fix off-by-one error in texture coordinate calculations for rrect gpu

src/effects/SkBlurMaskFilter.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMaskFilter.h"
 #include "SkBlurMask.h"
@@ skipping 1022 matching lines @@
     // warp the fragment position to the appropriate part of the 9patch blur texture
 
     builder->fsCodeAppendf("\t\tvec2 rectCenter = (%s.xy + %s.zw)/2.0;\n", rectName, rectName);
     builder->fsCodeAppendf("\t\tvec2 translatedFragPos = %s.xy - %s.xy;\n", fragmentPos, rectName);
     builder->fsCodeAppendf("\t\tfloat threshold = %s + 2.0*%s;\n", cornerRadiusName, blurRadiusName );
     builder->fsCodeAppendf("\t\tvec2 middle = %s.zw - %s.xy - 2.0*threshold;\n", rectName, rectName );
 
     builder->fsCodeAppendf("\t\tif (translatedFragPos.x >= threshold && translatedFragPos.x < (middle.x+threshold)) {\n" );
     builder->fsCodeAppendf("\t\t\ttranslatedFragPos.x = threshold;\n");
     builder->fsCodeAppendf("\t\t} else if (translatedFragPos.x >= (middle.x + threshold)) {\n");
-    builder->fsCodeAppendf("\t\t\ttranslatedFragPos.x -= middle.x;\n");
+    builder->fsCodeAppendf("\t\t\ttranslatedFragPos.x -= middle.x - 1.0;\n");
     builder->fsCodeAppendf("\t\t}\n");
 
     builder->fsCodeAppendf("\t\tif (translatedFragPos.y > threshold && translatedFragPos.y < (middle.y+threshold)) {\n" );
     builder->fsCodeAppendf("\t\t\ttranslatedFragPos.y = threshold;\n");
     builder->fsCodeAppendf("\t\t} else if (translatedFragPos.y >= (middle.y + threshold)) {\n");
-    builder->fsCodeAppendf("\t\t\ttranslatedFragPos.y -= middle.y;\n");
+    builder->fsCodeAppendf("\t\t\ttranslatedFragPos.y -= middle.y - 1.0;\n");
     builder->fsCodeAppendf("\t\t}\n");
 
     builder->fsCodeAppendf("\t\tvec2 proxyDims = vec2(2.0*threshold+1.0);\n");
     builder->fsCodeAppendf("\t\tvec2 texCoord = translatedFragPos / proxyDims;\n");
 
     builder->fsCodeAppendf("\t%s = ", outputColor);
     builder->fsAppendTextureLookupAndModulate(inputColor, samplers[0], "texCoord");
     builder->fsCodeAppend(";\n");
 }
 
@@ skipping 165 matching lines @@
     } else {
         str->append("None");
     }
     str->append("))");
 }
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkBlurMaskFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurMaskFilterImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END