecognizer *)gestureRecognizerForInteractiveTransition:(_UINavigationInteractiveTransitionBase *)transition WithTarget:(id)target action:(SEL)action
 {
     UIScreenEdgePanGestureRecognizer *recognizer = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:target action:action];

     bool isLTR = [UIView userInterfaceLayoutDirectionForSemanticContentAttribute:[_gestureRecognizerView.get() semanticContentAttribute]] == UIUserInterfaceLayoutDirectionLeftToRight;

     switch ([self directionForTransition:transition]) {
     case WebKit::ViewGestureController::SwipeDirection::Back:
         [recognizer setEdges:isLTR ? UIRectEdgeLeft : UIRectEdgeRight];
         break;
     case WebKit::ViewGestureController::SwipeDirection::Forward:
         [recognizer setEdges:isLTR ? UIRectEdgeRight : UIRectEdgeLeft];
         break;
     }
     return [recognizer autorelease];
 }

 - (BOOL)isNavigationSwipeGestureRecognizer:(UIGestureRecognizer *)recognizer
 {
     return recognizer == [_backTransitionController gestureRecognizer] || recognizer == [_forwardTransitionController gestureRecognizer];
 }

 @end

 namespace WebKit {

 void ViewGestureController::platformTeardown()
 {
     [m_swipeTransitionContext _setTransitionIsInFlight:NO];
     [m_swipeTransitionContext _setInteractor:nil];
     [m_swipeTransitionContext _setAnimator:nil];
     [m_swipeInteractiveTransitionDelegate invalidate];
 }

 bool ViewGestureController::isNavigationSwipeGestureRecognizer(UIGestureRecognizer *recognizer) const
 {
     return [m_swipeInteractiveTransitionDelegate isNavigationSwipeGestureRecognizer:recognizer];
 }

 void ViewGestureController::installSwipeHandler(UIView *gestureRecognizerView, UIView *swipingView)
 {
     ASSERT(!m_swipeInteractiveTransitionDelegate);
     m_swipeInteractiveTransitionDelegate = adoptNS([[WKSwipeTransitionController alloc] initWithViewGestureController:this gestureRecognizerView:gestureRecognizerView]);
     m_liveSwipeView = swipingView;
 }

 void ViewGestureController::beginSwipeGesture(_UINavigationInteractiveTransitionBase *transition, SwipeDirection direction)
 {
     if (m_activeGestureType != ViewGestureType::None)
         return;

     m_webPageProxy.recordAutomaticNavigationSnapshot();

     RefPtr<WebPageProxy> alternateBackForwardListSourcePage = m_alternateBackForwardListSourcePage.get();
     m_webPageProxyForBackForwardListForCurrentSwipe = alternateBackForwardListSourcePage ? alternateBackForwardListSourcePage.get() : &m_webPageProxy;

     m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidBegin();
     if (&m_webPageProxy != m_webPageProxyForBackForwardListForCurrentSwipe)
         m_webPageProxy.navigationGestureDidBegin();

     auto& backForwardList = m_webPageProxyForBackForwardListForCurrentSwipe->backForwardList();

     // Copy the snapshot from this view to the one that owns the back forward list, so that
     // swiping forward will have the correct snapshot.
     if (m_webPageProxyForBackForwardListForCurrentSwipe != &m_webPageProxy) {
         if (auto* currentViewHistoryItem = m_webPageProxy.backForwardList().currentItem())
             backForwardList.currentItem()->setSnapshot(currentViewHistoryItem->snapshot());
     }

     RefPtr<WebBackForwardListItem> targetItem = direction == SwipeDirection::Back ? backForwardList.backItem() : backForwardList.forwardItem();

     CGRect liveSwipeViewFrame = [m_liveSwipeView frame];

     RetainPtr<UIViewController> snapshotViewController = adoptNS([[UIViewController alloc] init]);
     m_snapshotView = adoptNS([[UIView alloc] initWithFrame:liveSwipeViewFrame]);
     [m_snapshotView layer].name = @"SwipeSnapshot";

