Implement InterpolationMedium to filter animated images

Source/platform/graphics/skia/NativeImageSkia.cpp

Index: Source/platform/graphics/skia/NativeImageSkia.cpp
diff --git a/Source/platform/graphics/skia/NativeImageSkia.cpp b/Source/platform/graphics/skia/NativeImageSkia.cpp
index a963e3e14b50cdf6b0063eddd972d4914828345a..539950d32864b58eee3896ffd69c4172ada26107 100644
--- a/Source/platform/graphics/skia/NativeImageSkia.cpp
+++ b/Source/platform/graphics/skia/NativeImageSkia.cpp
@@ -144,13 +144,14 @@ static ResamplingMode limitResamplingMode(GraphicsContext* context, ResamplingMo
     case InterpolationNone:
         return NoResampling;
     case InterpolationMedium:
-        // For now we treat InterpolationMedium and InterpolationLow the same.
-    case InterpolationLow:
         if (resampling == AwesomeResampling)
+            return MediumResampling;
+        break;
+    case InterpolationLow:
+        if (resampling == AwesomeResampling || resampling == MediumResampling)
             return LinearResampling;
         break;
     case InterpolationHigh:
-    case InterpolationDefault:

[Stephen Chennney, 2014/03/18 12:56:32]

I think you'll get build errors due to enum not in the switch.

[Alpha Left Google, 2014/03/18 22:59:13]

Actually this is correct since InterpolationDefault equals InterpolationLow or
InterpolationHigh. The code now is actually cleaner.

         break;
     }
 
@@ -353,7 +354,6 @@ void NativeImageSkia::draw(GraphicsContext* context, const SkRect& srcRect, cons
         resampling = LinearResampling;
     }
     resampling = limitResamplingMode(context, resampling);
-    paint.setFilterBitmap(resampling == LinearResampling);
 
     bool isLazyDecoded = DeferredImageDecoder::isLazyDecoded(bitmap());
     // FIXME: Bicubic filtering in Skia is only applied to defer-decoded images
@@ -363,6 +363,12 @@ void NativeImageSkia::draw(GraphicsContext* context, const SkRect& srcRect, cons
 
     if (useBicubicFilter)
         paint.setFilterLevel(SkPaint::kHigh_FilterLevel);
+    else if (resampling == MediumResampling)

[Stephen White, 2014/03/18 17:26:43]

I'd suggest to refactor this out into a helper function that converts between
resampling mode + useBicubicFilter and filterlevel, and call that here and
below.

[Alpha Left Google, 2014/03/18 22:59:13]

Done.

+        paint.setFilterLevel(SkPaint::kMedium_FilterLevel);
+    else if (resampling == LinearResampling)
+        paint.setFilterLevel(SkPaint::kLow_FilterLevel);
+    else
+        paint.setFilterLevel(SkPaint::kNone_FilterLevel);
 
     if (resampling == AwesomeResampling && !useBicubicFilter) {
         // Resample the image and then draw the result to canvas with bilinear
@@ -497,9 +503,14 @@ void NativeImageSkia::drawPattern(
     paint.setXfermode(WebCoreCompositeToSkiaComposite(compositeOp, blendMode).get());
     paint.setColorFilter(context->colorFilter());
 
-    paint.setFilterBitmap(resampling == LinearResampling);
     if (useBicubicFilter)
         paint.setFilterLevel(SkPaint::kHigh_FilterLevel);
+    else if (resampling == MediumResampling)
+        paint.setFilterLevel(SkPaint::kMedium_FilterLevel);
+    else if (resampling == LinearResampling)
+        paint.setFilterLevel(SkPaint::kLow_FilterLevel);
+    else
+        paint.setFilterLevel(SkPaint::kNone_FilterLevel);
     if (isLazyDecoded)
         PlatformInstrumentation::didDrawLazyPixelRef(bitmap().getGenerationID());