Put back the 0.5 bias in the shader. Only adjust the radii for the geometry, not the radii constant…

src/gpu/GrOvalRenderer.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 "GrOvalRenderer.h"
 
 #include "GrBatchFlushState.h"
@@ skipping 279 matching lines @@
             // for outer curve
             fragBuilder->codeAppendf("vec2 scaledOffset = %s*%s.xy;", ellipseOffsets.fsIn(),
                                      ellipseRadii.fsIn());
             fragBuilder->codeAppend("float test = dot(scaledOffset, scaledOffset) - 1.0;");
             fragBuilder->codeAppendf("vec2 grad = 2.0*scaledOffset*%s.xy;", ellipseRadii.fsIn());
             fragBuilder->codeAppend("float grad_dot = dot(grad, grad);");
 
             // avoid calling inversesqrt on zero.
             fragBuilder->codeAppend("grad_dot = max(grad_dot, 1.0e-4);");
             fragBuilder->codeAppend("float invlen = inversesqrt(grad_dot);");
-            fragBuilder->codeAppend("float edgeAlpha = clamp(-test*invlen, 0.0, 1.0);");
+            fragBuilder->codeAppend("float edgeAlpha = clamp(0.5-test*invlen, 0.0, 1.0);");
 
             // for inner curve
             if (ee.isStroked()) {
                 fragBuilder->codeAppendf("scaledOffset = %s*%s.zw;",
                                          ellipseOffsets.fsIn(), ellipseRadii.fsIn());
                 fragBuilder->codeAppend("test = dot(scaledOffset, scaledOffset) - 1.0;");
                 fragBuilder->codeAppendf("grad = 2.0*scaledOffset*%s.zw;",
                                          ellipseRadii.fsIn());
                 fragBuilder->codeAppend("invlen = inversesqrt(dot(grad, grad));");
                 fragBuilder->codeAppend("edgeAlpha *= clamp(0.5+test*invlen, 0.0, 1.0);");
@@ skipping 763 matching lines @@
             innerYRadius = yRadius - scaledStroke.fY;
         }
 
         xRadius += scaledStroke.fX;
         yRadius += scaledStroke.fY;
     }
 
     // We've extended the outer x radius out half a pixel to antialias.
     // This will also expand the rect so all the pixels will be captured.
     // TODO: Consider if we should use sqrt(2)/2 instead
-    xRadius += SK_ScalarHalf;
-    yRadius += SK_ScalarHalf;
+    SkScalar geoXRadius = xRadius + SK_ScalarHalf;
+    SkScalar geoYRadius = yRadius + SK_ScalarHalf;
 
     EllipseBatch::Geometry geometry;
     geometry.fViewMatrix = viewMatrix;
     geometry.fColor = color;
     geometry.fXRadius = xRadius;
     geometry.fYRadius = yRadius;
     geometry.fInnerXRadius = innerXRadius;
     geometry.fInnerYRadius = innerYRadius;
     geometry.fStroke = isStrokeOnly && innerXRadius > 0 && innerYRadius > 0;
-    geometry.fDevBounds = SkRect::MakeLTRB(center.fX - xRadius, center.fY - yRadius,
-                                           center.fX + xRadius, center.fY + yRadius);
+    geometry.fDevBounds = SkRect::MakeLTRB(center.fX - geoXRadius, center.fY - geoYRadius,
+                                           center.fX + geoXRadius, center.fY + geoYRadius);
 
     return EllipseBatch::Create(geometry);
 }
 
 bool GrOvalRenderer::DrawEllipse(GrDrawTarget* target,
                                  const GrPipelineBuilder& pipelineBuilder,
                                  GrColor color,
                                  const SkMatrix& viewMatrix,
                                  bool useCoverageAA,
                                  const SkRect& ellipse,
@@ skipping 951 matching lines @@
 }
 
 DRAW_BATCH_TEST_DEFINE(RRectBatch) {
     SkMatrix viewMatrix = GrTest::TestMatrixRectStaysRect(random);
     GrColor color = GrRandomColor(random);
     const SkRRect& rrect = GrTest::TestRRectSimple(random);
     return create_rrect_batch(color, viewMatrix, rrect, GrTest::TestStrokeRec(random));
 }
 
 #endif