ctx.globalCompositeStyle = 'lighter';是什么意思

HTML5里canvas画布的这句ctx.globalCompositeStyle = 'lighter';是什么意思

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问题似有误，应是globalCompositeOperation：

组合 Compositing

lighter
Where both shapes overlap the color is determined by adding color values.
两图形中重叠部分作加色处理。