Source/WebCore/page/FrameSnapshotting.cpp

/*
 * Copyright (C) 2004-2022 Apple Inc. All rights reserved.
 * Copyright (C) 2006 Alexey Proskuryakov (ap@nypop.com)
 * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2013 University of Washington.
 *
 * 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 THE COPYRIGHT HOLDERS AND 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 THE COPYRIGHT
 * HOLDER OR 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.
 */


#include "config.h"
#include "FrameSnapshotting.h"

#include "ColorBlending.h"
#include "Document.h"
#include "FloatRect.h"
#include "Frame.h"
#include "FrameSelection.h"
#include "FrameView.h"
#include "GeometryUtilities.h"
#include "GraphicsContext.h"
#include "ImageBuffer.h"
#include "Page.h"
#include "RenderAncestorIterator.h"
#include "RenderObject.h"
#include "Settings.h"

namespace WebCore {

struct ScopedFramePaintingState {
    ScopedFramePaintingState(Frame& frame, Node* node)
        : frame(frame)
        , node(node)
        , paintBehavior(frame.view()->paintBehavior())
        , backgroundColor(frame.view()->baseBackgroundColor())
    {
        ASSERT(!node || node->renderer());
    }

    ~ScopedFramePaintingState()
    {
        frame.view()->setPaintBehavior(paintBehavior);
        frame.view()->setBaseBackgroundColor(backgroundColor);
        frame.view()->setNodeToDraw(nullptr);
    }

    const Frame& frame;
    const Node* node;
    const OptionSet<PaintBehavior> paintBehavior;
    const Color backgroundColor;
};

RefPtr<ImageBuffer> snapshotFrameRect(Frame& frame, const IntRect& imageRect, SnapshotOptions&& options)
{
    Vector<FloatRect> clipRects;
    return snapshotFrameRectWithClip(frame, imageRect, clipRects, WTFMove(options));
}

RefPtr<ImageBuffer> snapshotFrameRectWithClip(Frame& frame, const IntRect& imageRect, const Vector<FloatRect>& clipRects, SnapshotOptions&& options)
{
    if (!frame.page())
        return nullptr;

    Ref document = *frame.document();
    document->updateLayout();

    FrameView::SelectionInSnapshot shouldIncludeSelection = FrameView::IncludeSelection;
    if (options.flags.contains(SnapshotFlags::ExcludeSelectionHighlighting))
        shouldIncludeSelection = FrameView::ExcludeSelection;

    FrameView::CoordinateSpaceForSnapshot coordinateSpace = FrameView::DocumentCoordinates;
    if (options.flags.contains(SnapshotFlags::InViewCoordinates))
        coordinateSpace = FrameView::ViewCoordinates;

    ScopedFramePaintingState state(frame, nullptr);

    auto paintBehavior = state.paintBehavior;
    if (options.flags.contains(SnapshotFlags::ForceBlackText))
        paintBehavior.add(PaintBehavior::ForceBlackText);
    if (options.flags.contains(SnapshotFlags::PaintSelectionOnly))
        paintBehavior.add(PaintBehavior::SelectionOnly);
    if (options.flags.contains(SnapshotFlags::PaintSelectionAndBackgroundsOnly))
        paintBehavior.add(PaintBehavior::SelectionAndBackgroundsOnly);
    if (options.flags.contains(SnapshotFlags::PaintEverythingExcludingSelection))
        paintBehavior.add(PaintBehavior::ExcludeSelection);

    // Other paint behaviors are set by paintContentsForSnapshot.
    frame.view()->setPaintBehavior(paintBehavior);

    float scaleFactor = frame.page()->deviceScaleFactor();

    if (frame.page()->delegatesScaling())
        scaleFactor *= frame.page()->pageScaleFactor();

    if (options.flags.contains(SnapshotFlags::PaintWithIntegralScaleFactor))
        scaleFactor = ceilf(scaleFactor);

    auto purpose = options.flags.contains(SnapshotFlags::Shareable) ? RenderingPurpose::ShareableSnapshot : RenderingPurpose::Snapshot;
    auto hostWindow = (document->view() && document->view()->root()) ? document->view()->root()->hostWindow() : nullptr;

