libwebp/src/dec/io.c

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// Copyright 2011 Google Inc. All Rights Reserved.
//
// This code is licensed under the same terms as WebM:
// Software License Agreement: http://www.webmproject.org/license/software/
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// functions for sample output.
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include "../dec/vp8i.h"
#include "./webpi.h"
#include "../dsp/dsp.h"
#include "../dsp/yuv.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
//------------------------------------------------------------------------------
// 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;
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 < (mb_h + 1) / 2; ++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* output = p->output;
const WebPRGBABuffer* const buf = &output->u.RGBA;
uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
const uint8_t* y_src = io->y;
const uint8_t* u_src = io->u;
const uint8_t* v_src = io->v;
const WebPSampleLinePairFunc sample =
io->a ? WebPSamplersKeepAlpha[output->colorspace]
: WebPSamplers[output->colorspace];
const int mb_w = io->mb_w;
const int last = io->mb_h - 1;
int j;
for (j = 0; j < last; j += 2) {
sample(y_src, y_src + io->y_stride, u_src, v_src,
dst, dst + buf->stride, mb_w);
y_src += 2 * io->y_stride;
u_src += io->uv_stride;
v_src += io->uv_stride;
dst += 2 * buf->stride;
}
if (j == last) { // Just do the last line twice
sample(y_src, y_src, u_src, v_src, dst, dst, mb_w);
}
return io->mb_h;
}
//------------------------------------------------------------------------------
// YUV444 -> RGB conversion
#if 0 // TODO(skal): this is for future rescaling.
static int EmitRGB(const VP8Io* const io, WebPDecParams* const p) {
WebPDecBuffer* output = p->output;
const WebPRGBABuffer* const buf = &output->u.RGBA;
uint8_t* dst = buf->rgba + io->mb_y * buf->stride;
const uint8_t* y_src = io->y;
const uint8_t* u_src = io->u;
const uint8_t* v_src = io->v;
const WebPYUV444Converter convert = WebPYUV444Converters[output->colorspace];
const int mb_w = io->mb_w;
const int last = io->mb_h;
int j;
for (j = 0; j < last; ++j) {
convert(y_src, u_src, v_src, dst, mb_w);
y_src += io->y_stride;
u_src += io->uv_stride;
v_src += io->uv_stride;
dst += buf->stride;
}
return io->mb_h;
}
#endif
//------------------------------------------------------------------------------
// 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;
const WebPUpsampleLinePairFunc upsample =
io->a ? WebPUpsamplersKeepAlpha[p->output->colorspace]
: 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;
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(NULL, cur_y, cur_u, cur_v, cur_u, cur_v, NULL, dst, mb_w);
} else {
// We can finish the left-over line from previous call.
// Warning! Don't overwrite the alpha values (if any), as they
// are not lagging one line behind but are already written.
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 int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p) {
const int mb_w = io->mb_w;
const int mb_h = io->mb_h;
int j;
const WebPYUVABuffer* const buf = &p->output->u.YUVA;
uint8_t* dst = buf->a + io->mb_y * buf->a_stride;
const uint8_t* alpha = io->a;
if (alpha) {
for (j = 0; j < mb_h; ++j) {
memcpy(dst, alpha, mb_w * sizeof(*dst));
alpha += io->width;
dst += buf->a_stride;
}
}
return 0;
}
static int EmitAlphaRGB(const VP8Io* const io, WebPDecParams* const p) {
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* dst = buf->rgba + io->mb_y * buf->stride +
(p->output->colorspace == MODE_ARGB ? 0 : 3);
const uint8_t* alpha = io->a;
if (alpha) {
for (j = 0; j < mb_h; ++j) {
for (i = 0; i < mb_w; ++i) {
dst[4 * i] = alpha[i];
}
alpha += io->width;
dst += buf->stride;
}
}
return 0;
}
static int EmitAlphaRGBA4444(const VP8Io* const io, WebPDecParams* const p) {
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* dst = buf->rgba + io->mb_y * buf->stride + 1;
const uint8_t* alpha = io->a;
if (alpha) {
for (j = 0; j < mb_h; ++j) {
for (i = 0; i < mb_w; ++i) {
// Fill in the alpha value (converted to 4 bits).
const uint8_t alpha_val = (alpha[i] + 8) >> 4;
dst[2 * i] = (dst[2 * i] & 0xf0) | alpha_val;
}
alpha += io->width;
dst += buf->stride;
}
}
return 0;
}
//------------------------------------------------------------------------------
// Simple picture rescaler
// TODO(skal): start a common library for encoder and decoder, and factorize
// this code in.
