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/*
* Copyright (C) 2012 Adobe Systems Incorporated. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
* 2. 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.
*
* 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 HOLDER 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 "core/rendering/shapes/PolygonShape.h"
#include "platform/geometry/LayoutPoint.h"
#include "wtf/MathExtras.h"
namespace WebCore {
static inline FloatSize inwardEdgeNormal(const FloatPolygonEdge& edge)
{
FloatSize edgeDelta = edge.vertex2() - edge.vertex1();
if (!edgeDelta.width())
return FloatSize((edgeDelta.height() > 0 ? -1 : 1), 0);
if (!edgeDelta.height())
return FloatSize(0, (edgeDelta.width() > 0 ? 1 : -1));
float edgeLength = edgeDelta.diagonalLength();
return FloatSize(-edgeDelta.height() / edgeLength, edgeDelta.width() / edgeLength);
}
static inline FloatSize outwardEdgeNormal(const FloatPolygonEdge& edge)
{
return -inwardEdgeNormal(edge);
}
static inline bool overlapsYRange(const FloatRect& rect, float y1, float y2) { return !rect.isEmpty() && y2 >= y1 && y2 >= rect.y() && y1 <= rect.maxY(); }
float OffsetPolygonEdge::xIntercept(float y) const
{
ASSERT(y >= minY() && y <= maxY());
if (vertex1().y() == vertex2().y() || vertex1().x() == vertex2().x())
return minX();
if (y == minY())
return vertex1().y() < vertex2().y() ? vertex1().x() : vertex2().x();
if (y == maxY())
return vertex1().y() > vertex2().y() ? vertex1().x() : vertex2().x();
return vertex1().x() + ((y - vertex1().y()) * (vertex2().x() - vertex1().x()) / (vertex2().y() - vertex1().y()));
}
FloatShapeInterval OffsetPolygonEdge::clippedEdgeXRange(float y1, float y2) const
{
if (!overlapsYRange(y1, y2) || (y1 == maxY() && minY() <= y1) || (y2 == minY() && maxY() >= y2))
return FloatShapeInterval();
if (isWithinYRange(y1, y2))
return FloatShapeInterval(minX(), maxX());
// Clip the edge line segment to the vertical range y1,y2 and then return
// the clipped line segment's horizontal range.
FloatPoint minYVertex;
FloatPoint maxYVertex;
if (vertex1().y() < vertex2().y()) {
minYVertex = vertex1();
maxYVertex = vertex2();
} else {
minYVertex = vertex2();
maxYVertex = vertex1();
}
float xForY1 = (minYVertex.y() < y1) ? xIntercept(y1) : minYVertex.x();
float xForY2 = (maxYVertex.y() > y2) ? xIntercept(y2) : maxYVertex.x();
return FloatShapeInterval(std::min(xForY1, xForY2), std::max(xForY1, xForY2));
}
static float circleXIntercept(float y, float radius)
{
ASSERT(radius > 0);
return radius * sqrt(1 - (y * y) / (radius * radius));
}
static FloatShapeInterval clippedCircleXRange(const FloatPoint& center, float radius, float y1, float y2)
{
if (y1 > center.y() + radius || y2 < center.y() - radius)
return FloatShapeInterval();
if (center.y() >= y1 && center.y() <= y2)
return FloatShapeInterval(center.x() - radius, center.x() + radius);
// Clip the circle to the vertical range y1,y2 and return the extent of the clipped circle's
// projection on the X axis
float xi = circleXIntercept((y2 < center.y() ? y2 : y1) - center.y(), radius);
return FloatShapeInterval(center.x() - xi, center.x() + xi);
}
LayoutRect PolygonShape::shapeMarginLogicalBoundingBox() const
{
FloatRect box = m_polygon.boundingBox();
box.inflate(shapeMargin());
return LayoutRect(box);
}
void PolygonShape::getExcludedIntervals(LayoutUnit logicalTop, LayoutUnit logicalHeight, SegmentList& result) const
{
float y1 = logicalTop.toFloat();
float y2 = logicalTop.toFloat() + logicalHeight.toFloat();
if (m_polygon.isEmpty() || !overlapsYRange(m_polygon.boundingBox(), y1 - shapeMargin(), y2 + shapeMargin()))
return;
Vector<const FloatPolygonEdge*> overlappingEdges;
if (!m_polygon.overlappingEdges(y1 - shapeMargin(), y2 + shapeMargin(), overlappingEdges))
return;
FloatShapeInterval excludedInterval;
for (unsigned i = 0; i < overlappingEdges.size(); i++) {
const FloatPolygonEdge& edge = *(overlappingEdges[i]);
if (edge.maxY() == edge.minY())
continue;
if (!shapeMargin()) {
excludedInterval.unite(OffsetPolygonEdge(edge, FloatSize()).clippedEdgeXRange(y1, y2));
} else {
excludedInterval.unite(OffsetPolygonEdge(edge, outwardEdgeNormal(edge) * shapeMargin()).clippedEdgeXRange(y1, y2));
excludedInterval.unite(OffsetPolygonEdge(edge, inwardEdgeNormal(edge) * shapeMargin()).clippedEdgeXRange(y1, y2));
excludedInterval.unite(clippedCircleXRange(edge.vertex1(), shapeMargin(), y1, y2));
}
}
if (!excludedInterval.isEmpty())
result.append(LineSegment(excludedInterval.x1(), excludedInterval.x2()));
}
void PolygonShape::buildDisplayPaths(DisplayPaths& paths) const
{
if (!m_polygon.numberOfVertices())
return;
paths.shape.moveTo(m_polygon.vertexAt(0));
for (size_t i = 1; i < m_polygon.numberOfVertices(); ++i)
paths.shape.addLineTo(m_polygon.vertexAt(i));
paths.shape.closeSubpath();
}
} // namespace WebCore
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