113 lines
2.9 KiB
TypeScript
113 lines
2.9 KiB
TypeScript
/**
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* Convert big-endian u32 to native JavaScript number.
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*/
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export function uint_bytes_to_num(value: Uint8Array): number {
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if (value.length != 4) { throw new Error("can't convert non 4-byte integer"); }
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const data_view = new DataView(value.buffer);
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return data_view.getUint32(0, false);
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}
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export function utf8_encode(value: string): Uint8Array {
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const encoder = new TextEncoder();
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let res: Uint8Array = new Uint8Array(0);
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for (const ch of value) {
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const cur = encoder.encode(ch)[0];
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const prev = res;
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res = new Uint8Array(prev.length + 1);
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res.set(prev, 0);
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res.set([cur], prev.length);
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}
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return res;
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}
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export function utf8_decode(value: Uint8Array): string {
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const decoder = new TextDecoder("utf-8");
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return decoder.decode(value);
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}
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export async function sleep(millis: number): Promise<void> {
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await new Promise<void>((resolver) => {
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setTimeout(resolver, millis);
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});
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}
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export function wait_for_dom_refresh(): Promise<void> {
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return new Promise<void>((resolver) => {
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requestAnimationFrame(() => {
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requestAnimationFrame(() => {
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resolver();
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});
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});
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});
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}
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export namespace el {
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function add_classes(target: HTMLElement, classes?: string[]): void {
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if (classes === undefined) { return; }
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for (const cls of classes) {
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target.classList.add(cls);
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}
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}
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export function div(children: HTMLElement[], classes?: string[]): HTMLDivElement {
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const el = document.createElement("div");
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add_classes(el, classes);
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el.append(...children);
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return el;
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}
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export function h1(text: string, classes?: string[]): HTMLHeadingElement {
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const el = document.createElement("h1");
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el.innerText = text;
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add_classes(el, classes);
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return el;
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}
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export function h2(text: string, classes?: string[]): HTMLHeadingElement {
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const el = document.createElement("h2");
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el.innerText = text;
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add_classes(el, classes);
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return el;
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}
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export function p(text: string, classes?: string[]): HTMLParagraphElement {
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const el = document.createElement("p");
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el.innerText = text;
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add_classes(el, classes);
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return el;
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}
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export async function img(src: string, classes?: string[]): Promise<HTMLImageElement> {
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const el = new Image();
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el.src = src;
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el.draggable = false;
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add_classes(el, classes);
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await new Promise<void>((resolver) => {
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el.addEventListener("load", () => { resolver(); });
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});
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return el;
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}
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export async function video(
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src: string,
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subtitles_url: string | null,
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classes?: string[],
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): Promise<HTMLVideoElement> {
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const blob = await (await fetch(src)).blob();
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const el = document.createElement("video");
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el.autoplay = true;
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const source = document.createElement("source");
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source.src = URL.createObjectURL(blob);
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el.appendChild(source);
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if (subtitles_url !== null) {
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const subs = document.createElement("track");
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subs.src = subtitles_url;
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subs.kind = "subtitles";
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subs.default = true;
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el.appendChild(subs);
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}
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add_classes(el, classes);
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return el;
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}
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}
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