     RetainPtr<UIColor> backgroundColor = [UIColor whiteColor];
     if (ViewSnapshot* snapshot = targetItem->snapshot()) {
         float deviceScaleFactor = m_webPageProxy.deviceScaleFactor();
         FloatSize swipeLayerSizeInDeviceCoordinates(liveSwipeViewFrame.size);
         swipeLayerSizeInDeviceCoordinates.scale(deviceScaleFactor);

         BOOL shouldRestoreScrollPosition = targetItem->pageState().mainFrameState.shouldRestoreScrollPosition;
         IntPoint currentScrollPosition = roundedIntPoint(m_webPageProxy.viewScrollPosition());

         if (snapshot->hasImage() && snapshot->size() == swipeLayerSizeInDeviceCoordinates && deviceScaleFactor == snapshot->deviceScaleFactor() && (shouldRestoreScrollPosition || (currentScrollPosition == snapshot->viewScrollPosition())))
             [m_snapshotView layer].contents = snapshot->asLayerContents();
         Color coreColor = snapshot->backgroundColor();
         if (coreColor.isValid())
             backgroundColor = adoptNS([[UIColor alloc] initWithCGColor:cachedCGColor(coreColor)]);
     }

     [m_snapshotView setBackgroundColor:backgroundColor.get()];
     [m_snapshotView layer].contentsGravity = kCAGravityTopLeft;
     [m_snapshotView layer].contentsScale = m_liveSwipeView.window.screen.scale;
     [snapshotViewController setView:m_snapshotView.get()];

     m_transitionContainerView = adoptNS([[UIView alloc] initWithFrame:liveSwipeViewFrame]);
     [m_transitionContainerView layer].name = @"SwipeTransitionContainer";
     m_liveSwipeViewClippingView = adoptNS([[UIView alloc] initWithFrame:liveSwipeViewFrame]);
     [m_liveSwipeViewClippingView layer].name = @"LiveSwipeViewClipping";

     [m_liveSwipeViewClippingView setClipsToBounds:YES];

     [m_liveSwipeView.superview insertSubview:m_transitionContainerView.get() belowSubview:m_liveSwipeView];
     [m_transitionContainerView addSubview:m_liveSwipeViewClippingView.get()];
     [m_liveSwipeViewClippingView addSubview:m_liveSwipeView];

     RetainPtr<UIViewController> targettedViewController = adoptNS([[UIViewController alloc] init]);
     [targettedViewController setView:m_liveSwipeViewClippingView.get()];

     UINavigationControllerOperation transitionOperation = direction == SwipeDirection::Back ? UINavigationControllerOperationPop : UINavigationControllerOperationPush;
     RetainPtr<_UINavigationParallaxTransition> animationController = adoptNS([[_UINavigationParallaxTransition alloc] initWithCurrentOperation:transitionOperation]);

     m_swipeTransitionContext = adoptNS([[_UIViewControllerOneToOneTransitionContext alloc] init]);
     [m_swipeTransitionContext _setFromViewController:targettedViewController.get()];
     [m_swipeTransitionContext _setToViewController:snapshotViewController.get()];
     [m_swipeTransitionContext _setContainerView:m_transitionContainerView.get()];
     [m_swipeTransitionContext _setFromStartFrame:liveSwipeViewFrame];
     [m_swipeTransitionContext _setToEndFrame:liveSwipeViewFrame];
     [m_swipeTransitionContext _setToStartFrame:CGRectZero];
     [m_swipeTransitionContext _setFromEndFrame:CGRectZero];
     [m_swipeTransitionContext _setAnimator:animationController.get()];
     [m_swipeTransitionContext _setInteractor:transition];
     [m_swipeTransitionContext _setTransitionIsInFlight:YES];
     [m_swipeTransitionContext _setInteractiveUpdateHandler:^(BOOL finish, CGFloat percent, BOOL transitionCompleted, _UIViewControllerTransitionContext *) {
         if (finish)
             m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureWillEnd(transitionCompleted, *targetItem);
     }];
     uint64_t pageID = m_webPageProxy.pageID();
     [m_swipeTransitionContext _setCompletionHandler:^(_UIViewControllerTransitionContext *context, BOOL didComplete) {
         if (auto gestureController = gestureControllerForPage(pageID))
             gestureController->endSwipeGesture(targetItem.get(), context, !didComplete);
     }];

