fix bounds for BW lines, AA Hairlines

src/gpu/GrContext.cpp

Index: src/gpu/GrContext.cpp
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index b361b671c3b3080b9373ee30a76daf9ce91d7b7a..83fa60e5d5553f98ec3a367bc29d3ff741450c5c 100755
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -522,6 +522,10 @@ private:
         SkScalar rad = SkScalarHalf(geometry.fStrokeWidth);
         fBounds.outset(rad, rad);
         geometry.fViewMatrix.mapRect(&fBounds);
+

[robertphillips, 2015/05/07 13:17:17]

rm "then" ?

+        // Since we don't have AA then we outset for a half pixel in each direction to account for
+        // snapping

[robertphillips, 2015/05/07 13:17:17]

// This is conservative but, b.c. the hardware can employ somewhat arbitrary
snapping rules to BW lines, it is the best we can do.

?

+        fBounds.outset(0.5f, 0.5f);

[robertphillips, 2015/05/07 13:17:17]

Shouldn't this only occur for hairlines? For fills we could actually snap
correctly.

     }
 
     /*  create a triangle strip that strokes the specified rect. There are 8
@@ -1021,6 +1025,12 @@ void GrContext::drawVertices(GrRenderTarget* rt,
 
     viewMatrix.mapRect(&bounds);
 
+    // If we don't have AA then we outset for a half pixel in each direction to account for
+    // snapping
+    if (!paint.isAntiAlias()) {
+        bounds.outset(0.5f, 0.5f);
+    }
+
     DrawVerticesBatch::Geometry geometry;
     geometry.fColor = paint.getColor();
     SkAutoTUnref<GrBatch> batch(DrawVerticesBatch::Create(geometry, primitiveType, viewMatrix,