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

include/core/SkPathEffect.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 SkPathEffect_DEFINED
@@ skipping 86 matching lines @@
     };
 
     /**
      *  Does applying this path effect to 'src' yield a set of points? If so,
      *  optionally return the points in 'results'.
      */
     virtual bool asPoints(PointData* results, const SkPath& src,
                           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:
     SkPathEffect() {}
     SkPathEffect(SkReadBuffer& buffer) : INHERITED(buffer) {}
 
 private:
     // illegal
     SkPathEffect(const SkPathEffect&);
     SkPathEffect& operator=(const SkPathEffect&);
@@ skipping 93 matching lines @@
 
 private:
     // illegal
     SkSumPathEffect(const SkSumPathEffect&);
     SkSumPathEffect& operator=(const SkSumPathEffect&);
 
     typedef SkPairPathEffect INHERITED;
 };
 
 #endif