javascript结合html5 canvas实现(可调画笔颜色/粗细/橡皮)的涂鸦板

摘要：js+html5canvas实现的涂鸦画板特效,可调画笔颜色|粗细|橡皮,可以保存涂鸦效果为图片编码，非常适合学习html5的canvas,...

js+html5 canvas实现的涂鸦画板特效,可调画笔颜色|粗细|橡皮,可以保存涂鸦效果为图片编码，非常适合学习html5的canvas,必须支持html5的浏览器才能看到效果。

复制代码代码如下:

<!doctype html>

<head>

<title>javascript结合html5 canvas实现的涂鸦板 - 分享JavaScript-sharejs.com</title>

</head>

<body>

<style>

*{margin:0;padding:0;}

.fa{width:740px;margin:0 auto;}

.top{margin:20px 0;}

.top input{width:25px;height:25px;border:1px solid #fff;border-radius:4px;background:#ddd;}

.top .i1{background:#000000;}

.top .i2{background:#FF0000;}

.top .i3{background:#80FF00;}

.top .i4{background:#00FFFF;}

.top .i5{background:#808080;}

.top .i6{background:#FF8000;}

.top .i7{background:#408080;}

.top .i8{background:#8000FF;}

.top .i9{background:#CCCC00;}

#canvas{background:#eee;cursor:default;}

.font input{font-size:14px;}

.top .grea{background:#aaa;}

</style>

</head>

<body>

<div>

请选择画笔颜色：

</div>

请选择画笔的宽度：

</div>

<div>

<span id="error">如果有错误，请使用橡皮擦：</span>

</div>

</div>

<canvas id="canvas" width="740" height="420">您的浏览器不支持 canvas 标签</canvas>

</div>

</div>

(function(){

var paint={

init:function()

{

this.load();

load:function()

{

this.x=[];//记录鼠标移动是的X坐标

this.y=[];//记录鼠标移动是的Y坐标

this.clickDrag=[];

this.lock=false;//鼠标移动前，判断鼠标是否按下

this.isEraser=false;

//this.Timer=null;//橡皮擦启动计时器

//this.radius=5;

this.storageColor="#000000";

this.eraserRadius=15;//擦除半径值

this.color=["#000000","#FF0000","#80FF00","#00FFFF","#808080","#FF8000","#408080","#8000FF","#CCCC00"];//画笔颜色值

this.fontWeight=[2,5,8];

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

this.canvas=this.$("canvas");

if (this.canvas.getContext) {

} else {

alert("您的浏览器不支持 canvas 标签");

return;

}

this.cxt=this.canvas.getContext('2d');

this.cxt.lineJoin = "round";//context.lineJoin - 指定两条线段的连接方式

this.cxt.lineWidth = 5;//线条的宽度

this.iptClear=this.$("clear");

this.revocation=this.$("revocation");

this.imgurl=this.$("imgurl");//图片路径按钮

this.w=this.canvas.width;//取画布的宽

this.h=this.canvas.height;//取画布的高

this.touch =("createTouch" in document);//判定是否为手持设备

this.StartEvent = this.touch ? "touchstart" : "mousedown";//支持触摸式使用相应的事件替代

this.MoveEvent = this.touch ? "touchmove" : "mousemove";

this.EndEvent = this.touch ? "touchend" : "mouseup";

this.bind();

bind:function()

{

var t=this;

/*清除画布*/

this.iptClear.onclick=function()

{

t.clear();

};

/*鼠标按下事件，记录鼠标位置，并绘制，解锁lock，打开mousemove事件*/

this.canvas['on'+t.StartEvent]=function(e)

{

var touch=t.touch ? e.touches[0] : e;

var _x=touch.clientX - touch.target.offsetLeft;//鼠标在画布上的x坐标，以画布左上角为起点

var _y=touch.clientY - touch.target.offsetTop;//鼠标在画布上的y坐标，以画布左上角为起点

if(t.isEraser)

{

t.cxt.globalCompositeOperation = "destination-out";

t.cxt.beginPath();

t.cxt.arc(_x, _y,t.eraserRadius, 0, Math.PI * 2);

t.cxt.strokeStyle = "rgba(250,250,250,0)";

t.cxt.fill();

t.cxt.globalCompositeOperation = "source-over";

t.resetEraser(_x,_y,touch);

}else

{

t.movePoint(_x,_y);//记录鼠标位置

t.drawPoint();//绘制路线

}

t.lock=true;

};

/*鼠标移动事件*/

this.canvas['on'+t.MoveEvent]=function(e)

