make OpenCL optional for skpdiff

experimental/skpdiff/SkDifferentPixelsMetric_cpu.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 "SkDifferentPixelsMetric.h"
+#include "skpdiff_util.h"
+
+struct SkDifferentPixelsMetric::QueuedDiff {
+    bool finished;
+    double result;
+    SkTDArray<SkIPoint>* poi;
+};
+
+const char* SkDifferentPixelsMetric::getName() {
+    return "different_pixels";
+}
+
+int SkDifferentPixelsMetric::queueDiff(SkBitmap* baseline, SkBitmap* test) {
+    double startTime = get_seconds();
+    int diffID = fQueuedDiffs.count();
+    QueuedDiff* diff = fQueuedDiffs.push();
+    SkTDArray<SkIPoint>* poi = diff->poi = new SkTDArray<SkIPoint>();
+
+    // If we never end up running the kernel, include some safe defaults in the result.
+    diff->finished = false;
+    diff->result = -1;
+
+    // Ensure the images are comparable
+    if (baseline->width() != test->width() || baseline->height() != test->height() ||
+        baseline->width() <= 0 || baseline->height() <= 0 ||
+        baseline->config() != test->config()) {
+        diff->finished = true;
+        return diffID;
+    }
+
+    int width = baseline->width();
+    int height = baseline->height();
+    int differentPixelsCount = 0;
+
+    // Prepare the pixels for comparison
+    baseline->lockPixels();
+    test->lockPixels();
+    for (int y = 0; y < height; y++) {
+        // Grab a row from each image for easy comparison
+        unsigned char* baselineRow = (unsigned char*)baseline->getAddr(0, y);
+        unsigned char* testRow = (unsigned char*)test->getAddr(0, y);
+        for (int x = 0; x < width; x++) {
+            // Compare one pixel at a time so each differing pixel can be noted
+            if (std::memcmp(&baselineRow[x * 4], &testRow[x * 4], 4) != 0) {
+                poi->push()->set(x, y);
+                differentPixelsCount++;
+            }
+        }
+    }
+    test->unlockPixels();
+    baseline->unlockPixels();
+
+    // Calculates the percentage of identical pixels
+    diff->result = 1.0 - ((double)differentPixelsCount / (width * height));
+
+    SkDebugf("Time: %f\n", (get_seconds() - startTime));
+
+    return diffID;
+}
+
+void SkDifferentPixelsMetric::deleteDiff(int id) {
+    if (NULL != fQueuedDiffs[id].poi)
+    {
+        delete fQueuedDiffs[id].poi;
+        fQueuedDiffs[id].poi = NULL;
+    }
+}
+
+bool SkDifferentPixelsMetric::isFinished(int id) {
+    return fQueuedDiffs[id].finished;
+}
+
+double SkDifferentPixelsMetric::getResult(int id) {
+    return fQueuedDiffs[id].result;
+}
+
+int SkDifferentPixelsMetric::getPointsOfInterestCount(int id) {
+    return fQueuedDiffs[id].poi->count();
+}
+
+SkIPoint* SkDifferentPixelsMetric::getPointsOfInterest(int id) {
+    return fQueuedDiffs[id].poi->begin();
+}