Source/WebKit/UIProcess/ios/DragDropInteractionState.mm - WebKit - Git at Google

 /*
  * Copyright (C) 2017-2022 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 "DragDropInteractionState.h"

 #if PLATFORM(IOS_FAMILY) && ENABLE(DRAG_SUPPORT)

 #import "Logging.h"
 #import <WebCore/ColorCocoa.h>
 #import <WebCore/DragItem.h>
 #import <WebCore/Image.h>
 #import <wtf/cocoa/VectorCocoa.h>

 namespace WebKit {
 using namespace WebCore;

 static UIDragItem *dragItemMatchingIdentifier(id <UIDragSession> session, NSInteger identifier)
 {
     for (UIDragItem *item in session.items) {
         id context = item.privateLocalContext;
         if ([context isKindOfClass:[NSNumber class]] && [context integerValue] == identifier)
             return item;
     }
     return nil;
 }

 static RetainPtr<UITargetedDragPreview> createTargetedDragPreview(UIImage *image, UIView *rootView, UIView *previewContainer, const FloatRect& frameInRootViewCoordinates, const Vector<FloatRect>& clippingRectsInFrameCoordinates, UIColor *backgroundColor, UIBezierPath *visiblePath)
 {
     if (frameInRootViewCoordinates.isEmpty() || !image || !previewContainer.window)
         return nullptr;

     FloatRect frameInContainerCoordinates = [rootView convertRect:frameInRootViewCoordinates toView:previewContainer];
     if (frameInContainerCoordinates.isEmpty())
         return nullptr;

     FloatSize scalingRatio = frameInContainerCoordinates.size() / frameInRootViewCoordinates.size();
     auto clippingRectValuesInFrameCoordinates = createNSArray(clippingRectsInFrameCoordinates, [&] (auto rect) {
         rect.scale(scalingRatio);
         return [NSValue valueWithCGRect:rect];
     });

     auto imageView = adoptNS([[UIImageView alloc] initWithImage:image]);
     [imageView setFrame:frameInContainerCoordinates];

     RetainPtr<UIDragPreviewParameters> parameters;
     if ([clippingRectValuesInFrameCoordinates count])
         parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:clippingRectValuesInFrameCoordinates.get()]);
     else
         parameters = adoptNS([[UIDragPreviewParameters alloc] init]);

     if (backgroundColor)
         [parameters setBackgroundColor:backgroundColor];

     if (visiblePath)
         [parameters setVisiblePath:visiblePath];

     CGPoint centerInContainerCoordinates = { CGRectGetMidX(frameInContainerCoordinates), CGRectGetMidY(frameInContainerCoordinates) };
     auto target = adoptNS([[UIDragPreviewTarget alloc] initWithContainer:previewContainer center:centerInContainerCoordinates]);
     return adoptNS([[UITargetedDragPreview alloc] initWithView:imageView.get() parameters:parameters.get() target:target.get()]);
 }

 static RetainPtr<UIImage> uiImageForImage(Image* image)
 {
     if (!image)
         return nullptr;

     auto nativeImage = image->nativeImage();
     if (!nativeImage)
         return nullptr;

     return adoptNS([[UIImage alloc] initWithCGImage:nativeImage->platformImage().get()]);
 }

 static bool shouldUseDragImageToCreatePreviewForDragSource(const DragSourceState& source)
 {
     if (!source.image)
         return false;

 #if ENABLE(INPUT_TYPE_COLOR)
     if (source.action.contains(DragSourceAction::Color))
         return true;
 #endif

 #if ENABLE(MODEL_ELEMENT)
     if (source.action.contains(DragSourceAction::Model))
         return true;
 #endif

     return source.action.containsAny({ DragSourceAction::DHTML, DragSourceAction::Image });
 }

 static bool shouldUseVisiblePathToCreatePreviewForDragSource(const DragSourceState& source)
 {
     if (!source.visiblePath)
         return false;

 #if ENABLE(INPUT_TYPE_COLOR)
     if (source.action.contains(DragSourceAction::Color))
         return true;
 #endif

     return false;
 }

 static bool shouldUseTextIndicatorToCreatePreviewForDragSource(const DragSourceState& source)
 {
     if (!source.indicatorData)
         return false;

     if (source.action.containsAny({ DragSourceAction::Link, DragSourceAction::Selection }))
         return true;

