Add SkCachedData and use it for SkMipMap

src/core/SkBitmapProcState.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapCache.h"
 #include "SkBitmapProcState.h"
 #include "SkColorPriv.h"
@@ skipping 242 matching lines @@
     SkASSERT(SkPaint::kMedium_FilterLevel == fFilterLevel);
 
     /**
      *  Medium quality means use a mipmap for down-scaling, and just bilper
      *  for upscaling. Since we're examining the inverse matrix, we look for
      *  a scale > 1 to indicate down scaling by the CTM.
      */
     if (scaleSqd > SK_Scalar1) {
         fCurrMip.reset(SkMipMapCache::FindAndRef(fOrigBitmap));
         if (NULL == fCurrMip.get()) {
-            fCurrMip.reset(SkMipMap::Build(fOrigBitmap));
+            fCurrMip.reset(SkMipMapCache::AddAndRef(fOrigBitmap));
             if (NULL == fCurrMip.get()) {
                 return false;
             }
-            SkMipMapCache::Add(fOrigBitmap, fCurrMip);
+        }
+        // diagnostic for a crasher...
+        if (NULL == fCurrMip->data()) {
+            sk_throw();
         }
 
         SkScalar levelScale = SkScalarInvert(SkScalarSqrt(scaleSqd));
         SkMipMap::Level level;
         if (fCurrMip->extractLevel(levelScale, &level)) {
             SkScalar invScaleFixup = level.fScale;
             fInvMatrix.postScale(invScaleFixup, invScaleFixup);
 
             const SkImageInfo info = fOrigBitmap.info().makeWH(level.fWidth, level.fHeight);
             // 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.
             fScaledBitmap.installPixels(info, level.fPixels, level.fRowBytes);
             fBitmap = &fScaledBitmap;
             fFilterLevel = SkPaint::kLow_FilterLevel;
             return true;
+        } else {
+            // failed to extract, so release the mipmap
+            fCurrMip.reset(NULL);
         }
     }
 
     return false;
 }
 
 static bool get_locked_pixels(const SkBitmap& src, int pow2, SkBitmap* dst) {
     SkPixelRef* pr = src.pixelRef();
     if (pr && pr->decodeInto(pow2, dst)) {
         return true;
@@ skipping 713 matching lines @@
     } else {
         size >>= 2;
     }
 
     if (fFilterLevel != SkPaint::kNone_FilterLevel) {
         size >>= 1;
     }
 
     return size;
 }