1// Copyright (C) 2013 Google Inc. All rights reserved.
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28
29#include "config.h"
30#include "platform/graphics/StrokeData.h"
31#include "wtf/OwnPtr.h"
32#include "wtf/PassOwnPtr.h"
33
34namespace blink {
35
36static const int dashRatio = 3; // Ratio of the length of a dash to its width.
37
38void 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
60void 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
71void 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