注意:web
var img = new Image() img.src = '' img.onload = function () { var can = document.querySelector('canvas'); can.width = this.height can.height = this.width var ctx = can.getContext('2d') //旋转90度 ctx.rotate(90 * Math.PI / 180) //绘制 ctx.drawImage(img, 0, -can.width) }