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import type { CanvasRenderer } from "../canvas-renderer";
import { VisualNode, type VisualNodeParams } from "./visual-node";
export interface ImageNodeParams extends VisualNodeParams {
url: string;
maxSourceSize?: number;
}
interface CachedImageSource {
source: HTMLImageElement | OffscreenCanvas;
width: number;
height: number;
}
const imageSourceCache = new Map<string, Promise<CachedImageSource>>();
function loadImageSource(
url: string,
maxSourceSize?: number,
): Promise<CachedImageSource> {
const cacheKey = `${url}::${maxSourceSize ?? "full"}`;
const cached = imageSourceCache.get(cacheKey);
if (cached) return cached;
const promise = (async (): Promise<CachedImageSource> => {
const image = new Image();
await new Promise<void>((resolve, reject) => {
image.onload = () => resolve();
image.onerror = () => reject(new Error("Image load failed"));
image.src = url;
});
const naturalWidth = image.naturalWidth;
const naturalHeight = image.naturalHeight;
const exceedsLimit =
maxSourceSize &&
(naturalWidth > maxSourceSize || naturalHeight > maxSourceSize);
if (exceedsLimit) {
const scale = Math.min(
maxSourceSize / naturalWidth,
maxSourceSize / naturalHeight,
);
const scaledWidth = Math.round(naturalWidth * scale);
const scaledHeight = Math.round(naturalHeight * scale);
const offscreen = new OffscreenCanvas(scaledWidth, scaledHeight);
const ctx = offscreen.getContext("2d");
if (ctx) {
ctx.drawImage(image, 0, 0, scaledWidth, scaledHeight);
return { source: offscreen, width: scaledWidth, height: scaledHeight };
}
}
return { source: image, width: naturalWidth, height: naturalHeight };
})();
imageSourceCache.set(cacheKey, promise);
return promise;
}
export class ImageNode extends VisualNode<ImageNodeParams> {
private cachedSource: Promise<CachedImageSource>;
constructor(params: ImageNodeParams) {
super(params);
this.cachedSource = loadImageSource(params.url, params.maxSourceSize);
}
async render({ renderer, time }: { renderer: CanvasRenderer; time: number }) {
await super.render({ renderer, time });
if (!this.isInRange(time)) {
return;
}
const { source, width, height } = await this.cachedSource;
this.renderVisual({
renderer,
source,
sourceWidth: width || renderer.width,
sourceHeight: height || renderer.height,
});
}
}
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