Initial error handling code

src/core/SkValidationUtils.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 SkValidationUtils_DEFINED
+#define SkValidationUtils_DEFINED
+
+#include "SkBitmap.h"
+#include "SkXfermode.h"
+
+/** Returns true if coeff's value is in the SkXfermode::Coeff enum.
+  */
+static inline bool SkIsValidCoeff(SkXfermode::Coeff coeff) {
+    return coeff >= 0 && coeff < SkXfermode::kCoeffCount;
+}
+
+/** Returns true if mode's value is in the SkXfermode::Mode enum.
+  */
+static inline bool SkIsValidMode(SkXfermode::Mode mode) {
+    return (mode >= 0) && (mode <= SkXfermode::kLastMode);
+}
+
+/** Returns true if config's value is in the SkBitmap::Config enum.
+  */
+static inline bool SkIsValidConfig(SkBitmap::Config config) {
+    return (config >= 0) && (config <= static_cast<int>(SkBitmap::kConfigCount));
+}
+
+/** Returns true if the rect's dimensions are between 0 and SK_MaxS32
+  */
+static inline bool SkIsValidIRect(const SkIRect& rect) {
+    return rect.width() >= 0 && rect.height() >= 0;
+}
+
+/** Returns true if the rect's dimensions are between 0 and SK_ScalarMax
+  */
+static inline bool SkIsValidRect(const SkRect& rect) {
+    return (rect.fLeft <= rect.fRight) &&
+           (rect.fTop <= rect.fBottom) &&
+           SkScalarIsFinite(rect.width()) &&
+           SkScalarIsFinite(rect.height());
+}
+
+#endif