Anisotropic mipmap fixes

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 142 matching lines @@
     }
     
     // Our default return state is to downgrade the request to Low, w/ or w/o setting fBitmap
     // to a valid bitmap.
     fQuality = kLow_SkFilterQuality;
     
     SkSize invScaleSize;
     if (!fInvMatrix.decomposeScale(&invScaleSize, nullptr)) {
         return false;
     }
+
+#ifdef SK_SUPPORT_LEGACY_ANISOTROPIC_MIPMAPS
     SkScalar invScale = SkScalarSqrt(invScaleSize.width() * invScaleSize.height());
-    
+#else
+    // Use the largest (non-inverse) scale, to ensure anisotropic consistency.
+    SkASSERT(invScaleSize.width() >= 0 && invScaleSize.height() >= 0);
+    const SkScalar invScale = SkTMin(invScaleSize.width(), invScaleSize.height());
+#endif
+
     if (invScale > SK_Scalar1) {
         fCurrMip.reset(SkMipMapCache::FindAndRef(provider.makeCacheDesc()));
         if (nullptr == fCurrMip.get()) {
             SkBitmap orig;
             if (!provider.asBitmap(&orig)) {
                 return false;
             }
             fCurrMip.reset(SkMipMapCache::AddAndRef(orig));
             if (nullptr == fCurrMip.get()) {
                 return false;
             }
         }
         // diagnostic for a crasher...
         if (nullptr == fCurrMip->data()) {
             sk_throw();
         }
         
         SkScalar levelScale = SkScalarInvert(invScale);
         SkMipMap::Level level;
         if (fCurrMip->extractLevel(levelScale, &level)) {
-            SkScalar invScaleFixup = level.fScale;
-            fInvMatrix.postScale(invScaleFixup, invScaleFixup);
-            
+            const SkSize& invScaleFixup = level.fScale;
+            fInvMatrix.postScale(invScaleFixup.width(), invScaleFixup.height());
+
             // todo: if we could wrap the fCurrMip in a pixelref, then we could just install
             //       that here, and not need to explicitly track it ourselves.
             return fResultBitmap.installPixels(level.fPixmap);
         } else {
             // failed to extract, so release the mipmap
             fCurrMip.reset(nullptr);
         }
     }
     return false;
 }
@@ skipping 19 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);
 }