     [transition setAnimationController:animationController.get()];
     [transition startInteractiveTransition:m_swipeTransitionContext.get()];

     m_activeGestureType = ViewGestureType::Swipe;
 }

 void ViewGestureController::endSwipeGesture(WebBackForwardListItem* targetItem, _UIViewControllerTransitionContext *context, bool cancelled)
 {
     [context _setTransitionIsInFlight:NO];
     [context _setInteractor:nil];
     [context _setAnimator:nil];

     [[m_transitionContainerView superview] insertSubview:m_snapshotView.get() aboveSubview:m_transitionContainerView.get()];
     [[m_transitionContainerView superview] insertSubview:m_liveSwipeView aboveSubview:m_transitionContainerView.get()];
     [m_liveSwipeViewClippingView removeFromSuperview];
     m_liveSwipeViewClippingView = nullptr;
     [m_transitionContainerView removeFromSuperview];
     m_transitionContainerView = nullptr;

     if (cancelled) {
         // removeSwipeSnapshot will clear m_webPageProxyForBackForwardListForCurrentSwipe, so hold on to it here.
         RefPtr<WebPageProxy> webPageProxyForBackForwardListForCurrentSwipe = m_webPageProxyForBackForwardListForCurrentSwipe;
         removeSwipeSnapshot();
         webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidEnd(false, *targetItem);
         if (&m_webPageProxy != webPageProxyForBackForwardListForCurrentSwipe)
             m_webPageProxy.navigationGestureDidEnd();
         return;
     }

     m_snapshotRemovalTargetRenderTreeSize = 0;
     if (ViewSnapshot* snapshot = targetItem->snapshot())
         m_snapshotRemovalTargetRenderTreeSize = snapshot->renderTreeSize() * swipeSnapshotRemovalRenderTreeSizeTargetFraction;

     m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidEnd(true, *targetItem);
     if (&m_webPageProxy != m_webPageProxyForBackForwardListForCurrentSwipe)
         m_webPageProxy.navigationGestureDidEnd();

     m_webPageProxyForBackForwardListForCurrentSwipe->goToBackForwardItem(targetItem);

     if (auto drawingArea = m_webPageProxy.drawingArea()) {
         uint64_t pageID = m_webPageProxy.pageID();
         uint64_t gesturePendingSnapshotRemoval = m_gesturePendingSnapshotRemoval;
         drawingArea->dispatchAfterEnsuringDrawing([pageID, gesturePendingSnapshotRemoval] (CallbackBase::Error error) {
             if (auto gestureController = gestureControllerForPage(pageID)) {
                 if (gestureController->m_gesturePendingSnapshotRemoval == gesturePendingSnapshotRemoval)
                     gestureController->willCommitPostSwipeTransitionLayerTree(error == CallbackBase::Error::None);
             }
         });
         drawingArea->hideContentUntilPendingUpdate();
     } else {
         removeSwipeSnapshot();
         return;
     }

