dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2024-12-25 13:18:22 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

fix RGBA4444 output w/fancy upsampling

Browse Source 
compensates for the 1-line delay in the upscaler, outputting the correct
alpha row

Change-Id: Ia9a65bcb3cfa19e42185523cc6e706101a39d45d
This commit is contained in:
James Zern 2012-08-11 20:08:21 -07:00
parent f06c1d8f7b
commit 681cb30ad2
1 changed files with 46 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
src/dec/io.c
View File

@ -184,38 +184,45 @@ static int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p) {
return 0;
}
static int GetAlphaSourceRow(const VP8Io* const io,
const uint8_t** alpha, int* const num_rows) {
int start_y = io->mb_y;
*num_rows = io->mb_h;
// Compensate for the 1-line delay of the fancy upscaler.
// This is similar to EmitFancyRGB().
if (io->fancy_upsampling) {
if (start_y == 0) {
// We don't process the last row yet. It'll be done during the next call.
--*num_rows;
} else {
--start_y;
// Fortunately, *alpha data is persistent, so we can go back
// one row and finish alpha blending, now that the fancy upscaler
// completed the YUV->RGB interpolation.
*alpha -= io->width;
}
if (io->crop_top + io->mb_y + io->mb_h == io->crop_bottom) {
// If it's the very last call, we process all the remaing rows!
*num_rows = io->crop_bottom - io->crop_top - start_y;
}
}
return start_y;
}
static int EmitAlphaRGB(const VP8Io* const io, WebPDecParams* const p) {
const uint8_t* alpha = io->a;
if (alpha != NULL) {
const int mb_w = io->mb_w;
const int mb_h = io->mb_h;
int i, j;
const WEBP_CSP_MODE colorspace = p->output->colorspace;
const int alpha_first =
(colorspace == MODE_ARGB || colorspace == MODE_Argb);
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
int start_y = io->mb_y;
int num_rows = mb_h;
int num_rows;
const int start_y = GetAlphaSourceRow(io, &alpha, &num_rows);
uint32_t alpha_mask = 0xff;
// We compensate for the 1-line delay of fancy upscaler.
// This is similar to EmitFancyRGB().
if (io->fancy_upsampling) {
if (start_y == 0) {
// We don't process the last row yet. It'll be done during next call.
--num_rows;
} else {
--start_y;
// Fortunately, *alpha data is persistent, so we can go back
// one row and finish alpha blending, now that the fancy upscaler
// completed the YUV->RGB interpolation.
alpha -= io->width;
}
if (io->crop_top + io->mb_y + mb_h == io->crop_bottom) {
// If it's the very last call, we process all the remaing rows!
num_rows = io->crop_bottom - io->crop_top - start_y;
}
}
{
uint8_t* const base_rgba = buf->rgba + start_y * buf->stride;
uint8_t* dst = base_rgba + (alpha_first ? 0 : 3);
@ -242,24 +249,28 @@ static int EmitAlphaRGBA4444(const VP8Io* const io, WebPDecParams* const p) {
const uint8_t* alpha = io->a;
if (alpha != NULL) {
const int mb_w = io->mb_w;
const int mb_h = io->mb_h;
int i, j;
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* const base_rgba = buf->rgba + io->mb_y * buf->stride;
uint8_t* alpha_dst = base_rgba + 1;
int num_rows;
const int start_y = GetAlphaSourceRow(io, &alpha, &num_rows);
uint32_t alpha_mask = 0x0f;
for (j = 0; j < mb_h; ++j) {
for (i = 0; i < mb_w; ++i) {
// Fill in the alpha value (converted to 4 bits).
const uint32_t alpha_value = VP8Clip4Bits(alpha[i]);
alpha_dst[2 * i] = (alpha_dst[2 * i] & 0xf0) | alpha_value;
alpha_mask &= alpha_value;
{
uint8_t* const base_rgba = buf->rgba + start_y * buf->stride;
uint8_t* alpha_dst = base_rgba + 1;
for (j = 0; j < num_rows; ++j) {
for (i = 0; i < mb_w; ++i) {
// Fill in the alpha value (converted to 4 bits).
const uint32_t alpha_value = VP8Clip4Bits(alpha[i]);
alpha_dst[2 * i] = (alpha_dst[2 * i] & 0xf0) | alpha_value;
alpha_mask &= alpha_value;
}
alpha += io->width;
alpha_dst += buf->stride;
}
if (alpha_mask != 0x0f && p->output->colorspace == MODE_rgbA_4444) {
WebPApplyAlphaMultiply4444(base_rgba, mb_w, num_rows, buf->stride);
}
alpha += io->width;
alpha_dst += buf->stride;
}
if (alpha_mask != 0x0f && p->output->colorspace == MODE_rgbA_4444) {
WebPApplyAlphaMultiply4444(base_rgba, mb_w, mb_h, buf->stride);
}
}
return 0;