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canvas-line-width](http://www.domyself.me/wp-content/uploads/2014/09/canvas-300x136.jpg)
canvas-line-width](http://www.domyself.me/wp-content/uploads/2014/09/canvas-300x136.jpg)

关于在canvas中的线宽,需要注意的是,线的宽度是以线的起点坐标,向两边各半个线宽值形成的。