static int ExportAlpha(WebPDecParams* const p, int y_pos, int max_lines_out) {
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* const base_rgba = buf->rgba + y_pos * buf->stride;
const WEBP_CSP_MODE colorspace = p->output->colorspace;
const int alpha_first =
(colorspace == MODE_ARGB || colorspace == MODE_Argb);
uint8_t* dst = base_rgba + (alpha_first ? 0 : 3);
int num_lines_out = 0;
const int is_premult_alpha = WebPIsPremultipliedMode(colorspace);
uint32_t non_opaque = 0;
const int width = p->scaler_a->dst_width;
while (WebPRescalerHasPendingOutput(p->scaler_a) &&
num_lines_out < max_lines_out) {
assert(y_pos + num_lines_out < p->output->height);
WebPRescalerExportRow(p->scaler_a);
non_opaque |= WebPDispatchAlpha(p->scaler_a->dst, 0, width, 1, dst, 0);
dst += buf->stride;
++num_lines_out;
}
if (is_premult_alpha && non_opaque) {
WebPApplyAlphaMultiply(base_rgba, alpha_first,
width, num_lines_out, buf->stride);
}
return num_lines_out;
}
static int ExportAlphaRGBA4444(WebPDecParams* const p, int y_pos,
int max_lines_out) {
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* const base_rgba = buf->rgba + y_pos * buf->stride;
#ifdef WEBP_SWAP_16BIT_CSP
uint8_t* alpha_dst = base_rgba;
#else
uint8_t* alpha_dst = base_rgba + 1;
#endif
int num_lines_out = 0;
const WEBP_CSP_MODE colorspace = p->output->colorspace;
const int width = p->scaler_a->dst_width;
const int is_premult_alpha = WebPIsPremultipliedMode(colorspace);
uint32_t alpha_mask = 0x0f;
while (WebPRescalerHasPendingOutput(p->scaler_a) &&
num_lines_out < max_lines_out) {
int i;
assert(y_pos + num_lines_out < p->output->height);
WebPRescalerExportRow(p->scaler_a);
for (i = 0; i < width; ++i) {
// Fill in the alpha value (converted to 4 bits).
const uint32_t alpha_value = p->scaler_a->dst[i] >> 4;
alpha_dst[2 * i] = (alpha_dst[2 * i] & 0xf0) | alpha_value;
alpha_mask &= alpha_value;
}
alpha_dst += buf->stride;
++num_lines_out;
}
if (is_premult_alpha && alpha_mask != 0x0f) {
WebPApplyAlphaMultiply4444(base_rgba, width, num_lines_out, buf->stride);
}
return num_lines_out;
}
static int ExportAlpha(WebPDecParams* const p, int y_pos) {
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* const base_rgba = buf->rgba + (p->last_y + y_pos) * buf->stride;
const WEBP_CSP_MODE colorspace = p->output->colorspace;
const int alpha_first =
(colorspace == MODE_ARGB || colorspace == MODE_Argb);
uint8_t* dst = base_rgba + (alpha_first ? 0 : 3);
int num_lines_out = 0;
const int is_premult_alpha = WebPIsPremultipliedMode(colorspace);
uint32_t alpha_mask = 0xff;
const int width = p->scaler_a.dst_width;
while (WebPRescalerHasPendingOutput(&p->scaler_a)) {
int i;
assert(p->last_y + y_pos + num_lines_out < p->output->height);
WebPRescalerExportRow(&p->scaler_a);
for (i = 0; i < width; ++i) {
const uint32_t alpha_value = p->scaler_a.dst[i];
dst[4 * i] = alpha_value;
alpha_mask &= alpha_value;
}
dst += buf->stride;
++num_lines_out;
}
if (is_premult_alpha && alpha_mask != 0xff) {
WebPApplyAlphaMultiply(base_rgba, alpha_first,
width, num_lines_out, buf->stride);
}
return num_lines_out;
}
int WebPRescalerExport(WebPRescaler* const rescaler) {
int total_exported = 0;
while (WebPRescalerHasPendingOutput(rescaler)) {
WebPRescalerExportRow(rescaler);
++total_exported;
}
return total_exported;
}
static int ExportRGB(WebPDecParams* const p, int y_pos) {
const WebPYUV444Converter convert =
WebPYUV444Converters[p->output->colorspace];
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* dst = buf->rgba + y_pos * buf->stride;
int num_lines_out = 0;
// For RGB rescaling, because of the YUV420, current scan position
// U/V can be +1/-1 line from the Y one. Hence the double test.
while (WebPRescalerHasPendingOutput(p->scaler_y) &&
WebPRescalerHasPendingOutput(p->scaler_u)) {
assert(y_pos + num_lines_out < p->output->height);
assert(p->scaler_u->y_accum == p->scaler_v->y_accum);
WebPRescalerExportRow(p->scaler_y);
WebPRescalerExportRow(p->scaler_u);
WebPRescalerExportRow(p->scaler_v);
convert(p->scaler_y->dst, p->scaler_u->dst, p->scaler_v->dst,
dst, p->scaler_y->dst_width);
dst += buf->stride;
++num_lines_out;
}
return num_lines_out;
}
static int ExportRGB(WebPDecParams* const p, int y_pos) {
const WebPYUV444Converter convert =
WebPYUV444Converters[p->output->colorspace];
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* dst = buf->rgba + (p->last_y + y_pos) * buf->stride;
int num_lines_out = 0;
while (WebPRescalerHasPendingOutput(&p->scaler_y) &&
WebPRescalerHasPendingOutput(&p->scaler_u)) {
assert(p->last_y + y_pos + num_lines_out < p->output->height);
assert(p->scaler_u.y_accum == p->scaler_v.y_accum);
WebPRescalerExportRow(&p->scaler_y);
WebPRescalerExportRow(&p->scaler_u);
WebPRescalerExportRow(&p->scaler_v);
convert(p->scaler_y.dst, p->scaler_u.dst, p->scaler_v.dst,
dst, p->scaler_y.dst_width);
dst += buf->stride;
++num_lines_out;
}
return num_lines_out;
}
int WebPRescalerImport(WebPRescaler* const wrk, int num_lines,
const uint8_t* src, int src_stride) {
int total_imported = 0;
while (total_imported < num_lines && !WebPRescalerHasPendingOutput(wrk)) {
if (wrk->y_expand) {
rescaler_t* const tmp = wrk->irow;
wrk->irow = wrk->frow;
wrk->frow = tmp;
}
WebPRescalerImportRow(wrk, src);
if (!wrk->y_expand) { // Accumulate the contribution of the new row.
int x;
for (x = 0; x < wrk->num_channels * wrk->dst_width; ++x) {
wrk->irow[x] += wrk->frow[x];
}
}
++wrk->src_y;
src += src_stride;
++total_imported;
wrk->y_accum -= wrk->y_sub;
}
return total_imported;
}
