Report first GIF frame after knowing its meta data

Previously, we reported the first image as soon as it was available. As
a result, in crrev.com/2565323003, InitializeNewFrame might be called
before the metadata is known, meaning it would read the wrong metadata.

Instead of looking at the imagesCount(), SkGifCodec::NewFromStream looks
at frameContext(0), which may still exist even if it's not yet counted
in imagesCount().

Add a test that confirms the desired behavior.

Change-Id: Ib392721ecd2218ba0fcd35aaa64117c0ba3e4ea6
Reviewed-on: https://skia-review.googlesource.com/24405
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>

1 files changed, 3 insertions, 4 deletions

diff --git a/src/codec/SkGifCodec.cpp b/src/codec/SkGifCodec.cpp
index 9b3d4b5ed5..7b31a618ea 100644
--- a/src/codec/SkGifCodec.cpp
+++ b/src/codec/SkGifCodec.cpp
@@ -76,7 +76,8 @@ SkCodec* SkGifCodec::NewFromStream(SkStream* stream, Result* result) {
 
     // If no images are in the data, or the first header is not yet defined, we cannot
     // create a codec. In either case, the width and height are not yet known.
-    if (0 == reader->imagesCount() || !reader->frameContext(0)->isHeaderDefined()) {
+    auto* frame = reader->frameContext(0);
+    if (!frame || !frame->isHeaderDefined()) {
         *result = kInvalidInput;
         return nullptr;
     }
@@ -136,9 +137,7 @@ bool SkGifCodec::onGetFrameInfo(int i, SkCodec::FrameInfo* frameInfo) const {
     }
 
     const SkGIFFrameContext* frameContext = fReader->frameContext(i);
-    if (!frameContext->reachedStartOfData()) {
-        return false;
-    }
+    SkASSERT(frameContext->reachedStartOfData());
 
     if (frameInfo) {
         frameInfo->fDuration = frameContext->getDuration();