Bug 740963 - [Skia] Handle non-multiple-of-two dash lengths in HelpersSkia::StrokeOptionsToPaint(). r=jrmuizel

gfx/2d/HelpersSkia.h

@@ -118,22 +118,29 @@ StrokeOptionsToPaint(SkPaint& aPaint, const StrokeOptions &aOptions)
   aPaint.setStrokeCap(CapStyleToSkiaCap(aOptions.mLineCap));
   aPaint.setStrokeJoin(JoinStyleToSkiaJoin(aOptions.mLineJoin));
 
-  // XXX: According to the webkit code skia seems to only
+  if (aOptions.mDashLength > 0) {
-  // support dash arrays that are multiples of 2. Therefor,
+    // Skia only supports dash arrays that are multiples of 2.
-  // We need to double the array when % 2 != 0
+    uint32_t dashCount;
-  MOZ_ASSERT(aOptions.mDashLength % 2 == 0);
+
-  if (aOptions.mDashLength > 1) {
+    if (aOptions.mDashLength % 2 == 0) {
+      dashCount = aOptions.mDashLength;
+    } else {
+      dashCount = aOptions.mDashLength * 2;
+    }
+
     std::vector<SkScalar> pattern;
-    pattern.resize(aOptions.mDashLength);
+    pattern.resize(dashCount);
-    for (uint32_t i = 0; i < aOptions.mDashLength; i++) {
+
-      pattern[i] = SkFloatToScalar(aOptions.mDashPattern[i]);
+    for (uint32_t i = 0; i < dashCount; i++) {
+      pattern[i] = SkFloatToScalar(aOptions.mDashPattern[i % aOptions.mDashLength]);
     }
 
     SkDashPathEffect* dash = new SkDashPathEffect(&pattern.front(),
-                                                  aOptions.mDashLength, 
+                                                  dashCount, 
                                                   SkFloatToScalar(aOptions.mDashOffset));
     SkSafeUnref(aPaint.setPathEffect(dash));
   }
+
   aPaint.setStyle(SkPaint::kStroke_Style);
   return true;
 }