Initial error handling code

include/core/SkXfermode.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 SkXfermode_DEFINED
@@ skipping 61 matching lines @@
         dstover     ida             one
      */
     virtual bool asCoeff(Coeff* src, Coeff* dst) const;
 
     /**
      *  The same as calling xfermode->asCoeff(..), except that this also checks
      *  if the xfermode is NULL, and if so, treats it as kSrcOver_Mode.
      */
     static bool AsCoeff(const SkXfermode*, Coeff* src, Coeff* dst);
 
+    /** Returns true if coeff's value is in the Coeff enum.
+     */
+    static bool IsValidCoeff(Coeff coeff);

[reed1, 2013/09/03 20:25:21]

Move this to some validating helper file?

[sugoi1, 2013/09/04 18:01:10]

Done.

+
     /** List of predefined xfermodes.
         The algebra for the modes uses the following symbols:
         Sa, Sc  - source alpha and color
         Da, Dc - destination alpha and color (before compositing)
         [a, c] - Resulting (alpha, color) values
         For these equations, the colors are in premultiplied state.
         If no xfermode is specified, kSrcOver is assumed.
         The modes are ordered by those that can be expressed as a pair of Coeffs, followed by those
         that aren't Coeffs but have separable r,g,b computations, and finally
         those that are not separable.
@@ skipping 61 matching lines @@
      *  correctly even if the xfermode is NULL (which equates to kSrcOver.) Thus
      *  you can say this without checking for a null...
      *
      *  If (SkXfermode::IsMode(paint.getXfermode(),
      *                         SkXfermode::kDstOver_Mode)) {
      *      ...
      *  }
      */
     static bool IsMode(const SkXfermode* xfer, Mode mode);
 
+    /** Returns true if mode's value is in the Mode enum.
+     */
+    static bool IsValidMode(Mode mode);
+
     /** Return an SkXfermode object for the specified mode.
      */
     static SkXfermode* Create(Mode mode);
 
     /** Return a function pointer to a routine that applies the specified
         porter-duff transfer mode.
      */
     static SkXfermodeProc GetProc(Mode mode);
 
     /** Return a function pointer to a routine that applies the specified
@@ skipping 98 matching lines @@
         fProc = proc;
     }
 
 private:
     SkXfermodeProc  fProc;
 
     typedef SkXfermode INHERITED;
 };
 
 #endif