canvas实现简易画板

移动端：

<!DOCTYPE html>
<html lang="en"><head>    
<meta charset="UTF-8">    
<title>Canvas实现简易涂鸦板</title>
</head>
<body>
    <canvas id="canvas" width="500" height="500" style="box-shadow:0 5px 40px black;background-color: rgba(0,0,0,0.1)"></canvas>
    <script>    
          canvas = document.getElementById('canvas');    
          if(canvas.getContext){        
                context = canvas.getContext('2d');    
           }   
       context.lineWidth = 5;    
      context.strokeStyle = '#0000ff';    
      canvas.addEventListener('touchstart',touchstart);    
      function touchstart(e){        
          e.preventDefault();        
          var touches = e.changedTouches;        
          var x = touches[0].clientX - canvas.offsetLeft;        
          var y = touches[0].clientY - canvas.offsetTop;       
           context.moveTo(x,y);   
       }    
      canvas.addEventListener('touchmove',touchmove);    
      function touchmove(e){        
          e.preventDefault();        
          var touches = e.changedTouches;        
          var x = touches[0].clientX - canvas.offsetLeft;        
          var y = touches[0].clientY - canvas.offsetTop;        
          context.lineTo(x,y);        
          context.stroke();    
       }
  </script>
</body>
</html>

mobile.gif

电脑端：

<!DOCTYPE html>
<html lang="en">
<head>    
<meta charset="UTF-8">    
<title>Canvas实现简易涂鸦板</title>
</head>
<body>
    <canvas id="canvas" width="500" height="500" style="box-shadow:0 5px 40px black;background-color:         rgba(0,0,0,0.1)"></canvas>
    <script>   
         canvas = document.getElementById('canvas');   
         if(canvas.getContext){        
            context = canvas.getContext('2d');   
         }    
        context.lineWidth = 5;    
        context.strokeStyle = '#0000ff';  
        canvas.onmousedown = function(e){        
        e.preventDefault();        
        var x = e.clientX - canvas.offsetLeft;        
        var y = e.clientY - canvas.offsetTop;        
        context.moveTo(x,y);        
        canvas.onmousemove = function(e){            
        e.preventDefault();            
        var x = e.clientX - canvas.offsetLeft;            
        var y = e.clientY - canvas.offsetTop;           
        context.lineTo(x,y);            
        context.stroke();        
    };        
    canvas.onmouseup = function(e){            
            canvas.onmousemove = null;       
    };    
};
</script>
</body>
</html>

pc.gif

canvas实现简易画板

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