Bug 927892 - Resolve the parsed canvas filter to a FilterDescription. r=roc

--HG--
extra : rebase_source : 46fa0017ccc4ee3ab2e0edcf143703cf0100d422

dom/canvas/CanvasRenderingContext2D.cpp

@@ -102,6 +102,8 @@
 #include "SVGContentUtils.h"
 #include "SVGImageContext.h"
 #include "nsIScreenManager.h"
+#include "nsFilterInstance.h"
+#include "nsSVGLength2.h"
 
 #undef free // apparently defined by some windows header, clashing with a free()
             // method in SkTypes.h
@@ -1858,9 +1860,47 @@ CanvasRenderingContext2D::SetFilter(const nsAString& filter, ErrorResult& error)
   if (ParseFilter(filter, filterChain, error)) {
     CurrentState().filterString = filter;
     filterChain.SwapElements(CurrentState().filterChain);
+    if (mCanvasElement) {
+      UpdateFilter();
+    }
   }
 }
 
+class CanvasUserSpaceMetrics : public UserSpaceMetricsWithSize
+{
+public:
+  CanvasUserSpaceMetrics(const gfx::IntSize& aSize)
+    : mSize(aSize)
+  {
+  }
+
+  virtual float GetEmLength() const MOZ_OVERRIDE
+  { return 10.0f; }
+  virtual float GetExLength() const MOZ_OVERRIDE
+  { return 10.0f; }
+  virtual gfx::Size GetSize() const MOZ_OVERRIDE
+  { return Size(mSize); }
+
+private:
+  gfx::IntSize mSize;
+};
+
+void
+CanvasRenderingContext2D::UpdateFilter()
+{
+  nsIPresShell* presShell = GetPresShell();
+  if (!presShell || presShell->IsDestroying()) {
+    return;
+  }
+
+  CurrentState().filter =
+    nsFilterInstance::GetFilterDescription(mCanvasElement,
+      CurrentState().filterChain,
+      CanvasUserSpaceMetrics(IntSize(mWidth, mHeight)),
+      gfxRect(0, 0, mWidth, mHeight),
+      CurrentState().filterAdditionalImages);
+}
+
 //
 // rects
 //

dom/canvas/CanvasRenderingContext2D.h

@@ -25,6 +25,7 @@
 #include "imgIEncoder.h"
 #include "nsLayoutUtils.h"
 #include "mozilla/EnumeratedArray.h"
+#include "FilterSupport.h"
 
 class nsGlobalWindow;
 class nsXULElement;
@@ -704,6 +705,12 @@ protected:
     */
   mozilla::gfx::SurfaceFormat GetSurfaceFormat() const;
 
+  /**
+   * Update CurrentState().filter with the filter description for
+   * CurrentState().filterChain.
+   */
+  void UpdateFilter();
+
   void DrawImage(const HTMLImageOrCanvasOrVideoElement &imgElt,
                  double sx, double sy, double sw, double sh,
                  double dx, double dy, double dw, double dh,
@@ -838,6 +845,16 @@ protected:
       (state.shadowBlur != 0.f || state.shadowOffset.x != 0.f || state.shadowOffset.y != 0.f);
   }
 
+  /**
+    * Returns true if the result of a drawing operation should be
+    * drawn with a filter.
+    */
+  bool NeedToApplyFilter()
+  {
+    const ContextState& state = CurrentState();
+    return state.filter.mPrimitives.Length() > 0;
+  }
+
   mozilla::gfx::CompositionOp UsedOperation()
   {
     if (NeedToDrawShadow()) {
@@ -932,6 +949,8 @@ protected:
           lineJoin(other.lineJoin),
           filterString(other.filterString),
           filterChain(other.filterChain),
+          filter(other.filter),
+          filterAdditionalImages(other.filterAdditionalImages),
           imageSmoothingEnabled(other.imageSmoothingEnabled)
     { }
 
@@ -992,6 +1011,9 @@ protected:
 
     nsString filterString;
     nsTArray<nsStyleFilter> filterChain;
+    mozilla::gfx::FilterDescription filter;
+    nsTArray<mozilla::RefPtr<mozilla::gfx::SourceSurface>> filterAdditionalImages;
+
     bool imageSmoothingEnabled;
   };