Add asADash entry point into SkPathEffect to allow extracting Dash info from PathEffects

include/core/SkPathEffect.h

Index: include/core/SkPathEffect.h
diff --git a/include/core/SkPathEffect.h b/include/core/SkPathEffect.h
index 86ccf86a9223eedb59dfb7361102bfb067177868..25175d5d5aaf40e37c1e81740deead9a6502170c 100644
--- a/include/core/SkPathEffect.h
+++ b/include/core/SkPathEffect.h
@@ -104,6 +104,37 @@ public:
                           const SkStrokeRec&, const SkMatrix&,
                           const SkRect* cullR) const;
 
+    /**

[bsalomon, 2014/03/28 14:57:22]

Maybe I'm alone in this but I'd feel better about the comment if it didn't
reference a specific subclass but rather used language like "If the path effect
can be represented as a dash pattern"

+     *  If the PathEffect is a DashedPathEffect asADash will return kDash_DashType and None
+     *  otherwise. If a non NULL info is passed in the various DashInfo will be filled
+     *  in if the PathEffect is a DashedPathEffect. If passed in info has an fCount equal or
+     *  greater to that of the effect, it will memcpy the values of fIntervals into the info.
+     *  Thus the general approach will be call asADash once with default info to get DashType
+     *  and fCount. If it is a DashPathEffect, allocate space for the intervals in info, then call
+     *  asAGradient again with the same info and fIntervals will get copied in.

[bsalomon, 2014/03/28 14:57:22]

asAGradient -> asADash

+     *
+     *  None:

[reed1, 2014/03/28 14:52:53]

This part of the dox could be attached/associated directly with each enum below.

eg.

kNone_DashType,   //!< ignores the info parameter
kDash_DashType,   //!< fills in all of the info parameter

+     *      info is ignored.
+     *  Dash:
+     *      uses all info.
+     */
+
+    enum DashType {
+        kNone_DashType,
+        kDash_DashType,
+    };
+
+    struct DashInfo {
+        SkScalar*   fIntervals;         //!< Length of on/off intervals for dashed lines
+                                        //   Even values represent ons, and odds offs
+        int32_t     fCount;             //!< Number of intervals in the dash. Should be even number
+        SkScalar    fPhase;             //!< Offset into the dashed interval pattern
+                                        //   mod the sum of all intervals
+        bool        fScaleToFit;

[bsalomon, 2014/03/28 14:57:22]

Of all the fields, this one needs a comment :) I'm not particularly familiar
with the dash effect class and the others are pretty obvious while this one is
not.

+    };
+
+    virtual DashType asADash(DashInfo* info) const;
+
     SK_DEFINE_FLATTENABLE_TYPE(SkPathEffect)
 
 protected: