add skpdiff tool to compare bitmaps

experimental/skpdiff/SkImageDiffer.cpp

+/*
+ * 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 <cstring>
+
+#include "SkBitmap.h"
+#include "SkImageDecoder.h"
+
+#include "SkImageDiffer.h"
+
+#include "skpdiff_util.h"
+
+
+SkImageDiffer::SkImageDiffer()
+    : fIsGood(true) {
+
+}
+
+SkImageDiffer::~SkImageDiffer() {
+
+}
+
+int SkImageDiffer::queueDiffOfFile(const char baseline[], const char test[]) {
+    SkBitmap baselineBitmap;
+    SkBitmap testBitmap;
+    if (!SkImageDecoder::DecodeFile(baseline, &baselineBitmap)) {
+        SkDebugf("Failed to load bitmap \"%s\"\n", baseline);
+        return -1;
+    }
+    if (!SkImageDecoder::DecodeFile(test, &testBitmap)) {
+        SkDebugf("Failed to load bitmap \"%s\"\n", test);
+        return -1;
+    }
+    return this->queueDiff(&baselineBitmap, &testBitmap);
+}