globalCompositeOperation的值:
下面分别来演示上面各个值的具体使用方法:
1.source-in:
2.source-out:
3.destination-over:
4.destination-in:
5.destination-out:
6.destination-atop:
7.lighter:
8.copy:
//注:globalCompositeOperation要写在绘制之前
