canvas-实现拓扑图

https://www.cnblogs.com/xiaohualu/p/10383801.html  转载

http://www.jtopo.com/introduction-in-5-minutes.html 官网

https://blog.csdn.net/ilovepengqi/article/details/78989288  转一个实例

https://www.jianshu.com/p/e4dde83a7282

https://blog.csdn.net/linkedin_37345339/article/details/54598527

https://www.pianshen.com/article/369812234/

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//下面是文本位置显示属性值汇总：

node.textPosition = 'Top_Center'; // 文本位置

Top_Left,Top_Rigth,Top_Center

Middle_Letf,Middle_Rigth,Middle_Center

Bottom_Left,Bottom,Rigth,Bottom_Center