Cap filtering to kMedium_SkFilterQuality when downsampling

src/core/SkBitmapController.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkBitmapController.h"
 #include "SkBitmapProvider.h"
@@ skipping 82 matching lines @@
         SkSize scale;
         if (!fInvMatrix.decomposeScale(&scale)) {
             return false;
         }
         invScaleX = scale.width();
         invScaleY = scale.height();
     }
     if (SkScalarNearlyEqual(invScaleX, 1) && SkScalarNearlyEqual(invScaleY, 1)) {
         return false; // no need for HQ
     }
+
+#ifndef SK_SUPPORT_LEGACY_HQ_DOWNSAMPLING
+    if (invScaleX > 1 || invScaleY > 1) {
+        return false; // only use HQ when upsampling
+    }
+#endif
     
     const int dstW = SkScalarRoundToScalar(provider.width() / invScaleX);
     const int dstH = SkScalarRoundToScalar(provider.height() / invScaleY);
     const SkBitmapCacheDesc desc = provider.makeCacheDesc(dstW, dstH);
 
     if (!SkBitmapCache::FindWH(desc, &fResultBitmap)) {
         SkBitmap orig;
         if (!provider.asBitmap(&orig)) {
             return false;
         }
@@ skipping 99 matching lines @@
                   fResultBitmap.getColorTable());
 }
 
 SkBitmapController::State* SkDefaultBitmapController::onRequestBitmap(const SkBitmapProvider& bm,
                                                                       const SkMatrix& inverse,
                                                                       SkFilterQuality quality,
                                                                       void* storage, size_t size) {
     return SkInPlaceNewCheck<SkDefaultBitmapControllerState>(storage, size, bm, inverse, quality);
 }