60 lines
1.9 KiB
C++
60 lines
1.9 KiB
C++
#include <emscripten/bind.h>
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#include <emscripten/val.h>
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#include "avif/avif.h"
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using namespace emscripten;
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class RawImage {
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public:
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val buffer;
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uint32_t width;
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uint32_t height;
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RawImage(val b, uint32_t w, uint32_t h) : buffer(b), width(w), height(h) {}
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};
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RawImage decode(std::string avifimage) {
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// point raw.data and raw.size to the contents of an .avif(s)
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avifROData raw;
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raw.data = (uint8_t*)avifimage.c_str();
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raw.size = avifimage.length();
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avifImage* image = avifImageCreateEmpty();
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avifDecoder* decoder = avifDecoderCreate();
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avifResult decodeResult = avifDecoderRead(decoder, image, &raw);
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// image is an independent copy of decoded data, decoder may be destroyed here
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avifDecoderDestroy(decoder);
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if (decodeResult != AVIF_RESULT_OK) {
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return RawImage(val::null(), -1, -1);
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}
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// Convert to interleaved RGB(A)/BGR(A) using a libavif-allocated buffer.
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avifRGBImage rgb;
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avifRGBImageSetDefaults(&rgb, image); // Defaults to AVIF_RGB_FORMAT_RGBA which is what we want.
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rgb.depth = 8; // Does not need to match image->depth. We always want 8-bit pixels.
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avifRGBImageAllocatePixels(&rgb);
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avifImageYUVToRGB(image, &rgb);
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// Image has been converted to RGB, we don't need the original anymore.
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avifImageDestroy(image);
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// We want to create a *copy* of the decoded data to be owned by the JavaScript side.
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// For that, we perform `new Uint8Array(wasmMemBuffer, wasmPtr, wasmSize).slice()`:
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auto result = val(typed_memory_view(rgb.rowBytes * rgb.height, rgb.pixels)).call<val>("slice");
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// Now we can safely free the RGB pixels:
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avifRGBImageFreePixels(&rgb);
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return RawImage(result, rgb.width, rgb.height);
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}
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EMSCRIPTEN_BINDINGS(my_module) {
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class_<RawImage>("RawImage")
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.property("buffer", &RawImage::buffer)
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.property("width", &RawImage::width)
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.property("height", &RawImage::height);
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function("decode", &decode);
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}
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