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Fix assertions in WebPRescalerExportRow()

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Change-Id: I25711dd54e71c90a25f7b18e0ef9155e8151a15e
This commit is contained in:
Hui Su
2016-08-11 18:28:40 +00:00
committed by James Zern
parent 74f6f9e793
commit 27b5d991e2
2 changed files with 8 additions and 4 deletions
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8
src/utils/rescaler.c
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@ -48,11 +48,15 @@ void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
wrk->y_sub = wrk->y_expand ? y_sub - 1 : y_sub;
wrk->y_accum = wrk->y_expand ? wrk->y_sub : wrk->y_add;
if (!wrk->y_expand) {
// this is WEBP_RESCALER_FRAC(dst_height, x_add * y_add) without the cast.
// This is WEBP_RESCALER_FRAC(dst_height, x_add * y_add) without the cast.
// Its value is <= WEBP_RESCALER_ONE, because dst_height <= wrk->y_add, and
// wrk->x_add >= 1;
const uint64_t ratio =
(uint64_t)dst_height * WEBP_RESCALER_ONE / (wrk->x_add * wrk->y_add);
if (ratio != (uint32_t)ratio) {
// We can't represent the ratio with the current fixed-point precision.
// When ratio == WEBP_RESCALER_ONE, we can't represent the ratio with the
// current fixed-point precision. This happens when src_height ==
// wrk->y_add (which == src_height), and wrk->x_add == 1.
// => We special-case fxy_scale = 0, in WebPRescalerExportRow().
wrk->fxy_scale = 0;
} else {