fixup precision with configurable atlas

src/gpu/effects/GrBitmapTextGeoProc.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrBitmapTextGeoProc.h"
 #include "GrFontAtlasSizes.h"
 #include "GrInvariantOutput.h"
@@ skipping 13 matching lines @@
 
         GrGLGPBuilder* pb = args.fPB;
         GrGLVertexBuilder* vsBuilder = pb->getVertexShaderBuilder();
 
         // emit attributes
         vsBuilder->emitAttributes(cte);
 
         // compute numbers to be hardcoded to convert texture coordinates from int to float
         SkASSERT(cte.numTextures() == 1);
         GrTexture* atlas = cte.textureAccess(0).getTexture();
-        SkASSERT(atlas);
+        SkASSERT(atlas && SkIsPow2(atlas->width()) && SkIsPow2(atlas->height()));
         SkScalar recipWidth = 1.0f / atlas->width();
         SkScalar recipHeight = 1.0f / atlas->height();
 
         GrGLVertToFrag v(kVec2f_GrSLType);
         pb->addVarying("TextureCoords", &v);
         vsBuilder->codeAppendf("%s = vec2(%.*f, %.*f) * %s;", v.vsOut(),
-                               SK_FLT_DECIMAL_DIG, recipWidth,
-                               SK_FLT_DECIMAL_DIG, recipHeight,
+                               GR_SIGNIFICANT_POW2_DECIMAL_DIG, recipWidth,
+                               GR_SIGNIFICANT_POW2_DECIMAL_DIG, recipHeight,
                                cte.inTextureCoords()->fName);
 
         // Setup pass through color
         if (!cte.colorIgnored()) {
             if (cte.hasVertexColor()) {
                 pb->addPassThroughAttribute(cte.inColor(), args.fOutputColor);
             } else {
                 this->setupUniformColor(pb, args.fOutputColor, &fColorUniform);
             }
         }
@@ skipping 132 matching lines @@
             break;
         case 2:
             format = kARGB_GrMaskFormat;
             break;
     }
 
     return GrBitmapTextGeoProc::Create(GrRandomColor(d->fRandom), d->fTextures[texIdx], params,
                                        format, GrTest::TestMatrix(d->fRandom),
                                        d->fRandom->nextBool());
 }