Add asRRect method to SkClipStack::Element

include/core/SkClipStack.h

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkClipStack_DEFINED
 #define SkClipStack_DEFINED
 
@@ skipping 80 matching lines @@
             SkASSERT(kRect_Type == fType && (fRRect.isRect() || fRRect.isEmpty()));
             return fRRect.getBounds();
         }
 
         //!< Call if getType() is not kEmpty to get the set operation used to combine this element.
         SkRegion::Op getOp() const { return fOp; }
 
         //!< Call to get the element as a path, regardless of its type.
         void asPath(SkPath* path) const;
 
+        //!< Call to get the element as a round rect. Returns nullptr if this is not satisfiable.
+        const SkRRect* asRRect() const {

[bsalomon, 2016/03/16 13:17:11]

Maybe we should just loosen the restrictions on when getRRect() can be called?
This shares the "as" Name with "asPath". However, that method always succeeds,
whereas this one does not.

[Chris Dalton, 2016/03/16 15:17:56]

Right, I gave it the "as" name because they both have the property of
generalizing specialized types to a more general type of shape.

The problem with loosening the restrictions on getRRect() is that it seems we
would then have to loosen the restrictions on getPath() as well, just out if
principle.

What if we keep the "as" name, but assert it's not a path instead of returning
null when we can't generalize it? Then it's the caller's responsibility to check
it isn't a path before calling.

+            switch (fType) {
+                case kRect_Type:
+                    SkASSERT(SkRRect::kRect_Type == fRRect.getType());
+                    // fallthrough
+                case kRRect_Type:
+                    return &fRRect;
+                default:
+                    return nullptr;
+            }
+        }
+
         /** If getType() is not kEmpty this indicates whether the clip shape should be anti-aliased
             when it is rasterized. */
         bool isAA() const { return fDoAA; }
 
         //!< Inverts the fill of the clip shape. Note that a kEmpty element remains kEmpty.
         void invertShapeFillType();
 
         //!< Sets the set operation represented by the element.
         void setOp(SkRegion::Op op) { fOp = op; }
 
@@ skipping 357 matching lines @@
      */
     void restoreTo(int saveCount);
 
     /**
      * Return the next unique generation ID.
      */
     static int32_t GetNextGenID();
 };
 
 #endif