Implement drawDRRect for GPU

src/gpu/effects/GrOvalEffect.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrOvalEffect.h"
 
 #include "gl/GrGLEffect.h"
@@ skipping 119 matching lines @@
 
 void GLCircleEffect::emitCode(GrGLShaderBuilder* builder,
                               const GrDrawEffect& drawEffect,
                               EffectKey key,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
                               const TextureSamplerArray& samplers) {
     const CircleEffect& ce = drawEffect.castEffect<CircleEffect>();
     const char *circleName;
-    // The circle uniform is (center.x, center.y, radius + 0.5)
+    // The circle uniform is (center.x, center.y, radius + 0.5) for regular fills and
+    // (... ,radius - 0.5) for inverse fills.
     fCircleUniform = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
                                          kVec3f_GrSLType,
                                          "circle",
                                          &circleName);
     const char* fragmentPos = builder->fragmentPosition();
 
     SkASSERT(kHairlineAA_GrEffectEdgeType != ce.getEdgeType());
     if (GrEffectEdgeTypeIsInverseFill(ce.getEdgeType())) {
         builder->fsCodeAppendf("\t\tfloat d = length(%s.xy - %s.xy) - %s.z;\n",
                                 circleName, fragmentPos, circleName);
@@ skipping 13 matching lines @@
 
 GrGLEffect::EffectKey GLCircleEffect::GenKey(const GrDrawEffect& drawEffect,
                                              const GrGLCaps&) {
     const CircleEffect& ce = drawEffect.castEffect<CircleEffect>();
     return ce.getEdgeType();
 }
 
 void GLCircleEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
     const CircleEffect& ce = drawEffect.castEffect<CircleEffect>();
     if (ce.getRadius() != fPrevRadius || ce.getCenter() != fPrevCenter) {
-        uman.set3f(fCircleUniform, ce.getCenter().fX, ce.getCenter().fY, ce.getRadius() + 0.5f);
+        SkScalar radius = ce.getRadius();
+        if (GrEffectEdgeTypeIsInverseFill(ce.getEdgeType())) {
+            radius -= 0.5f;
+        } else {
+            radius += 0.5f;
+        }
+        uman.set3f(fCircleUniform, ce.getCenter().fX, ce.getCenter().fY, radius);
         fPrevCenter = ce.getCenter();
         fPrevRadius = ce.getRadius();
     }
 }
 
 //////////////////////////////////////////////////////////////////////////////
 
 class GLEllipseEffect;
 
 class EllipseEffect : public GrEffect {
@@ skipping 186 matching lines @@
         w /= 2;
         return CircleEffect::Create(edgeType, SkPoint::Make(oval.fLeft + w, oval.fTop + w), w);
     } else {
         w /= 2;
         h /= 2;
         return EllipseEffect::Create(edgeType, SkPoint::Make(oval.fLeft + w, oval.fTop + h), w, h);
     }
 
     return NULL;
 }