     // FIXME: Should we wait for VisuallyNonEmptyLayout like we do on Mac?
     m_snapshotRemovalTracker.start(SnapshotRemovalTracker::RenderTreeSizeThreshold
         | SnapshotRemovalTracker::RepaintAfterNavigation
         | SnapshotRemovalTracker::MainFrameLoad
         | SnapshotRemovalTracker::SubresourceLoads
         | SnapshotRemovalTracker::ScrollPositionRestoration, [this] {
             this->removeSwipeSnapshot();
     });

     if (ViewSnapshot* snapshot = targetItem->snapshot()) {
         m_backgroundColorForCurrentSnapshot = snapshot->backgroundColor();
         m_webPageProxy.didChangeBackgroundColor();
     }
 }

 void ViewGestureController::setRenderTreeSize(uint64_t renderTreeSize)
 {
     if (m_activeGestureType != ViewGestureType::Swipe)
         return;

     if (!m_snapshotRemovalTargetRenderTreeSize || renderTreeSize > m_snapshotRemovalTargetRenderTreeSize)
         didHitRenderTreeSizeThreshold();
 }

 void ViewGestureController::willCommitPostSwipeTransitionLayerTree(bool successful)
 {
     if (m_activeGestureType != ViewGestureType::Swipe)
         return;

     if (!successful) {
         removeSwipeSnapshot();
         return;
     }

     didRepaintAfterNavigation();
 }

 void ViewGestureController::removeSwipeSnapshot()
 {
     m_snapshotRemovalTracker.reset();

     if (m_activeGestureType != ViewGestureType::Swipe)
         return;

     ++m_gesturePendingSnapshotRemoval;

     [m_snapshotView removeFromSuperview];
     m_snapshotView = nullptr;

     m_snapshotRemovalTargetRenderTreeSize = 0;
     m_activeGestureType = ViewGestureType::None;

     m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureSnapshotWasRemoved();
     m_webPageProxyForBackForwardListForCurrentSwipe = nullptr;

     m_swipeTransitionContext = nullptr;

     m_backgroundColorForCurrentSnapshot = Color();
 }

 } // namespace WebKit

 #endif // PLATFORM(IOS)
	/*
	* Copyright (C) 2013, 2014 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 "ViewGestureController.h"

	#if PLATFORM(IOS)

	#import "DrawingAreaProxy.h"
	#import "UIKitSPI.h"
	#import "ViewGestureControllerMessages.h"
	#import "ViewGestureGeometryCollectorMessages.h"
	#import "ViewSnapshotStore.h"
	#import "WKBackForwardListItemInternal.h"
	#import "WKWebViewInternal.h"
	#import "WeakObjCPtr.h"
	#import "WebBackForwardList.h"
	#import "WebPageGroup.h"
	#import "WebPageMessages.h"
	#import "WebPageProxy.h"
	#import "WebProcessProxy.h"
	#import <UIKit/UIScreenEdgePanGestureRecognizer.h>
	#import <WebCore/IOSurface.h>
	#import <WebCore/QuartzCoreSPI.h>

	using namespace WebCore;

	@interface WKSwipeTransitionController : NSObject <_UINavigationInteractiveTransitionBaseDelegate>
	- (instancetype)initWithViewGestureController:(WebKit::ViewGestureController)gestureController gestureRecognizerView:(UIView )gestureRecognizerView;
	- (void)invalidate;
	@end

	@interface _UIViewControllerTransitionContext (WKDetails)
	@property (nonatomic, copy, setter=_setInteractiveUpdateHandler:) void (^_interactiveUpdateHandler)(BOOL interactionIsOver, CGFloat percentComplete, BOOL transitionCompleted, _UIViewControllerTransitionContext *);
	@end

	@implementation WKSwipeTransitionController
	{
	WebKit::ViewGestureController *_gestureController;
	RetainPtr<_UINavigationInteractiveTransitionBase> _backTransitionController;
	RetainPtr<_UINavigationInteractiveTransitionBase> _forwardTransitionController;
	WebKit::WeakObjCPtr<UIView> _gestureRecognizerView;
	}

	static const float swipeSnapshotRemovalRenderTreeSizeTargetFraction = 0.5;

