third_party/WebKit/Source/web/FindInPageCoordinates.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * 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