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126 lines
4.9 KiB
C++
126 lines
4.9 KiB
C++
/*
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* Copyright (C) 2013 Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include "web/ViewportAnchor.h"
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#include "core/dom/ContainerNode.h"
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#include "core/dom/Node.h"
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#include "core/page/EventHandler.h"
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#include "core/rendering/HitTestResult.h"
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namespace blink {
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namespace {
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static const float viewportAnchorRelativeEpsilon = 0.1f;
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static const int viewportToNodeMaxRelativeArea = 2;
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template <typename RectType>
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int area(const RectType& rect) {
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return rect.width() * rect.height();
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}
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Node* findNonEmptyAnchorNode(const IntPoint& point, const IntRect& viewRect, EventHandler* eventHandler)
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{
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Node* node = eventHandler->hitTestResultAtPoint(point, HitTestRequest::ReadOnly | HitTestRequest::Active).innerNode();
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// If the node bounding box is sufficiently large, make a single attempt to
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// find a smaller node; the larger the node bounds, the greater the
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// variability under resize.
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const int maxNodeArea = area(viewRect) * viewportToNodeMaxRelativeArea;
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if (node && area(node->boundingBox()) > maxNodeArea) {
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IntSize pointOffset = viewRect.size();
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pointOffset.scale(viewportAnchorRelativeEpsilon);
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node = eventHandler->hitTestResultAtPoint(point + pointOffset, HitTestRequest::ReadOnly | HitTestRequest::Active).innerNode();
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}
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while (node && node->boundingBox().isEmpty())
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node = node->parentNode();
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return node;
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}
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} // namespace
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ViewportAnchor::ViewportAnchor(EventHandler* eventHandler)
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: m_eventHandler(eventHandler) { }
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void ViewportAnchor::setAnchor(const IntRect& viewRect, const FloatSize& anchorInViewCoords)
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{
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m_viewRect = viewRect;
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m_anchorNode.clear();
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m_anchorNodeBounds = LayoutRect();
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m_anchorInNodeCoords = FloatSize();
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m_anchorInViewCoords = anchorInViewCoords;
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if (viewRect.isEmpty())
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return;
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// Preserve origins at the absolute screen origin
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if (viewRect.location() == IntPoint::zero())
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return;
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FloatSize anchorOffset = viewRect.size();
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anchorOffset.scale(anchorInViewCoords.width(), anchorInViewCoords.height());
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const FloatPoint anchorPoint = FloatPoint(viewRect.location()) + anchorOffset;
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Node* node = findNonEmptyAnchorNode(flooredIntPoint(anchorPoint), viewRect, m_eventHandler);
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if (!node)
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return;
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m_anchorNode = node;
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m_anchorNodeBounds = node->boundingBox();
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m_anchorInNodeCoords = anchorPoint - m_anchorNodeBounds.location();
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m_anchorInNodeCoords.scale(1.f / m_anchorNodeBounds.width(), 1.f / m_anchorNodeBounds.height());
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}
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IntPoint ViewportAnchor::computeOrigin(const IntSize& currentViewSize) const
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{
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if (!m_anchorNode || !m_anchorNode->inDocument())
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return m_viewRect.location();
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const LayoutRect currentNodeBounds = m_anchorNode->boundingBox();
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if (m_anchorNodeBounds == currentNodeBounds)
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return m_viewRect.location();
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// Compute the new anchor point relative to the node position
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FloatSize anchorOffsetFromNode = currentNodeBounds.size();
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anchorOffsetFromNode.scale(m_anchorInNodeCoords.width(), m_anchorInNodeCoords.height());
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FloatPoint anchorPoint = currentNodeBounds.location() + anchorOffsetFromNode;
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// Compute the new origin point relative to the new anchor point
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FloatSize anchorOffsetFromOrigin = currentViewSize;
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anchorOffsetFromOrigin.scale(m_anchorInViewCoords.width(), m_anchorInViewCoords.height());
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return flooredIntPoint(anchorPoint - anchorOffsetFromOrigin);
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}
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} // namespace blink
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