	- (instancetype)initWithViewGestureController:(WebKit::ViewGestureController)gestureController gestureRecognizerView:(UIView )gestureRecognizerView
	{
	self = [super init];
	if (self) {
	_gestureController = gestureController;
	_gestureRecognizerView = gestureRecognizerView;

	_backTransitionController = adoptNS([_UINavigationInteractiveTransitionBase alloc]);
	_backTransitionController = [_backTransitionController initWithGestureRecognizerView:gestureRecognizerView animator:nil delegate:self];

	_forwardTransitionController = adoptNS([_UINavigationInteractiveTransitionBase alloc]);
	_forwardTransitionController = [_forwardTransitionController initWithGestureRecognizerView:gestureRecognizerView animator:nil delegate:self];
	[_forwardTransitionController setShouldReverseTranslation:YES];
	}
	return self;
	}

	- (void)invalidate
	{
	_gestureController = nullptr;
	}

	- (WebKit::ViewGestureController::SwipeDirection)directionForTransition:(_UINavigationInteractiveTransitionBase *)transition
	{
	return transition == _backTransitionController ? WebKit::ViewGestureController::SwipeDirection::Back : WebKit::ViewGestureController::SwipeDirection::Forward;
	}

	- (void)startInteractiveTransition:(_UINavigationInteractiveTransitionBase *)transition
	{
	_gestureController->beginSwipeGesture(transition, [self directionForTransition:transition]);
	}

	- (BOOL)shouldBeginInteractiveTransition:(_UINavigationInteractiveTransitionBase *)transition
	{
	return _gestureController->canSwipeInDirection([self directionForTransition:transition]);
	}

	- (BOOL)interactiveTransition:(_UINavigationInteractiveTransitionBase )transition gestureRecognizer:(UIGestureRecognizer )gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
	{
	return [otherGestureRecognizer isKindOfClass:[UITapGestureRecognizer class]];
	}

	- (BOOL)interactiveTransition:(_UINavigationInteractiveTransitionBase )transition gestureRecognizer:(UIGestureRecognizer )gestureRecognizer shouldReceiveTouch:(UITouch *)touch
	{
	return YES;
	}

	- (UIPanGestureRecognizer )gestureRecognizerForInteractiveTransition:(_UINavigationInteractiveTransitionBase )transition WithTarget:(id)target action:(SEL)action
	{
	UIScreenEdgePanGestureRecognizer *recognizer = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:target action:action];

	bool isLTR = [UIView userInterfaceLayoutDirectionForSemanticContentAttribute:[_gestureRecognizerView.get() semanticContentAttribute]] == UIUserInterfaceLayoutDirectionLeftToRight;

	switch ([self directionForTransition:transition]) {
	case WebKit::ViewGestureController::SwipeDirection::Back:
	[recognizer setEdges:isLTR ? UIRectEdgeLeft : UIRectEdgeRight];
	break;
	case WebKit::ViewGestureController::SwipeDirection::Forward:
	[recognizer setEdges:isLTR ? UIRectEdgeRight : UIRectEdgeLeft];
	break;
	}
	return [recognizer autorelease];
	}

	- (BOOL)isNavigationSwipeGestureRecognizer:(UIGestureRecognizer *)recognizer
	{
	return recognizer == [_backTransitionController gestureRecognizer] \|\| recognizer == [_forwardTransitionController gestureRecognizer];
	}

	@end

	namespace WebKit {

	void ViewGestureController::platformTeardown()
	{
	[m_swipeTransitionContext _setTransitionIsInFlight:NO];
	[m_swipeTransitionContext _setInteractor:nil];
	[m_swipeTransitionContext _setAnimator:nil];
	[m_swipeInteractiveTransitionDelegate invalidate];
	}

	bool ViewGestureController::isNavigationSwipeGestureRecognizer(UIGestureRecognizer *recognizer) const
	{
	return [m_swipeInteractiveTransitionDelegate isNavigationSwipeGestureRecognizer:recognizer];
	}

	void ViewGestureController::installSwipeHandler(UIView gestureRecognizerView, UIView swipingView)
	{
	ASSERT(!m_swipeInteractiveTransitionDelegate);
	m_swipeInteractiveTransitionDelegate = adoptNS([[WKSwipeTransitionController alloc] initWithViewGestureController:this gestureRecognizerView:gestureRecognizerView]);
	m_liveSwipeView = swipingView;
	}

	void ViewGestureController::beginSwipeGesture(_UINavigationInteractiveTransitionBase *transition, SwipeDirection direction)
	{
	if (m_activeGestureType != ViewGestureType::None)
	return;

	m_webPageProxy.recordAutomaticNavigationSnapshot();

	RefPtr<WebPageProxy> alternateBackForwardListSourcePage = m_alternateBackForwardListSourcePage.get();
	m_webPageProxyForBackForwardListForCurrentSwipe = alternateBackForwardListSourcePage ? alternateBackForwardListSourcePage.get() : &m_webPageProxy;

	m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidBegin();
	if (&m_webPageProxy != m_webPageProxyForBackForwardListForCurrentSwipe)
	m_webPageProxy.navigationGestureDidBegin();

	auto& backForwardList = m_webPageProxyForBackForwardListForCurrentSwipe->backForwardList();

	// Copy the snapshot from this view to the one that owns the back forward list, so that
	// swiping forward will have the correct snapshot.
	if (m_webPageProxyForBackForwardListForCurrentSwipe != &m_webPageProxy) {
	if (auto* currentViewHistoryItem = m_webPageProxy.backForwardList().currentItem())
	backForwardList.currentItem()->setSnapshot(currentViewHistoryItem->snapshot());
	}

	RefPtr<WebBackForwardListItem> targetItem = direction == SwipeDirection::Back ? backForwardList.backItem() : backForwardList.forwardItem();

	CGRect liveSwipeViewFrame = [m_liveSwipeView frame];

	RetainPtr<UIViewController> snapshotViewController = adoptNS([[UIViewController alloc] init]);
	m_snapshotView = adoptNS([[UIView alloc] initWithFrame:liveSwipeViewFrame]);
	[m_snapshotView layer].name = @"SwipeSnapshot";

	RetainPtr<UIColor> backgroundColor = [UIColor whiteColor];
	if (ViewSnapshot* snapshot = targetItem->snapshot()) {
	float deviceScaleFactor = m_webPageProxy.deviceScaleFactor();
	FloatSize swipeLayerSizeInDeviceCoordinates(liveSwipeViewFrame.size);
	swipeLayerSizeInDeviceCoordinates.scale(deviceScaleFactor);

	BOOL shouldRestoreScrollPosition = targetItem->pageState().mainFrameState.shouldRestoreScrollPosition;
	IntPoint currentScrollPosition = roundedIntPoint(m_webPageProxy.viewScrollPosition());

	if (snapshot->hasImage() && snapshot->size() == swipeLayerSizeInDeviceCoordinates && deviceScaleFactor == snapshot->deviceScaleFactor() && (shouldRestoreScrollPosition \|\| (currentScrollPosition == snapshot->viewScrollPosition())))
	[m_snapshotView layer].contents = snapshot->asLayerContents();
	Color coreColor = snapshot->backgroundColor();
	if (coreColor.isValid())
	backgroundColor = adoptNS([[UIColor alloc] initWithCGColor:cachedCGColor(coreColor)]);
	}

	[m_snapshotView setBackgroundColor:backgroundColor.get()];
	[m_snapshotView layer].contentsGravity = kCAGravityTopLeft;
	[m_snapshotView layer].contentsScale = m_liveSwipeView.window.screen.scale;
	[snapshotViewController setView:m_snapshotView.get()];

	m_transitionContainerView = adoptNS([[UIView alloc] initWithFrame:liveSwipeViewFrame]);
	[m_transitionContainerView layer].name = @"SwipeTransitionContainer";
	m_liveSwipeViewClippingView = adoptNS([[UIView alloc] initWithFrame:liveSwipeViewFrame]);
	[m_liveSwipeViewClippingView layer].name = @"LiveSwipeViewClipping";

