canvas模拟hover事件
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<style>
html,body{ margin:0; padding:0;}
</style>
</head>
<body>
<canvas id="cvs" width="300" height="300" style="border:1px solid #333;">你的浏览器不支持canvas，狗日的IE。</canvas>
<div id="log"></div>
<script>
var cvs = document.getElementById("cvs");
var ctx = cvs.getContext('2d');
if(ctx){
var objs = [];
var CCircle = function(){
this.type = 'circle';
this.x = 0;
this.y = 0;
this.radius = 0;
this.isHover = false;
this.color = '#000';
};
var Draw = function(){
ctx.clearRect(0,0,cvs.width,cvs.height);
for(var i=0;i<objs.length;i++){
if(objs[i].type='circle'){
ctx.beginPath();
ctx.lineWidth = 2;
ctx.strokeStyle = objs[i].color;
ctx.arc(objs[i].x,objs[i].y,objs[i].radius,0,Math.PI*2,false);
ctx.stroke();
ctx.closePath();
}
}
}// end function
for(var i=0;i<100;i++){
var c = new CCircle();
c.x = (Math.random()*300)|0;
c.y = (Math.random()*300)|0;
c.radius = 10;
c.hover = function(){
this.color = "#f00";
Draw();
}
c.out = function(){
this.color = "#000";
Draw();
}
objs.push(c);
}// end for
Draw();
cvs.onmousemove = function(e){
var hasHover = false;
for(var i=objs.length-1;i>-1;i--){
var c = objs[i];
if(((e.clientX-c.x)*(e.clientX-c.x)+(e.clientY-c.y)*(e.clientY-c.y)<=c.radius*c.radius) && (!hasHover)){
c.isHover = true;
hasHover = true;
c.hover && c.hover();
}else{
if(c.isHover){
c.isHover = false;
c.out && c.out();
}
}//end if
}// end for
}// end function
}
</script>
</body>
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