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Regression fix for lossless decoding

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Reported here: https://code.google.com/p/webp/issues/detail?id=239

At the beginning of method 'DecodeImageData', pixels up to
'dec->last_pixel_' are assumed to be already cached. So, at the end of
previous call to that method also, that assumption should hold true.

Hence, we should cache all pixels up to 'src' regardless of 'src_last'.

This affects lossless incremental decoding only, as that is when
src_last and src_end differ.
Note: alpha decoding is implicitly incremental, as alpha decoding of
only the rows 'y_end - y_start' happens during FinishRow() call. So, this bug
affects alpha decoding in non-incremental decoding flow as well.

This bug was introduced in: https://gerrit.chromium.org/gerrit/#/c/59716.

(cherry picked from commit 783a8cda2470f313f454538a149a82ea12171c74)

Change-Id: Ide6edfeb2609b02aff701e1bd9fd776da0a16be0
This commit is contained in:
Urvang Joshi 2015-01-23 12:12:27 -08:00 committed by James Zern
parent 6e3a31d595
commit 5a0c2207f4
1 changed files with 1 additions and 1 deletions
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2
src/dec/vp8l.c
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@ -900,7 +900,7 @@ static int DecodeImageData(VP8LDecoder* const dec, uint32_t* const data,
process_func(dec, row); process_func(dec, row);
} }
} }
if (src < src_last) { if (src < src_end) {
if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row); if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row);
if (color_cache != NULL) { if (color_cache != NULL) {
while (last_cached < src) { while (last_cached < src) {