#define RFIX 30
#define MULT(x,y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX)
static void InitRescaler(WebPRescaler* const wrk,
int src_width, int src_height,
uint8_t* dst,
int dst_width, int dst_height, int dst_stride,
int x_add, int x_sub, int y_add, int y_sub,
int32_t* work) {
wrk->x_expand = (src_width < dst_width);
wrk->src_width = src_width;
wrk->src_height = src_height;
wrk->dst_width = dst_width;
wrk->dst_height = dst_height;
wrk->dst = dst;
wrk->dst_stride = dst_stride;
// for 'x_expand', we use bilinear interpolation
wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add - x_sub;
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;
wrk->fx_scale = (1 << RFIX) / x_sub;
wrk->fy_scale = (1 << RFIX) / y_sub;
wrk->fxy_scale = wrk->x_expand ?
((int64_t)dst_height << RFIX) / (x_sub * src_height) :
((int64_t)dst_height << RFIX) / (x_add * src_height);
wrk->irow = work;
wrk->frow = work + dst_width;
}
static WEBP_INLINE void ImportRow(const uint8_t* const src,
WebPRescaler* const wrk) {
int x_in = 0;
int x_out;
int accum = 0;
if (!wrk->x_expand) {
int sum = 0;
for (x_out = 0; x_out < wrk->dst_width; ++x_out) {
accum += wrk->x_add;
for (; accum > 0; accum -= wrk->x_sub) {
sum += src[x_in++];
}
{ // Emit next horizontal pixel.
const int32_t base = src[x_in++];
const int32_t frac = base * (-accum);
wrk->frow[x_out] = (sum + base) * wrk->x_sub - frac;
// fresh fractional start for next pixel
sum = MULT(frac, wrk->fx_scale);
}
}
} else { // simple bilinear interpolation
int left = src[0], right = src[0];
for (x_out = 0; x_out < wrk->dst_width; ++x_out) {
if (accum < 0) {
left = right;
right = src[++x_in];
accum += wrk->x_add;
}
wrk->frow[x_out] = right * wrk->x_add + (left - right) * accum;
accum -= wrk->x_sub;
}
}
// Accumulate the new row's contribution
for (x_out = 0; x_out < wrk->dst_width; ++x_out) {
wrk->irow[x_out] += wrk->frow[x_out];
}
}
static void ExportRow(WebPRescaler* const wrk) {
int x_out;
const int yscale = wrk->fy_scale * (-wrk->y_accum);
assert(wrk->y_accum <= 0);
for (x_out = 0; x_out < wrk->dst_width; ++x_out) {
const int frac = MULT(wrk->frow[x_out], yscale);
const int v = (int)MULT(wrk->irow[x_out] - frac, wrk->fxy_scale);
wrk->dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
wrk->irow[x_out] = frac; // new fractional start
}
wrk->y_accum += wrk->y_add;
wrk->dst += wrk->dst_stride;
}
#undef MULT
#undef RFIX
//------------------------------------------------------------------------------
// 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 contribution of one source row.
ImportRow(src, wrk);
src += src_stride;
wrk->y_accum -= wrk->y_sub;
while (wrk->y_accum <= 0) { // emit output row(s)
ExportRow(wrk);
num_lines_out++;
}
}
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;
const int num_lines_out = Rescale(io->y, io->y_stride, mb_h, &p->scaler_y);
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) {
if (io->a) {
Rescale(io->a, io->width, io->mb_h, &p->scaler_a);
}
return 0;
}
static int IsAlphaMode(WEBP_CSP_MODE mode) {
return (mode == MODE_RGBA || mode == MODE_BGRA || mode == MODE_ARGB ||
mode == MODE_RGBA_4444 || mode == MODE_YUVA);
}
static int InitYUVRescaler(const VP8Io* const io, WebPDecParams* const p) {
const int has_alpha = IsAlphaMode(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;
int32_t* work;
tmp_size = work_size + 2 * uv_work_size;
if (has_alpha) {
tmp_size += work_size;
}
p->memory = calloc(1, tmp_size * sizeof(*work));
if (p->memory == NULL) {
return 0; // memory error
}
work = (int32_t*)p->memory;
InitRescaler(&p->scaler_y, io->mb_w, io->mb_h,
buf->y, out_width, out_height, buf->y_stride,
io->mb_w, out_width, io->mb_h, out_height,
work);
InitRescaler(&p->scaler_u, uv_in_width, uv_in_height,
buf->u, uv_out_width, uv_out_height, buf->u_stride,
uv_in_width, uv_out_width,
uv_in_height, uv_out_height,
work + work_size);
InitRescaler(&p->scaler_v, uv_in_width, uv_in_height,
buf->v, uv_out_width, uv_out_height, buf->v_stride,
uv_in_width, uv_out_width,
uv_in_height, uv_out_height,
work + work_size + uv_work_size);
p->emit = EmitRescaledYUV;
if (has_alpha) {
InitRescaler(&p->scaler_a, io->mb_w, io->mb_h,
buf->a, out_width, out_height, buf->a_stride,
io->mb_w, out_width, io->mb_h, out_height,
work + work_size + 2 * uv_work_size);
p->emit_alpha = EmitRescaledAlphaYUV;
}
return 1;
}
//------------------------------------------------------------------------------
// RGBA rescaling
// import new contributions until one row is ready to be output, or all input
// is consumed.
