html5 - canvas 跨域问题

问题描述

在微信上给用户修改头像的时候，用canvas来截图。结果报错：Owechat_login.js:226 Uncaught TypeError: Failed to execute ’getImageData’ on ’CanvasRenderingContext2D’: The provided double value is non-finite.代码：function cropImage(targetCanvas, x, y, width, height) {

var targetctx = targetCanvas.getContext(’2d’);var targetctxImageData = targetctx.getImageData(x, y, width, height); // sx, sy, sWidth, sHeight var c = document.createElement(’canvas’);var ctx = c.getContext(’2d’); c.width = width;c.height = height; ctx.rect(0, 0, width, height);ctx.fillStyle = ’white’;ctx.fill();ctx.putImageData(targetctxImageData, 0, 0); // imageData, dx, dy document.getElementById(’image’).src = c.toDataURL(’image/jpeg’, 0.92);document.getElementById(’image’).style.display = ’initial’; }

问题解答

初步看了下代码貌似没什么问题的,排除掉图片可能存在的跨域问题,还有一个问题楼主可以查看下就是getImageData 的传参,需要是number类型,楼主可以先使用

console.log(typeof x, typeof y, typeof width, typeof height)

来看看

应该不是跨域吧，跨域会写 The canvas has been tainted by cross-origin data

console.log一下getImageData的参数吧。The provided double value is non-finite有可能是吧string当数传进来了。