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opencv/3rdparty/libwebp/dec/io_dec.c

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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// functions for sample output.
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include "../dec/vp8i_dec.h"
#include "./webpi_dec.h"
#include "../dsp/dsp.h"
#include "../dsp/yuv.h"
#include "../utils/utils.h"
//------------------------------------------------------------------------------
// Main YUV<->RGB conversion functions
static int EmitYUV(const VP8Io* const io, WebPDecParams* const p) {
WebPDecBuffer* output = p->output;
const WebPYUVABuffer* const buf = &output->u.YUVA;
uint8_t* const y_dst = buf->y + io->mb_y * buf->y_stride;
uint8_t* const u_dst = buf->u + (io->mb_y >> 1) * buf->u_stride;
uint8_t* const v_dst = buf->v + (io->mb_y >> 1) * buf->v_stride;
const int mb_w = io->mb_w;
const int mb_h = io->mb_h;
const int uv_w = (mb_w + 1) / 2;
const int uv_h = (mb_h + 1) / 2;
int j;
for (j = 0; j < mb_h; ++j) {
memcpy(y_dst + j * buf->y_stride, io->y + j * io->y_stride, mb_w);
}
for (j = 0; j < uv_h; ++j) {
memcpy(u_dst + j * buf->u_stride, io->u + j * io->uv_stride, uv_w);
memcpy(v_dst + j * buf->v_stride, io->v + j * io->uv_stride, uv_w);
}
return io->mb_h;
}
// Point-sampling U/V sampler.
static int EmitSampledRGB(const VP8Io* const io, WebPDecParams* const p) {
WebPDecBuffer* const output = p->output;
WebPRGBABuffer* const buf = &output->u.RGBA;
uint8_t* const dst = buf->rgba + io->mb_y * buf->stride;
WebPSamplerProcessPlane(io->y, io->y_stride,
io->u, io->v, io->uv_stride,
dst, buf->stride, io->mb_w, io->mb_h,
WebPSamplers[output->colorspace]);
return io->mb_h;
}
//------------------------------------------------------------------------------
// Fancy upsampling
#ifdef FANCY_UPSAMPLING
static int EmitFancyRGB(const VP8Io* const io, WebPDecParams* const p) {
int num_lines_out = io->mb_h; // a priori guess
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
WebPUpsampleLinePairFunc upsample = WebPUpsamplers[p->output->colorspace];
const uint8_t* cur_y = io->y;
const uint8_t* cur_u = io->u;
const uint8_t* cur_v = io->v;
const uint8_t* top_u = p->tmp_u;
const uint8_t* top_v = p->tmp_v;
int y = io->mb_y;
const int y_end = io->mb_y + io->mb_h;
const int mb_w = io->mb_w;
const int uv_w = (mb_w + 1) / 2;
if (y == 0) {
// First line is special cased. We mirror the u/v samples at boundary.
upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v, dst, NULL, mb_w);
} else {
// We can finish the left-over line from previous call.
upsample(p->tmp_y, cur_y, top_u, top_v, cur_u, cur_v,
dst - buf->stride, dst, mb_w);
++num_lines_out;
}
// Loop over each output pairs of row.
for (; y + 2 < y_end; y += 2) {
top_u = cur_u;
top_v = cur_v;
cur_u += io->uv_stride;
cur_v += io->uv_stride;
dst += 2 * buf->stride;
cur_y += 2 * io->y_stride;
upsample(cur_y - io->y_stride, cur_y,
top_u, top_v, cur_u, cur_v,
dst - buf->stride, dst, mb_w);
}
// move to last row
cur_y += io->y_stride;
if (io->crop_top + y_end < io->crop_bottom) {
// Save the unfinished samples for next call (as we're not done yet).
