@visactor/vrender-core/es/core/contributions/layerHandler/offscreen2d-contribution.js

```typescript import { xxx } from '@visactor/vrender-core'; ```

import { wrapCanvas } from "../../../canvas/util";

import { application } from "../../../application";

export class OffscreenLayerHandlerContribution {
    constructor() {
        this.offscreen = !0, this.type = "dynamic", this.global = application.global;
    }
    setDpr(dpr) {
        this.canvas.dpr = dpr;
    }
    init(layer, window, params) {
        this.layer = layer;
        const nativeCanvas = this.global.createOffscreenCanvas({
            width: params.width,
            height: params.height,
            dpr: window.dpr
        }), canvas = wrapCanvas({
            nativeCanvas: nativeCanvas,
            width: params.width,
            height: params.height,
            dpr: window.dpr,
            canvasControled: !0
        });
        this.canvas = canvas, this.context = canvas.getContext();
    }
    resize(w, h) {
        this.canvas.resize(w, h);
    }
    resizeView(w, h) {
        this.canvas.resize(w, h);
    }
    render(group, params) {
        var _a;
        params.renderService.render(group, Object.assign(Object.assign({
            context: this.context,
            viewBox: params.stage.window.getViewBox(),
            transMatrix: params.stage.window.getViewBoxTransform()
        }, params), {
            clear: null !== (_a = params.background) && void 0 !== _a ? _a : "#ffffff"
        }));
    }
    prepare(dirtyBounds, params) {}
    release() {
        this.canvas.release();
    }
    getContext() {
        return this.context;
    }
    drawTo(target, group, params) {
        const context = target.getContext(), targetDpr = target.dpr, {viewBox: viewBox} = params, x = viewBox.x1, y = viewBox.y1, width = viewBox.width(), height = viewBox.height();
        context.nativeContext.save(), context.nativeContext.setTransform(targetDpr, 0, 0, targetDpr, 0, 0), 
        params.clear && context.clearRect(x, y, width, height), context.drawImage(this.canvas.nativeCanvas, 0, 0, this.canvas.width, this.canvas.height, x, y, width, height), 
        context.nativeContext.restore();
    }
    merge(layerHandlers) {}
}
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