fix bounds for BW lines, AA Hairlines

src/gpu/GrAAHairLinePathRenderer.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrAAHairLinePathRenderer.h"
 
 #include "GrBatch.h"
@@ skipping 712 matching lines @@
     typedef SkTArray<int, true> IntArray;
     typedef SkTArray<float, true> FloatArray;
 
     AAHairlineBatch(const Geometry& geometry) {
         this->initClassID<AAHairlineBatch>();
         fGeoData.push_back(geometry);
 
         // compute bounds
         fBounds = geometry.fPath.getBounds();
         geometry.fViewMatrix.mapRect(&fBounds);
+
+        // This is b.c. hairlines are notionally infinitely thin so without expansion
+        // two overlapping lines could be reordered even though they hit the same pixels.
+        fBounds.outset(0.5f, 0.5f);
     }
 
     bool onCombineIfPossible(GrBatch* t) override {
         AAHairlineBatch* that = t->cast<AAHairlineBatch>();
 
         if (this->viewMatrix().hasPerspective() != that->viewMatrix().hasPerspective()) {
             return false;
         }
 
         // We go to identity if we don't have perspective
@@ skipping 270 matching lines @@
     GrColor color = GrRandomColor(random);
     SkMatrix viewMatrix = GrTest::TestMatrix(random);
     GrStrokeInfo stroke(SkStrokeRec::kHairline_InitStyle);
     SkPath path = GrTest::TestPath(random);
     SkIRect devClipBounds;
     devClipBounds.setEmpty();
     return create_hairline_batch(color, viewMatrix, path, stroke, devClipBounds);
 }
 
 #endif