memcpy(p->tmp_y, cur_y, mb_w * sizeof(*p->tmp_y));
memcpy(p->tmp_u, cur_u, uv_w * sizeof(*p->tmp_u));
memcpy(p->tmp_v, cur_v, uv_w * sizeof(*p->tmp_v));
// The fancy upsampler leaves a row unfinished behind
// (except for the very last row)
num_lines_out--;
} else {
// Process the very last row of even-sized picture
if (!(y_end & 1)) {
upsample(cur_y, NULL, cur_u, cur_v, cur_u, cur_v,
dst + buf->stride, NULL, mb_w);
}
}
return num_lines_out;
}
#endif /* FANCY_UPSAMPLING */
//------------------------------------------------------------------------------
static void FillAlphaPlane(uint8_t* dst, int w, int h, int stride) {
int j;
for (j = 0; j < h; ++j) {
memset(dst, 0xff, w * sizeof(*dst));
dst += stride;
}
}
static int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p,
int expected_num_lines_out) {
const uint8_t* alpha = io->a;
const WebPYUVABuffer* const buf = &p->output->u.YUVA;
const int mb_w = io->mb_w;
const int mb_h = io->mb_h;
uint8_t* dst = buf->a + io->mb_y * buf->a_stride;
int j;
(void)expected_num_lines_out;
assert(expected_num_lines_out == mb_h);
if (alpha != NULL) {
for (j = 0; j < mb_h; ++j) {
memcpy(dst, alpha, mb_w * sizeof(*dst));
alpha += io->width;
dst += buf->a_stride;
}
} else if (buf->a != NULL) {
// the user requested alpha, but there is none, set it to opaque.
FillAlphaPlane(dst, mb_w, mb_h, buf->a_stride);
}
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 remaining rows!
*num_rows = io->crop_bottom - io->crop_top - start_y;
}
}
return start_y;
}
static int EmitAlphaRGB(const VP8Io* const io, WebPDecParams* const p,
int expected_num_lines_out) {
const uint8_t* alpha = io->a;
if (alpha != NULL) {
const int mb_w = io->mb_w;
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 num_rows;
const int start_y = GetAlphaSourceRow(io, &alpha, &num_rows);
uint8_t* const base_rgba = buf->rgba + start_y * buf->stride;
uint8_t* const dst = base_rgba + (alpha_first ? 0 : 3);
const int has_alpha = WebPDispatchAlpha(alpha, io->width, mb_w,
num_rows, dst, buf->stride);
(void)expected_num_lines_out;
assert(expected_num_lines_out == num_rows);
// has_alpha is true if there's non-trivial alpha to premultiply with.
if (has_alpha && WebPIsPremultipliedMode(colorspace)) {
WebPApplyAlphaMultiply(base_rgba, alpha_first,
mb_w, num_rows, buf->stride);
}
}
return 0;
}
static int EmitAlphaRGBA4444(const VP8Io* const io, WebPDecParams* const p,
int expected_num_lines_out) {
const uint8_t* alpha = io->a;
if (alpha != NULL) {
const int mb_w = io->mb_w;
const WEBP_CSP_MODE colorspace = p->output->colorspace;
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
int num_rows;
const int start_y = GetAlphaSourceRow(io, &alpha, &num_rows);
uint8_t* const base_rgba = buf->rgba + start_y * buf->stride;
#ifdef WEBP_SWAP_16BIT_CSP
uint8_t* alpha_dst = base_rgba;
#else
uint8_t* alpha_dst = base_rgba + 1;
#endif
uint32_t alpha_mask = 0x0f;
int i, j;
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 = alpha[i] >> 4;
alpha_dst[2 * i] = (alpha_dst[2 * i] & 0xf0) | alpha_value;
alpha_mask &= alpha_value;
}
alpha += io->width;
alpha_dst += buf->stride;
}
(void)expected_num_lines_out;
assert(expected_num_lines_out == num_rows);
if (alpha_mask != 0x0f && WebPIsPremultipliedMode(colorspace)) {
WebPApplyAlphaMultiply4444(base_rgba, mb_w, num_rows, buf->stride);
}
}
return 0;
}
//------------------------------------------------------------------------------
// YUV rescaling (no final RGB conversion needed)
static int Rescale(const uint8_t* src, int src_stride,
int new_lines, WebPRescaler* const wrk) {
int num_lines_out = 0;
while (new_lines > 0) { // import new contributions of source rows.
const int lines_in = WebPRescalerImport(wrk, new_lines, src, src_stride);
src += lines_in * src_stride;
new_lines -= lines_in;
num_lines_out += WebPRescalerExport(wrk); // emit output row(s)
}
return num_lines_out;
}
static int EmitRescaledYUV(const VP8Io* const io, WebPDecParams* const p) {
const int mb_h = io->mb_h;
const int uv_mb_h = (mb_h + 1) >> 1;
WebPRescaler* const scaler = p->scaler_y;
int num_lines_out = 0;
if (WebPIsAlphaMode(p->output->colorspace) && io->a != NULL) {
// Before rescaling, we premultiply the luma directly into the io->y
// internal buffer. This is OK since these samples are not used for
// intra-prediction (the top samples are saved in cache_y_/u_/v_).
