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使用JavaScript实现使用鼠标画线的效果

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12/02
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<!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 1</title>

<style type="text/css">

.style1 {

    font-size: x-small;

}

</style>

<script type="text/javascript">

/**

    画点

*/

function makedot(x, y){

  pointDiv = "<div style='height:1px;position:absolute;left:" + x +

      "px;top:" + y + "px;width:1px;background:#f00;overflow:hidden'></div>";

  return pointDiv;

}

/**

  根据两点坐标画直线。

*/  

function line(x1,y1,x2,y2){

  var slope; //斜率

  var direction;//坐标运动方向

  var tx = x2 - x1;

  var ty = y2 - y1;

  if(tx == 0 && ty == 0)return;

  var points = "";

  var axis;//坐标轴上的坐标

  if(Math.abs(tx) >= Math.abs(ty)){//在x轴上移动

      direction = tx > 0 ? 1 : -1;

      tx = Math.abs(tx);

      slope = ty / tx;

      axis = x1;

      for(i = 0; i < tx; i ++){

          points += makedot(axis, y1 + i * slope);

          axis += direction;

      }

  }else{//在y轴上移动

      direction = ty > 0 ? 1 : -1;

      ty = Math.abs(ty);

      slope = tx / ty;

      axis = y1;

      for(i = 0; i < ty; i ++){

          points += makedot(x1 + i * slope, axis);

          axis += direction;

      }

  }

  var container = document.getElementById("container");

  container.innerHTML += points;

}

var oldPoint = null;

//获取鼠标位置

function mousePosition(ev){

    ev = ev || window.event;

    if(ev.pageX || ev.pageY){

        return {x:ev.pageX, y:ev.pageY};

    }

    var doc = document.documentElement, body = document.body;

    var pageX = event.clientX + (doc && doc.scrollLeft || body && body.scrollLeft || 0) - (doc && doc.clientLeft || body && body.clientLeft || 0);

    var pageY = event.clientY + (doc && doc.scrollTop  || body && body.scrollTop  || 0) - (doc && doc.clientTop  || body && body.clientTop  || 0);

    return {x:pageX, y:pageY};

}

function recordPoint(ev){

    var point = mousePosition(ev);

    if(oldPoint != null){

        line(oldPoint.x, oldPoint.y, point.x, point.y);

    }

    oldPoint = point;

}

</script>

</head>  

<body>

<div id="container" style="width: 1000px; height: 600px; border:1px #bfbfbf solid;" onclick="recordPoint(event);">

</div>

<script type="text/javascript">

    //line(19,19,22,300);

</script>

</body>  

</html>

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