Add support for multiple frames in SkCodec

src/codec/SkGifCodec.cpp

Index: src/codec/SkGifCodec.cpp
diff --git a/src/codec/SkGifCodec.cpp b/src/codec/SkGifCodec.cpp
index cbe87938b1bb15ac9a748dc41f465faa5f84825e..46b8beee163d7c18d5bdbd358fc741377b17f7f5 100644
--- a/src/codec/SkGifCodec.cpp
+++ b/src/codec/SkGifCodec.cpp
@@ -266,7 +266,7 @@ SkGifCodec::SkGifCodec(int width, int height, const SkEncodedInfo& info, SkStrea
         const SavedImage* image = &gif->SavedImages[i];
         const GifImageDesc& desc = image->ImageDesc;
 
-        auto& frame = fFrameInfos.push_back();
+        auto& frame = fFrameInfos[i];
         // FIXME: Probably want to intersect this with the bounds, just in case.
         // But then we'll need to make sure we draw the right thing...
         // i.e. if the top is cut off (desc.Top < 0), we want to start off drawing line -desc.Top
@@ -307,20 +307,19 @@ SkGifCodec::SkGifCodec(int width, int height, const SkEncodedInfo& info, SkStrea
     }
 }
 
-size_t SkGifCodec::onGetRequiredFrame(size_t index) {
-    if ((int) index >= fFrameInfos.count()) {
-        return kIndependentFrame;
+std::vector<SkCodec::FrameInfo> SkGifCodec::onGetFrameInfo() {
+    const size_t size = fFrameInfos.size();
+    if (1 == size) {
+        // As with other formats, return empty set for non-animated
+        // FIXME: But it might be animated, we just haven't received the second frame?
+        // I suppose we could check the duration? But even that might not be perfect...
+        return {};
     }
-
-    return fFrameInfos[index].fRequiredFrame;
-}
-
-size_t SkGifCodec::onGetFrameDuration(size_t index) {
-    if ((int) index >= fFrameInfos.count()) {
-        return 0;
+    std::vector<FrameInfo> result(size);
+    for (size_t i = 0; i < size; i++) {
+        result[i] = (FrameInfo) fFrameInfos[i];
     }
-
-    return fFrameInfos[index].fDuration;
+    return result;
 }
 
 bool SkGifCodec::GetDimensions(GifFileType* gif, SkISize* size) {
@@ -428,7 +427,7 @@ SkCodec::Result SkGifCodec::prepareToDecode(const SkImageInfo& dstInfo, SkPMColo
                          kInvalidConversion);
     }
 
-    if (opts.fFrameOptions && (int) opts.fFrameOptions->fIndex > fFrameInfos.count()) {
+    if (opts.fFrameOptions && opts.fFrameOptions->fIndex > fFrameInfos.size()) {
         return gif_error("frame index out of range!\n", kInvalidParameters);
     }
 
@@ -466,7 +465,7 @@ void SkGifCodec::decodeFrame(const SkImageInfo& dstInfo, void* pixels, size_t ds
     void* dst = pixels;
 
     const size_t frameIndex = opts.fFrameOptions ? opts.fFrameOptions->fIndex : 0;
-    SkASSERT((int) frameIndex < fFrameInfos.count());
+    SkASSERT(frameIndex < fFrameInfos.size());
     const auto& frameInfo = fFrameInfos[frameIndex];
     const SkIRect& frameRect = frameInfo.fFrameRect;
     const bool independent = frameInfo.fRequiredFrame == kIndependentFrame;