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"
 #include "effects/GrDistanceFieldTextureEffect.h"
 
 static const int kGlyphCoordsAttributeIndex = 1;
+static const int kGlyphOffsetAttributeIndex = 2;
 
 static const int kBaseDFFontSize = 32;
 
 SK_CONF_DECLARE(bool, c_DumpFontCache, "gpu.dumpFontCache", false,
                 "Dump the contents of the font cache before every purge.");
 
 GrDistanceFieldTextContext::GrDistanceFieldTextContext(GrContext* context,
                                                        const SkDeviceProperties& properties)
                                                     : GrTextContext(context, properties) {
     fStrike = NULL;
 
     fCurrTexture = NULL;
     fCurrVertex = 0;
 
     fVertices = NULL;
     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(fCurrVertex % 6 == 0);
         SkASSERT(fCurrTexture);
         GrTextureParams params(SkShader::kRepeat_TileMode, GrTextureParams::kBilerp_FilterMode);
 
         // This effect could be stored with one of the cache objects (atlas?)
         drawState->addCoverageEffect(
                                 GrDistanceFieldTextureEffect::Create(fCurrTexture, params),
-                                kGlyphCoordsAttributeIndex)->unref();
+                                kGlyphCoordsAttributeIndex, kGlyphOffsetAttributeIndex)->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
             // the mask texture color. The end result is that we get
             //            mask*paintAlpha*paintColor + (1-mask*paintAlpha)*dstColor
             int a = SkColorGetA(fSkPaint.getColor());
             // paintAlpha
             drawState->setColor(SkColorSetARGB(a, a, a, a));
             // paintColor
             drawState->setBlendConstant(skcolor_to_grcolor_nopremultiply(fSkPaint.getColor()));
             drawState->setBlendFunc(kConstC_GrBlendCoeff, kISC_GrBlendCoeff);
         } else {
             // set back to normal in case we took LCD path previously.
             drawState->setBlendFunc(fPaint.getSrcBlendCoeff(), fPaint.getDstBlendCoeff());
             drawState->setColor(fPaint.getColor());
         }
 
-        int nGlyphs = fCurrVertex / 4;
+        int nGlyphs = fCurrVertex / 6;
         fDrawTarget->setIndexSourceToBuffer(fContext->getQuadIndexBuffer());
         fDrawTarget->drawIndexedInstances(kTriangles_GrPrimitiveType,
                                           nGlyphs,
                                           4, 6);
         fDrawTarget->resetVertexSource();
         fVertices = NULL;
         fMaxVertices = 0;
         fCurrVertex = 0;
         SkSafeSetNull(fCurrTexture);
     }
 }
 
 namespace {
 
 // position + texture coord
 extern const GrVertexAttrib gTextVertexAttribs[] = {
-    {kVec2f_GrVertexAttribType, 0,               kPosition_GrVertexAttribBinding},
-    {kVec2f_GrVertexAttribType, sizeof(GrPoint), kEffect_GrVertexAttribBinding}
+    {kVec2f_GrVertexAttribType, 0,                 kPosition_GrVertexAttribBinding},
+    {kVec2f_GrVertexAttribType, sizeof(GrPoint),   kEffect_GrVertexAttribBinding},
+    {kVec2f_GrVertexAttribType, 2*sizeof(GrPoint), kEffect_GrVertexAttribBinding}
 };
 
 };
 
 void GrDistanceFieldTextContext::drawPackedGlyph(GrGlyph::PackedID packed,
                                                  GrFixed vx, GrFixed vy,
                                                  GrFontScaler* scaler) {
     if (NULL == fDrawTarget) {
         return;
     }
@@ skipping 111 matching lines @@
             fMaxVertices = kDefaultRequestedVerts;
         } else if (fMaxVertices > maxQuadVertices) {
             // don't exceed the limit of the index buffer
             fMaxVertices = maxQuadVertices;
         }
         bool success = fDrawTarget->reserveVertexAndIndexSpace(fMaxVertices,
                                                                0,
                                                                GrTCast<void**>(&fVertices),
                                                                NULL);
         GrAlwaysAssert(success);
-        SkASSERT(2*sizeof(GrPoint) == fDrawTarget->getDrawState().getVertexSize());
+        SkASSERT(3*sizeof(GrPoint) == fDrawTarget->getDrawState().getVertexSize());
     }
 
     SkScalar dx = SkIntToScalar(glyph->fBounds.fLeft);
     SkScalar dy = SkIntToScalar(glyph->fBounds.fTop);
     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());
 
+    SkISize texSize = fStrike->getAtlasSize();

[bsalomon, 2014/02/05 20:19:10]

AFAICT this is the same for the lifetime of the program. Perhaps we should use a
uniform rather than a vertex attribute?

[jvanverth1, 2014/02/10 18:34:02]

Done.

+
     fVertices[2*fCurrVertex].setRectFan(sx,
                                         sy,
                                         sx + width,
                                         sy + height,
-                                        2 * sizeof(SkPoint));
+                                        3 * sizeof(SkPoint));

[bsalomon, 2014/02/05 20:19:10]

this 3 * sizeof(SkPoint) is repeated here three times and once above. Maybe

static const size_t kVertexSize = 3 * sizeof(SkPoint);

[jvanverth1, 2014/02/10 18:34:02]

Done.

     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));
-    fCurrVertex += 4;
+                                          3 * sizeof(SkPoint));
+    fVertices[2*fCurrVertex+2].setRectFan(SkIntToScalar(texSize.fWidth),
+                                          SkIntToScalar(texSize.fHeight),
+                                          SkIntToScalar(texSize.fWidth),
+                                          SkIntToScalar(texSize.fHeight),
+                                          3 * sizeof(SkPoint));
+    fCurrVertex += 6;
 }
 
 inline void GrDistanceFieldTextContext::init(const GrPaint& paint, const SkPaint& skPaint) {
     GrTextContext::init(paint, skPaint);
 
     fStrike = NULL;
 
     fCurrTexture = NULL;
     fCurrVertex = 0;
 
@@ skipping 146 matching lines @@
                                       SkScalarToFixed(y) - (glyph.fAdvanceY >> alignShift)
                                         + SK_FixedHalf, //d1g.fHalfSampleY,
                                       fontScaler);
             }
             pos += scalarsPerPosition;
         }
     }
 
     this->finish();
 }