Method customDrawWithCache

packages/office-viewer/src/excel/render/Canvas.ts:403–426

* 运行绘制并缓存

(
    cacheKey: string,
    x: number,
    y: number,
    width: number,
    height: number,
    func: (ctx: OffscreenCanvasRenderingContext2D, ratio: number) => void
  )

   * 运行绘制并缓存
   */
  async customDrawWithCache(
    cacheKey: string,
    x: number,
    y: number,
    width: number,
    height: number,
    func: (ctx: OffscreenCanvasRenderingContext2D, ratio: number) => void
  ): Promise<void> {
    return new Promise<void>((resolve, reject) => {
      const ratio = this.ratio * this.zoom;
      const cache = this.imageCache.get(cacheKey);
      if (cache) {
        this.ctx.drawImage(cache, x, y, width, height);
        resolve();
        return;
      }
      const imageBitmap = drawOffscreenCanvas(ratio, width, height, ctx => {
        func(ctx, ratio);
      });
      this.ctx.drawImage(imageBitmap, x, y, width, height);
      this.imageCache.set(cacheKey, imageBitmap);
      resolve();
    });
  }

  /**
   * 清空缓存