Randomize seed for SkDiscretePathEffect::filterPath()

include/effects/SkDiscretePathEffect.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 SkDiscretePathEffect_DEFINED
 #define SkDiscretePathEffect_DEFINED
 
 #include "SkPathEffect.h"
+#include "SkRandom.h"

[scroggo, 2014/06/05 16:09:30]

No need for this include here, since the header does not appear to reference
anything from SkRandom.

[rs.prinja, 2014/06/07 10:46:05]

Done.

 
 /** \class SkDiscretePathEffect
 
     This path effect chops a path into discrete segments, and randomly displaces them.
 */
 class SK_API SkDiscretePathEffect : public SkPathEffect {
 public:
     /** Break the path into segments of segLength length, and randomly move the endpoints
         away from the original path by a maximum of deviation.
         Note: works on filled or framed paths
     */
-    static SkDiscretePathEffect* Create(SkScalar segLength, SkScalar deviation) {
-        return SkNEW_ARGS(SkDiscretePathEffect, (segLength, deviation));
+    static SkDiscretePathEffect* Create(SkScalar segLength, SkScalar deviation, uint32_t seedAssist=1) {

[scroggo, 2014/06/05 16:09:30]

Please use a line break so the line is not over 100 chars. Skia's coding style
guidelines are here:
https://sites.google.com/site/skiadocs/developer-documentation/contributing-c...

[rs.prinja, 2014/06/07 10:46:04]

Done.

+        return SkNEW_ARGS(SkDiscretePathEffect, (segLength, deviation, seedAssist));
     }
 
     virtual bool filterPath(SkPath* dst, const SkPath& src,
                             SkStrokeRec*, const SkRect*) const SK_OVERRIDE;
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkDiscretePathEffect)
 
 protected:
-    SkDiscretePathEffect(SkScalar segLength, SkScalar deviation);
+    SkDiscretePathEffect(SkScalar segLength, SkScalar deviation, uint32_t seedAssist=1);

[scroggo, 2014/06/05 16:09:30]

In general, we only want a default parameter on the user-facing API. (We also
don't want these two to get out of sync.)

[rs.prinja, 2014/06/07 10:46:05]

Done.

     explicit SkDiscretePathEffect(SkReadBuffer&);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
 private:
     SkScalar fSegLength, fPerterb;
 
+    /* Caller-supplied 32 bit seed assist */
+    uint32_t fSeedAssist;
+
+    static uint32_t fObjectIdGenerator;

[scroggo, 2014/06/05 16:09:30]

This is not needed. As discussed in skbug.com/2581, we want to only make it
random based on the seed and and path length.

(As a side note, though it's not mentioned in the style guide, we generally use
a different naming convention for static variables. This should be
gObjectIdGenerator. It also need not be in the class definition. See
SkNextPixelRefGenerationID() in
https://skia.googlesource.com/skia/+/1b918af0d86cc4bebdebd5fd1d76f63359009f01...)

[rs.prinja, 2014/06/07 10:46:04]

Done.

+    uint32_t fObjectId;

[scroggo, 2014/06/05 16:09:30]

Please remove.

[rs.prinja, 2014/06/07 10:46:04]

Done.

+
     typedef SkPathEffect INHERITED;
 };
 
 #endif