Bug 721855 - Honour the gfx.canvas.azure.prefer-skia pref on OS X, r=joe

--HG--
extra : rebase_source : 93aba135b44e5e0f944a8bf604b77a5b414185cf

gfx/2d/Types.h

@@ -68,6 +68,7 @@ enum SurfaceFormat
 
 enum BackendType
 {
+  BACKEND_NONE,
   BACKEND_DIRECT2D,
   BACKEND_COREGRAPHICS,
   BACKEND_CAIRO,

gfx/thebes/gfxPlatform.cpp

@@ -237,6 +237,12 @@ gfxPlatform::gfxPlatform()
     mGraphiteShapingEnabled = UNINITIALIZED_VALUE;
 #endif
     mBidiNumeralOption = UNINITIALIZED_VALUE;
+
+    if (Preferences::GetBool("gfx.canvas.azure.prefer-skia", false)) {
+        mPreferredDrawTargetBackend = BACKEND_SKIA;
+    } else {
+        mPreferredDrawTargetBackend = BACKEND_NONE;
+    }
 }
 
 gfxPlatform*

gfx/thebes/gfxPlatform.h

@@ -158,6 +158,8 @@ GetBackendName(mozilla::gfx::BackendType aBackend)
         return "cairo";
       case mozilla::gfx::BACKEND_SKIA:
         return "skia";
+      case mozilla::gfx::BACKEND_NONE:
+        return "none";
       default:
         NS_ERROR("Invalid backend type!");
         return "";
@@ -448,6 +450,9 @@ protected:
     // which scripts should be shaped with harfbuzz
     PRInt32 mUseHarfBuzzScripts;
 
+    // The preferred draw target backend to use
+    mozilla::gfx::BackendType mPreferredDrawTargetBackend;
+
 private:
     virtual qcms_profile* GetPlatformCMSOutputProfile();
 

gfx/thebes/gfxPlatformMac.cpp

@@ -163,7 +163,12 @@ gfxPlatformMac::GetScaledFontForFont(gfxFont *aFont)
 bool
 gfxPlatformMac::SupportsAzure(BackendType& aBackend)
 {
-  aBackend = BACKEND_COREGRAPHICS;
+  if (mPreferredDrawTargetBackend != BACKEND_NONE) {
+    aBackend = mPreferredDrawTargetBackend;
+  } else {
+    aBackend = BACKEND_COREGRAPHICS;
+  }
+
   return true;
 }
 

gfx/thebes/gfxWindowsPlatform.cpp

@@ -552,10 +552,11 @@ gfxWindowsPlatform::SupportsAzure(BackendType& aBackend)
   }
 #endif
   
-  if (Preferences::GetBool("gfx.canvas.azure.prefer-skia", false)) {
+  if (mPreferredDrawTargetBackend != BACKEND_NONE) {
-    aBackend = BACKEND_SKIA;
+    aBackend = mPreferredDrawTargetBackend;
     return true;
   }
+
   return false;
 }