fix trivial matrix computation

src/core/SkBitmapProcState.h

Index: src/core/SkBitmapProcState.h
diff --git a/src/core/SkBitmapProcState.h b/src/core/SkBitmapProcState.h
index 5c6a4152fc285dd9c92fedc65f8e727f8bb920dc..a644dd1e021c3453c2144bbc1aa203e48ff9176d 100644
--- a/src/core/SkBitmapProcState.h
+++ b/src/core/SkBitmapProcState.h
@@ -64,8 +64,8 @@ struct SkBitmapProcState {
     typedef U16CPU (*FixedTileLowBitsProc)(SkFixed, int);   // returns 0..0xF
     typedef U16CPU (*IntTileProc)(int value, int count);   // returns 0..count-1
 
-    const SkBitmap*     fBitmap;            // chooseProcs - orig or mip
-    const SkMatrix*     fInvMatrix;         // chooseProcs
+    const SkBitmap*     fBitmap;            // chooseProcs - orig or scaled
+    SkMatrix            fInvMatrix;         // chooseProcs
     SkMatrix::MapXYProc fInvProc;           // chooseProcs
 
     SkFractionalInt     fInvSxFractionalInt;
@@ -86,7 +86,18 @@ struct SkBitmapProcState {
     uint8_t             fInvType;           // chooseProcs
     uint8_t             fTileModeX;         // CONSTRUCTOR
     uint8_t             fTileModeY;         // CONSTRUCTOR
-    SkBool8             fDoFilter;          // chooseProcs
+
+    enum {
+        kNone_BitmapFilter,
+        kBilerp_BitmapFilter,
+        kHQ_BitmapFilter
+    } fFilterQuality;          // chooseProcs
+
+    /** The shader will let us know when we can release some of our resources
+      * like scaled bitmaps.
+      */
+
+    void endContext();
 
     /** Platforms implement this, and can optionally overwrite only the
         following fields:
@@ -140,18 +151,18 @@ private:
     SampleProc32        fSampleProc32;      // chooseProcs
     SampleProc16        fSampleProc16;      // chooseProcs
 
-    SkMatrix            fUnitInvMatrix;     // chooseProcs
     SkBitmap            fOrigBitmap;        // CONSTRUCTOR
-    SkBitmap            fMipBitmap;
+    SkBitmap            fScaledBitmap;      // chooseProcs
 
     MatrixProc chooseMatrixProc(bool trivial_matrix);
     bool chooseProcs(const SkMatrix& inv, const SkPaint&);
     ShaderProc32 chooseShaderProc32();
 
-    void buildFilterCoefficients(SkFixed dst[4], float t) const;
+    void possiblyScaleImage();
+
     SkBitmapFilter *fBitmapFilter;
 
-    ShaderProc32 chooseBitmapFilterProc(const SkPaint &paint);
+    ShaderProc32 chooseBitmapFilterProc();
 
     // Return false if we failed to setup for fast translate (e.g. overflow)
     bool setupForTranslate();