 #if ENABLE(ATTACHMENT_ELEMENT)
     if (source.action.contains(DragSourceAction::Attachment))
         return true;
 #endif

     return false;
 }

 static bool canUpdatePreviewForActiveDragSource(const DragSourceState& source)
 {
     if (!source.possiblyNeedsDragPreviewUpdate)
         return false;

 #if ENABLE(INPUT_TYPE_COLOR)
     if (source.action.contains(DragSourceAction::Color))
         return true;
 #endif

     if (source.action.contains(DragSourceAction::Link) && !source.action.contains(DragSourceAction::Image))
         return true;

     return false;
 }

 std::optional<DragSourceState> DragDropInteractionState::activeDragSourceForItem(UIDragItem *item) const
 {
     if (![item.privateLocalContext isKindOfClass:[NSNumber class]])
         return std::nullopt;

     auto identifier = [(NSNumber *)item.privateLocalContext integerValue];
     for (auto& source : m_activeDragSources) {
         if (source.itemIdentifier == identifier)
             return source;
     }
     return std::nullopt;
 }

 bool DragDropInteractionState::anyActiveDragSourceIs(WebCore::DragSourceAction action) const
 {
     for (auto& source : m_activeDragSources) {
         if (source.action.contains(action))
             return true;
     }
     return false;
 }

 void DragDropInteractionState::prepareForDragSession(id <UIDragSession> session, dispatch_block_t completionHandler)
 {
     m_dragSession = session;
     m_dragStartCompletionBlock = completionHandler;
 }

 void DragDropInteractionState::dragSessionWillBegin()
 {
     m_didBeginDragging = true;
     updatePreviewsForActiveDragSources();
 }

 void DragDropInteractionState::setDefaultDropPreview(UIDragItem *item, UITargetedDragPreview *preview)
 {
     m_defaultDropPreviews.append({ item, preview });
 }

 UITargetedDragPreview *DragDropInteractionState::defaultDropPreview(UIDragItem *item) const
 {
     auto matchIndex = m_defaultDropPreviews.findIf([&] (auto& itemAndPreview) {
         return itemAndPreview.item == item;
     });
     return matchIndex == notFound ? nil : m_defaultDropPreviews[matchIndex].preview.get();
 }

 BlockPtr<void(UITargetedDragPreview *)> DragDropInteractionState::dropPreviewProvider(UIDragItem *item)
 {
     auto matchIndex = m_delayedItemPreviewProviders.findIf([&] (auto& itemAndProvider) {
         return itemAndProvider.item == item;
     });

     if (matchIndex == notFound)
         return nil;

     return m_delayedItemPreviewProviders[matchIndex].provider;
 }

 void DragDropInteractionState::prepareForDelayedDropPreview(UIDragItem *item, void(^provider)(UITargetedDragPreview *preview))
 {
     m_delayedItemPreviewProviders.append({ item, provider });
 }

 void DragDropInteractionState::deliverDelayedDropPreview(UIView *contentView, UIView *previewContainer, const WebCore::TextIndicatorData& indicator)
 {
     if (m_delayedItemPreviewProviders.isEmpty())
         return;

     auto textIndicatorImage = uiImageForImage(indicator.contentImage.get());
     auto preview = createTargetedDragPreview(textIndicatorImage.get(), contentView, previewContainer, indicator.textBoundingRectInRootViewCoordinates, indicator.textRectsInBoundingRectCoordinates, cocoaColor(indicator.estimatedBackgroundColor).get(), nil);
     for (auto& itemAndPreviewProvider : m_delayedItemPreviewProviders)
         itemAndPreviewProvider.provider(preview.get());
     m_delayedItemPreviewProviders.clear();
 }

 void DragDropInteractionState::deliverDelayedDropPreview(UIView *contentView, CGRect unobscuredContentRect, NSArray<UIDragItem *> *items, const Vector<IntRect>& placeholderRects)
 {
     if (items.count != placeholderRects.size()) {
         RELEASE_LOG(DragAndDrop, "Failed to animate image placeholders: number of drag items (%tu) does not match number of placeholders (%tu)", items.count, placeholderRects.size());
         clearAllDelayedItemPreviewProviders();
         return;
     }

     for (size_t i = 0; i < placeholderRects.size(); ++i) {
         UIDragItem *item = [items objectAtIndex:i];
         auto& placeholderRect = placeholderRects[i];
         auto provider = dropPreviewProvider(item);
         if (!provider)
             continue;

         auto defaultPreview = defaultDropPreview(item);
         auto defaultPreviewSize = [defaultPreview size];
         if (!defaultPreview || defaultPreviewSize.width <= 0 || defaultPreviewSize.height <= 0 || placeholderRect.isEmpty()) {
             provider(nil);
             continue;
         }

