really fix gif movie registration

git-svn-id: http://skia.googlecode.com/svn/trunk@223 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 6 insertions, 0 deletions

diff --git a/src/images/SkImageDecoder_Factory.cpp b/src/images/SkImageDecoder_Factory.cpp
index 9dd9913bb5..bd81d1fc1d 100644
--- a/src/images/SkImageDecoder_Factory.cpp
+++ b/src/images/SkImageDecoder_Factory.cpp
@@ -28,6 +28,8 @@ SkImageDecoder* SkImageDecoder::Factory(SkStream* stream) {
     const DecodeReg* curr = DecodeReg::Head();
     while (curr) {
         SkImageDecoder* codec = curr->factory()(stream);
+        // we rewind here, because we promise later when we call "decode", that
+        // the stream will be at its beginning.
         stream->rewind();
         if (codec) {
             return codec;
@@ -48,6 +50,8 @@ SkMovie* SkMovie::DecodeStream(SkStream* stream) {
         if (movie) {
             return movie;
         }
+        // we must rewind only if we got NULL, since we gave the stream to the
+        // movie, who may have already started reading from it
         stream->rewind();
         curr = curr->next();
     }
diff --git a/src/images/SkMovie_gif.cpp b/src/images/SkMovie_gif.cpp
index 68af85a94b..113804462a 100644
--- a/src/images/SkMovie_gif.cpp
+++ b/src/images/SkMovie_gif.cpp
@@ -220,6 +220,8 @@ SkMovie* Factory(SkStream* stream) {
         if (memcmp(GIF_STAMP,   buf, GIF_STAMP_LEN) == 0 ||
                 memcmp(GIF87_STAMP, buf, GIF_STAMP_LEN) == 0 ||
                 memcmp(GIF89_STAMP, buf, GIF_STAMP_LEN) == 0) {
+            // must rewind here, since our construct wants to re-read the data
+            stream->rewind();
             return SkNEW_ARGS(SkGIFMovie, (stream));
         }
     }