基于HTML5 canvas的画箭头组件

浏览数：20 / 时间：2015年06月09日

/**
 * 实现两点间画箭头的功能
 * @author [email protected]
 * @version 1.0
 * @date 2013.05.23
 */
(function(window,document){
    if 
(window.mapleque==undefined)
        window.mapleque={};
    if 
(window.mapleque.arrow!=undefined)
        return;
     
    /**
     * 组件对外接口
     */
    var 
proc={
        /**
         * 接收canvas对象，并在此上画箭头（箭头起止点已经设置）
         * @param context
         */
        paint:function(context){paint(this,context);},
        /**
         * 设置箭头起止点
         * @param sp起点
         * @param ep终点
         * @param st强度
         */
        set:function(sp,ep,st){init(this,sp,ep,st);},
        /**
         * 设置箭头外观
         * @param args
         */
        setPara:function(args){
            this.size=args.arrow_size;//箭头大小
            this.sharp=args.arrow_sharp;//箭头锐钝
        }
    };
     
    var 
init=function(a,sp,ep,st){
        a.sp=sp;//起点
        a.ep=ep;//终点
        a.st=st;//强度
    };
    var 
paint=function(a,context){
        var 
sp=a.sp;
        var 
ep=a.ep;
        if 
(context==undefined)
            return;
        //画箭头主线
        context.beginPath();
        context.moveTo(sp.x,sp.y);
        context.lineTo(ep.x,ep.y);
        //画箭头头部
        var 
h=_calcH(a,sp,ep,context);
        context.moveTo(ep.x,ep.y);
        context.lineTo(h.h1.x,h.h1.y);
        context.moveTo(ep.x,ep.y);
        context.lineTo(h.h2.x,h.h2.y);
        context.stroke();
    };
    //计算头部坐标
    var 
_calcH=function(a,sp,ep,context){
        var 
theta=Math.atan((ep.x-sp.x)/(ep.y-sp.y));
        var 
cep=_scrollXOY(ep,-theta);
        var 
csp=_scrollXOY(sp,-theta);
        var 
ch1={x:0,y:0};
        var 
ch2={x:0,y:0};
        var 
l=cep.y-csp.y;
        ch1.x=cep.x+l*(a.sharp||0.025);
        ch1.y=cep.y-l*(a.size||0.05);
        ch2.x=cep.x-l*(a.sharp||0.025);
        ch2.y=cep.y-l*(a.size||0.05);
        var 
h1=_scrollXOY(ch1,theta);
        var 
h2=_scrollXOY(ch2,theta);
        return 
{
            h1:h1,
            h2:h2
                };
    };
    //旋转坐标
    var 
_scrollXOY=function(p,theta){
        return 
{
            x:p.x*Math.cos(theta)+p.y*Math.sin(theta),
            y:p.y*Math.cos(theta)-p.x*Math.sin(theta)
        };
    };
     
    var 
arrow=new 
Function();
    arrow.prototype=proc;
    window.mapleque.arrow=arrow;
})(window,document);

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>sample of the arrow</title>
<script type="text/javascript" src="./arrow.js"></script>
</head>
<body>
<canvas width=800 height=600 id="arrowLine">请使用支持HTML5的浏览器</canvas>
<script type="text/javascript">
var cont=document.getElementById("arrowLine").getContext(‘2d‘);
var a1=new window.mapleque.arrow();
a1.set({x:350,y:300},{x:200,y:200});
a1.paint(cont);
var a2=new window.mapleque.arrow();
a2.set({x:100,y:100},{x:200,y:250});
a2.paint(cont);
var a3=new window.mapleque.arrow();
a3.set({x:100,y:300},{x:150,y:150});
a3.paint(cont);
var a4=new window.mapleque.arrow();
a4.set({x:350,y:150},{x:150,y:250});
a4.setPara({
	arrow_size:0.5,
	arrow_sharp:0.5
})
a4.paint(cont);
</script>
</body>
</html>

效果还不错，不满意可以自己调试

郑重声明：本站内容如果来自互联网及其他传播媒体，其版权均属原媒体及文章作者所有。转载目的在于传递更多信息及用于网络分享，并不代表本站赞同其观点和对其真实性负责，也不构成任何其他建议。

基于HTML5 canvas的画箭头组件