html5 canvas画板

点击查看演示地址
<!DOCTYPE HTML>

<html>

<title>HTML5-CanvasDrawDemo</title>

<meta charset="utf-8"/>

<body>

    <style>

		div {

			border:0;

			margin:auto;

			width:500px;

		}

		#div_head {

			border:0;

		}

		#div_head span{

		font-size:10px;

		}

		body canvas

        {

            border: 2px solid blue;

			border-radius:10px;

        }

		#txt_alpha { width:20px;}

		#txt_width{ width:30px;}

		footer {

			margin:auto;

			text-align:center;

			font-size:10px;

			}

    </style>

	<div id="div_head">

	<fieldset>

	<legend>Controller</legend>

	Color:<input id='btn_color' type='color' />

	Alpha:<input id="txt_alpha" type='range' min="0" max="1" step="0.1" value="1"/>

	Size:

	<input id='txt_width' type='range' min="1" max="10" step="1" value="4"/>

	<input id="btn_pre" type='button' value="撤销"/>

	<input id="btn_next" type='button' value="恢复"/>

	<input id="btn_clear" type='button' value="Clear"/>

	</fieldset>

	</div>

	<div>

    <canvas id="drawgph" width="500" height="400" >

	<span><font color='red'>浏览器不支持Html5中的Canvas元素!</font></span>

	</canvas>

	</div>

	<footer>

	<span>Google Chrome 版本 33.0.1750.154 m 测试通过!</span></br>

	<span>IE9.0 不支持颜色选择,需手动填入颜色值,格式为“#FFFFFF”。</span></br>

	<span><a target="_blank" href="http://wpa.qq.com/msgrd?v=3&uin=170515071&site=qq&menu=yes"><img border="0" src="http://wpa.qq.com/pa?p=2:170515071:51" alt="点击这里给我发消息" title="点击这里给我发消息"/></a></span></br>

	<span>

	<a target="_blank" href="http://mail.qq.com/cgi-bin/qm_share?t=qm_mailme&email=2qKzu7Wjr_-q7Oiaq6v0ubW3" style="text-decoration:none;"><img src="http://rescdn.qqmail.com/zh_CN/htmledition/images/function/qm_open/ico_mailme_12.png"/></a>

	</span>

	</footer>

	<script type="text/javascript">

		//检测浏览器版本

		var Sys = {};

        var ua = navigator.userAgent.toLowerCase();

        window.ActiveXObject ? Sys.ie = ua.match(/msie ([\d.]+)/)[1] :

        document.getBoxObjectFor ? Sys.firefox = ua.match(/firefox\/([\d.]+)/)[1] :

        window.MessageEvent && !document.getBoxObjectFor ? Sys.chrome = ua.match(/chrome\/([\d.]+)/)[1] :

        window.opera ? Sys.opera = ua.match(/opera.([\d.]+)/)[1] :

        window.openDatabase ? Sys.safari = ua.match(/version\/([\d.]+)/)[1] : 0;

		if(Sys.ie>=9){//IE9.0目前不支持type=color

			document.getElementById('btn_color').value="#000000";

		}

        if(Sys.firefox) ver='Firefox: '+Sys.firefox;

        if(Sys.chrome) ver='Chrome: '+Sys.chrome;

        if(Sys.opera) ver='Opera: '+Sys.opera;

        if(Sys.safari) ver='Safari: '+Sys.safari;

        var obj = document.getElementById('drawgph');

        var ctx = obj.getContext('2d');

        var start_X = 0;//起点X轴位置

        var start_Y = 0;//起点Y轴位置

        var isMove = false;//是否绘制图形

		var history=[];//历史操作记录

		var count=0;//记录当前执行的步骤数(绘制+1;撤销-1 ;恢复+1)

		var colorObj=document.getElementById('btn_color');//颜色对象

		var alpha=document.getElementById('txt_alpha');//透明对象

		var size=document.getElementById('txt_width');//画笔宽度

        obj.addEventListener("mousedown", function (e) {

            start_X = e.pageX-e.target.offsetLeft;

            start_Y = e.pageY-e.target.offsetTop;

			//console.log('mousedown on ('+start_X+','+start_Y+')');

            isMove = true;

			ctx.lineWidth =size.value;

			ctx.strokeStyle=colorObj.value;

			ctx.globalAlpha=alpha.value;

			ctx.save();

        });

        obj.addEventListener("mousemove", function (e) {

            if (isMove) {

				ctx.beginPath();

				ctx.moveTo(start_X,start_Y);

				ctx.lineTo(e.pageX-e.target.offsetLeft, e.pageY-e.target.offsetTop);

                ctx.stroke();

				start_X = e.pageX-e.target.offsetLeft;

				start_Y = e.pageY-e.target.offsetTop;

            }

        });

        obj.addEventListener("mouseup", function (e) {

			ctx.restore();

			//如果有产生绘图则记录操作

			if(isMove){

				historyLog();

			}

            isMove = false;

			//如果在内部释放中断冒泡事件

			window.event.cancelBubble=true;

        });

		//防止用户画笔在画布范围外释放后回到画布持续绘画状态

		window.addEventListener('mouseup',function(e){

			ctx.restore();

			//如果有产生绘图则记录操作

			if(isMove){

				historyLog();

			}

			isMove=false;

		});

		//首次加载时保存空白画布历史记录

		window.addEventListener('load',historyLog);

		//Clear按钮清除画布内容

		btn_clear.onclick=function(){

			//console.log("Action: btn_clear.onclick" );

			ctx.clearRect(0,0,500,400);

			count=0;

			history=[];

			historyLog();

		}

		//撤销

		btn_pre.onclick=function(){

			count--;

			//console.log("撤销操作时变量Count:"+count);

			if(count==0){

				count++;

			}

			ctx.putImageData(history[count-1],0,0);

			//console.log(history);

		}

		//恢复

		btn_next.onclick=function(){

			//console.log("恢复操作时变量Count:"+count);

			if(history[count]){

				ctx.putImageData(history[count],0,0);

				count++;

			}

		}

		//记录操作

		function historyLog(){

			//console.log("记录操作时变量Count:"+count);

			history[count]=(ctx.getImageData(0,0,500,400));

			count++;

			//console.log(history);

		}

    </script>

</body>

</html>
点击查看演示地址
巴特西

html5 canvas画板

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