    auto buffer = ImageBuffer::create(imageRect.size(), purpose, scaleFactor, options.colorSpace, options.pixelFormat, { }, { hostWindow });
    if (!buffer)
        return nullptr;

    buffer->context().translate(-imageRect.location());

    if (!clipRects.isEmpty()) {
        Path clipPath;
        for (auto& rect : clipRects)
            clipPath.addRect(encloseRectToDevicePixels(rect, scaleFactor));
        buffer->context().clipPath(clipPath);
    }

    frame.view()->paintContentsForSnapshot(buffer->context(), imageRect, shouldIncludeSelection, coordinateSpace);
    return buffer;
}

RefPtr<ImageBuffer> snapshotSelection(Frame& frame, SnapshotOptions&& options)
{
    auto& selection = frame.selection();

    if (!selection.isRange())
        return nullptr;

    FloatRect selectionBounds = selection.selectionBounds();

    // It is possible for the selection bounds to be empty; see https://bugs.webkit.org/show_bug.cgi?id=56645.
    if (selectionBounds.isEmpty())
        return nullptr;

    options.flags.add(SnapshotFlags::PaintSelectionOnly);
    return snapshotFrameRect(frame, enclosingIntRect(selectionBounds), WTFMove(options));
}

RefPtr<ImageBuffer> snapshotNode(Frame& frame, Node& node, SnapshotOptions&& options)
{
    if (!node.renderer())
        return nullptr;

    ScopedFramePaintingState state(frame, &node);

    frame.view()->setBaseBackgroundColor(Color::transparentBlack);
    frame.view()->setNodeToDraw(&node);

    LayoutRect topLevelRect;
    return snapshotFrameRect(frame, snappedIntRect(node.renderer()->paintingRootRect(topLevelRect)), WTFMove(options));
}

static bool styleContainsComplexBackground(const RenderStyle& style)
{
    return style.hasBlendMode() || style.hasBackgroundImage() || style.hasBackdropFilter();
}

Color estimatedBackgroundColorForRange(const SimpleRange& range, const Frame& frame)
{
    auto estimatedBackgroundColor = frame.view() ? frame.view()->documentBackgroundColor() : Color::transparentBlack;

    RenderElement* renderer = nullptr;
    auto commonAncestor = commonInclusiveAncestor<ComposedTree>(range);
    while (commonAncestor) {
        if (is<RenderElement>(commonAncestor->renderer())) {
            renderer = downcast<RenderElement>(commonAncestor->renderer());
            break;
        }
        commonAncestor = commonAncestor->parentOrShadowHostElement();
    }
    
    auto boundingRectForRange = enclosingIntRect(unionRectIgnoringZeroRects(RenderObject::absoluteBorderAndTextRects(range, {
        RenderObject::BoundingRectBehavior::RespectClipping,
        RenderObject::BoundingRectBehavior::UseVisibleBounds,
        RenderObject::BoundingRectBehavior::IgnoreTinyRects,
    })));

    Vector<Color> parentRendererBackgroundColors;
    for (auto& ancestor : lineageOfType<RenderElement>(*renderer)) {
        auto absoluteBoundingBox = ancestor.absoluteBoundingBoxRect();
        auto& style = ancestor.style();
        if (!absoluteBoundingBox.contains(boundingRectForRange) || !style.hasBackground())
            continue;

        if (styleContainsComplexBackground(style))
            return estimatedBackgroundColor;

        auto visitedDependentBackgroundColor = style.visitedDependentColor(CSSPropertyBackgroundColor);
        if (visitedDependentBackgroundColor != Color::transparentBlack)
            parentRendererBackgroundColors.append(visitedDependentBackgroundColor);
    }
    parentRendererBackgroundColors.reverse();
    for (const auto& backgroundColor : parentRendererBackgroundColors)
        estimatedBackgroundColor = blendSourceOver(estimatedBackgroundColor, backgroundColor);

    return estimatedBackgroundColor;
}

} // namespace WebCore