html 中的 canvas 大小设置问题

To set the canvas width and height you must use the HTML width/height attributes. You can use CSS if you wish but if you do then the canvas will be scaled up from the HTML dimensions to fit the CSS dimensions - so your canvas will look blocky and blurry.
这个是在canvas标签里面设置height\width
这个是在css里面设置canvas的height\width
请问这个是怎么影响canvas中画的图的