commit b994c6e748b76a4fe0e707db66f8d7b65a472ee9 · kitten.sh/frag-canvas-element

.changeset/nice-streets-taste.md

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       ---

     

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       'frag-canvas': patch

     

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       ---

     

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       Pause rendering when element isn't visible

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src/frag-canvas-element.ts

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       import { trackVisibility, trackResizes, trackTextUpdates } from './observers';

     

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       const VERSION_300 = '#version 300 es';

     

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       const VS_SOURCE_100 =

     
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       }

     

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       class FragCanvas extends HTMLElement implements HTMLCanvasElement {

     

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         static observedAttributes = [];

     

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         static observedAttributes = ['pause'];

     

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         private subscriptions: (() => void)[] = [];

     

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         private state: ReturnType<typeof createState> | null = null;

     

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         private input: HTMLCanvasElement | HTMLImageElement | HTMLVideoElement;

     

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         private output: HTMLCanvasElement;

     

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         #mutationObserver = new MutationObserver(() => {

     

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           if (this.state) {

     

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             this.state.updateFragShader(this.source);

     

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           }

     

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         });

     

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         #resizeObserver = new ResizeObserver(entries => {

     

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           const entry = entries[0];

     

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           if (this.state && entry) {

     

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             const width = entry.devicePixelContentBoxSize[0].inlineSize;

     

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             const height = entry.devicePixelContentBoxSize[0].blockSize;

     

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             if (this.autoresize) {

     

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               this.input.width = width;

     

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               this.input.height = height;

     

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             }

     

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             this.state.updateViewport(width, height);

     

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             this.state.drawImmediate();

     

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             this.#rescheduleDraw();

     

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           }

     

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         });

     

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         public pause: boolean = false;

     

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         constructor() {

     

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           super();

     
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             cancelAnimationFrame(this.#frameID);

     

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             this.#frameID = undefined;

     

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           }

     

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           this.#frameID = requestAnimationFrame(function draw(

     

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             timestamp: DOMHighResTimeStamp

     

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           ) {

     

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             if (self.state) {

     

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               self.state.draw(self.input, timestamp);

     

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               self.#frameID = requestAnimationFrame(draw);

     

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             }

     

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           });

     

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           if (!this.pause) {

     

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             this.#frameID = requestAnimationFrame(function draw(

     

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               timestamp: DOMHighResTimeStamp

     

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             ) {

     

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               if (self.state && !self.pause) {

     

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                 self.state.draw(self.input, timestamp);

     

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                 self.#frameID = requestAnimationFrame(draw);

     

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               }

     

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             });

     

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           }

     

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         }

     

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         connectedCallback() {

     

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           this.pause = !!this.getAttribute('pause');

     

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           const gl = this.output.getContext('webgl2', {

     

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             alpha: true,

     

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             desynchronized: true,

     
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           const state = (this.state = gl && createState(gl, init));

     

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           if (state) {

     

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             this.#mutationObserver.observe(this, {

     

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               subtree: true,

     

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               characterData: true,

     

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             });

     

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             this.#resizeObserver.observe(this, { box: 'device-pixel-content-box' });

     

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             this.subscriptions.push(

     

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               trackResizes(this, entry => {

     

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                 const { inlineSize: width, blockSize: height } = entry;

     

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                 if (this.autoresize) {

     

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                   this.input.width = width;

     

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                   this.input.height = height;

     

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                 }

     

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                 state.updateViewport(width, height);

     

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                 state.drawImmediate();

     

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                 this.#rescheduleDraw();

     

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               }),

     

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               trackTextUpdates(this, () => {

     

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                 state.updateFragShader(this.source);

     

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               }),

     

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               trackVisibility(this, isVisible => {

     

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                 this.pause = !isVisible;

     

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                 this.#rescheduleDraw();

     

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               })

     

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             );

     

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             this.#rescheduleDraw();

     

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           }

     

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         }

     

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         attributeChangedCallback(

     

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           name: string,

     

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           _oldValue: unknown,

     

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           newValue: unknown

     

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         ) {

     

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           if (name === 'pause') {

     

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             this.pause = !!newValue;

     

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             this.#rescheduleDraw();

     

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           }

     

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         }

     

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         disconnectedCallback() {

     

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           this.#mutationObserver.disconnect();

     

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           this.#resizeObserver.disconnect();

     

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           this.pause = true;

     

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           this.subscriptions.forEach(unsubscribe => unsubscribe());

     

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           this.subscriptions.length = 0;

     

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           if (this.#frameID !== undefined) {

     

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             cancelAnimationFrame(this.#frameID);

     

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             this.#frameID = undefined;

+62

src/observers.ts

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       let intersectionObserver: IntersectionObserver | undefined;

     

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       const intersectionListeners = new Map<Element, (isVisible: boolean) => void>();

     

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       const getIntersectionObserver = () =>

     

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         intersectionObserver ||

     

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         (intersectionObserver = new IntersectionObserver(entries => {

     

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           for (const entry of entries) {

     

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             const listener = intersectionListeners.get(entry.target);

     

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             if (listener) {

     

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               listener(entry.isIntersecting);

     

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             }

     

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           }

     

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         }));

     

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       export function trackVisibility(

     

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         element: Element,

     

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         onChange: (isVisible: boolean) => void

     

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       ): () => void {

     

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         const observer = getIntersectionObserver();

     

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         intersectionListeners.set(element, onChange);

     

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         observer.observe(element);

     

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         return () => {

     

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           observer.unobserve(element);

     

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           intersectionListeners.delete(element);

     

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         };

     

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       }

     

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       let resizeObserver: ResizeObserver | undefined;

     

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       const resizeListeners = new Map<

     

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         Element,

     

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         (box: { inlineSize: number; blockSize: number }) => void

     

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       >();

     

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       const getResizeObserver = () =>

     

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         resizeObserver ||

     

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         (resizeObserver = new ResizeObserver(entries => {

     

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           for (const entry of entries) {

     

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             const listener = resizeListeners.get(entry.target);

     

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             if (listener) listener(entry.devicePixelContentBoxSize[0]);

     

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           }

     

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         }));

     

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       export function trackResizes(

     

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         element: Element,

     

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         onChange: (box: { inlineSize: number; blockSize: number }) => void

     

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       ): () => void {

     

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         const observer = getResizeObserver();

     

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         resizeListeners.set(element, onChange);

     

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         observer.observe(element, { box: 'device-pixel-content-box' });

     

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         return () => {

     

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           resizeListeners.delete(element);

     

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         };

     

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       }

     

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       export function trackTextUpdates(

     

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         element: Element,

     

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         onChange: () => void

     

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       ): () => void {

     

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         const observer = new MutationObserver(onChange);

     

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         observer.observe(element, { subtree: true, characterData: true });

     

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         return () => {

     

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           observer.disconnect();

     

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         };

     

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       }