Error checking / reporting API
Review URL: https://codereview.chromium.org/13699004
git-svn-id: http://skia.googlecode.com/svn/trunk/include@8566 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/core/SkError.h b/core/SkError.h
new file mode 100644
index 0000000..ce2994c
--- /dev/null
+++ b/core/SkError.h
@@ -0,0 +1,86 @@
+/*
+ * 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,
+
+ /** 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,
+
+ /** 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,
+
+ /** 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,
+
+ /** 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,
+
+ /** Skia was unable to allocate memory to perform some task.
+ */
+ kOutOfMemory_SkError,
+
+ /** Skia failed while trying to consume some external resource.
+ */
+ kParseError_SkError
+};
+
+/** 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();
+
+/** Type for callback functions to be invoked whenever an error is registered.
+ * Callback functions take the error code being set, as well as a context
+ * argument that is provided when the callback is registered.
+ */
+typedef void (*SkErrorCallbackFunction)(SkError, void *);
+
+/** Set the current per-thread error callback.
+ *
+ * @param cb The callback function to be invoked. Passing NULL
+ * for cb will revert to the default error callback which
+ * does nothing on release builds, but on debug builds will
+ * print an informative error message to the screen.
+ * @param context An arbitrary pointer that will be passed to
+ * the provided callback function.
+ */
+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 */