// But we need to cast the const away, though.
WebPMultRows((uint8_t*)io->y, io->y_stride,
io->a, io->width, io->mb_w, mb_h, 0);
}
num_lines_out = Rescale(io->y, io->y_stride, mb_h, scaler);
Rescale(io->u, io->uv_stride, uv_mb_h, p->scaler_u);
Rescale(io->v, io->uv_stride, uv_mb_h, p->scaler_v);
return num_lines_out;
}
static int EmitRescaledAlphaYUV(const VP8Io* const io, WebPDecParams* const p,
int expected_num_lines_out) {
const WebPYUVABuffer* const buf = &p->output->u.YUVA;
uint8_t* const dst_a = buf->a + p->last_y * buf->a_stride;
if (io->a != NULL) {
uint8_t* const dst_y = buf->y + p->last_y * buf->y_stride;
const int num_lines_out = Rescale(io->a, io->width, io->mb_h, p->scaler_a);
assert(expected_num_lines_out == num_lines_out);
if (num_lines_out > 0) { // unmultiply the Y
WebPMultRows(dst_y, buf->y_stride, dst_a, buf->a_stride,
p->scaler_a->dst_width, num_lines_out, 1);
}
} else if (buf->a != NULL) {
// the user requested alpha, but there is none, set it to opaque.
assert(p->last_y + expected_num_lines_out <= io->scaled_height);
FillAlphaPlane(dst_a, io->scaled_width, expected_num_lines_out,
buf->a_stride);
}
return 0;
}
static int InitYUVRescaler(const VP8Io* const io, WebPDecParams* const p) {
const int has_alpha = WebPIsAlphaMode(p->output->colorspace);
const WebPYUVABuffer* const buf = &p->output->u.YUVA;
const int out_width = io->scaled_width;
const int out_height = io->scaled_height;
const int uv_out_width = (out_width + 1) >> 1;
const int uv_out_height = (out_height + 1) >> 1;
const int uv_in_width = (io->mb_w + 1) >> 1;
const int uv_in_height = (io->mb_h + 1) >> 1;
const size_t work_size = 2 * out_width; // scratch memory for luma rescaler
const size_t uv_work_size = 2 * uv_out_width; // and for each u/v ones
size_t tmp_size, rescaler_size;
rescaler_t* work;
WebPRescaler* scalers;
const int num_rescalers = has_alpha ? 4 : 3;
tmp_size = (work_size + 2 * uv_work_size) * sizeof(*work);
if (has_alpha) {
tmp_size += work_size * sizeof(*work);
}
rescaler_size = num_rescalers * sizeof(*p->scaler_y) + WEBP_ALIGN_CST;
p->memory = WebPSafeMalloc(1ULL, tmp_size + rescaler_size);
if (p->memory == NULL) {
return 0; // memory error
}
work = (rescaler_t*)p->memory;
scalers = (WebPRescaler*)WEBP_ALIGN((const uint8_t*)work + tmp_size);
p->scaler_y = &scalers[0];
p->scaler_u = &scalers[1];
p->scaler_v = &scalers[2];
p->scaler_a = has_alpha ? &scalers[3] : NULL;
WebPRescalerInit(p->scaler_y, io->mb_w, io->mb_h,
buf->y, out_width, out_height, buf->y_stride, 1,
work);
WebPRescalerInit(p->scaler_u, uv_in_width, uv_in_height,
buf->u, uv_out_width, uv_out_height, buf->u_stride, 1,
work + work_size);
WebPRescalerInit(p->scaler_v, uv_in_width, uv_in_height,
buf->v, uv_out_width, uv_out_height, buf->v_stride, 1,
work + work_size + uv_work_size);
p->emit = EmitRescaledYUV;
if (has_alpha) {
WebPRescalerInit(p->scaler_a, io->mb_w, io->mb_h,
buf->a, out_width, out_height, buf->a_stride, 1,
work + work_size + 2 * uv_work_size);
p->emit_alpha = EmitRescaledAlphaYUV;
WebPInitAlphaProcessing();
}
return 1;
}