         FloatRect previewIntersectionRect = enclosingIntRect(CGRectIntersection(unobscuredContentRect, placeholderRect));
         if (previewIntersectionRect.isEmpty()) {
             // If the preview rect is completely offscreen, don't bother trying to clip out or scale the default preview;
             // simply retarget the default preview.
             auto target = adoptNS([[UIDragPreviewTarget alloc] initWithContainer:contentView center:placeholderRect.center()]);
             provider([defaultPreview retargetedPreviewWithTarget:target.get()]);
             continue;
         }

         // Targeted previews don't clip to the bounds of any enclosing view; this means that when targeting previews outside
         // the visible bounds of the content view, the preview will spill out the web view. This is most noticeable when
         // dropping a tall image into Mail compose on iOS 13, where the bottom of the compose window is not flush against
         // the bottom of the window. To mitigate this, we use the preview target's `visiblePath` property to clip the default
         // drop preview's view, by the same proportion that the final placeholder image is clipped (with respect to the
         // unobscured content rect).
         auto previewBounds = [defaultPreview view].bounds;
         auto insetPreviewBounds = UIEdgeInsetsInsetRect(previewBounds, {
             (previewIntersectionRect.y() - placeholderRect.y()) / placeholderRect.height() * previewBounds.size.height,
             (previewIntersectionRect.x() - placeholderRect.x()) / placeholderRect.width() * previewBounds.size.width,
             (placeholderRect.maxY() - previewIntersectionRect.maxY()) / placeholderRect.height() * previewBounds.size.height,
             (placeholderRect.maxX() - previewIntersectionRect.maxX()) / placeholderRect.width() * previewBounds.size.width
         });

         auto transform = CGAffineTransformMakeScale(placeholderRect.width() / defaultPreviewSize.width, placeholderRect.height() / defaultPreviewSize.height);
         auto target = adoptNS([[UIDragPreviewTarget alloc] initWithContainer:contentView center:previewIntersectionRect.center() transform:transform]);
         [defaultPreview parameters].visiblePath = [UIBezierPath bezierPathWithRect:insetPreviewBounds];
         auto newPreview = adoptNS([[UITargetedDragPreview alloc] initWithView:[defaultPreview view] parameters:[defaultPreview parameters] target:target.get()]);
         provider(newPreview.get());
     }

     m_delayedItemPreviewProviders.clear();
 }

 void DragDropInteractionState::clearAllDelayedItemPreviewProviders()
 {
     for (auto& itemAndPreviewProvider : m_delayedItemPreviewProviders)
         itemAndPreviewProvider.provider(nil);
     m_delayedItemPreviewProviders.clear();
 }

 UITargetedDragPreview *DragDropInteractionState::previewForDragItem(UIDragItem *item, UIView *contentView, UIView *previewContainer) const
 {
     auto foundSource = activeDragSourceForItem(item);
     if (!foundSource)
         return nil;

     auto& source = foundSource.value();
     if (shouldUseDragImageToCreatePreviewForDragSource(source)) {
         if (shouldUseVisiblePathToCreatePreviewForDragSource(source)) {
             auto path = source.visiblePath.value();
             UIBezierPath *visiblePath = [UIBezierPath bezierPathWithCGPath:path.ensurePlatformPath()];
             return createTargetedDragPreview(source.image.get(), contentView, previewContainer, source.dragPreviewFrameInRootViewCoordinates, { }, nil, visiblePath).autorelease();
         }
         return createTargetedDragPreview(source.image.get(), contentView, previewContainer, source.dragPreviewFrameInRootViewCoordinates, { }, nil, nil).autorelease();
     }

     if (shouldUseTextIndicatorToCreatePreviewForDragSource(source)) {
         auto indicator = source.indicatorData.value();
         auto textIndicatorImage = uiImageForImage(indicator.contentImage.get());
         return createTargetedDragPreview(textIndicatorImage.get(), contentView, previewContainer, indicator.textBoundingRectInRootViewCoordinates, indicator.textRectsInBoundingRectCoordinates, cocoaColor(indicator.estimatedBackgroundColor).get(), nil).autorelease();
     }

