Remove SkShader virtual method validContext

include/core/SkShader.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 SkShader_DEFINED
 #define SkShader_DEFINED
@@ skipping 195 matching lines @@
 
     private:
         SkMatrix            fTotalInverse;
         uint8_t             fPaintAlpha;
         uint8_t             fTotalInverseClass;
 
         typedef SkNoncopyable INHERITED;
     };
 
     /**
-     *  Subclasses should be sure to call their INHERITED::validContext() if
-     *  they override this method.
+     *  Create the actual object that does the shading.
+     *  Size of storage must be >= contextSize.
      */
-    virtual bool validContext(const ContextRec&, SkMatrix* totalInverse = NULL) const;
-
-    /**
-     *  Create the actual object that does the shading.
-     *  Returns NULL if validContext() returns false.
-     *  Size of storage must be >= contextSize.
-     *  Your subclass must also override contextSize() if it overrides createContext().
-     *
-     *  Base class implementation returns NULL.
-     */
-    virtual Context* createContext(const ContextRec&, void* storage) const;
+    Context* createContext(const ContextRec&, void* storage) const;
 
     /**
      *  Return the size of a Context returned by createContext.
      *
      *  Override this if your subclass overrides createContext, to return the correct size of
      *  your subclass' context.
      */
     virtual size_t contextSize() const;
 
     /**
@@ skipping 127 matching lines @@
      *  The incoming color to the effect has r=g=b=a all extracted from the SkPaint's alpha.
      *  The output color should be the computed SkShader premul color modulated by the incoming
      *  color. The GrContext may be used by the effect to create textures. The GPU device does not
      *  call createContext. Instead we pass the SkPaint here in case the shader needs paint info.
      */
     virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint& paint) const;
 
     //////////////////////////////////////////////////////////////////////////
     //  Factory methods for stock shaders
 
+    /**
+     *  Call this to create a new "empty" shader, that will not draw anything.
+     */
+    static SkShader* CreateEmptyShader();
+
     /** Call this to create a new shader that will draw with the specified bitmap.
      *
      *  If the bitmap cannot be used (e.g. has no pixels, or its dimensions
      *  exceed implementation limits (currently at 64K - 1)) then SkEmptyShader
      *  may be returned.
      *
      *  If the src is kA8_Config then that mask will be colorized using the color on
      *  the paint.
      *
      *  @param src  The bitmap to use inside the shader
@@ skipping 15 matching lines @@
      *  @param tmy  The tiling mode to use when sampling the bitmap in the y-direction.
      *  @return     Returns a new shader object. Note: this function never returns null.
     */
     static SkShader* CreatePictureShader(SkPicture* src, TileMode tmx, TileMode tmy,
                                          const SkMatrix* localMatrix = NULL);
 
     SK_TO_STRING_VIRT()
     SK_DEFINE_FLATTENABLE_TYPE(SkShader)
 
 protected:
-
     SkShader(SkReadBuffer& );
     virtual void flatten(SkWriteBuffer&) const SK_OVERRIDE;
 
+    bool computeTotalInverse(const ContextRec&, SkMatrix* totalInverse) const;
+
+    /**
+     *  Your subclass must also override contextSize() if it overrides onCreateContext().
+     *  Base class impl returns NULL.
+     */
+    virtual Context* onCreateContext(const ContextRec&, void* storage) const;
+
 private:
-    SkMatrix            fLocalMatrix;
-
-    bool computeTotalInverse(const SkMatrix& matrix, SkMatrix* totalInverse) const;
+    SkMatrix fLocalMatrix;
 
     typedef SkFlattenable INHERITED;
 };
 
 #endif