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/*
* 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
* 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 "TouchDisambiguation.h"
#include "Document.h"
#include "Element.h"
#include "Frame.h"
#include "FrameView.h"
#include "HTMLNames.h"
#include "HitTestResult.h"
#include "NodeTraversal.h"
#include "RenderBlock.h"
#include <algorithm>
#include <cmath>
using namespace std;
namespace WebCore {
static IntRect boundingBoxForEventNodes(Node* eventNode)
{
if (!eventNode->document()->view())
return IntRect();
IntRect result;
Node* node = eventNode;
while (node) {
// Skip the whole sub-tree if the node doesn't propagate events.
if (node != eventNode && node->willRespondToMouseClickEvents()) {
node = NodeTraversal::nextSkippingChildren(node, eventNode);
continue;
}
result.unite(node->pixelSnappedBoundingBox());
node = NodeTraversal::next(node, eventNode);
}
return eventNode->document()->view()->contentsToWindow(result);
}
static float scoreTouchTarget(IntPoint touchPoint, int padding, IntRect boundingBox)
{
if (boundingBox.isEmpty())
return 0;
float reciprocalPadding = 1.f / padding;
float score = 1;
IntSize distance = boundingBox.differenceToPoint(touchPoint);
score *= max((padding - abs(distance.width())) * reciprocalPadding, 0.f);
score *= max((padding - abs(distance.height())) * reciprocalPadding, 0.f);
return score;
}
struct TouchTargetData {
IntRect windowBoundingBox;
float score;
};
void findGoodTouchTargets(const IntRect& touchBox, Frame* mainFrame, Vector<IntRect>& goodTargets)
{
goodTargets.clear();
int touchPointPadding = ceil(max(touchBox.width(), touchBox.height()) * 0.5);
// FIXME: Rect-based hit test doesn't transform the touch point size.
// We have to pre-apply frame scale factor here.
int padding = ceil(touchPointPadding / mainFrame->frameScaleFactor());
IntPoint touchPoint = touchBox.center();
IntPoint contentsPoint = mainFrame->view()->windowToContents(touchPoint);
HitTestResult result = mainFrame->eventHandler()->hitTestResultAtPoint(contentsPoint, HitTestRequest::ReadOnly | HitTestRequest::Active | HitTestRequest::DisallowShadowContent, IntSize(padding, padding));
const ListHashSet<RefPtr<Node> >& hitResults = result.rectBasedTestResult();
// Blacklist nodes that are container of disambiguated nodes.
// It is not uncommon to have a clickable <div> that contains other clickable objects.
// This heuristic avoids excessive disambiguation in that case.
HashSet<Node*> blackList;
for (ListHashSet<RefPtr<Node> >::const_iterator it = hitResults.begin(); it != hitResults.end(); ++it) {
// Ignore any Nodes that can't be clicked on.
RenderObject* renderer = it->get()->renderer();
if (!renderer || !it->get()->willRespondToMouseClickEvents())
continue;
// Blacklist all of the Node's containers.
for (RenderBlock* container = renderer->containingBlock(); container; container = container->containingBlock()) {
Node* containerNode = container->node();
if (!containerNode)
continue;
if (!blackList.add(containerNode).isNewEntry)
break;
}
}
HashMap<Node*, TouchTargetData> touchTargets;
float bestScore = 0;
for (ListHashSet<RefPtr<Node> >::const_iterator it = hitResults.begin(); it != hitResults.end(); ++it) {
for (Node* node = it->get(); node; node = node->parentNode()) {
if (blackList.contains(node))
continue;
if (node->isDocumentNode() || node->hasTagName(HTMLNames::htmlTag) || node->hasTagName(HTMLNames::bodyTag))
break;
if (node->willRespondToMouseClickEvents()) {
TouchTargetData& targetData = touchTargets.add(node, TouchTargetData()).iterator->value;
targetData.windowBoundingBox = boundingBoxForEventNodes(node);
targetData.score = scoreTouchTarget(touchPoint, touchPointPadding, targetData.windowBoundingBox);
bestScore = max(bestScore, targetData.score);
break;
}
}
}
for (HashMap<Node*, TouchTargetData>::iterator it = touchTargets.begin(); it != touchTargets.end(); ++it) {
// Currently the scoring function uses the overlap area with the fat point as the score.
// We ignore the candidates that has less than 1/2 overlap (we consider not really ambiguous enough) than the best candidate to avoid excessive popups.
if (it->value.score < bestScore * 0.5)
continue;
goodTargets.append(it->value.windowBoundingBox);
}
}
} // namespace WebCore