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Decoder for webp

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Surma
2018-06-13 23:40:24 +01:00
parent 79dfe39978
commit 00e73daabd
9 changed files with 1475 additions and 180 deletions
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codecs/webp_dec/.gitignore vendored Normal file
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/*.wasm
/*.js

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codecs/webp_dec/README.md Normal file
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# WebP encoder
- Source: <https://github.com/webmproject/libwebp>
- Version: v0.6.1
## Example
See `example.html`
## API
### `int version()`
Returns the version of libwebp as a number. va.b.c is encoded as 0x0a0b0c
### `uint8_t* create_buffer(int width, int height)`
Allocates an RGBA buffer for an image with the given dimension.
### `void destroy_buffer(uint8_t* p)`
Frees a buffer created with `create_buffer`.
### `void encode(uint8_t* image_buffer, int image_width, int image_height, float quality)`
Encodes the given image with given dimension to WebP. `quality` is a number between 0 and 100. The higher the number, the better the quality of the encoded image. The result is implicitly stored and can be accessed using the `get_result_*()` functions.
### `void free_result()`
Frees the result created by `encode()`.
### `int get_result_pointer()`
Returns the pointer to the start of the buffer holding the encoded data.
### `int get_result_size()`
Returns the length of the buffer holding the encoded data.

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codecs/webp_dec/example.html Normal file
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<!doctype html>
<script src='webp_dec.js'></script>
<script>
const Module = webp_dec();
async function loadFile(src) {
const resp = await fetch(src);
return await resp.arrayBuffer();
}
Module.onRuntimeInitialized = async _ => {
const api = {
version: Module.cwrap('version', 'number', []),
create_buffer: Module.cwrap('create_buffer', 'number', ['number', 'number']),
destroy_buffer: Module.cwrap('destroy_buffer', '', ['number']),
decode: Module.cwrap('decode', '', ['number', 'number']),
free_result: Module.cwrap('free_result', '', ['number']),
get_result_pointer: Module.cwrap('get_result_pointer', 'number', []),
get_result_width: Module.cwrap('get_result_width', 'number', []),
get_result_height: Module.cwrap('get_result_height', 'number', []),
};
const image = await loadFile('../example.webp');
const p = api.create_buffer(image.byteLength);
Module.HEAP8.set(new Uint8Array(image), p);
api.decode(p, image.byteLength);
const resultPointer = api.get_result_pointer();
if(resultPointer === 0) {
throw new Error("Could not decode image");
}
const resultWidth = api.get_result_width();
const resultHeight = api.get_result_height();
const resultView = new Uint8Array(Module.HEAP8.buffer, resultPointer, resultWidth * resultHeight * 4);
const result = new Uint8ClampedArray(resultView);
const imageData = new ImageData(result, resultWidth, resultHeight);
api.free_result(resultPointer);
api.destroy_buffer(p);
const canvas = document.createElement('canvas');
canvas.width = resultWidth;
canvas.height = resultHeight;
document.body.appendChild(canvas);
const ctx = canvas.getContext('2d');
ctx.putImageData(imageData, 0, 0);
};
</script>

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codecs/webp_dec/package-lock.json generated Normal file
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codecs/webp_dec/package.json Normal file
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{
"name": "webp_dec",
"scripts": {
"install": "napa",
"build": "docker run --rm -v $(pwd):/src trzeci/emscripten emcc -O3 -s WASM=1 -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]' -s ALLOW_MEMORY_GROWTH=1 -s MODULARIZE=1 -s 'EXPORT_NAME=\"webp_dec\"' -I node_modules/libwebp -o ./webp_dec.js webp_dec.c node_modules/libwebp/src/{dec,dsp,demux,enc,mux,utils}/*.c"
},
"napa": {
"libwebp": "webmproject/libwebp#v0.6.1"
},
"devDependencies": {
"napa": "^3.0.0"
}
}

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codecs/webp_dec/webp_dec.c Normal file
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#include "emscripten.h"
#include "src/webp/decode.h"
#include "src/webp/demux.h"
#include <stdlib.h>
EMSCRIPTEN_KEEPALIVE
int version() {
return WebPGetDecoderVersion();
}
EMSCRIPTEN_KEEPALIVE
uint8_t* create_buffer(int size) {
return malloc(size);
}
EMSCRIPTEN_KEEPALIVE
void destroy_buffer(uint8_t* p) {
free(p);
}
int result[3];
EMSCRIPTEN_KEEPALIVE
void decode(uint8_t* img_in, int size) {
int width, height;
uint8_t* img_out = WebPDecodeRGBA(img_in, size, &width, &height);
result[0] = (int)img_out;
result[1] = width;
result[2] = height;
}
EMSCRIPTEN_KEEPALIVE
void free_result() {
WebPFree(result[0]);
}
EMSCRIPTEN_KEEPALIVE
int get_result_pointer() {
return result[0];
}
EMSCRIPTEN_KEEPALIVE
int get_result_width() {
return result[1];
}
EMSCRIPTEN_KEEPALIVE
int get_result_height() {
return result[2];
}