Pre-crop filled rects to avoid scissor

include/gpu/GrClip.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrClip_DEFINED
 #define GrClip_DEFINED
 
@@ skipping 84 matching lines @@
     SkRect                     fDeviceBounds;
     typedef SkNoncopyable INHERITED;
 };
 
 /**
  * GrClip is an abstract base class for applying a clip. It constructs a clip mask if necessary, and
  * fills out a GrAppliedClip instructing the caller on how to set up the draw state.
  */
 class GrClip {
 public:
+    // This is the maximum distance that a draw may extend beyond a clip's scissor and still count
+    // as inside. We use a sloppy compare because the draw may have chosen its bounds in a different
+    // coord system. The rationale for 1e-3 is that in the coverage case (and barring unexpected
+    // rounding), as long as coverage stays below 0.5 * 1/256 we ought to be OK.
+    constexpr static SkScalar kScissorIgnoreFuzz = 1e-3f;
+
     virtual bool quickContains(const SkRect&) const = 0;
     virtual void getConservativeBounds(int width, int height, SkIRect* devResult,
                                        bool* isIntersectionOfRects = nullptr) const = 0;
     virtual bool apply(GrContext*, const GrPipelineBuilder&, GrDrawContext*,
                        const SkRect* devBounds, GrAppliedClip*) const = 0;
 
     virtual ~GrClip() {}
 };
 
 /**
@@ skipping 96 matching lines @@
                                bool* isIntersectionOfRects) const final;
     bool apply(GrContext*, const GrPipelineBuilder&, GrDrawContext*,
                const SkRect* devBounds, GrAppliedClip*) const final;
 
 private:
     SkIPoint                          fOrigin;
     SkAutoTUnref<const SkClipStack>   fStack;
 };
 
 #endif