Bug 781731 - Use a similar surface for non-blurred shadows to improve performance. r=joe

content/canvas/src/nsCanvasRenderingContext2DAzure.cpp

@@ -313,7 +313,7 @@ public:
       
     mTarget =
       mCtx->mTarget->CreateShadowDrawTarget(IntSize(int32_t(mTempRect.width), int32_t(mTempRect.height)),
-                                             FORMAT_B8G8R8A8);
+                                             FORMAT_B8G8R8A8, mSigma);
 
     if (!mTarget) {
       // XXX - Deal with the situation where our temp size is too big to

gfx/2d/2D.h

@@ -729,9 +729,15 @@ public:
 
   /*
    * Create a draw target optimized for drawing a shadow.
+   *
+   * Note that aSigma is the blur radius that must be used when we draw the
+   * shadow. Also note that this doesn't affect the size of the allocated
+   * surface, the caller is still responsible for including the shadow area in
+   * its size.
    */
   virtual TemporaryRef<DrawTarget>
-    CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFormat) const
+    CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFormat,
+                           float aSigma) const
   {
     return CreateSimilarDrawTarget(aSize, aFormat);
   }

gfx/2d/DrawTargetCairo.cpp

@@ -393,16 +393,26 @@ DrawTargetCairo::DrawSurfaceWithShadow(SourceSurface *aSurface,
  
   SourceSurfaceCairo* source = static_cast<SourceSurfaceCairo*>(aSurface);
   cairo_surface_t* sourcesurf = source->GetSurface();
-  cairo_surface_t* blursurf = cairo_tee_surface_index(sourcesurf, 0);
-  cairo_surface_t* surf = cairo_tee_surface_index(sourcesurf, 1);
- 
-  MOZ_ASSERT(cairo_surface_get_type(blursurf) == CAIRO_SURFACE_TYPE_IMAGE);
-  Rect extents(0, 0, width, height);
-  AlphaBoxBlur blur(cairo_image_surface_get_data(blursurf),
-                    extents,
-                    cairo_image_surface_get_stride(blursurf),
-                    aSigma);
-  blur.Blur();
+  cairo_surface_t* blursurf;
+  cairo_surface_t* surf;
+
+  // We only use the A8 surface for blurred shadows. Unblurred shadows can just
+  // use the RGBA surface directly.
+  if (cairo_surface_get_type(sourcesurf) == CAIRO_SURFACE_TYPE_TEE) {
+    blursurf = cairo_tee_surface_index(sourcesurf, 0);
+    surf = cairo_tee_surface_index(sourcesurf, 1);
+
+    MOZ_ASSERT(cairo_surface_get_type(blursurf) == CAIRO_SURFACE_TYPE_IMAGE);
+    Rect extents(0, 0, width, height);
+    AlphaBoxBlur blur(cairo_image_surface_get_data(blursurf),
+                      extents,
+                      cairo_image_surface_get_stride(blursurf),
+                      aSigma);
+    blur.Blur();
+  } else {
+    blursurf = sourcesurf;
+    surf = sourcesurf;
+  }
 
   WillChange();
   ClearSurfaceForUnboundedSource(aOperator);
@@ -792,7 +802,8 @@ DrawTargetCairo::InitAlreadyReferenced(cairo_surface_t* aSurface, const IntSize&
 }
 
 TemporaryRef<DrawTarget>
-DrawTargetCairo::CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFormat) const
+DrawTargetCairo::CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFormat,
+                                        float aSigma) const
 {
   cairo_surface_t* similar = cairo_surface_create_similar(cairo_get_target(mContext),
                                                           GfxFormatToCairoContent(aFormat),
@@ -802,6 +813,14 @@ DrawTargetCairo::CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFor
     return nullptr;
   }
 
+  // If we don't have a blur then we can use the RGBA mask and keep all the
+  // operations in graphics memory.
+  if (aSigma == 0.0F) {
+    RefPtr<DrawTargetCairo> target = new DrawTargetCairo();
+    target->InitAlreadyReferenced(similar, aSize);
+    return target;
+  }
+
   cairo_surface_t* blursurf = cairo_image_surface_create(CAIRO_FORMAT_A8,
                                                          aSize.width,
                                                          aSize.height);

gfx/2d/DrawTargetCairo.h

@@ -116,7 +116,8 @@ public:
   virtual TemporaryRef<DrawTarget>
     CreateSimilarDrawTarget(const IntSize &aSize, SurfaceFormat aFormat) const;
   virtual TemporaryRef<DrawTarget>
-    CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFormat) const;
+    CreateShadowDrawTarget(const IntSize &aSize, SurfaceFormat aFormat,
+                           float aSigma) const;
 
   virtual TemporaryRef<GradientStops>
     CreateGradientStops(GradientStop *aStops,