//------------------------------------------------------------------------------
// RGBA rescaling
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 EmitRescaledRGB(const VP8Io* const io, WebPDecParams* const p) {
const int mb_h = io->mb_h;
const int uv_mb_h = (mb_h + 1) >> 1;
int j = 0, uv_j = 0;
int num_lines_out = 0;
while (j < mb_h) {
const int y_lines_in =
WebPRescalerImport(p->scaler_y, mb_h - j,
io->y + j * io->y_stride, io->y_stride);
j += y_lines_in;
if (WebPRescaleNeededLines(p->scaler_u, uv_mb_h - uv_j)) {
const int u_lines_in =
WebPRescalerImport(p->scaler_u, uv_mb_h - uv_j,
io->u + uv_j * io->uv_stride, io->uv_stride);
const int v_lines_in =
WebPRescalerImport(p->scaler_v, uv_mb_h - uv_j,
io->v + uv_j * io->uv_stride, io->uv_stride);
(void)v_lines_in; // remove a gcc warning
assert(u_lines_in == v_lines_in);
uv_j += u_lines_in;
}
num_lines_out += ExportRGB(p, p->last_y + num_lines_out);
}
return num_lines_out;
}
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 EmitRescaledAlphaRGB(const VP8Io* const io, WebPDecParams* const p,
int expected_num_out_lines) {
if (io->a != NULL) {
WebPRescaler* const scaler = p->scaler_a;
int lines_left = expected_num_out_lines;
const int y_end = p->last_y + lines_left;
while (lines_left > 0) {
const int row_offset = scaler->src_y - io->mb_y;
WebPRescalerImport(scaler, io->mb_h + io->mb_y - scaler->src_y,
io->a + row_offset * io->width, io->width);
lines_left -= p->emit_alpha_row(p, y_end - lines_left, lines_left);
}
}
return 0;
}
static int InitRGBRescaler(const VP8Io* const io, WebPDecParams* const p) {
const int has_alpha = WebPIsAlphaMode(p->output->colorspace);
const int out_width = io->scaled_width;
const int out_height = io->scaled_height;
const int uv_in_width = (io->mb_w + 1) >> 1;
const int uv_in_height = (io->mb_h + 1) >> 1;
const size_t work_size = 2 * out_width; // scratch memory for one rescaler
rescaler_t* work; // rescalers work area
uint8_t* tmp; // tmp storage for scaled YUV444 samples before RGB conversion
size_t tmp_size1, tmp_size2, total_size, rescaler_size;
WebPRescaler* scalers;
const int num_rescalers = has_alpha ? 4 : 3;
tmp_size1 = 3 * work_size;
tmp_size2 = 3 * out_width;
if (has_alpha) {
tmp_size1 += work_size;
tmp_size2 += out_width;
}
total_size = tmp_size1 * sizeof(*work) + tmp_size2 * sizeof(*tmp);
rescaler_size = num_rescalers * sizeof(*p->scaler_y) + WEBP_ALIGN_CST;
p->memory = WebPSafeMalloc(1ULL, total_size + rescaler_size);
if (p->memory == NULL) {
return 0; // memory error
}
work = (rescaler_t*)p->memory;
tmp = (uint8_t*)(work + tmp_size1);
scalers = (WebPRescaler*)WEBP_ALIGN((const uint8_t*)work + total_size);
p->scaler_y = &scalers[0];
p->scaler_u = &scalers[1];
p->scaler_v = &scalers[2];
p->scaler_a = has_alpha ? &scalers[3] : NULL;
WebPRescalerInit(p->scaler_y, io->mb_w, io->mb_h,
tmp + 0 * out_width, out_width, out_height, 0, 1,
work + 0 * work_size);
WebPRescalerInit(p->scaler_u, uv_in_width, uv_in_height,
tmp + 1 * out_width, out_width, out_height, 0, 1,
work + 1 * work_size);
WebPRescalerInit(p->scaler_v, uv_in_width, uv_in_height,
