Fix kMediumQuality invMatrix setup for sizes == mip levels

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 "SkBitmapController.h"
 #include "SkBitmapProcState.h"
@@ skipping 140 matching lines @@
     bool clampClamp = SkShader::kClamp_TileMode == fTileModeX &&
                       SkShader::kClamp_TileMode == fTileModeY;
 
     // Most of the scanline procs deal with "unit" texture coordinates, as this
     // makes it easy to perform tiling modes (repeat = (x & 0xFFFF)). To generate
     // those, we divide the matrix by its dimensions here.
     //
     // We don't do this if we're either trivial (can ignore the matrix) or clamping
     // in both X and Y since clamping to width,height is just as easy as to 0xFFFF.
 
-    if (!(clampClamp || trivialMatrix)) {
+    // Note that we cannot ignore the matrix when allow_ignore_fractional_translate is false.
+
+    if (!(clampClamp || (trivialMatrix && allow_ignore_fractional_translate))) {
         fInvMatrix.postIDiv(fPixmap.width(), fPixmap.height());
     }
 
     // Now that all possible changes to the matrix have taken place, check
     // to see if we're really close to a no-scale matrix.  If so, explicitly
     // set it to be so.  Subsequent code may inspect this matrix to choose
     // a faster path in this case.
 
     // This code will only execute if the matrix has some scale component;
     // if it's already pure translate then we won't do this inversion.
@@ skipping 648 matching lines @@
             *dst++ = src[index];
             fx += dx;
         }
     } else {
         for (int i = 0; i < count; ++i) {
             dst[i] = src[SkClampMax(SkFractionalIntToInt(fx), maxX)];
             fx += dx;
         }
     }
 }