Add SkRRect::transform.

include/core/SkRRect.h

Index: include/core/SkRRect.h
diff --git a/include/core/SkRRect.h b/include/core/SkRRect.h
index 32d62856bc90fddec1a33196f8f691ce8506de68..d8029bb5c72aab7420c95af3a56e7743f5e578f8 100644
--- a/include/core/SkRRect.h
+++ b/include/core/SkRRect.h
@@ -12,6 +12,7 @@
 #include "SkPoint.h"
 
 class SkPath;
+class SkMatrix;
 
 // Path forward:
 //   core work
@@ -277,6 +278,17 @@ public:
      */
     uint32_t readFromMemory(const void* buffer);
 
+    /**
+     *  Transform by the specified matrix, and put the result in dst.
+     *
+     *  @param matrix SkMatrix specifying the transform. Must only contain
+     *      scale and/or translate, or this call will fail.
+     *  @param dst SkRRect to store the result. It is an error to use this,

[reed1, 2013/11/04 20:21:09]

FYI -- we explicitly support modifying self in SkPath, allowing the 2nd
parameter to be this. We even offer a built-in helper for this:

e.g.

bool SkRRect::transform(const SkMatrix& matrix) {
    return this->transform(matrix, this);
}

[scroggo, 2013/11/04 22:29:55]

In patch set 1 I allowed modifying the SkRRect, following the pattern of SkPath
(though I didn't add the helper), but Robert and I ultimately agreed that we
didn't like that API, which allows modifying a const object through a const
method.

+     *      which would make this function no longer const.
+     *  @return true on success, false on failure. If false, dst is unmodified.
+     */
+    bool transform(const SkMatrix& matrix, SkRRect* dst) const;
+
 private:
     SkRect fRect;
     // Radii order is UL, UR, LR, LL. Use Corner enum to index into fRadii[]