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      1 /*
      2  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * 1. Redistributions of source code must retain the above
      9  *    copyright notice, this list of conditions and the following
     10  *    disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above
     12  *    copyright notice, this list of conditions and the following
     13  *    disclaimer in the documentation and/or other materials
     14  *    provided with the distribution.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     19  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     20  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
     21  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
     23  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     25  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
     27  * OF THE POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include "config.h"
     31 #include "core/rendering/shapes/RasterShape.h"
     32 
     33 #include "wtf/MathExtras.h"
     34 
     35 namespace blink {
     36 
     37 class MarginIntervalGenerator {
     38 public:
     39     MarginIntervalGenerator(unsigned radius);
     40     void set(int y, const IntShapeInterval&);
     41     IntShapeInterval intervalAt(int y) const;
     42 
     43 private:
     44     Vector<int> m_xIntercepts;
     45     int m_y;
     46     int m_x1;
     47     int m_x2;
     48 };
     49 
     50 MarginIntervalGenerator::MarginIntervalGenerator(unsigned radius)
     51     : m_y(0)
     52     , m_x1(0)
     53     , m_x2(0)
     54 {
     55     m_xIntercepts.resize(radius + 1);
     56     unsigned radiusSquared = radius * radius;
     57     for (unsigned y = 0; y <= radius; y++)
     58         m_xIntercepts[y] = sqrt(static_cast<double>(radiusSquared - y * y));
     59 }
     60 
     61 void MarginIntervalGenerator::set(int y, const IntShapeInterval& interval)
     62 {
     63     ASSERT(y >= 0 && interval.x1() >= 0);
     64     m_y = y;
     65     m_x1 = interval.x1();
     66     m_x2 = interval.x2();
     67 }
     68 
     69 IntShapeInterval MarginIntervalGenerator::intervalAt(int y) const
     70 {
     71     unsigned xInterceptsIndex = abs(y - m_y);
     72     int dx = (xInterceptsIndex >= m_xIntercepts.size()) ? 0 : m_xIntercepts[xInterceptsIndex];
     73     return IntShapeInterval(m_x1 - dx, m_x2 + dx);
     74 }
     75 
     76 PassOwnPtr<RasterShapeIntervals> RasterShapeIntervals::computeShapeMarginIntervals(int shapeMargin) const
     77 {
     78     int marginIntervalsSize = (offset() > shapeMargin) ? size() : size() - offset() * 2 + shapeMargin * 2;
     79     OwnPtr<RasterShapeIntervals> result = adoptPtr(new RasterShapeIntervals(marginIntervalsSize, std::max(shapeMargin, offset())));
     80     MarginIntervalGenerator marginIntervalGenerator(shapeMargin);
     81 
     82     for (int y = bounds().y(); y < bounds().maxY(); ++y) {
     83         const IntShapeInterval& intervalAtY = intervalAt(y);
     84         if (intervalAtY.isEmpty())
     85             continue;
     86 
     87         marginIntervalGenerator.set(y, intervalAtY);
     88         int marginY0 = std::max(minY(), y - shapeMargin);
     89         int marginY1 = std::min(maxY(), y + shapeMargin + 1);
     90 
     91         for (int marginY = y - 1; marginY >= marginY0; --marginY) {
     92             if (marginY > bounds().y() && intervalAt(marginY).contains(intervalAtY))
     93                 break;
     94             result->intervalAt(marginY).unite(marginIntervalGenerator.intervalAt(marginY));
     95         }
     96 
     97         result->intervalAt(y).unite(marginIntervalGenerator.intervalAt(y));
     98 
     99         for (int marginY = y + 1; marginY < marginY1; ++marginY) {
    100             if (marginY < bounds().maxY() && intervalAt(marginY).contains(intervalAtY))
    101                 break;
    102             result->intervalAt(marginY).unite(marginIntervalGenerator.intervalAt(marginY));
    103         }
    104     }
    105 
    106     result->initializeBounds();
    107     return result.release();
    108 }
    109 
    110 void RasterShapeIntervals::initializeBounds()
    111 {
    112     m_bounds = IntRect();
    113     for (int y = minY(); y < maxY(); ++y) {
    114         const IntShapeInterval& intervalAtY = intervalAt(y);
    115         if (intervalAtY.isEmpty())
    116             continue;
    117         m_bounds.unite(IntRect(intervalAtY.x1(), y, intervalAtY.width(), 1));
    118     }
    119 }
    120 
    121 void RasterShapeIntervals::buildBoundsPath(Path& path) const
    122 {
    123     int maxY = bounds().maxY();
    124     for (int y = bounds().y(); y < maxY; y++) {
    125         if (intervalAt(y).isEmpty())
    126             continue;
    127 
    128         IntShapeInterval extent = intervalAt(y);
    129         int endY = y + 1;
    130         for (; endY < maxY; endY++) {
    131             if (intervalAt(endY).isEmpty() || intervalAt(endY) != extent)
    132                 break;
    133         }
    134         path.addRect(FloatRect(extent.x1(), y, extent.width(), endY - y));
    135         y = endY - 1;
    136     }
    137 }
    138 
    139 const RasterShapeIntervals& RasterShape::marginIntervals() const
    140 {
    141     ASSERT(shapeMargin() >= 0);
    142     if (!shapeMargin())
    143         return *m_intervals;
    144 
    145     int shapeMarginInt = clampToPositiveInteger(ceil(shapeMargin()));
    146     int maxShapeMarginInt = std::max(m_marginRectSize.width(), m_marginRectSize.height()) * sqrtf(2);
    147     if (!m_marginIntervals)
    148         m_marginIntervals = m_intervals->computeShapeMarginIntervals(std::min(shapeMarginInt, maxShapeMarginInt));
    149 
    150     return *m_marginIntervals;
    151 }
    152 
    153 LineSegment RasterShape::getExcludedInterval(LayoutUnit logicalTop, LayoutUnit logicalHeight) const
    154 {
    155     const RasterShapeIntervals& intervals = marginIntervals();
    156     if (intervals.isEmpty())
    157         return LineSegment();
    158 
    159     int y1 = logicalTop;
    160     int y2 = logicalTop + logicalHeight;
    161     ASSERT(y2 >= y1);
    162     if (y2 < intervals.bounds().y() || y1 >= intervals.bounds().maxY())
    163         return LineSegment();
    164 
    165     y1 = std::max(y1, intervals.bounds().y());
    166     y2 = std::min(y2, intervals.bounds().maxY());
    167     IntShapeInterval excludedInterval;
    168 
    169     if (y1 == y2) {
    170         excludedInterval = intervals.intervalAt(y1);
    171     } else {
    172         for (int y = y1; y < y2; y++)
    173             excludedInterval.unite(intervals.intervalAt(y));
    174     }
    175 
    176     // Note: |marginIntervals()| returns end-point exclusive
    177     // intervals. |excludedInterval.x2()| contains the left-most pixel
    178     // offset to the right of the calculated union.
    179     return LineSegment(excludedInterval.x1(), excludedInterval.x2());
    180 }
    181 
    182 } // namespace blink
    183