我明白这是通常更快的预渲染的图形的一个屏幕画布。

I understand it's often faster to pre-render graphics to an off-screen canvas.

youdao

因此，要注意的是一定要确保画布对象已经全部渲染到屏幕上；否则输出文件将是空的。

Therefore, take care that the Canvas object in fact has been rendered to the screen; otherwise the output file will be empty.

youdao

如果屏幕改变大小或者改变方案，这个画布将会自动改变尺寸匹配它。

If the screen is resized or changes resolution, the Canvas will automatically change size to match this.

youdao