     return nil;
 }

 void DragDropInteractionState::dragSessionWillDelaySetDownAnimation(dispatch_block_t completion)
 {
     m_dragCancelSetDownBlock = completion;
 }

 bool DragDropInteractionState::shouldRequestAdditionalItemForDragSession(id <UIDragSession> session) const
 {
     return m_dragSession == session && !m_addDragItemCompletionBlock && !m_dragStartCompletionBlock;
 }

 void DragDropInteractionState::dragSessionWillRequestAdditionalItem(void (^completion)(NSArray <UIDragItem *> *))
 {
     clearStagedDragSource();
     m_addDragItemCompletionBlock = completion;
 }

 void DragDropInteractionState::dropSessionDidEnterOrUpdate(id <UIDropSession> session, const DragData& dragData)
 {
     m_dropSession = session;
     m_lastGlobalPosition = dragData.globalPosition();
 }

 void DragDropInteractionState::stageDragItem(const DragItem& item, UIImage *dragImage)
 {
     static NSInteger currentDragSourceItemIdentifier = 0;

     m_adjustedPositionForDragEnd = item.eventPositionInContentCoordinates;
     m_stagedDragSource = {{
         item.sourceAction,
         item.eventPositionInContentCoordinates,
         item.dragPreviewFrameInRootViewCoordinates,
         dragImage,
         item.image.indicatorData(),
         item.image.visiblePath(),
         item.title.isEmpty() ? nil : (NSString *)item.title,
         item.url.isEmpty() ? nil : (NSURL *)item.url,
         true, // We assume here that drag previews need to be updated until proven otherwise in updatePreviewsForActiveDragSources().
         ++currentDragSourceItemIdentifier
     }};
 }

 bool DragDropInteractionState::hasStagedDragSource() const
 {
     return m_stagedDragSource && !stagedDragSource().action.isEmpty();
 }

 void DragDropInteractionState::clearStagedDragSource(DidBecomeActive didBecomeActive)
 {
     if (didBecomeActive == DidBecomeActive::Yes)
         m_activeDragSources.append(stagedDragSource());
     m_stagedDragSource = std::nullopt;
 }

 void DragDropInteractionState::dragAndDropSessionsDidEnd()
 {
     clearAllDelayedItemPreviewProviders();

     // If any of UIKit's completion blocks are still in-flight when the drag interaction ends, we need to ensure that they are still invoked
     // to prevent UIKit from getting into an inconsistent state.
     if (auto completionBlock = takeDragCancelSetDownBlock())
         completionBlock();

     if (auto completionBlock = takeAddDragItemCompletionBlock())
         completionBlock(@[ ]);

     if (auto completionBlock = takeDragStartCompletionBlock())
         completionBlock();
 }

 void DragDropInteractionState::updatePreviewsForActiveDragSources()
 {
     for (auto& source : m_activeDragSources) {
         if (!canUpdatePreviewForActiveDragSource(source))
             continue;

         UIDragItem *dragItem = dragItemMatchingIdentifier(m_dragSession.get(), source.itemIdentifier);
         if (!dragItem)
             continue;

         if (source.action.contains(DragSourceAction::Link)) {
             dragItem.previewProvider = [title = retainPtr((NSString *)source.linkTitle), url = retainPtr((NSURL *)source.linkURL), center = source.adjustedOrigin] () -> UIDragPreview * {
                 UIURLDragPreviewView *previewView = [UIURLDragPreviewView viewWithTitle:title.get() URL:url.get()];
                 previewView.center = center;
                 auto parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:@[ [NSValue valueWithCGRect:previewView.bounds] ]]);
                 return adoptNS([[UIDragPreview alloc] initWithView:previewView parameters:parameters.get()]).autorelease();
             };
         }
 #if ENABLE(INPUT_TYPE_COLOR)
         else if (source.action.contains(DragSourceAction::Color)) {
             dragItem.previewProvider = [image = source.image] () -> UIDragPreview * {
                 auto imageView = adoptNS([[UIImageView alloc] initWithImage:image.get()]);
                 auto parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:@[ [NSValue valueWithCGRect:[imageView bounds]] ]]);
                 return adoptNS([[UIDragPreview alloc] initWithView:imageView.get() parameters:parameters.get()]).autorelease();
             };
         }
 #endif

         source.possiblyNeedsDragPreviewUpdate = false;
     }
 }

 } // namespace WebKit

 #endif // PLATFORM(IOS_FAMILY) && ENABLE(DRAG_SUPPORT)
	/*
	* Copyright (C) 2017-2022 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 "DragDropInteractionState.h"

