Initial error handling code

include/core/SkError.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 SkError_DEFINED
 #define SkError_DEFINED
 
 
 /** \file SkError.h
 */
 
 enum SkError {
     /** All is well
      */
-    kNoError_SkError=0,
+    kNoError_SkError = 0x00,

[sugoi1, 2013/08/21 15:33:41]

Changed these values so that they can be used as flags to be able to signal
multiple ones simultaneously, in case we want to handle different cases
differently.

[scroggo, 2013/08/21 23:56:00]

If we're going to change this, should we change the other use of SkError (using
SkErrorInternal)?

[scroggo, 2013/08/21 23:57:16]

nvm

 
     /** User argument passed to Skia function was invalid: NULL when that’s
      *  not allowed, out of numeric range, bad enum, or violating some
      *  other general precondition.
      */
-    kInvalidArgument_SkError,
+    kInvalidArgument_SkError = 0x01,

[scroggo, 2013/08/21 23:56:00]

Typically we make these line up horizontally. i.e.:

kNoError_SkError         = 0x00,
kInvalidArgument_SkError = 0x01,
.
.
.

[scroggo, 2013/08/21 23:57:16]

nvm

 
     /** User tried to perform some operation in a state when the operation
      *  was not legal, or the operands make no sense (e.g., asking for
      *  pixels from an SkPictureCanvas).  Other examples might be
      *  inset()’ing a rectangle to make it degenerate (negative width/height).
      */
-    kInvalidOperation_SkError,
+    kInvalidOperation_SkError = 0x02,
 
     /** Probably not needed right now, but in the future we could have opaque
      *  handles for SkPictures floating around, and it would be a good idea
      *  to anticipate this kind of issue.
      */
-    kInvalidHandle_SkError,
+    kInvalidHandle_SkError = 0x04,
 
     /** This is probably not possible because paint surely has defaults for
      *  everything, but perhaps a paint can get into a bad state somehow.
      */
-    kInvalidPaint_SkError,
+    kInvalidPaint_SkError = 0x08,
 
     /** Skia was unable to allocate memory to perform some task.
      */
-    kOutOfMemory_SkError,
+    kOutOfMemory_SkError = 0x10,
 
     /** Skia failed while trying to consume some external resource.
      */
-    kParseError_SkError
+    kParseError_SkError = 0x20
 };
 
 /** Return the current per-thread error code.  Error codes are "sticky"; they
  *  are not not reset by subsequent successful operations.
  */
 SkError SkGetLastError();
 
 /** Clear the current per-thread error code back to kNoError_SkError.
  */
 void SkClearLastError();
@@ skipping 16 matching lines @@
 void SkSetErrorCallback(SkErrorCallbackFunction cb, void *context);
 
 /** Get a human-readable description of the last (per-thread) error that
  *  occurred.  The returned error message will include not only a human
  *  readable version of the error code, but also information about the
  *  conditions that led to the error itself.
  */
 const char *SkGetLastErrorString();
 
 #endif /* SkError_DEFINED */