<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title>www.vevb.com JS图片马赛克</title> <style type="text/css"> * { margin: 0; padding: 0; } body { background-color: grey; text-align: center; } #myCanvas { background-color: rgba(250, 0, 0, 0.3); } </style> </head> <body> <canvas id="myCanvas" width="500" height="400"></canvas> </body> <script type="text/javascript"> window.onload = function() { var myCanvas = document.getElementById('myCanvas'); var painting = myCanvas.getContext('2d'); //生成一个图片节点 var imgNode = new Image(); imgNode.src = '1.jpg'; //调用函数 drawImg(imgNode); function drawImg(imgNode) { //图片加载后执行马赛克实现语句：5个一组取到随机像素赋给新图里的五个一组 imgNode.onload = function() { painting.drawImage(imgNode, 0, 0, 250, 400); var size = 5; //获取老图所有像素点 var oldImg = painting.getImageData(0, 0, 250, 400) //创建新图像素对象 var newImg = painting.createImageData(250, 400) for(var i = 0; i < oldImg.width; i++) { for(var j = 0; j < oldImg.height; j++) { //从5*5中获取单个像素信息 var color = getPxInfo(oldImg, Math.floor(i * size + Math.random() * size), Math.floor(j * size + Math.random() * size)) //写入单个像素信息 for(var a = 0; a < size; a++) { for(var b = 0; b < size; b++) { // (a,b) setPxInfo(newImg, i * size + a, j * size + b, color); } } } } painting.putImageData(newImg, 250, 0) } } //读取单个像素信息 function getPxInfo(imgDate, x, y) { var colorArr = []; var width = imgDate.width; colorArr[0] = imgDate.data[(width * y + x) * 4 + 0] colorArr[1] = imgDate.data[(width * y + x) * 4 + 1] colorArr[2] = imgDate.data[(width * y + x) * 4 + 2] colorArr[3] = imgDate.data[(width * y + x) * 4 + 3] return colorArr; } //写入单个像素信息 function setPxInfo(imgDate, x, y, colors) { //（x,y） 之前有多少个像素点 == width*y + x var width = imgDate.width; imgDate.data[(width * y + x) * 4 + 0] = colors[0]; imgDate.data[(width * y + x) * 4 + 1] = colors[1]; imgDate.data[(width * y + x) * 4 + 2] = colors[2]; imgDate.data[(width * y + x) * 4 + 3] = colors[3]; } } </script></html> 
