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;
 
+    /**
+     *  If the PathEffect can be represented as a dash pattern, 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 can be a dash pattern. If passed in info has an fCount equal or
+     *  greater to that of the effect, it will memcpy the values of the dash intervals into the
+     *  info. Thus the general approach will be call asADash once with default info to get DashType
+     *  and fCount. If effect can be represented as a dash pattern, allocate space for the intervals
+     *  in info, then call asADash again with the same info and the intervals will get copied in.
+     */
+
+    enum DashType {
+        kNone_DashType, //!< ignores the info parameter
+        kDash_DashType, //!< fills in all of the info parameter
+    };
+
+    struct DashInfo {
+        DashInfo() : fIntervals(0), fCount(0), fPhase(0.0) {}

[reed1, 2014/04/22 13:49:01]

fPhase(0) is fine.

Sometimes saying 0.0 will make the compiler think you have a double, and then
you could get a (stupid) warning about double->float conversion.

fIntervals(NULL) is skia's convention for pointers.

+
+        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
+    };
+
+    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