	[m_liveSwipeViewClippingView setClipsToBounds:YES];

	[m_liveSwipeView.superview insertSubview:m_transitionContainerView.get() belowSubview:m_liveSwipeView];
	[m_transitionContainerView addSubview:m_liveSwipeViewClippingView.get()];
	[m_liveSwipeViewClippingView addSubview:m_liveSwipeView];

	RetainPtr<UIViewController> targettedViewController = adoptNS([[UIViewController alloc] init]);
	[targettedViewController setView:m_liveSwipeViewClippingView.get()];

	UINavigationControllerOperation transitionOperation = direction == SwipeDirection::Back ? UINavigationControllerOperationPop : UINavigationControllerOperationPush;
	RetainPtr<_UINavigationParallaxTransition> animationController = adoptNS([[_UINavigationParallaxTransition alloc] initWithCurrentOperation:transitionOperation]);

	m_swipeTransitionContext = adoptNS([[_UIViewControllerOneToOneTransitionContext alloc] init]);
	[m_swipeTransitionContext _setFromViewController:targettedViewController.get()];
	[m_swipeTransitionContext _setToViewController:snapshotViewController.get()];
	[m_swipeTransitionContext _setContainerView:m_transitionContainerView.get()];
	[m_swipeTransitionContext _setFromStartFrame:liveSwipeViewFrame];
	[m_swipeTransitionContext _setToEndFrame:liveSwipeViewFrame];
	[m_swipeTransitionContext _setToStartFrame:CGRectZero];
	[m_swipeTransitionContext _setFromEndFrame:CGRectZero];
	[m_swipeTransitionContext _setAnimator:animationController.get()];
	[m_swipeTransitionContext _setInteractor:transition];
	[m_swipeTransitionContext _setTransitionIsInFlight:YES];
	[m_swipeTransitionContext _setInteractiveUpdateHandler:^(BOOL finish, CGFloat percent, BOOL transitionCompleted, _UIViewControllerTransitionContext *) {
	if (finish)
	m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureWillEnd(transitionCompleted, *targetItem);
	}];
	uint64_t pageID = m_webPageProxy.pageID();
	[m_swipeTransitionContext _setCompletionHandler:^(_UIViewControllerTransitionContext *context, BOOL didComplete) {
	if (auto gestureController = gestureControllerForPage(pageID))
	gestureController->endSwipeGesture(targetItem.get(), context, !didComplete);
	}];

	[transition setAnimationController:animationController.get()];
	[transition startInteractiveTransition:m_swipeTransitionContext.get()];

	m_activeGestureType = ViewGestureType::Swipe;
	}

	void ViewGestureController::endSwipeGesture(WebBackForwardListItem* targetItem, _UIViewControllerTransitionContext *context, bool cancelled)
	{
	[context _setTransitionIsInFlight:NO];
	[context _setInteractor:nil];
	[context _setAnimator:nil];

	[[m_transitionContainerView superview] insertSubview:m_snapshotView.get() aboveSubview:m_transitionContainerView.get()];
	[[m_transitionContainerView superview] insertSubview:m_liveSwipeView aboveSubview:m_transitionContainerView.get()];
	[m_liveSwipeViewClippingView removeFromSuperview];
	m_liveSwipeViewClippingView = nullptr;
	[m_transitionContainerView removeFromSuperview];
	m_transitionContainerView = nullptr;

	if (cancelled) {
	// removeSwipeSnapshot will clear m_webPageProxyForBackForwardListForCurrentSwipe, so hold on to it here.
	RefPtr<WebPageProxy> webPageProxyForBackForwardListForCurrentSwipe = m_webPageProxyForBackForwardListForCurrentSwipe;
	removeSwipeSnapshot();
	webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidEnd(false, *targetItem);
	if (&m_webPageProxy != webPageProxyForBackForwardListForCurrentSwipe)
	m_webPageProxy.navigationGestureDidEnd();
	return;
	}

