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/*
* Copyright (C) 2013 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
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Google Inc. nor the names of its
* 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,
* 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 "ViewportAnchor.h"
#include "core/dom/ContainerNode.h"
#include "core/dom/Node.h"
#include "core/page/EventHandler.h"
#include "core/rendering/HitTestResult.h"
using namespace WebCore;
namespace WebKit {
namespace {
static const float viewportAnchorRelativeEpsilon = 0.1f;
static const int viewportToNodeMaxRelativeArea = 2;
template <typename RectType>
int area(const RectType& rect) {
return rect.width() * rect.height();
}
Node* findNonEmptyAnchorNode(const IntPoint& point, const IntRect& viewRect, EventHandler* eventHandler)
{
Node* node = eventHandler->hitTestResultAtPoint(point, HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::DisallowShadowContent).innerNode();
// If the node bounding box is sufficiently large, make a single attempt to
// find a smaller node; the larger the node bounds, the greater the
// variability under resize.
const int maxNodeArea = area(viewRect) * viewportToNodeMaxRelativeArea;
if (node && area(node->boundingBox()) > maxNodeArea) {
IntSize pointOffset = viewRect.size();
pointOffset.scale(viewportAnchorRelativeEpsilon);
node = eventHandler->hitTestResultAtPoint(point + pointOffset, HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::DisallowShadowContent).innerNode();
}
while (node && node->boundingBox().isEmpty())
node = node->parentNode();
return node;
}
} // namespace
ViewportAnchor::ViewportAnchor(EventHandler* eventHandler)
: m_eventHandler(eventHandler) { }
void ViewportAnchor::setAnchor(const IntRect& viewRect, const FloatSize& anchorInViewCoords)
{
m_viewRect = viewRect;
m_anchorNode.clear();
m_anchorNodeBounds = LayoutRect();
m_anchorInNodeCoords = FloatSize();
m_anchorInViewCoords = anchorInViewCoords;
if (viewRect.isEmpty())
return;
// Preserve origins at the absolute screen origin
if (viewRect.location() == IntPoint::zero())
return;
FloatSize anchorOffset = viewRect.size();
anchorOffset.scale(anchorInViewCoords.width(), anchorInViewCoords.height());
const FloatPoint anchorPoint = FloatPoint(viewRect.location()) + anchorOffset;
Node* node = findNonEmptyAnchorNode(flooredIntPoint(anchorPoint), viewRect, m_eventHandler);
if (!node)
return;
m_anchorNode = node;
m_anchorNodeBounds = node->boundingBox();
m_anchorInNodeCoords = anchorPoint - m_anchorNodeBounds.location();
m_anchorInNodeCoords.scale(1.f / m_anchorNodeBounds.width(), 1.f / m_anchorNodeBounds.height());
}
IntPoint ViewportAnchor::computeOrigin(const IntSize& currentViewSize) const
{
if (!m_anchorNode || !m_anchorNode->inDocument())
return m_viewRect.location();
const LayoutRect currentNodeBounds = m_anchorNode->boundingBox();
if (m_anchorNodeBounds == currentNodeBounds)
return m_viewRect.location();
// Compute the new anchor point relative to the node position
FloatSize anchorOffsetFromNode = currentNodeBounds.size();
anchorOffsetFromNode.scale(m_anchorInNodeCoords.width(), m_anchorInNodeCoords.height());
FloatPoint anchorPoint = currentNodeBounds.location() + anchorOffsetFromNode;
// Compute the new origin point relative to the new anchor point
FloatSize anchorOffsetFromOrigin = currentViewSize;
anchorOffsetFromOrigin.scale(m_anchorInViewCoords.width(), m_anchorInViewCoords.height());
return flooredIntPoint(anchorPoint - anchorOffsetFromOrigin);
}
} // namespace WebKit
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