canvas应用——将方形图片处理为圆形

//canvas 加载图圆形处理
var canvas = document.getElementById(‘canvas1‘);
var ctx = canvas.getContext(‘2d‘);
//加载图片
var img = new Image();
img.onload = function () {
    var width = img.width;
    var height = img.height;
    var circle = {
        x: width / 2,
        y: height / 2,
        r: width / 2
    }
    ctx.clearRect(0, 0, width, height);
    //开始路径画圆,剪切处理
    ctx.save();
    ctx.beginPath();
    ctx.arc(circle.x, circle.y, circle.r, 0, Math.PI * 2, false);
    ctx.clip(); //剪切路径
    ctx.drawImage(img, 0, 0);
    //恢复状态
    ctx.restore();
}
img.src = ‘https://wx.qlogo.cn/mmopen/vi_32/eANbKH1RvLW088qRtM96QLWWkgysk4T2TErm4F0lHcnhu2txL6Kk0PJokrxT4TLUmEtAZ2xqtxwTRIPWoZZ9RQ/132‘;