Improved distance field sampling

src/gpu/GrDistanceFieldTextContext.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 "GrDistanceFieldTextContext.h"
 #include "GrAtlas.h"
 #include "GrDrawTarget.h"
+#include "GrDrawTargetCaps.h"
 #include "GrFontScaler.h"
 #include "SkGlyphCache.h"
 #include "GrIndexBuffer.h"
 #include "GrTextStrike.h"
 #include "GrTextStrike_impl.h"
 #include "SkDraw.h"
 #include "SkGpuDevice.h"
 #include "SkPath.h"
 #include "SkRTConf.h"
 #include "SkStrokeRec.h"
@@ skipping 18 matching lines @@
     fMaxVertices = 0;
 }
 
 GrDistanceFieldTextContext::~GrDistanceFieldTextContext() {
     this->flushGlyphs();
 }
 
 bool GrDistanceFieldTextContext::canDraw(const SkPaint& paint) {
     return !paint.getRasterizer() && !paint.getMaskFilter() &&
            paint.getStyle() == SkPaint::kFill_Style &&
+           fContext->getTextTarget()->caps()->shaderDerivativeSupport() &&
            !SkDraw::ShouldDrawTextAsPaths(paint, fContext->getMatrix());
 }
 
 static inline GrColor skcolor_to_grcolor_nopremultiply(SkColor c) {
     unsigned r = SkColorGetR(c);
     unsigned g = SkColorGetG(c);
     unsigned b = SkColorGetB(c);
     return GrColorPackRGBA(r, g, b, 0xff);
 }
 
 void GrDistanceFieldTextContext::flushGlyphs() {
     if (NULL == fDrawTarget) {
         return;
     }
 
     GrDrawState* drawState = fDrawTarget->drawState();
     GrDrawState::AutoRestoreEffects are(drawState);
     drawState->setFromPaint(fPaint, fContext->getMatrix(), fContext->getRenderTarget());
 
     if (fCurrVertex > 0) {
         // setup our sampler state for our text texture/atlas
         SkASSERT(GrIsALIGN4(fCurrVertex));
         SkASSERT(fCurrTexture);
         GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
 
         // This effect could be stored with one of the cache objects (atlas?)
+        SkISize size = fStrike->getAtlasSize();
         drawState->addCoverageEffect(
-                                GrDistanceFieldTextureEffect::Create(fCurrTexture, params),
+                                GrDistanceFieldTextureEffect::Create(fCurrTexture, params, size),
                                 kGlyphCoordsAttributeIndex)->unref();
 
         if (!GrPixelConfigIsAlphaOnly(fCurrTexture->config())) {
             if (kOne_GrBlendCoeff != fPaint.getSrcBlendCoeff() ||
                 kISA_GrBlendCoeff != fPaint.getDstBlendCoeff() ||
                 fPaint.numColorStages()) {
                 GrPrintf("LCD Text will not draw correctly.\n");
             }
             // We don't use the GrPaint's color in this case because it's been premultiplied by
             // alpha. Instead we feed in a non-premultiplied color, and multiply its alpha by
@@ skipping 169 matching lines @@
     SkScalar width = SkIntToScalar(glyph->fBounds.width());
     SkScalar height = SkIntToScalar(glyph->fBounds.height());
 
     SkScalar scale = fTextRatio;
     dx *= scale;
     dy *= scale;
     sx += dx;
     sy += dy;
     width *= scale;
     height *= scale;
-
+     
     GrFixed tx = SkIntToFixed(glyph->fAtlasLocation.fX);
     GrFixed ty = SkIntToFixed(glyph->fAtlasLocation.fY);
     GrFixed tw = SkIntToFixed(glyph->fBounds.width());
     GrFixed th = SkIntToFixed(glyph->fBounds.height());
 
+    static const size_t kVertexSize = 2 * sizeof(SkPoint);
     fVertices[2*fCurrVertex].setRectFan(sx,
                                         sy,
                                         sx + width,
                                         sy + height,
-                                        2 * sizeof(SkPoint));
+                                        kVertexSize);
     fVertices[2*fCurrVertex+1].setRectFan(SkFixedToFloat(texture->normalizeFixedX(tx)),
                                           SkFixedToFloat(texture->normalizeFixedY(ty)),
                                           SkFixedToFloat(texture->normalizeFixedX(tx + tw)),
                                           SkFixedToFloat(texture->normalizeFixedY(ty + th)),
-                                          2 * sizeof(SkPoint));
+                                          kVertexSize);
     fCurrVertex += 4;
 }
 
 inline void GrDistanceFieldTextContext::init(const GrPaint& paint, const SkPaint& skPaint) {
     GrTextContext::init(paint, skPaint);
 
     fStrike = NULL;
 
     fCurrTexture = NULL;
     fCurrVertex = 0;
@@ skipping 147 matching lines @@
                                       SkScalarToFixed(y) - (glyph.fAdvanceY >> alignShift)
                                         + SK_FixedHalf, //d1g.fHalfSampleY,
                                       fontScaler);
             }
             pos += scalarsPerPosition;
         }
     }
 
     this->finish();
 }