Bug 1058040, part 7 - Make SVGContextPaint a ref counted class. r=dholbert

gfx/thebes/gfxFont.cpp

@@ -2073,15 +2073,15 @@ gfxFont::Draw(const gfxTextRun *aTextRun, uint32_t aStart, uint32_t aEnd,
         aRunParams.context->SetMatrix(mat);
     }
 
-    UniquePtr<SVGContextPaint> contextPaint;
+    RefPtr<SVGContextPaint> contextPaint;
     if (fontParams.haveSVGGlyphs && !fontParams.contextPaint) {
         // If no pattern is specified for fill, use the current pattern
         NS_ASSERTION((int(aRunParams.drawMode) & int(DrawMode::GLYPH_STROKE)) == 0,
                      "no pattern supplied for stroking text");
         RefPtr<gfxPattern> fillPattern = aRunParams.context->GetPattern();
-        contextPaint.reset(
+        contextPaint =
             new SimpleTextContextPaint(fillPattern, nullptr,
-                                       aRunParams.context->CurrentMatrix()));
+                                       aRunParams.context->CurrentMatrix());
         fontParams.contextPaint = contextPaint.get();
     }
 

layout/svg/SVGContextPaint.h

@@ -32,8 +32,17 @@ namespace mozilla {
  * computed style for the text that is being drawn, for example, or for color
  * in an SVG embedded by an <img> element to come from the embedding <img>
  * element.
+ *
+ * This class is reference counted so that it can be shared among many similar
+ * SVGImageContext objects. (SVGImageContext objects are frequently
+ * copy-constructed with small modifications, and we'd like for those copies to
+ * be able to share their context-paint data cheaply.)  However, in most cases,
+ * SVGContextPaint instances are stored in a local RefPtr and only last for the
+ * duration of a function call.
+ * XXX Note: SVGImageContext doesn't actually have a SVGContextPaint member yet,
+ * but it will in a later patch in the patch series that added this comment.
  */
-class SVGContextPaint
+class SVGContextPaint : public RefCounted<SVGContextPaint>
 {
 protected:
   typedef mozilla::gfx::DrawTarget DrawTarget;
@@ -41,6 +50,8 @@ protected:
   SVGContextPaint() {}
 
 public:
+  MOZ_DECLARE_REFCOUNTED_TYPENAME(SVGContextPaint)
+
   virtual ~SVGContextPaint() {}
 
   virtual already_AddRefed<gfxPattern> GetFillPattern(const DrawTarget* aDrawTarget,

layout/svg/SVGTextFrame.cpp

@@ -3657,10 +3657,10 @@ SVGTextFrame::PaintSVG(gfxContext& aContext,
     // when they use context-fill etc.
     aContext.SetMatrix(initialMatrix);
 
-    SVGContextPaintImpl contextPaint;
-    DrawMode drawMode = contextPaint.Init(&aDrawTarget,
-                                          aContext.CurrentMatrix(),
-                                          frame, outerContextPaint);
+    RefPtr<SVGContextPaintImpl> contextPaint = new SVGContextPaintImpl();
+    DrawMode drawMode = contextPaint->Init(&aDrawTarget,
+                                           aContext.CurrentMatrix(),
+                                           frame, outerContextPaint);
 
     if (drawMode & DrawMode::GLYPH_STROKE) {
       // This may change the gfxContext's transform (for non-scaling stroke),
@@ -3681,7 +3681,7 @@ SVGTextFrame::PaintSVG(gfxContext& aContext,
       params.framePt = gfxPoint();
       params.dirtyRect = LayoutDevicePixel::
         FromAppUnits(frame->GetVisualOverflowRect(), auPerDevPx);
-      params.contextPaint = &contextPaint;
+      params.contextPaint = contextPaint;
       if (ShouldRenderAsPath(frame, paintSVGGlyphs)) {
         SVGTextDrawPathCallbacks callbacks(&rendCtx, frame,
                                            matrixForPaintServers,