Add special case circle blur for Ganesh

include/core/SkMaskFilter.h

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #ifndef SkMaskFilter_DEFINED
@@ skipping 60 matching lines @@
      *  filtered coverage must only depend on the unfiltered mask value for that pixel and not on
      *  surrounding values.
      *
      * If effect is non-NULL, a new GrProcessor instance is stored in it. The caller assumes
      * ownership of the effect and must unref it.
      */
     virtual bool asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix& ctm) const;
 
     /**
      *  If asFragmentProcessor() fails the filter may be implemented on the GPU by a subclass
-     *  overriding filterMaskGPU (declared below). That code path requires constructing a src mask
-     *  as input. Since that is a potentially expensive operation, the subclass must also override
-     *  this function to indicate whether filterTextureMaskGPU would succeeed if the mask were to be
-     *  created.
+     *  overriding filterMaskGPU (declared below). That code path requires constructing a
+     *  src mask as input. Since that is a potentially expensive operation, the subclass must also
+     *  override this function to indicate whether filterTextureMaskGPU would succeeed if the mask
+     *  were to be created.
      *
      *  'maskRect' returns the device space portion of the mask that the filter needs. The mask
-     *  passed into 'filterMaskGPU' should have the same extent as 'maskRect' but be translated
-     *  to the upper-left corner of the mask (i.e., (maskRect.fLeft, maskRect.fTop) appears at
-     *  (0, 0) in the mask).
+     *  passed into 'filterMaskGPU' should have the same extent as 'maskRect' but be
+     *  translated to the upper-left corner of the mask (i.e., (maskRect.fLeft, maskRect.fTop)
+     *  appears at (0, 0) in the mask).
+     *
+     * Logically, how this works is:
+     *    canFilterMaskGPU is called
+     *    if (it returns true)
+     *        the returned mask rect is used for quick rejecting
+     *        either directFilterMaskGPU or directFilterRRectMaskGPU is then called
+     *        if (neither of them handle the blur)
+     *            the mask rect is used to generate the mask
+     *            filterMaskGPU is called to filter the mask
+     *
+     * TODO: this should work as:
+     *    if (canFilterMaskGPU(devShape, ...)) // rect, rrect, drrect, path
+     *        filterMaskGPU(devShape, ...)
+     * this would hide the RRect special case and the mask generation
      */
-    virtual bool canFilterMaskGPU(const SkRect& devBounds,
+    virtual bool canFilterMaskGPU(const SkRRect& devRRect,
                                   const SkIRect& clipBounds,
                                   const SkMatrix& ctm,
                                   SkRect* maskRect) const;
 
     /**
      *  Try to directly render the mask filter into the target.  Returns
      *  true if drawing was successful.
      */
     virtual bool directFilterMaskGPU(GrTextureProvider* texProvider,
                                      GrDrawContext* drawContext,
@@ skipping 122 matching lines @@
      mask and then call filterMask(). If this returns true, the specified blitter will be called
      to render that mask. Returns false if filterMask() returned false.
      */
     bool filterRRect(const SkRRect& devRRect, const SkMatrix& ctm, const SkRasterClip&,
                      SkBlitter*, SkPaint::Style style) const;
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif