代码实例:
<!DOCTYPE html>
<html>
<head>
<style>
canvas{
background:#eee;
}
</style>
<title>实例</title>
<meta charset="utf-8">
<link rel="stylesheet" href="" rel="external nofollow" >
<script>
window.onload=function () {
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
//绘制图片
var img=document.getElementById("img");
ctx.drawImage(img,0,0,200,200); var imgData=ctx.getImageData(0,0,200,200);
ctx.putImageData(draw(imgData),200,200);
//方法:反色
function draw(imgData){
for (var i=0;i<imgData.width*imgData.height;i++) {
imgData.data[i*4+0]=255-imgData.data[i*4+0];
imgData.data[i*4+1]=255-imgData.data[i*4+1];
imgData.data[i*4+2]=255-imgData.data[i*4+2];
imgData.data[i*4+3]=imgData.data[i*4+3];
}
return imgData;
} }
</script>x
</head>
<body>
<canvas id="canvas" width=500 height=500>
</canvas>
<img src="不二2.jpg" id="img" hidden>
</body>
</html>
图片:
效果:
2017-09-12 11:12:31