1. 程式人生 > >html5之canvas畫圖 1.寫字板功能

html5之canvas畫圖 1.寫字板功能

load har line client ctype 監聽事件 tle ntb csdn

寫字板事例:

技術分享

寫字板分析:1.點擊鼠標開始寫字(onmosedown)2.按下鼠標寫字(onmousemove)3.松開鼠標,停下寫字(撤銷onmousemove事件):

代碼:

<strong><!doctype html>  
</strong><html>  
    <head>  
        <meta charset="utf-8">  
        <title>Canvas</title>  
        <style type="text/css">  
            body {  
                margin: 0px;  
                padding: 0px;  
            }  
            #canvas {  
                margin: 0px;  
                padding: 0px;  
                border: 1px solid #000000;    
            }  
        </style>  
    </head>  
    <body>  
        <canvas id="canvas" width="400" height="400">當前瀏覽器不支持canvas</canvas>  
        <script type="text/javascript" src="utils.js"></script>  
        <script type="text/javascript" src="arrow.js"></script>  
        <script type="text/javascript">  
            window.onload=function(){  
            	
                var canvas=document.getElementById("canvas");  
                var context=canvas.getContext("2d"); 
               
                /*var mouse=utils.captureMousePosition(canvas); */ 
                              
                 //加入mousedown監聽事件。在用戶鼠標按下後開始畫線。並註冊mousemove事件  
                canvas.addEventListener("mousedown",function(event){ 
                	
                    context.beginPath();  
                    context.moveTo(event.clientX, event.clientY);
                    //alert("-------------")
                    canvas.addEventListener("mousemove",onMouseMove,false);  
                },false);  
                                  
                 //在鼠標移動時劃線   
                function onMouseMove(event){  
                    context.lineTo(event.clientX,event.clientY);  
                    context.stroke();     
                }  
                                //在鼠標按鍵松開後,註銷鼠標移動事件  
                canvas.addEventListener("mouseup",function(event){  
                    canvas.removeEventListener("mousemove",onMouseMove,false);  
                },false);  
            }  
        </script>  
    </body>
 </html>



html5之canvas畫圖 1.寫字板功能