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      1 // Copyright (C) 2013 Google Inc. All rights reserved.
      2 //
      3 // Redistribution and use in source and binary forms, with or without
      4 // modification, are permitted provided that the following conditions are
      5 // met:
      6 //
      7 //    * Redistributions of source code must retain the above copyright
      8 // notice, this list of conditions and the following disclaimer.
      9 //    * Redistributions in binary form must reproduce the above
     10 // copyright notice, this list of conditions and the following disclaimer
     11 // in the documentation and/or other materials provided with the
     12 // distribution.
     13 //    * Neither the name of Google Inc. nor the names of its
     14 // contributors may be used to endorse or promote products derived from
     15 // this software without specific prior written permission.
     16 //
     17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     18 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     19 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     20 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     21 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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     23 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     24 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     25 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     26 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     27 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28 
     29 #include "config.h"
     30 #include "platform/graphics/StrokeData.h"
     31 #include "wtf/OwnPtr.h"
     32 #include "wtf/PassOwnPtr.h"
     33 
     34 namespace blink {
     35 
     36 static const int dashRatio = 3; // Ratio of the length of a dash to its width.
     37 
     38 void StrokeData::setLineDash(const DashArray& dashes, float dashOffset)
     39 {
     40     // FIXME: This is lifted directly off SkiaSupport, lines 49-74
     41     // so it is not guaranteed to work correctly.
     42     size_t dashLength = dashes.size();
     43     if (!dashLength) {
     44         // If no dash is set, revert to solid stroke
     45         // FIXME: do we need to set NoStroke in some cases?
     46         m_style = SolidStroke;
     47         m_dash.clear();
     48         return;
     49     }
     50 
     51     size_t count = !(dashLength % 2) ? dashLength : dashLength * 2;
     52     OwnPtr<SkScalar[]> intervals = adoptArrayPtr(new SkScalar[count]);
     53 
     54     for (unsigned i = 0; i < count; i++)
     55         intervals[i] = dashes[i % dashLength];
     56 
     57     m_dash = adoptRef(SkDashPathEffect::Create(intervals.get(), count, dashOffset));
     58 }
     59 
     60 void StrokeData::setupPaint(SkPaint* paint, int length) const
     61 {
     62     paint->setStyle(SkPaint::kStroke_Style);
     63     paint->setStrokeWidth(SkFloatToScalar(m_thickness));
     64     paint->setStrokeCap(m_lineCap);
     65     paint->setStrokeJoin(m_lineJoin);
     66     paint->setStrokeMiter(SkFloatToScalar(m_miterLimit));
     67 
     68     setupPaintDashPathEffect(paint, length);
     69 }
     70 
     71 void StrokeData::setupPaintDashPathEffect(SkPaint* paint, int length) const
     72 {
     73     float width = m_thickness;
     74     if (m_dash) {
     75         paint->setPathEffect(m_dash.get());
     76     } else {
     77         switch (m_style) {
     78         case NoStroke:
     79         case SolidStroke:
     80         case DoubleStroke:
     81         case WavyStroke: // FIXME: https://code.google.com/p/chromium/issues/detail?id=229574
     82             paint->setPathEffect(0);
     83             return;
     84         case DashedStroke:
     85             width = dashRatio * width;
     86             // Fall through.
     87         case DottedStroke:
     88             // Truncate the width, since we don't want fuzzy dots or dashes.
     89             int dashLength = static_cast<int>(width);
     90             // Subtract off the endcaps, since they're rendered separately.
     91             int distance = length - 2 * static_cast<int>(m_thickness);
     92             int phase = 1;
     93             if (dashLength > 1) {
     94                 // Determine how many dashes or dots we should have.
     95                 int numDashes = distance / dashLength;
     96                 int remainder = distance % dashLength;
     97                 // Adjust the phase to center the dashes within the line.
     98                 if (numDashes % 2) {
     99                     // Odd: shift right a full dash, minus half the remainder.
    100                     phase = dashLength - remainder / 2;
    101                 } else {
    102                     // Even: shift right half a dash, minus half the remainder.
    103                     phase = (dashLength - remainder) / 2;
    104                 }
    105             }
    106             SkScalar dashLengthSk = SkIntToScalar(dashLength);
    107             SkScalar intervals[2] = { dashLengthSk, dashLengthSk };
    108             RefPtr<SkDashPathEffect> pathEffect = adoptRef(SkDashPathEffect::Create(intervals, 2, SkIntToScalar(phase)));
    109             paint->setPathEffect(pathEffect.get());
    110         }
    111     }
    112 }
    113 
    114 } // namespace blink
    115