77 lines
1.9 KiB
JavaScript
77 lines
1.9 KiB
JavaScript
import * as mpd from "./mpd.js";
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import * as parser from "./parser.js";
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import * as html from "./html.js";
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import * as conf from "../conf.js";
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let cache = {};
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const MIME = "image/jpeg";
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const STORAGE_PREFIX = `art-${conf.artSize}` ;
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function store(key, data) {
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localStorage.setItem(`${STORAGE_PREFIX}-${key}`, data);
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}
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function load(key) {
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return localStorage.getItem(`${STORAGE_PREFIX}-${key}`);
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}
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async function getImageData(songUrl) {
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let data = [];
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let offset = 0;
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while (1) {
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let params = ["albumart", `"${mpd.escape(songUrl)}"`, offset];
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let lines = await mpd.command(params.join(" "));
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data = data.concat(lines[2]);
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let metadata = parser.linesToStruct(lines.slice(0, 2));
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if (data.length >= Number(metadata["size"])) { return data; }
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offset += Number(metadata["binary"]);
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}
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}
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async function bytesToImage(bytes) {
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let blob = new Blob([bytes]);
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let src = URL.createObjectURL(blob);
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let image = html.node("img", {src});
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return new Promise(resolve => {
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image.onload = () => resolve(image);
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});
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}
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function resize(image) {
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let canvas = html.node("canvas", {width:conf.artSize, height:conf.artSize});
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let ctx = canvas.getContext("2d");
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ctx.drawImage(image, 0, 0, canvas.width, canvas.height);
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return canvas;
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}
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export async function get(artist, album, songUrl = null) {
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let key = `${artist}-${album}`;
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if (key in cache) { return cache[key]; }
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let loaded = await load(key);
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if (loaded) {
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cache[key] = loaded;
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return loaded;
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}
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if (!songUrl) { return null; }
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// promise to be returned in the meantime
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let resolve;
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let promise = new Promise(res => resolve = res);
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cache[key] = promise;
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try {
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let data = await getImageData(songUrl);
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let bytes = new Uint8Array(data);
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let image = await bytesToImage(bytes);
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let url = resize(image).toDataURL(MIME);
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store(key, url);
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cache[key] = url;
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resolve(url);
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} catch (e) {
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cache[key] = null;
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}
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return cache[key];
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}
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