拓扑新动画效果，可拖拽，可滚轮缩放。

展示效果网址 http://jstopo.top

!

         init(){  
            this.domRef = this.$refs.canvas;  
            this.w = this.domRef.width = this.domRef.clientWidth,  
            this.h = this.domRef.height = this.domRef.clientHeight;  
            this.ctx = this.domRef.getContext("2d");  
            this.ctx.textAlign = "center";  
            this.ctx.textBaseline = "top";  
            this.ctx.font = "18px 黑体";  
            this.dotMove();  
        },