canvas 操作像素窗帘效果

代码实例：

<!DOCTYPE html>
<html>
	<head>
		<style>
		canvas{
		background:#eee;
		}
		</style>
		<title>noTitle</title>
		<meta charset="utf-8">
		<script>
		
			window.onload=function  () {
			 var canvas=document.getElementById("canvas");
			 var cobj=canvas.getContext("2d");
			 var img=document.getElementById("img");
			 cobj.drawImage(img,0,0,200,240);
			 var imgData=cobj.getImageData(0,0,200,240)		 
			 cobj.putImageData(menl (imgData,6),200,240);
			}




			  function menl (imgData,num) {
				for (var i=0; i<imgData.width*imgData.height; i++) {
					   if(i%6==0){  
					   imgData.data[i*4+0]=0;
					   imgData.data[i*4+1]=0;
					   imgData.data[i*4+2]=0;
					   imgData.data[i*4+3]=0;
					   }
					 }
					 return imgData;
			  }
		</script>
	</head>
	<body>
		<canvas id="canvas" width=500  height=500>
		</canvas>
		<img src="图片.jpg" id="img" hidden>
	</body>
</html>

　　效果：

图片：

2017-09-12 11:29:35

canvas 操作像素 窗帘效果

canvas 操作像素窗帘效果