鼠标画线程序

最新推荐文章于 2021-05-21 12:06:16 发布

原创最新推荐文章于 2021-05-21 12:06:16 发布 · 1k 阅读

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CC 4.0 BY-SA版权

文章标签：

#function #object #xhtml #browser #fun #border

本文介绍了一款使用HTML5 Canvas实现的简易鼠标屏幕画线程序。该程序通过监听鼠标事件来绘制连续的线条，适用于简单的绘图应用或交互式网页设计。

最近研究了一个大牛的程序，用canvas终于做出来了一个小的鼠标屏幕画线程序

<!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=gb2312" />
<title>鼠标画线</title>
</head>

<body>

<canvas id="myCanvas" width="600" height="600" style="border:1px solid #c3c3c3;">
Your browser does not support the canvas element.
</canvas>

<script>
var c=document.getElementById("myCanvas");
var cxt=c.getContext("2d");

var isIE = (document.all) ? true : false;

var $ = function (id) {
   return "string" == typeof id ? document.getElementById(id) : id;
};

var Class = {
   create: function() {
       return function() { this.initialize.apply(this, arguments); }
   }
}

var Extend = function(destination, source) {
   for (var property in source) {
       destination[property] = source[property];
   }
}

var Bind = function(object, fun) {
   return function() {
       return fun.apply(object, arguments);
   }
}

var BindAsEventListener = function(object, fun) {
   return function(event) {
       return fun.call(object, (event || window.event));
   }
}

function addEventHandler(oTarget, sEventType, fnHandler) {
   if (oTarget.addEventListener) {
       oTarget.addEventListener(sEventType, fnHandler, false);
   } else if (oTarget.attachEvent) {
       oTarget.attachEvent("on" + sEventType, fnHandler);
   } else {
       oTarget["on" + sEventType] = fnHandler;
   }
};

function removeEventHandler(oTarget, sEventType, fnHandler) {
    if (oTarget.removeEventListener) {
        oTarget.removeEventListener(sEventType, fnHandler, false);
    } else if (oTarget.detachEvent) {
        oTarget.detachEvent("on" + sEventType, fnHandler);
    } else {
        oTarget["on" + sEventType] = null;
    }
};

//拖放程序
var SimpleDrag = Class.create();

SimpleDrag.prototype = {
//拖放对象,触发对象
initialize: function(drag) {
   this.Drag = $(drag);
   this._x = this._y = 0;
   this._fM = BindAsEventListener(this, this.Move);
   this._fS = Bind(this, this.Stop);
   this.Drag.style.position = "absolute";
   addEventHandler(this.Drag, "mousedown", BindAsEventListener(this, this.Start));
},
//准备拖动
Start: function(oEvent) {
   cxt.moveTo(oEvent.clientX,oEvent.clientY);
   addEventHandler(document, "mousemove", this._fM);
   addEventHandler(document, "mouseup", this._fS);
},
//拖动
Move: function(oEvent) {
   if(oEvent.button == 0){
   cxt.lineTo(oEvent.clientX,oEvent.clientY);
   cxt.stroke();
   cxt.moveTo(oEvent.clientX,oEvent.clientY);
   }

},
//停止拖动
Stop: function() {
   removeEventHandler(document, "mousemove", this._fM);
   removeEventHandler(document, "mouseup", this._fS);
}
};

</script>

<script>
new SimpleDrag("myCanvas");

</script>

</body>
</html>