static int Import(const uint8_t* src, int src_stride,
int new_lines, WebPRescaler* const wrk) {
int num_lines_in = 0;
while (num_lines_in < new_lines && wrk->y_accum > 0) {
ImportRow(src, wrk);
src += src_stride;
++num_lines_in;
wrk->y_accum -= wrk->y_sub;
}
return num_lines_in;
}
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;
// 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 (p->scaler_y.y_accum <= 0 && p->scaler_u.y_accum <= 0) {
assert(p->last_y + y_pos + num_lines_out < p->output->height);
assert(p->scaler_u.y_accum == p->scaler_v.y_accum);
ExportRow(&p->scaler_y);
ExportRow(&p->scaler_u);
ExportRow(&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 = Import(io->y + j * io->y_stride, io->y_stride,
mb_h - j, &p->scaler_y);
const int u_lines_in = Import(io->u + uv_j * io->uv_stride, io->uv_stride,
uv_mb_h - uv_j, &p->scaler_u);
const int v_lines_in = Import(io->v + uv_j * io->uv_stride, io->uv_stride,
uv_mb_h - uv_j, &p->scaler_v);
(void)v_lines_in; // remove a gcc warning
assert(u_lines_in == v_lines_in);
j += y_lines_in;
uv_j += u_lines_in;
num_lines_out += ExportRGB(p, num_lines_out);
}
return num_lines_out;
}
static int ExportAlpha(WebPDecParams* const p, int y_pos) {
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* dst = buf->rgba + (p->last_y + y_pos) * buf->stride +
(p->output->colorspace == MODE_ARGB ? 0 : 3);
int num_lines_out = 0;
while (p->scaler_a.y_accum <= 0) {
int i;
assert(p->last_y + y_pos + num_lines_out < p->output->height);
ExportRow(&p->scaler_a);
for (i = 0; i < p->scaler_a.dst_width; ++i) {
dst[4 * i] = p->scaler_a.dst[i];
}
dst += buf->stride;
num_lines_out++;
}
return num_lines_out;
}
static int ExportAlphaRGBA4444(WebPDecParams* const p, int y_pos) {
const WebPRGBABuffer* const buf = &p->output->u.RGBA;
uint8_t* dst = buf->rgba + (p->last_y + y_pos) * buf->stride + 1;
int num_lines_out = 0;
while (p->scaler_a.y_accum <= 0) {
int i;
assert(p->last_y + y_pos + num_lines_out < p->output->height);
ExportRow(&p->scaler_a);
for (i = 0; i < p->scaler_a.dst_width; ++i) {
// Fill in the alpha value (converted to 4 bits).
const uint8_t alpha_val = (p->scaler_a.dst[i] + 8) >> 4;
dst[2 * i] = (dst[2 * i] & 0xf0) | alpha_val;
}
dst += buf->stride;
num_lines_out++;
}
return num_lines_out;
}
static int EmitRescaledAlphaRGB(const VP8Io* const io, WebPDecParams* const p) {
if (io->a) {
int j = 0, pos = 0;
while (j < io->mb_h) {
j += Import(io->a + j * io->width, io->width, io->mb_h - j, &p->scaler_a);
pos += (p->output->colorspace == MODE_RGBA_4444) ?
