Files
squoosh/codecs/avif_dec/avif_dec.cpp
2020-08-05 14:36:21 +01:00

97 lines
3.0 KiB
C++

#include "avif/avif.h"
#include <emscripten/bind.h>
#include <emscripten/val.h>
using namespace emscripten;
class RawImage {
public:
val buffer;
int width;
int height;
RawImage(val b, int w, int h) : buffer(b), width(w), height(h) {}
};
// NOTE: avifDecoderRead() offers the simplest means to get an avifImage that is
// complete independent of an avifDecoder, but at the cost of additional
// allocations and copies, and no support for image sequences. If you don't mind
// keeping around the avifDecoder while you read in the image and/or need image
// sequence support, skip ahead to the Advanced Decoding example. It is only one
// additional function call, and the avifImage is owned by the avifDecoder.
uint8_t *result;
RawImage decode(std::string avifimage) {
// point raw.data and raw.size to the contents of an .avif(s)
avifROData raw;
raw.data = (uint8_t *)avifimage.c_str();
raw.size = avifimage.length();
avifImage *image = avifImageCreateEmpty();
avifDecoder *decoder = avifDecoderCreate();
avifResult decodeResult = avifDecoderRead(decoder, image, &raw);
if (decodeResult != AVIF_RESULT_OK) {
return RawImage(val::null(), -1, -1);
// printf("ERROR: Failed to decode: %s\n", avifResultToString(result));
}
int width = image->width;
int height = image->height;
int numBytes = width * height * 4;
result = new uint8_t[numBytes];
// image is an independent copy of decoded data, decoder may be destroyed here
// ... image->width;
// ... image->height;
// ... image->depth; // If >8, all plane ptrs below are uint16_t*
// ... image->yuvFormat; // U and V planes might be smaller than Y based on
// format, use avifGetPixelFormatInfo() to find out in a generic way
// Option 1: Use YUV planes directly
// ... image->yuvPlanes;
// ... image->yuvRowBytes;
// Option 2: Convert to RGB and use RGB planes
avifImageYUVToRGB(image);
// ... image->rgbPlanes;
// ... image->rgbRowBytes;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
int pixelOffset = y * image->width + x;
result[pixelOffset * 4 + 0] = image->rgbPlanes[0][pixelOffset];
result[pixelOffset * 4 + 1] = image->rgbPlanes[1][pixelOffset];
result[pixelOffset * 4 + 2] = image->rgbPlanes[2][pixelOffset];
if (image->alphaPlane) {
result[pixelOffset * 4 + 3] = image->alphaPlane[pixelOffset];
} else {
result[pixelOffset * 4 + 3] = 255;
}
}
}
// // Use alpha plane, if present
// if (image->alphaPlane) {
// ... image->alphaPlane;
// ... image->alphaRowBytes;
// }
avifImageDestroy(image);
avifDecoderDestroy(decoder);
return RawImage(val(typed_memory_view(numBytes, result)), (int)width,
(int)height);
}
void free_result() { delete result; }
EMSCRIPTEN_BINDINGS(my_module) {
class_<RawImage>("RawImage")
.property("buffer", &RawImage::buffer)
.property("width", &RawImage::width)
.property("height", &RawImage::height);
function("decode", &decode);
function("free_result", &free_result);
}