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import type { CanvasRenderer } from "../canvas-renderer";
import { BaseNode } from "./base-node";
export type BlurBackgroundNodeParams = {
blurIntensity: number;
contentNodes: BaseNode[];
};
export class BlurBackgroundNode extends BaseNode<BlurBackgroundNodeParams> {
private blurIntensity: number;
private contentNodes: BaseNode[];
constructor(params: BlurBackgroundNodeParams) {
super(params);
this.blurIntensity = params.blurIntensity;
this.contentNodes = params.contentNodes;
}
async render({
renderer,
time,
}: {
renderer: CanvasRenderer;
time: number;
}): Promise<void> {
let offscreen: OffscreenCanvas | HTMLCanvasElement;
let offscreenCtx:
| OffscreenCanvasRenderingContext2D
| CanvasRenderingContext2D;
try {
offscreen = new OffscreenCanvas(renderer.width, renderer.height);
const ctx = offscreen.getContext("2d");
if (!ctx) {
throw new Error("failed to get offscreen canvas context");
}
offscreenCtx = ctx;
} catch {
offscreen = document.createElement("canvas");
offscreen.width = renderer.width;
offscreen.height = renderer.height;
const ctx = offscreen.getContext("2d");
if (!ctx) {
throw new Error("failed to get canvas context");
}
offscreenCtx = ctx;
}
const originalContext = renderer.context;
renderer.context = offscreenCtx;
for (const node of this.contentNodes) {
await node.render({ renderer, time });
}
renderer.context = originalContext;
const zoomScale = 1.4;
const scaledWidth = renderer.width * zoomScale;
const scaledHeight = renderer.height * zoomScale;
const offsetX = (renderer.width - scaledWidth) / 2;
const offsetY = (renderer.height - scaledHeight) / 2;
renderer.context.save();
renderer.context.filter = `blur(${this.blurIntensity}px)`;
renderer.context.drawImage(
offscreen as CanvasImageSource,
offsetX,
offsetY,
scaledWidth,
scaledHeight,
);
renderer.context.restore();
}
}
|