static rasterizePicture()

in packages/core/src/compositing/raster-cache.ts [204:236]

• 29 lines of code
• 5 McCabe index (conditional complexity)

  static rasterizePicture(picture: Picture, matrix: Matrix) {
    const cacheBounds = RasterCache.getCacheBounds(picture.cullRect, matrix)

    // 太大了
    if (
      cacheBounds.width > RasterCache.DEFAULT_PICTURE_CACHE_LONG_SIDE
      || cacheBounds.height > RasterCache.DEFAULT_PICTURE_CACHE_LONG_SIDE
      || cacheBounds.width * cacheBounds.height > RasterCache.DEFAULT_PICTURE_CACHE_AREA) {
      return undefined
    }

    const surface = RasterCache.surfacePool.take()
    const frame = surface.acquireFrame(Size.fromWH(cacheBounds.width, cacheBounds.height))
    const canvas = frame.canvas

    // 从池子里拿出来的 frame，可能留有上一帧的渲染结果，需要手动 reset
    canvas.resetTransform()
    canvas.clear()

    // 然后执行缓存的绘制
    canvas.translate(-cacheBounds.left, -cacheBounds.top)
    canvas.transform(matrix)
    canvas.drawPicture(picture)
    if (DebugFlags.paintRasterCacheWaterMark) {
      canvas.resetTransform()
      canvas.debugDrawCheckerboard(1)
    }
    return new RasterCacheResult(
      surface.toImage(),
      picture.cullRect,
      surface,
    )
  }