{

var touch=t.touch ? e.touches[0] : e;

if(t.lock)//t.lock为true则执行

{

var _x=touch.clientX - touch.target.offsetLeft;//鼠标在画布上的x坐标，以画布左上角为起点

var _y=touch.clientY - touch.target.offsetTop;//鼠标在画布上的y坐标，以画布左上角为起点

if(t.isEraser)

{

//if(t.Timer)clearInterval(t.Timer);

//t.Timer=setInterval(function(){

t.resetEraser(_x,_y,touch);

//},10);

}

else

{

t.movePoint(_x,_y,true);//记录鼠标位置

t.drawPoint();//绘制路线

}

};

this.canvas['on'+t.EndEvent]=function(e)

{

/*重置数据*/

t.lock=false;

t.x=[];

t.y=[];

t.clickDrag=[];

clearInterval(t.Timer);

t.Timer=null;

};

this.revocation.onclick=function()

{

t.redraw();

};

this.changeColor();

this.imgurl.onclick=function()

{

t.getUrl();

};

/*橡皮擦*/

this.$("eraser").onclick=function(e)

{

t.isEraser=true;

t.$("error").style.color="red";

t.$("error").innerHTML="您已使用橡皮擦！";

};

movePoint:function(x,y,dragging)

{

/*将鼠标坐标添加到各自对应的数组里*/

this.x.push(x);

this.y.push(y);

this.clickDrag.push(y);

drawPoint:function(x,y,radius)

{

for(var i=0; i < this.x.length; i++)//循环数组

{

this.cxt.beginPath();//context.beginPath() , 准备绘制一条路径

if(this.clickDrag[i] && i){//当是拖动而且i!=0时，从上一个点开始画线。

this.cxt.moveTo(this.x[i-1], this.y[i-1]);//context.moveTo(x, y) , 新开一个路径，并指定路径的起点

}else{

this.cxt.moveTo(this.x[i]-1, this.y[i]);

}

this.cxt.lineTo(this.x[i], this.y[i]);//context.lineTo(x, y) , 将当前点与指定的点用一条笔直的路径连接起来

this.cxt.closePath();//context.closePath() , 如果当前路径是打开的则关闭它

this.cxt.stroke();//context.stroke() , 绘制当前路径

}

clear:function()

{

this.cxt.clearRect(0, 0, this.w, this.h);//清除画布，左上角为起点

redraw:function()

{

/*撤销*/

this.cxt.restore();

preventDefault:function(e){

/*阻止默认*/

var touch=this.touch ? e.touches[0] : e;

if(this.touch)touch.preventDefault();

else window.event.returnValue = false;

changeColor:function()

{

/*为按钮添加事件*/

var t=this,iptNum=this.$("color").getElementsByTagName("input"),fontIptNum=this.$("font").getElementsByTagName("input");

for(var i=0,l=iptNum.length;i<l;i++)

{

iptNum[i].index=i;

iptNum[i].onclick=function()

{

t.cxt.save();

t.cxt.strokeStyle = t.color[this.index];

t.storageColor=t.color[this.index];

t.$("error").style.color="#000";

t.$("error").innerHTML="如果有错误，请使用橡皮擦：";

t.cxt.strokeStyle = t.storageColor;

t.isEraser=false;

}

for(var i=0,l=fontIptNum.length;i<l;i++)

{

t.cxt.save();

fontIptNum[i].index=i;

fontIptNum[i].onclick=function()

{

t.changeBackground(this.index);

t.cxt.lineWidth = t.fontWeight[this.index];

t.$("error").style.color="#000";

t.$("error").innerHTML="如果有错误，请使用橡皮擦：";

t.isEraser=false;

t.cxt.strokeStyle = t.storageColor;

}

changeBackground:function(num)

{

/*添加画笔粗细的提示背景颜色切换，灰色为当前*/

var fontIptNum=this.$("font").getElementsByTagName("input");

for(var j=0,m=fontIptNum.length;j<m;j++)

{

fontIptNum[j].className="";

if(j==num) fontIptNum[j].className="grea";

}

getUrl:function()

{

this.$("html").innerHTML=this.canvas.toDataURL();

resetEraser:function(_x,_y,touch)

{

/*使用橡皮擦-提醒*/

var t=this;

//this.cxt.lineWidth = 30;

/*source-over 默认,相交部分由后绘制图形的填充(颜色,渐变,纹理)覆盖,全部浏览器通过*/

t.cxt.globalCompositeOperation = "destination-out";

t.cxt.beginPath();

t.cxt.arc(_x, _y, t.eraserRadius, 0, Math.PI * 2);

t.cxt.strokeStyle = "rgba(250,250,250,0)";

t.cxt.fill();

t.cxt.globalCompositeOperation = "source-over"

}

};

paint.init();

})();

</script>

</body>

</html>