tmp + 2 * out_width, out_width, out_height, 0, 1,
work + 2 * work_size);
p->emit = EmitRescaledRGB;
WebPInitYUV444Converters();
if (has_alpha) {
WebPRescalerInit(p->scaler_a, io->mb_w, io->mb_h,
tmp + 3 * out_width, out_width, out_height, 0, 1,
work + 3 * work_size);
p->emit_alpha = EmitRescaledAlphaRGB;
if (p->output->colorspace == MODE_RGBA_4444 ||
p->output->colorspace == MODE_rgbA_4444) {
p->emit_alpha_row = ExportAlphaRGBA4444;
} else {
p->emit_alpha_row = ExportAlpha;
}
WebPInitAlphaProcessing();
}
return 1;
}
//------------------------------------------------------------------------------
// Default custom functions
static int CustomSetup(VP8Io* io) {
WebPDecParams* const p = (WebPDecParams*)io->opaque;
const WEBP_CSP_MODE colorspace = p->output->colorspace;
const int is_rgb = WebPIsRGBMode(colorspace);
const int is_alpha = WebPIsAlphaMode(colorspace);
p->memory = NULL;
p->emit = NULL;
p->emit_alpha = NULL;
p->emit_alpha_row = NULL;
if (!WebPIoInitFromOptions(p->options, io, is_alpha ? MODE_YUV : MODE_YUVA)) {
return 0;
}
if (is_alpha && WebPIsPremultipliedMode(colorspace)) {
WebPInitUpsamplers();
}
if (io->use_scaling) {
const int ok = is_rgb ? InitRGBRescaler(io, p) : InitYUVRescaler(io, p);
if (!ok) {
return 0; // memory error
}
} else {
if (is_rgb) {
WebPInitSamplers();
p->emit = EmitSampledRGB; // default
if (io->fancy_upsampling) {
#ifdef FANCY_UPSAMPLING
const int uv_width = (io->mb_w + 1) >> 1;
p->memory = WebPSafeMalloc(1ULL, (size_t)(io->mb_w + 2 * uv_width));
if (p->memory == NULL) {
return 0; // memory error.
}
p->tmp_y = (uint8_t*)p->memory;
p->tmp_u = p->tmp_y + io->mb_w;
p->tmp_v = p->tmp_u + uv_width;
p->emit = EmitFancyRGB;
WebPInitUpsamplers();
#endif
}
} else {
p->emit = EmitYUV;
}
if (is_alpha) { // need transparency output
p->emit_alpha =
(colorspace == MODE_RGBA_4444 || colorspace == MODE_rgbA_4444) ?
EmitAlphaRGBA4444
: is_rgb ? EmitAlphaRGB
: EmitAlphaYUV;
if (is_rgb) {
WebPInitAlphaProcessing();
}
}
}
if (is_rgb) {
VP8YUVInit();
}
return 1;
}
//------------------------------------------------------------------------------
static int CustomPut(const VP8Io* io) {
WebPDecParams* const p = (WebPDecParams*)io->opaque;
const int mb_w = io->mb_w;
const int mb_h = io->mb_h;
int num_lines_out;
assert(!(io->mb_y & 1));
if (mb_w <= 0 || mb_h <= 0) {
return 0;
}
num_lines_out = p->emit(io, p);
if (p->emit_alpha != NULL) {
p->emit_alpha(io, p, num_lines_out);
}
p->last_y += num_lines_out;
return 1;
}
//------------------------------------------------------------------------------
static void CustomTeardown(const VP8Io* io) {
WebPDecParams* const p = (WebPDecParams*)io->opaque;
WebPSafeFree(p->memory);
p->memory = NULL;
}
//------------------------------------------------------------------------------
// Main entry point
void WebPInitCustomIo(WebPDecParams* const params, VP8Io* const io) {
io->put = CustomPut;
io->setup = CustomSetup;
io->teardown = CustomTeardown;
io->opaque = params;
}
//------------------------------------------------------------------------------
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