問題描述

在微信上給用戶修改頭像的時候，用canvas來截圖。結果報錯：Owechat_login.js:226 Uncaught TypeError: Failed to execute ’getImageData’ on ’CanvasRenderingContext2D’: The provided double value is non-finite.代碼：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’; }

問題解答

初步看了下代碼貌似沒什么問題的,排除掉圖片可能存在的跨域問題,還有一個問題樓主可以查看下就是getImageData 的傳參,需要是number類型,樓主可以先使用

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

來看看

應該不是跨域吧，跨域會寫 The canvas has been tainted by cross-origin data

console.log一下getImageData的參數(shù)吧。The provided double value is non-finite有可能是吧string當數(shù)傳進來了。