	#if PLATFORM(IOS_FAMILY) && ENABLE(DRAG_SUPPORT)

	#import "Logging.h"
	#import <WebCore/ColorCocoa.h>
	#import <WebCore/DragItem.h>
	#import <WebCore/Image.h>
	#import <wtf/cocoa/VectorCocoa.h>

	namespace WebKit {
	using namespace WebCore;

	static UIDragItem *dragItemMatchingIdentifier(id <UIDragSession> session, NSInteger identifier)
	{
	for (UIDragItem *item in session.items) {
	id context = item.privateLocalContext;
	if ([context isKindOfClass:[NSNumber class]] && [context integerValue] == identifier)
	return item;
	}
	return nil;
	}

	static RetainPtr<UITargetedDragPreview> createTargetedDragPreview(UIImage image, UIView rootView, UIView previewContainer, const FloatRect& frameInRootViewCoordinates, const Vector<FloatRect>& clippingRectsInFrameCoordinates, UIColor backgroundColor, UIBezierPath *visiblePath)
	{
	if (frameInRootViewCoordinates.isEmpty() \|\| !image \|\| !previewContainer.window)
	return nullptr;

	FloatRect frameInContainerCoordinates = [rootView convertRect:frameInRootViewCoordinates toView:previewContainer];
	if (frameInContainerCoordinates.isEmpty())
	return nullptr;

	FloatSize scalingRatio = frameInContainerCoordinates.size() / frameInRootViewCoordinates.size();
	auto clippingRectValuesInFrameCoordinates = createNSArray(clippingRectsInFrameCoordinates, [&] (auto rect) {
	rect.scale(scalingRatio);
	return [NSValue valueWithCGRect:rect];
	});

	auto imageView = adoptNS([[UIImageView alloc] initWithImage:image]);
	[imageView setFrame:frameInContainerCoordinates];

	RetainPtr<UIDragPreviewParameters> parameters;
	if ([clippingRectValuesInFrameCoordinates count])
	parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:clippingRectValuesInFrameCoordinates.get()]);
	else
	parameters = adoptNS([[UIDragPreviewParameters alloc] init]);

	if (backgroundColor)
	[parameters setBackgroundColor:backgroundColor];

	if (visiblePath)
	[parameters setVisiblePath:visiblePath];

	CGPoint centerInContainerCoordinates = { CGRectGetMidX(frameInContainerCoordinates), CGRectGetMidY(frameInContainerCoordinates) };
	auto target = adoptNS([[UIDragPreviewTarget alloc] initWithContainer:previewContainer center:centerInContainerCoordinates]);
	return adoptNS([[UITargetedDragPreview alloc] initWithView:imageView.get() parameters:parameters.get() target:target.get()]);
	}

	static RetainPtr<UIImage> uiImageForImage(Image* image)
	{
	if (!image)
	return nullptr;

	auto nativeImage = image->nativeImage();
	if (!nativeImage)
	return nullptr;

	return adoptNS([[UIImage alloc] initWithCGImage:nativeImage->platformImage().get()]);
	}

	static bool shouldUseDragImageToCreatePreviewForDragSource(const DragSourceState& source)
	{
	if (!source.image)
	return false;

	#if ENABLE(INPUT_TYPE_COLOR)
	if (source.action.contains(DragSourceAction::Color))
	return true;
	#endif

	#if ENABLE(MODEL_ELEMENT)
	if (source.action.contains(DragSourceAction::Model))
	return true;
	#endif

	return source.action.containsAny({ DragSourceAction::DHTML, DragSourceAction::Image });
	}

	static bool shouldUseVisiblePathToCreatePreviewForDragSource(const DragSourceState& source)
	{
	if (!source.visiblePath)
	return false;

	#if ENABLE(INPUT_TYPE_COLOR)
	if (source.action.contains(DragSourceAction::Color))
	return true;
	#endif

	return false;
	}

	static bool shouldUseTextIndicatorToCreatePreviewForDragSource(const DragSourceState& source)
	{
	if (!source.indicatorData)
	return false;

	if (source.action.containsAny({ DragSourceAction::Link, DragSourceAction::Selection }))
	return true;