ExportAlphaRGBA4444(p, pos) : ExportAlpha(p, pos);
}
}
return 0;
}
static int InitRGBRescaler(const VP8Io* const io, WebPDecParams* const p) {
const int has_alpha = IsAlphaMode(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
int32_t* work; // rescalers work area
uint8_t* tmp; // tmp storage for scaled YUV444 samples before RGB conversion
size_t tmp_size1, tmp_size2;
tmp_size1 = 3 * work_size;
tmp_size2 = 3 * out_width;
if (has_alpha) {
tmp_size1 += work_size;
tmp_size2 += out_width;
}
p->memory =
calloc(1, tmp_size1 * sizeof(*work) + tmp_size2 * sizeof(*tmp));
if (p->memory == NULL) {
return 0; // memory error
}
work = (int32_t*)p->memory;
tmp = (uint8_t*)(work + tmp_size1);
InitRescaler(&p->scaler_y, io->mb_w, io->mb_h,
tmp + 0 * out_width, out_width, out_height, 0,
io->mb_w, out_width, io->mb_h, out_height,
work + 0 * work_size);
InitRescaler(&p->scaler_u, uv_in_width, uv_in_height,
tmp + 1 * out_width, out_width, out_height, 0,
io->mb_w, 2 * out_width, io->mb_h, 2 * out_height,
work + 1 * work_size);
InitRescaler(&p->scaler_v, uv_in_width, uv_in_height,
tmp + 2 * out_width, out_width, out_height, 0,
io->mb_w, 2 * out_width, io->mb_h, 2 * out_height,
work + 2 * work_size);
p->emit = EmitRescaledRGB;
if (has_alpha) {
InitRescaler(&p->scaler_a, io->mb_w, io->mb_h,
tmp + 3 * out_width, out_width, out_height, 0,
io->mb_w, out_width, io->mb_h, out_height,
work + 3 * work_size);
p->emit_alpha = EmitRescaledAlphaRGB;
}
return 1;
}
//------------------------------------------------------------------------------
// Default custom functions
// Setup crop_xxx fields, mb_w and mb_h
static int InitFromOptions(const WebPDecoderOptions* const options,
VP8Io* const io) {
const int W = io->width;
const int H = io->height;
int x = 0, y = 0, w = W, h = H;
// Cropping
io->use_cropping = (options != NULL) && (options->use_cropping > 0);
if (io->use_cropping) {
w = options->crop_width;
h = options->crop_height;
// TODO(skal): take colorspace into account. Don't assume YUV420.
x = options->crop_left & ~1;
y = options->crop_top & ~1;
if (x < 0 || y < 0 || w <= 0 || h <= 0 || x + w > W || y + h > H) {
return 0; // out of frame boundary error
}
}
io->crop_left = x;
io->crop_top = y;
io->crop_right = x + w;
io->crop_bottom = y + h;
io->mb_w = w;
io->mb_h = h;
// Scaling
io->use_scaling = (options != NULL) && (options->use_scaling > 0);
if (io->use_scaling) {
if (options->scaled_width <= 0 || options->scaled_height <= 0) {
return 0;
}
io->scaled_width = options->scaled_width;
io->scaled_height = options->scaled_height;
}
// Filter
io->bypass_filtering = options && options->bypass_filtering;
// Fancy upsampler
#ifdef FANCY_UPSAMPLING
io->fancy_upsampling = (options == NULL) || (!options->no_fancy_upsampling);
#endif
if (io->use_scaling) {
// disable filter (only for large downscaling ratio).
io->bypass_filtering = (io->scaled_width < W * 3 / 4) &&
(io->scaled_height < H * 3 / 4);
io->fancy_upsampling = 0;
}
return 1;
}
static int CustomSetup(VP8Io* io) {
WebPDecParams* const p = (WebPDecParams*)io->opaque;
const int is_rgb = (p->output->colorspace < MODE_YUV);
p->memory = NULL;
p->emit = NULL;
p->emit_alpha = NULL;
if (!InitFromOptions(p->options, io)) {
return 0;
}
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) {
p->emit = EmitSampledRGB; // default
#ifdef FANCY_UPSAMPLING
if (io->fancy_upsampling) {
const int uv_width = (io->mb_w + 1) >> 1;
p->memory = malloc(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 (IsAlphaMode(p->output->colorspace)) {
// We need transparency output
p->emit_alpha =
is_rgb ? (p->output->colorspace == MODE_RGBA_4444 ?
EmitAlphaRGBA4444 : EmitAlphaRGB) : EmitAlphaYUV;
}
}
if (is_rgb) {
VP8YUVInit();
}
return 1;
}
//------------------------------------------------------------------------------
static int CustomPut(const VP8Io* io) {
WebPDecParams* 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) {
p->emit_alpha(io, p);
}
p->last_y += num_lines_out;
return 1;
}
//------------------------------------------------------------------------------
static void CustomTeardown(const VP8Io* io) {
WebPDecParams* const p = (WebPDecParams*)io->opaque;
free(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;
}
//------------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif