Distance field fixes for Android

src/core/SkDistanceFieldGen.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDistanceFieldGen.h"
 #include "SkPoint.h"
 
@@ skipping 318 matching lines @@
 
 // assumes an 8-bit image and distance field
 bool SkGenerateDistanceFieldFromImage(unsigned char* distanceField,
                                       const unsigned char* image,
                                       int width, int height,
                                       int distanceMagnitude) {
     SkASSERT(NULL != distanceField);
     SkASSERT(NULL != image);
 
     // the final distance field will have additional texels on each side to handle
-    // the maximum distance
+    // the maximum distance + 1 for bilerp
     // we expand our temp data by one more on each side to simplify
     // the scanning code -- will always be treated as infinitely far away
-    int pad = distanceMagnitude+1;
+    int pad = distanceMagnitude+2;
 
     // set params for distance field data
     int dataWidth = width + 2*pad;
     int dataHeight = height + 2*pad;
 
     // create temp data
     size_t dataSize = dataWidth*dataHeight*sizeof(DFData);
     SkAutoSMalloc<1024> dfStorage(dataSize);
     DFData* dataPtr = (DFData*) dfStorage.get();
     sk_bzero(dataPtr, dataSize);
@@ skipping 116 matching lines @@
 #endif
             ++currData;
             ++currEdge;
         }
         currData += 2;
         currEdge += 2;
     }
 
     return true;
 }