int WebPIoInitFromOptions(const WebPDecoderOptions* const options,
VP8Io* const io, WEBP_CSP_MODE src_colorspace) {
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;
x = options->crop_left;
y = options->crop_top;
if (!WebPIsRGBMode(src_colorspace)) { // only snap for YUV420
x &= ~1;
y &= ~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) {
int scaled_width = options->scaled_width;
int scaled_height = options->scaled_height;
if (!WebPRescalerGetScaledDimensions(w, h, &scaled_width, &scaled_height)) {
return 0;
}
io->scaled_width = scaled_width;
io->scaled_height = 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;
}
VP8StatusCode WebPAllocateDecBuffer(int w, int h,
const WebPDecoderOptions* const options,
WebPDecBuffer* const out) {
VP8StatusCode status;
if (out == NULL || w <= 0 || h <= 0) {
return VP8_STATUS_INVALID_PARAM;
}
if (options != NULL) { // First, apply options if there is any.
if (options->use_cropping) {
const int cw = options->crop_width;
const int ch = options->crop_height;
const int x = options->crop_left & ~1;
const int y = options->crop_top & ~1;
if (x < 0 || y < 0 || cw <= 0 || ch <= 0 || x + cw > w || y + ch > h) {
return VP8_STATUS_INVALID_PARAM; // out of frame boundary.
}
w = cw;
h = ch;
}
if (options->use_scaling) {
int scaled_width = options->scaled_width;
int scaled_height = options->scaled_height;
if (!WebPRescalerGetScaledDimensions(
w, h, &scaled_width, &scaled_height)) {
return VP8_STATUS_INVALID_PARAM;
}
w = scaled_width;
h = scaled_height;
}
}
out->width = w;
out->height = h;
// Then, allocate buffer for real.
status = AllocateBuffer(out);
if (status != VP8_STATUS_OK) return status;
// Use the stride trick if vertical flip is needed.
if (options != NULL && options->flip) {
status = WebPFlipBuffer(out);
}
return status;
}
