Add support for multiple frames in SkCodec

tests/CodecAnimTest.cpp

Index: tests/CodecAnimTest.cpp
diff --git a/tests/CodecAnimTest.cpp b/tests/CodecAnimTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..3821be9212b8dcccab061b663d4269ca2e531328
--- /dev/null
+++ b/tests/CodecAnimTest.cpp
@@ -0,0 +1,136 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCodec.h"
+#include "SkStream.h"
+
+#include "Resources.h"
+#include "Test.h"
+
+#include <initializer_list>
+#include <vector>
+
+DEF_TEST(Codec_frames, r) {
+    static const struct {
+        const char*         fName;
+        size_t              fFrameCount;
+        // One less than fFramecount, since the first frame is always
+        // independent.
+        std::vector<size_t> fRequiredFrames;
+        std::vector<size_t> fDurations;
+    } gRecs[] = {
+        { "box.gif", 1, {}, {} },
+        { "color_wheel.gif", 1, {}, {} },
+        { "test640x479.gif", 4, { 0, 1, 2 }, { 20, 20, 20, 20 } },
+
+        { "arrow.png",  1, {}, {} },
+        { "google_chrome.ico", 1, {}, {} },
+        { "brickwork-texture.jpg", 1, {}, {} },
+        { "dng_with_preview.dng", 1, {}, {} },
+        { "mandrill.wbmp", 1, {}, {} },
+        { "randPixels.bmp", 1, {}, {} },
+        { "yellow_rose.webp", 1, {}, {} },
+    };
+
+    for (auto rec : gRecs) {
+        std::unique_ptr<SkStream> stream(GetResourceAsStream(rec.fName));
+        if (!stream) {
+            // Useful error statement, but sometimes people run tests without
+            // resources, and they do not want to see these messages.
+            //ERRORF(r, "Missing resources? Could not find '%s'", rec.fName);
+            continue;
+        }
+
+        std::unique_ptr<SkCodec> codec(SkCodec::NewFromStream(stream.release()));
+        if (!codec) {
+            ERRORF(r, "Failed to create an SkCodec from '%s'", rec.fName);
+            continue;
+        }
+
+        const size_t expected = rec.fFrameCount;
+        const size_t frameCount = codec->getFrameCount();
+        if (frameCount != expected) {
+            ERRORF(r, "'%s' expected frame count: %i\tactual: %i", rec.fName, expected, frameCount);
+            continue;
+        }
+
+        REPORTER_ASSERT(r, codec->getRequiredFrame(0) == SkCodec::kIndependentFrame);
+
+        if (rec.fRequiredFrames.size() + 1 != expected) {
+            ERRORF(r, "'%s' has wrong number entries in fRequiredFrames; expected: %i\tactual: %i",
+                   rec.fName, expected, rec.fRequiredFrames.size());
+            continue;
+        }
+
+        if (1 == frameCount) {
+            continue;
+        }
+
+        // From here on, we are only concerned with animated images.
+        for (size_t i = 1; i < frameCount; i++) {
+            REPORTER_ASSERT(r, rec.fRequiredFrames[i-1] == codec->getRequiredFrame(i));
+        }
+
+        // Compare decoding in two ways:
+        // 1. Provide the frame that a frame depends on, so the codec just has to blend.
+        //    (in the array cachedFrames)
+        // 2. Do not provide the frame that a frame depends on, so the codec has to decode all the
+        //    way back to a key-frame. (in a local variable uncachedFrame)
+        // The two should look the same.
+        std::vector<SkBitmap> cachedFrames(frameCount);
+        const auto& info = codec->getInfo().makeColorType(kN32_SkColorType);
+
+        auto decode = [&](SkBitmap* bm, bool cached, size_t index) {
+            bm->allocPixels(info);
+            if (cached) {
+                // First copy the pixels from the cached frame
+                const size_t requiredFrame = codec->getRequiredFrame(index);
+                if (requiredFrame != SkCodec::kIndependentFrame) {
+                    const bool success = cachedFrames[requiredFrame].copyTo(bm);
+                    REPORTER_ASSERT(r, success);
+                }
+            }
+            SkCodec::Options opts;
+            opts.fFrameIndex = index;
+            opts.fHasPriorFrame = cached;
+            const SkCodec::Result result = codec->getPixels(info, bm->getPixels(), bm->rowBytes(),
+                                                            &opts, nullptr, nullptr);
+            REPORTER_ASSERT(r, result == SkCodec::kSuccess);
+        };
+
+        for (size_t i = 0; i < frameCount; i++) {
+            SkBitmap& cachedFrame = cachedFrames[i];
+            decode(&cachedFrame, true, i);
+            SkBitmap uncachedFrame;
+            decode(&uncachedFrame, false, i);
+
+            // Now verify they're equal.
+            const size_t rowLen = info.bytesPerPixel() * info.width();
+            for (int y = 0; y < info.height(); y++) {
+                const void* cachedAddr = cachedFrame.getAddr(0, y);
+                SkASSERT(cachedAddr != nullptr);
+                const void* uncachedAddr = uncachedFrame.getAddr(0, y);
+                SkASSERT(uncachedAddr != nullptr);
+                const bool lineMatches = memcmp(cachedAddr, uncachedAddr, rowLen) == 0;
+                if (!lineMatches) {
+                    ERRORF(r, "%s's frame %i is different depending on caching!", rec.fName, i);
+                    break;
+                }
+            }
+        }
+
+        if (rec.fDurations.size() != expected) {
+            ERRORF(r, "'%s' has wrong number entries in fDurations; expected: %i\tactual: %i",
+                   rec.fName, expected, rec.fDurations.size());
+            continue;
+        }
+
+        for (size_t i = 0; i < frameCount; i++) {
+            REPORTER_ASSERT(r, rec.fDurations[i] == codec->getFrameDuration(i));
+        }
+    }
+}