	#if ENABLE(ATTACHMENT_ELEMENT)
	if (source.action.contains(DragSourceAction::Attachment))
	return true;
	#endif

	return false;
	}

	static bool canUpdatePreviewForActiveDragSource(const DragSourceState& source)
	{
	if (!source.possiblyNeedsDragPreviewUpdate)
	return false;

	#if ENABLE(INPUT_TYPE_COLOR)
	if (source.action.contains(DragSourceAction::Color))
	return true;
	#endif

	if (source.action.contains(DragSourceAction::Link) && !source.action.contains(DragSourceAction::Image))
	return true;

	return false;
	}

	std::optional<DragSourceState> DragDropInteractionState::activeDragSourceForItem(UIDragItem *item) const
	{
	if (![item.privateLocalContext isKindOfClass:[NSNumber class]])
	return std::nullopt;

	auto identifier = [(NSNumber *)item.privateLocalContext integerValue];
	for (auto& source : m_activeDragSources) {
	if (source.itemIdentifier == identifier)
	return source;
	}
	return std::nullopt;
	}

	bool DragDropInteractionState::anyActiveDragSourceIs(WebCore::DragSourceAction action) const
	{
	for (auto& source : m_activeDragSources) {
	if (source.action.contains(action))
	return true;
	}
	return false;
	}

	void DragDropInteractionState::prepareForDragSession(id <UIDragSession> session, dispatch_block_t completionHandler)
	{
	m_dragSession = session;
	m_dragStartCompletionBlock = completionHandler;
	}

	void DragDropInteractionState::dragSessionWillBegin()
	{
	m_didBeginDragging = true;
	updatePreviewsForActiveDragSources();
	}

	void DragDropInteractionState::setDefaultDropPreview(UIDragItem item, UITargetedDragPreview preview)
	{
	m_defaultDropPreviews.append({ item, preview });
	}

	UITargetedDragPreview DragDropInteractionState::defaultDropPreview(UIDragItem item) const
	{
	auto matchIndex = m_defaultDropPreviews.findIf([&] (auto& itemAndPreview) {
	return itemAndPreview.item == item;
	});
	return matchIndex == notFound ? nil : m_defaultDropPreviews[matchIndex].preview.get();
	}

	BlockPtr<void(UITargetedDragPreview )> DragDropInteractionState::dropPreviewProvider(UIDragItem item)
	{
	auto matchIndex = m_delayedItemPreviewProviders.findIf([&] (auto& itemAndProvider) {
	return itemAndProvider.item == item;
	});

	if (matchIndex == notFound)
	return nil;

	return m_delayedItemPreviewProviders[matchIndex].provider;
	}

	void DragDropInteractionState::prepareForDelayedDropPreview(UIDragItem item, void(^provider)(UITargetedDragPreview preview))
	{
	m_delayedItemPreviewProviders.append({ item, provider });
	}

	void DragDropInteractionState::deliverDelayedDropPreview(UIView contentView, UIView previewContainer, const WebCore::TextIndicatorData& indicator)
	{
	if (m_delayedItemPreviewProviders.isEmpty())
	return;

	auto textIndicatorImage = uiImageForImage(indicator.contentImage.get());
	auto preview = createTargetedDragPreview(textIndicatorImage.get(), contentView, previewContainer, indicator.textBoundingRectInRootViewCoordinates, indicator.textRectsInBoundingRectCoordinates, cocoaColor(indicator.estimatedBackgroundColor).get(), nil);
	for (auto& itemAndPreviewProvider : m_delayedItemPreviewProviders)
	itemAndPreviewProvider.provider(preview.get());
	m_delayedItemPreviewProviders.clear();
	}

	void DragDropInteractionState::deliverDelayedDropPreview(UIView contentView, CGRect unobscuredContentRect, NSArray<UIDragItem > *items, const Vector<IntRect>& placeholderRects)
	{
	if (items.count != placeholderRects.size()) {
	RELEASE_LOG(DragAndDrop, "Failed to animate image placeholders: number of drag items (%tu) does not match number of placeholders (%tu)", items.count, placeholderRects.size());
	clearAllDelayedItemPreviewProviders();
	return;
	}

	for (size_t i = 0; i < placeholderRects.size(); ++i) {
	UIDragItem *item = [items objectAtIndex:i];
	auto& placeholderRect = placeholderRects[i];
	auto provider = dropPreviewProvider(item);
	if (!provider)
	continue;

	auto defaultPreview = defaultDropPreview(item);
	auto defaultPreviewSize = [defaultPreview size];
	if (!defaultPreview \|\| defaultPreviewSize.width <= 0 \|\| defaultPreviewSize.height <= 0 \|\| placeholderRect.isEmpty()) {
	provider(nil);
	continue;
	}

	FloatRect previewIntersectionRect = enclosingIntRect(CGRectIntersection(unobscuredContentRect, placeholderRect));
	if (previewIntersectionRect.isEmpty()) {
	// If the preview rect is completely offscreen, don't bother trying to clip out or scale the default preview;
	// simply retarget the default preview.
	auto target = adoptNS([[UIDragPreviewTarget alloc] initWithContainer:contentView center:placeholderRect.center()]);
	provider([defaultPreview retargetedPreviewWithTarget:target.get()]);
	continue;
	}

	// Targeted previews don't clip to the bounds of any enclosing view; this means that when targeting previews outside
	// the visible bounds of the content view, the preview will spill out the web view. This is most noticeable when
	// dropping a tall image into Mail compose on iOS 13, where the bottom of the compose window is not flush against
	// the bottom of the window. To mitigate this, we use the preview target's `visiblePath` property to clip the default
	// drop preview's view, by the same proportion that the final placeholder image is clipped (with respect to the
	// unobscured content rect).
	auto previewBounds = [defaultPreview view].bounds;
	auto insetPreviewBounds = UIEdgeInsetsInsetRect(previewBounds, {
	(previewIntersectionRect.y() - placeholderRect.y()) / placeholderRect.height() * previewBounds.size.height,
	(previewIntersectionRect.x() - placeholderRect.x()) / placeholderRect.width() * previewBounds.size.width,
	(placeholderRect.maxY() - previewIntersectionRect.maxY()) / placeholderRect.height() * previewBounds.size.height,
	(placeholderRect.maxX() - previewIntersectionRect.maxX()) / placeholderRect.width() * previewBounds.size.width
	});

	auto transform = CGAffineTransformMakeScale(placeholderRect.width() / defaultPreviewSize.width, placeholderRect.height() / defaultPreviewSize.height);
	auto target = adoptNS([[UIDragPreviewTarget alloc] initWithContainer:contentView center:previewIntersectionRect.center() transform:transform]);
	[defaultPreview parameters].visiblePath = [UIBezierPath bezierPathWithRect:insetPreviewBounds];
	auto newPreview = adoptNS([[UITargetedDragPreview alloc] initWithView:[defaultPreview view] parameters:[defaultPreview parameters] target:target.get()]);
	provider(newPreview.get());
	}

	m_delayedItemPreviewProviders.clear();
	}

	void DragDropInteractionState::clearAllDelayedItemPreviewProviders()
	{
	for (auto& itemAndPreviewProvider : m_delayedItemPreviewProviders)
	itemAndPreviewProvider.provider(nil);
	m_delayedItemPreviewProviders.clear();
	}

	UITargetedDragPreview DragDropInteractionState::previewForDragItem(UIDragItem item, UIView contentView, UIView previewContainer) const
	{
	auto foundSource = activeDragSourceForItem(item);
	if (!foundSource)
	return nil;

	auto& source = foundSource.value();
	if (shouldUseDragImageToCreatePreviewForDragSource(source)) {
	if (shouldUseVisiblePathToCreatePreviewForDragSource(source)) {
	auto path = source.visiblePath.value();
	UIBezierPath *visiblePath = [UIBezierPath bezierPathWithCGPath:path.ensurePlatformPath()];
	return createTargetedDragPreview(source.image.get(), contentView, previewContainer, source.dragPreviewFrameInRootViewCoordinates, { }, nil, visiblePath).autorelease();
	}
	return createTargetedDragPreview(source.image.get(), contentView, previewContainer, source.dragPreviewFrameInRootViewCoordinates, { }, nil, nil).autorelease();
	}

	if (shouldUseTextIndicatorToCreatePreviewForDragSource(source)) {
	auto indicator = source.indicatorData.value();
	auto textIndicatorImage = uiImageForImage(indicator.contentImage.get());
	return createTargetedDragPreview(textIndicatorImage.get(), contentView, previewContainer, indicator.textBoundingRectInRootViewCoordinates, indicator.textRectsInBoundingRectCoordinates, cocoaColor(indicator.estimatedBackgroundColor).get(), nil).autorelease();
	}

