third_party/WebKit/Source/platform/graphics/StrokeData.cpp

   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,
  22 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  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