	m_snapshotRemovalTargetRenderTreeSize = 0;
	if (ViewSnapshot* snapshot = targetItem->snapshot())
	m_snapshotRemovalTargetRenderTreeSize = snapshot->renderTreeSize() * swipeSnapshotRemovalRenderTreeSizeTargetFraction;

	m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureDidEnd(true, *targetItem);
	if (&m_webPageProxy != m_webPageProxyForBackForwardListForCurrentSwipe)
	m_webPageProxy.navigationGestureDidEnd();

	m_webPageProxyForBackForwardListForCurrentSwipe->goToBackForwardItem(targetItem);

	if (auto drawingArea = m_webPageProxy.drawingArea()) {
	uint64_t pageID = m_webPageProxy.pageID();
	uint64_t gesturePendingSnapshotRemoval = m_gesturePendingSnapshotRemoval;
	drawingArea->dispatchAfterEnsuringDrawing([pageID, gesturePendingSnapshotRemoval] (CallbackBase::Error error) {
	if (auto gestureController = gestureControllerForPage(pageID)) {
	if (gestureController->m_gesturePendingSnapshotRemoval == gesturePendingSnapshotRemoval)
	gestureController->willCommitPostSwipeTransitionLayerTree(error == CallbackBase::Error::None);
	}
	});
	drawingArea->hideContentUntilPendingUpdate();
	} else {
	removeSwipeSnapshot();
	return;
	}

	// FIXME: Should we wait for VisuallyNonEmptyLayout like we do on Mac?
	m_snapshotRemovalTracker.start(SnapshotRemovalTracker::RenderTreeSizeThreshold
	\| SnapshotRemovalTracker::RepaintAfterNavigation
	\| SnapshotRemovalTracker::MainFrameLoad
	\| SnapshotRemovalTracker::SubresourceLoads
	\| SnapshotRemovalTracker::ScrollPositionRestoration, [this] {
	this->removeSwipeSnapshot();
	});

	if (ViewSnapshot* snapshot = targetItem->snapshot()) {
	m_backgroundColorForCurrentSnapshot = snapshot->backgroundColor();
	m_webPageProxy.didChangeBackgroundColor();
	}
	}

	void ViewGestureController::setRenderTreeSize(uint64_t renderTreeSize)
	{
	if (m_activeGestureType != ViewGestureType::Swipe)
	return;

	if (!m_snapshotRemovalTargetRenderTreeSize \|\| renderTreeSize > m_snapshotRemovalTargetRenderTreeSize)
	didHitRenderTreeSizeThreshold();
	}

	void ViewGestureController::willCommitPostSwipeTransitionLayerTree(bool successful)
	{
	if (m_activeGestureType != ViewGestureType::Swipe)
	return;

	if (!successful) {
	removeSwipeSnapshot();
	return;
	}

	didRepaintAfterNavigation();
	}

	void ViewGestureController::removeSwipeSnapshot()
	{
	m_snapshotRemovalTracker.reset();

	if (m_activeGestureType != ViewGestureType::Swipe)
	return;

	++m_gesturePendingSnapshotRemoval;

	[m_snapshotView removeFromSuperview];
	m_snapshotView = nullptr;

	m_snapshotRemovalTargetRenderTreeSize = 0;
	m_activeGestureType = ViewGestureType::None;

	m_webPageProxyForBackForwardListForCurrentSwipe->navigationGestureSnapshotWasRemoved();
	m_webPageProxyForBackForwardListForCurrentSwipe = nullptr;

	m_swipeTransitionContext = nullptr;

	m_backgroundColorForCurrentSnapshot = Color();
	}

	} // namespace WebKit

	#endif // PLATFORM(IOS)