first draft of error checking / reporting API

src/core/SkError.cpp

Index: src/core/SkError.cpp
diff --git a/src/core/SkError.cpp b/src/core/SkError.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3555c6961c0fac40286e5382faa7eb09300d2b32
--- /dev/null
+++ b/src/core/SkError.cpp
@@ -0,0 +1,143 @@
+
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTLS.h"
+#include "SkTypes.h"
+#include "SkError.h"
+#include "SkErrorInternals.h"
+
+#include <stdio.h>
+#include <stdarg.h>
+
+namespace {
+    void *CreateThreadError() {
+        return SkNEW_ARGS(SkError, (kNoError_SkError));
+    }
+    void DeleteThreadError(void* v) {
+        SkDELETE(reinterpret_cast<SkError*>(v));
+    }
+    #define THREAD_ERROR \
+        (*reinterpret_cast<SkError*>(SkTLS::Get(CreateThreadError, DeleteThreadError)))
+
+    void *CreateThreadErrorCallback() {
+        return SkNEW_ARGS(SkErrorCallbackFunction, (SkErrorInternals::DefaultErrorCallback));
+    }
+    void DeleteThreadErrorCallback(void* v) {
+        SkDELETE(reinterpret_cast<SkErrorCallbackFunction *>(v));
+    }
+
+    #define THREAD_ERROR_CALLBACK                                                             \
+        *(reinterpret_cast<SkErrorCallbackFunction *>(SkTLS::Get(CreateThreadErrorCallback,   \
+                                                                 DeleteThreadErrorCallback)))
+   
+    void *CreateThreadErrorContext() {
+        return SkNEW_ARGS(void **, (NULL));
+    }
+    void DeleteThreadErrorContext(void* v) {
+        SkDELETE(reinterpret_cast<void **>(v));
+    }
+    #define THREAD_ERROR_CONTEXT \
+        (*reinterpret_cast<void **>(SkTLS::Get(CreateThreadErrorContext, DeleteThreadErrorContext)))
+
+    #define ERROR_STRING_LENGTH 2048
+
+    void *CreateThreadErrorString() {
+        return SkNEW_ARRAY(char, (ERROR_STRING_LENGTH));
+    }
+    void DeleteThreadErrorString(void* v) {
+        SkDELETE_ARRAY(reinterpret_cast<char *>(v));
+    }
+    #define THREAD_ERROR_STRING \
+        (reinterpret_cast<char *>(SkTLS::Get(CreateThreadErrorString, DeleteThreadErrorString)))
+}
+
+SkError SkGetLastError() {
+    return SkErrorInternals::GetLastError();
+}
+void SkClearLastError() {
+    SkErrorInternals::ClearError();
+}
+void SkSetErrorCallback(SkErrorCallbackFunction cb, void *context) {
+    SkErrorInternals::SetErrorCallback(cb, context);
+}
+const char *SkGetLastErrorString() {
+    return SkErrorInternals::GetLastErrorString();
+}
+
+// ------------ Private Error functions ---------
+
+void SkErrorInternals::SetErrorCallback(SkErrorCallbackFunction cb, void *context) {
+    if (cb == NULL) {
+        THREAD_ERROR_CALLBACK = SkErrorInternals::DefaultErrorCallback;
+    } else {
+        THREAD_ERROR_CALLBACK = cb;
+    }
+    THREAD_ERROR_CONTEXT = context;
+}
+
+void SkErrorInternals::DefaultErrorCallback(SkError code, void *context) {
+    SkDebugf("Skia Error: %s\n", SkGetLastErrorString());
+}
+
+void SkErrorInternals::ClearError() {
+    SkErrorInternals::SetError( kNoError_SkError, "All is well" );
+}
+
+SkError SkErrorInternals::GetLastError() {
+    return THREAD_ERROR;
+}
+
+const char *SkErrorInternals::GetLastErrorString() {
+    return THREAD_ERROR_STRING;
+}
+
+void SkErrorInternals::SetError(SkError code, const char *fmt, ...) {
+    THREAD_ERROR = code;
+    va_list args;
+    
+    char *str = THREAD_ERROR_STRING;
+    const char *error_name = NULL;
+    switch( code ) {
+        case kNoError_SkError:
+            error_name = "No Error";
+            break;
+        case kInvalidArgument_SkError:
+            error_name = "Invalid Argument";  
+            break;
+        case kInvalidOperation_SkError: 
+            error_name = "Invalid Operation"; 
+            break;
+        case kInvalidHandle_SkError:
+            error_name = "Invalid Handle";
+            break;
+        case kInvalidPaint_SkError:
+            error_name = "Invalid Paint";
+            break;
+        case kOutOfMemory_SkError:
+            error_name = "Out Of Memory";
+            break;
+        case kParseError_SkError:
+            error_name = "Parse Error";
+            break;
+        default:
+            error_name = "Unknown error";
+            break;
+    }
+    
+    sprintf( str, "%s: ", error_name );
+    int string_left = ERROR_STRING_LENGTH - strlen( str );
+    str += strlen(str);
+    
+    va_start( args, fmt );
+    vsnprintf( str, string_left, fmt, args );
+    va_end( args );
+    SkErrorCallbackFunction fn = THREAD_ERROR_CALLBACK;
+    if (fn && code != kNoError_SkError) {
+        fn(code, THREAD_ERROR_CONTEXT);
+    }
+}