assemblyscript-jpeg-decoder/index.html at master · glovas/assemblyscript-jpeg-decoder · GitHub

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<html>
    <body>
      <script>
        let mem, wasmInstance;


        function fetchAndInstantiateWasm (imports) {
            return fetch('jpeg-decode.wasm').then(response =>
                response.arrayBuffer()
            )
            .then(bytes => WebAssembly.compile(bytes))
            .then(module =>
            WebAssembly.instantiate(module, imports || {})
            )
            .then(instance => instance.exports)
            .then(instance => {
                mem = instance.memory;
                wasmInstance = instance;
            });
        }

        function writeBytes(byteArray, offset) {
            console.log('Write bytes to offset: ',offset);
            const outBuf = new Uint8Array(mem.buffer, offset, byteArray.length);
            for (let i = 0; i < byteArray.length; i++) {
                outBuf[i] = byteArray[i];
            }
        }

        function readBytes(offset, length) {
            console.log('Read bytes from offset: ', offset);
            const outBuf = new Uint8Array(mem.buffer, offset, length);
            let result = new Uint8Array(length);
            for (let i = 0; i < outBuf.length; i++) {
                result[i] = outBuf[i];
            }
            return result;
        }

        function convertBytesWithWASM(jpegBytes) {
            console.log('Convert bytes: ', jpegBytes);
            writeBytes(jpegBytes, wasmInstance.getInOffset(jpegBytes.length));
            let resultPointer = wasmInstance.jpeg_decode();
            let resultSize = wasmInstance.getResultSize();
            console.log('Result bytes: ', readBytes(resultPointer, resultSize));
        }

        function test() {
            var xhr = new XMLHttpRequest();
            xhr.open('get', 'test.jpg');
            xhr.responseType = 'blob';
            xhr.onload = function(){
                var fr = new FileReader();

                fr.onload = function(){
                    let arr = new Uint8Array(this.result);
                    convertBytesWithWASM(arr);
                };

                fr.readAsArrayBuffer(xhr.response);
            }
            xhr.send();
        }

        fetchAndInstantiateWasm();
      </script>
    </body>
</html>