Begin making SkPerlinNoiseShader const.

include/effects/SkPerlinNoiseShader.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPerlinNoiseShader_DEFINED
 #define SkPerlinNoiseShader_DEFINED
 
@@ skipping 64 matching lines @@
 protected:
     SkPerlinNoiseShader(SkReadBuffer&);
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
 private:
     SkPerlinNoiseShader(SkPerlinNoiseShader::Type type, SkScalar baseFrequencyX,
                         SkScalar baseFrequencyY, int numOctaves, SkScalar seed,
                         const SkISize* tileSize = NULL);
     virtual ~SkPerlinNoiseShader();
 
-    void setTileSize(const SkISize&);
-
-    void initPaint(PaintingData& paintingData);
-
     SkScalar noise2D(int channel, const PaintingData& paintingData,
                      const StitchData& stitchData, const SkPoint& noiseVector);
 
     SkScalar calculateTurbulenceValueForPoint(int channel, const PaintingData& paintingData,
                                               StitchData& stitchData, const SkPoint& point);
 
     SkPMColor shade(const SkPoint& point, StitchData& stitchData);
 
-    SkPerlinNoiseShader::Type fType;
-    SkScalar fBaseFrequencyX;
-    SkScalar fBaseFrequencyY;
-    int fNumOctaves;
-    SkScalar fSeed;
-    SkISize fTileSize;
-    bool fStitchTiles;
+    // TODO (scroggo): Once all SkShaders are created from a factory, and we have removed the
+    // constructor that creates SkPerlinNoiseShader from an SkReadBuffer, several fields can
+    // be made constant.

[Dominik Grewe, 2014/02/18 15:00:33]

Is it always feasible to make all fields const? If so, that would be great. I
haven't really thought about that yet, but it feels like the right thing to do
when making effects immutable.
I'm just worried that there might be some initialization code in a constructor
that you can't easily place into an initializer list. But maybe there isn't.

All effects currently have constructors that take an SkReadBuffer as parameter.
If we wanted to get rid of them (which we'd have to as you said above), maybe we
can introduce a macro similar to
SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS but using the factory
methods instead. Would be a separate patch I suppose :)

[scroggo, 2014/02/18 16:42:57]

I don't know of any other way to make them immutable.
That may be so. I tend to think that's a bridge we can cross when we get there.

+    /*const*/ SkPerlinNoiseShader::Type fType;
+    /*const*/ SkScalar                  fBaseFrequencyX;
+    /*const*/ SkScalar                  fBaseFrequencyY;
+    /*const*/ int                       fNumOctaves;
+    /*const*/ SkScalar                  fSeed;
+    /*const*/ SkISize                   fTileSize;
+    /*const*/ bool                      fStitchTiles;
+    // TODO (scroggo): Once setContext creates a new object, place this on that object.
     SkMatrix fMatrix;
 
     PaintingData* fPaintingData;
 
     typedef SkShader INHERITED;
 };
 
 #endif