third_party/WebKit/Source/web/FindInPageCoordinates.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
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 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * 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
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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#include "web/FindInPageCoordinates.h"

#include "core/dom/Node.h"
#include "core/dom/Range.h"
#include "core/frame/FrameView.h"
#include "core/frame/LocalFrame.h"
#include "core/layout/LayoutBlock.h"
#include "core/layout/LayoutBox.h"
#include "core/layout/LayoutObject.h"
#include "core/layout/LayoutPart.h"
#include "core/layout/LayoutView.h"
#include "core/style/ComputedStyle.h"
#include "platform/geometry/FloatPoint.h"
#include "platform/geometry/FloatQuad.h"
#include "platform/geometry/IntPoint.h"

namespace blink {

static const LayoutBlock* enclosingScrollableAncestor(const LayoutObject* layoutObject)
{
    DCHECK(!layoutObject->isLayoutView());

    // Trace up the containingBlocks until we reach either the layoutObject view or a scrollable object.
    const LayoutBlock* container = layoutObject->containingBlock();
    while (!container->hasOverflowClip() && !container->isLayoutView())
        container = container->containingBlock();
    return container;
}

static FloatRect toNormalizedRect(const FloatRect& absoluteRect, const LayoutObject* layoutObject, const LayoutBlock* container)
{
    DCHECK(layoutObject);

    DCHECK(container || layoutObject->isLayoutView());
    if (!container)
        return FloatRect();

    // We want to normalize by the max layout overflow size instead of only the visible bounding box.
    // Quads and their enclosing bounding boxes need to be used in order to keep results transform-friendly.
    FloatPoint scrolledOrigin;

    // For overflow:scroll we need to get where the actual origin is independently of the scroll.
    if (container->hasOverflowClip())
        scrolledOrigin = -IntPoint(container->scrolledContentOffset());

    FloatRect overflowRect(scrolledOrigin, FloatSize(container->maxLayoutOverflow()));
    FloatRect containerRect = container->localToAbsoluteQuad(FloatQuad(overflowRect)).enclosingBoundingBox();

    if (containerRect.isEmpty())
        return FloatRect();

    // Make the coordinates relative to the container enclosing bounding box.
    // Since we work with rects enclosing quad unions this is still transform-friendly.
    FloatRect normalizedRect = absoluteRect;
    normalizedRect.moveBy(-containerRect.location());

    // Fixed positions do not make sense in this coordinate system, but need to leave consistent tickmarks.
    // So, use their position when the view is not scrolled, like an absolute position.
    if (layoutObject->style()->position() == FixedPosition && container->isLayoutView())
        normalizedRect.moveBy(-toLayoutView(container)->frameView()->scrollPosition());

    normalizedRect.scale(1 / containerRect.width(), 1 / containerRect.height());
    return normalizedRect;
}

FloatRect findInPageRectFromAbsoluteRect(const FloatRect& inputRect, const LayoutObject* baseLayoutObject)
{
    if (!baseLayoutObject || inputRect.isEmpty())
        return FloatRect();

    // Normalize the input rect to its container block.
    const LayoutBlock* baseContainer = enclosingScrollableAncestor(baseLayoutObject);
    FloatRect normalizedRect = toNormalizedRect(inputRect, baseLayoutObject, baseContainer);

    // Go up across frames.
    for (const LayoutBox* layoutObject = baseContainer; layoutObject; ) {

        // Go up the layout tree until we reach the root of the current frame (the LayoutView).
        while (!layoutObject->isLayoutView()) {
            const LayoutBlock* container = enclosingScrollableAncestor(layoutObject);

            // Compose the normalized rects.
            FloatRect normalizedBoxRect = toNormalizedRect(layoutObject->absoluteBoundingBoxRect(), layoutObject, container);
            normalizedRect.scale(normalizedBoxRect.width(), normalizedBoxRect.height());
            normalizedRect.moveBy(normalizedBoxRect.location());

            layoutObject = container;
        }

        DCHECK(layoutObject->isLayoutView());

        // Jump to the layoutObject owning the frame, if any.
        layoutObject = layoutObject->frame() ? layoutObject->frame()->ownerLayoutObject() : 0;
    }

    return normalizedRect;
}

FloatRect findInPageRectFromRange(Range* range)
{
    if (!range || !range->firstNode())
        return FloatRect();

    return findInPageRectFromAbsoluteRect(LayoutObject::absoluteBoundingBoxRectForRange(range), range->firstNode()->layoutObject());
}

} // namespace blink