Telegram Web K with changes to work inside I2P https://web.telegram.i2p/
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/**
* @returns duration in ms
*/
export default function getGifDuration(image: HTMLImageElement) {
const src = image.src;
return fetch(src)
.then(response => response.arrayBuffer())
.then(arrayBuffer => {
const d = new Uint8Array(arrayBuffer);
// Thanks to http://justinsomnia.org/2006/10/gif-animation-duration-calculation/
// And http://www.w3.org/Graphics/GIF/spec-gif89a.txt
let duration = 0;
for(let i = 0, length = d.length; i < length; ++i) {
// Find a Graphic Control Extension hex(21F904__ ____ __00)
if(d[i] == 0x21
&& d[i + 1] == 0xF9
&& d[i + 2] == 0x04
&& d[i + 7] == 0x00) {
// Swap 5th and 6th bytes to get the delay per frame
const delay = (d[i + 5] << 8) | (d[i + 4] & 0xFF);
// Should be aware browsers have a minimum frame delay
// e.g. 6ms for IE, 2ms modern browsers (50fps)
duration += delay < 2 ? 10 : delay;
}
}
return duration / 1000;
});
}