	return nil;
	}

	void DragDropInteractionState::dragSessionWillDelaySetDownAnimation(dispatch_block_t completion)
	{
	m_dragCancelSetDownBlock = completion;
	}

	bool DragDropInteractionState::shouldRequestAdditionalItemForDragSession(id <UIDragSession> session) const
	{
	return m_dragSession == session && !m_addDragItemCompletionBlock && !m_dragStartCompletionBlock;
	}

	void DragDropInteractionState::dragSessionWillRequestAdditionalItem(void (^completion)(NSArray <UIDragItem > ))
	{
	clearStagedDragSource();
	m_addDragItemCompletionBlock = completion;
	}

	void DragDropInteractionState::dropSessionDidEnterOrUpdate(id <UIDropSession> session, const DragData& dragData)
	{
	m_dropSession = session;
	m_lastGlobalPosition = dragData.globalPosition();
	}

	void DragDropInteractionState::stageDragItem(const DragItem& item, UIImage *dragImage)
	{
	static NSInteger currentDragSourceItemIdentifier = 0;

	m_adjustedPositionForDragEnd = item.eventPositionInContentCoordinates;
	m_stagedDragSource = {{
	item.sourceAction,
	item.eventPositionInContentCoordinates,
	item.dragPreviewFrameInRootViewCoordinates,
	dragImage,
	item.image.indicatorData(),
	item.image.visiblePath(),
	item.title.isEmpty() ? nil : (NSString *)item.title,
	item.url.isEmpty() ? nil : (NSURL *)item.url,
	true, // We assume here that drag previews need to be updated until proven otherwise in updatePreviewsForActiveDragSources().
	++currentDragSourceItemIdentifier
	}};
	}

	bool DragDropInteractionState::hasStagedDragSource() const
	{
	return m_stagedDragSource && !stagedDragSource().action.isEmpty();
	}

	void DragDropInteractionState::clearStagedDragSource(DidBecomeActive didBecomeActive)
	{
	if (didBecomeActive == DidBecomeActive::Yes)
	m_activeDragSources.append(stagedDragSource());
	m_stagedDragSource = std::nullopt;
	}

	void DragDropInteractionState::dragAndDropSessionsDidEnd()
	{
	clearAllDelayedItemPreviewProviders();

	// If any of UIKit's completion blocks are still in-flight when the drag interaction ends, we need to ensure that they are still invoked
	// to prevent UIKit from getting into an inconsistent state.
	if (auto completionBlock = takeDragCancelSetDownBlock())
	completionBlock();

	if (auto completionBlock = takeAddDragItemCompletionBlock())
	completionBlock(@[ ]);

	if (auto completionBlock = takeDragStartCompletionBlock())
	completionBlock();
	}

	void DragDropInteractionState::updatePreviewsForActiveDragSources()
	{
	for (auto& source : m_activeDragSources) {
	if (!canUpdatePreviewForActiveDragSource(source))
	continue;

	UIDragItem *dragItem = dragItemMatchingIdentifier(m_dragSession.get(), source.itemIdentifier);
	if (!dragItem)
	continue;

	if (source.action.contains(DragSourceAction::Link)) {
	dragItem.previewProvider = [title = retainPtr((NSString )source.linkTitle), url = retainPtr((NSURL )source.linkURL), center = source.adjustedOrigin] () -> UIDragPreview * {
	UIURLDragPreviewView *previewView = [UIURLDragPreviewView viewWithTitle:title.get() URL:url.get()];
	previewView.center = center;
	auto parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:@[ [NSValue valueWithCGRect:previewView.bounds] ]]);
	return adoptNS([[UIDragPreview alloc] initWithView:previewView parameters:parameters.get()]).autorelease();
	};
	}
	#if ENABLE(INPUT_TYPE_COLOR)
	else if (source.action.contains(DragSourceAction::Color)) {
	dragItem.previewProvider = [image = source.image] () -> UIDragPreview * {
	auto imageView = adoptNS([[UIImageView alloc] initWithImage:image.get()]);
	auto parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:@[ [NSValue valueWithCGRect:[imageView bounds]] ]]);
	return adoptNS([[UIDragPreview alloc] initWithView:imageView.get() parameters:parameters.get()]).autorelease();
	};
	}
	#endif

	source.possiblyNeedsDragPreviewUpdate = false;
	}
	}

	} // namespace WebKit

	#endif // PLATFORM(IOS_FAMILY) && ENABLE(DRAG_SUPPORT)