play with animated gif

Bug: skia:
Change-Id: If86314cda6aa84f4824958cca30cde88a78d4b59
Reviewed-on: https://skia-review.googlesource.com/c/158562
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
diff --git a/src/utils/SkAnimCodecPlayer.cpp b/src/utils/SkAnimCodecPlayer.cpp
new file mode 100644
index 0000000..0a9bbc0
--- /dev/null
+++ b/src/utils/SkAnimCodecPlayer.cpp
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkAnimCodecPlayer.h"
+#include "SkCodec.h"
+#include "SkData.h"
+#include "SkImage.h"
+#include <algorithm>
+
+SkAnimCodecPlayer::SkAnimCodecPlayer(std::unique_ptr<SkCodec> codec) : fCodec(std::move(codec)) {
+    fImageInfo = fCodec->getInfo();
+    fFrameInfos = fCodec->getFrameInfo();
+    fImages.resize(fFrameInfos.size());
+
+    // change the interpretation of fDuration to a end-time for that frame
+    size_t dur = 0;
+    for (auto& f : fFrameInfos) {
+        dur += f.fDuration;
+        f.fDuration = dur;
+    }
+    fTotalDuration = dur;
+}
+
+SkAnimCodecPlayer::~SkAnimCodecPlayer() {}
+
+SkISize SkAnimCodecPlayer::dimensions() {
+    return { fImageInfo.width(), fImageInfo.height() };
+}
+
+sk_sp<SkImage> SkAnimCodecPlayer::getFrameAt(int index) {
+    SkASSERT((unsigned)index < fFrameInfos.size());
+
+    if (fImages[index]) {
+        return fImages[index];
+    }
+
+    size_t rb = fImageInfo.minRowBytes();
+    size_t size = fImageInfo.computeByteSize(rb);
+    auto data = SkData::MakeUninitialized(size);
+
+    SkCodec::Options opts;
+    opts.fFrameIndex = index;
+
+    const int requiredFrame = fFrameInfos[index].fRequiredFrame;
+    if (requiredFrame != SkCodec::kNoFrame) {
+        auto requiredImage = fImages[requiredFrame];
+        SkPixmap requiredPM;
+        if (requiredImage && requiredImage->peekPixels(&requiredPM)) {
+            sk_careful_memcpy(data->writable_data(), requiredPM.addr(), size);
+            opts.fPriorFrame = requiredFrame;
+        }
+    }
+    if (SkCodec::kSuccess == fCodec->getPixels(fImageInfo, data->writable_data(), rb, &opts)) {
+        return fImages[index] = SkImage::MakeRasterData(fImageInfo, std::move(data), rb);
+    }
+    return nullptr;
+}
+
+sk_sp<SkImage> SkAnimCodecPlayer::getFrame() {
+    return this->getFrameAt(fCurrIndex);
+}
+
+bool SkAnimCodecPlayer::seek(uint32_t msec) {
+    msec %= fTotalDuration;
+
+    auto lower = std::lower_bound(fFrameInfos.begin(), fFrameInfos.end(), msec,
+                                  [](const SkCodec::FrameInfo& info, uint32_t msec) {
+                                      return (uint32_t)info.fDuration < msec;
+                                  });
+    int prevIndex = fCurrIndex;
+    fCurrIndex = lower - fFrameInfos.begin();
+    return fCurrIndex != prevIndex;
+}
+
+