没效果
<!DOCTYPE html><html> <head> <meta charset="utf-8"> <title></title> <style type="text/css"> canvas { border: 1px dashed gray; } </style> <script type="text/javascript"> window.onload = function() { // 获取canvas对象 var oCanvas = document.getElementById("canvas"); if (oCanvas.getContext) { // 得到2d绘图上下文环境 var oContext = oCanvas.getContext("2d"); var oImageData = oContext.createImageData(100, 100); var data = oImageData.data; for (var i = 0; i < data.length; i += 4) { // 红色 data[i + 0] = 255； // 绿色 data[i + 1] = 0； // 蓝色 data[i + 2] = 0； // 透明度 data[i + 3] = 100； } oContext.putImageData(oImageData, 10, 10); } } </script> </head> <body> <canvas id="canvas" height="600" width="600"></canvas> </body></html>
