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preparatory cosmetics for Rescaler code fix and clean-up

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Change-Id: I1278837c8d7813192e8099d6fceaede75f38755b
This commit is contained in:
Pascal Massimino 2015-08-19 04:33:18 +00:00 committed by James Zern
parent 77fb41c2f1
commit 7b83adbee6
2 changed files with 14 additions and 8 deletions
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16
src/utils/rescaler.c
View File

@ -26,6 +26,7 @@ void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
const int x_add = src_width, x_sub = dst_width;
const int y_add = src_height, y_sub = dst_height;
wrk->x_expand = (src_width < dst_width);
wrk->y_expand = (src_height < dst_height);
wrk->src_width = src_width;
wrk->src_height = src_height;
wrk->dst_width = dst_width;
@ -33,18 +34,23 @@ void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height,
wrk->dst = dst;
wrk->dst_stride = dst_stride;
wrk->num_channels = num_channels;
// for 'x_expand', we use bilinear interpolation
wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add;
wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub;
wrk->y_accum = y_add;
wrk->y_add = y_add;
wrk->y_sub = y_sub;
if (!wrk->x_expand) { // fx_scale is not used otherwise
wrk->fx_scale = (1 << WEBP_RESCALER_RFIX) / wrk->x_sub;
}
// vertical scaling parameters
wrk->y_accum = y_add;
wrk->y_add = y_add;
wrk->y_sub = y_sub;
wrk->fy_scale = (1 << WEBP_RESCALER_RFIX) / wrk->y_sub;
wrk->fxy_scale =
((int64_t)dst_height << WEBP_RESCALER_RFIX) / (wrk->x_add * src_height);
((int64_t)dst_height << WEBP_RESCALER_RFIX) / (wrk->x_add * wrk->y_add);
wrk->irow = work;
wrk->frow = work + num_channels * dst_width;
memset(work, 0, 2 * dst_width * num_channels * sizeof(*work));
@ -91,7 +97,7 @@ int WebPRescaleNeededLines(const WebPRescaler* const wrk, int max_num_lines) {
int WebPRescalerImport(WebPRescaler* const wrk, int num_lines,
const uint8_t* src, int src_stride) {
int total_imported = 0;
while (total_imported < num_lines && wrk->y_accum > 0) {
while (total_imported < num_lines && !WebPRescalerHasPendingOutput(wrk)) {
int channel;
for (channel = 0; channel < wrk->num_channels; ++channel) {
WebPRescalerImportRow(wrk, src, channel);

6
src/utils/rescaler.h
View File

@ -26,13 +26,13 @@ extern "C" {
typedef struct WebPRescaler WebPRescaler;
struct WebPRescaler {
int x_expand; // true if we're expanding in the x direction
int y_expand; // true if we're expanding in the y direction
int num_channels; // bytes to jump between pixels
int fy_scale, fx_scale; // fixed-point scaling factor
int64_t fxy_scale; // ''
// we need hpel-precise add/sub increments, for the downsampled U/V planes.
int y_accum; // vertical accumulator
int y_add, y_sub; // vertical increments (add ~= src, sub ~= dst)
int x_add, x_sub; // horizontal increments (add ~= src, sub ~= dst)
int y_add, y_sub; // vertical increments
int x_add, x_sub; // horizontal increments
int src_width, src_height; // source dimensions
int dst_width, dst_height; // destination dimensions
uint8_t* dst;