skia: Fix text subpixel half sample default for GPU rasterization

src/gpu/GrBitmapTextContext.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 "GrBitmapTextContext.h"
 #include "GrAtlas.h"
 #include "GrDefaultGeoProcFactory.h"
@@ skipping 209 matching lines @@
         SkDebugf("Cannot invert viewmatrix\n");
         return;
     }
 
     int numGlyphs = fSkPaint.textToGlyphs(text, byteLength, NULL);
     fTotalVertexCount = kVerticesPerGlyph*numGlyphs;
 
     const char*        stop = text + byteLength;
     SkTextAlignProc    alignProc(fSkPaint.getTextAlign());
     SkTextMapStateProc tmsProc(viewMatrix, offset, scalarsPerPosition);
-    SkScalar halfSampleX = 0, halfSampleY = 0;
 
     if (cache->isSubpixel()) {
         // maybe we should skip the rounding if linearText is set
         SkAxisAlignment baseline = SkComputeAxisAlignmentForHText(viewMatrix);
 
         SkFixed fxMask = ~0;
         SkFixed fyMask = ~0;
+        SkScalar halfSampleX = SkFixedToScalar(SkGlyph::kSubpixelRound);
+        SkScalar halfSampleY = SkFixedToScalar(SkGlyph::kSubpixelRound);
         if (kX_SkAxisAlignment == baseline) {
             fyMask = 0;
             halfSampleY = SK_ScalarHalf;
         } else if (kY_SkAxisAlignment == baseline) {
             fxMask = 0;
             halfSampleX = SK_ScalarHalf;
         }
 
         if (SkPaint::kLeft_Align == fSkPaint.getTextAlign()) {
             while (text < stop) {
@@ skipping 55 matching lines @@
 
         if (SkPaint::kLeft_Align == fSkPaint.getTextAlign()) {
             while (text < stop) {
                 // the last 2 parameters are ignored
                 const SkGlyph& glyph = glyphCacheProc(cache, &text, 0, 0);
 
                 if (glyph.fWidth) {
                     SkPoint tmsLoc;
                     tmsProc(pos, &tmsLoc);
 
-                    Sk48Dot16 fx = SkScalarTo48Dot16(tmsLoc.fX + SK_ScalarHalf); //halfSampleX;
-                    Sk48Dot16 fy = SkScalarTo48Dot16(tmsLoc.fY + SK_ScalarHalf); //halfSampleY;
+                    Sk48Dot16 fx = SkScalarTo48Dot16(tmsLoc.fX + SK_ScalarHalf);
+                    Sk48Dot16 fy = SkScalarTo48Dot16(tmsLoc.fY + SK_ScalarHalf);
                     this->appendGlyph(GrGlyph::Pack(glyph.getGlyphID(),
                                                     glyph.getSubXFixed(),
                                                     glyph.getSubYFixed(),
                                                     GrGlyph::kCoverage_MaskStyle),
                                       Sk48Dot16FloorToInt(fx),
                                       Sk48Dot16FloorToInt(fy),
                                       fontScaler);
                 }
                 pos += scalarsPerPosition;
             }
         } else {
             while (text < stop) {
                 // the last 2 parameters are ignored
                 const SkGlyph& glyph = glyphCacheProc(cache, &text, 0, 0);
 
                 if (glyph.fWidth) {
                     SkPoint tmsLoc;
                     tmsProc(pos, &tmsLoc);
 
                     SkPoint alignLoc;
                     alignProc(tmsLoc, glyph, &alignLoc);
 
-                    Sk48Dot16 fx = SkScalarTo48Dot16(alignLoc.fX + SK_ScalarHalf); //halfSampleX;
-                    Sk48Dot16 fy = SkScalarTo48Dot16(alignLoc.fY + SK_ScalarHalf); //halfSampleY;
+                    Sk48Dot16 fx = SkScalarTo48Dot16(alignLoc.fX + SK_ScalarHalf);
+                    Sk48Dot16 fy = SkScalarTo48Dot16(alignLoc.fY + SK_ScalarHalf);
                     this->appendGlyph(GrGlyph::Pack(glyph.getGlyphID(),
                                                     glyph.getSubXFixed(),
                                                     glyph.getSubYFixed(),
                                                     GrGlyph::kCoverage_MaskStyle),
                                       Sk48Dot16FloorToInt(fx),
                                       Sk48Dot16FloorToInt(fy),
                                       fontScaler);
                 }
                 pos += scalarsPerPosition;
             }
@@ skipping 283 matching lines @@
     }
 }
 
 inline void GrBitmapTextContext::finish() {
     this->flush();
     fTotalVertexCount = 0;
 
     GrTextContext::finish();
 }