layer弹出图片大小自适应

• 首先获取图片大小
  参考这里：https://www.jianshu.com/p/41ff1d103d3f
• 代码示例:监听数据表格单元格，实现点击单元格弹出原始尺寸的图片

//监听单元格事件,点击认证按钮出现对应认证图片
            table.on('tool(dataTable)', function (obj) {

                if (obj.event === 'checkYishou') {
                    //整行数据
                    var data = obj.data;

                    var img = new Image();
                    //图片地址
                    img.src = data.yishou_path;
                    if (img.complete) {
                        var areaW = img.width;
                        var areaH = img.height;
                        showImg(areaW, areaH, data);

                    } else {
                        img.onload = function () {
                            var areaW = img.width;
                            var areaH = img.height;
                            showImg(areaW, areaH, data);
                        }
                    }
                }

                //显示认证图片
                function showImg(w, h, data) {
                    var setting = {
                        type: 1,
                        title: false,
                        offset: 'auto',
                        area: [w, h],
                        closeBtn: 0,
                        skin: 'layui-layer-nobg', //没有背景色
                        shadeClose: true,
                        shade: 0.6, //遮罩透明度
                        content: '<img src="' + data.yishou_path + '" alt="一手认证">'
                    };
                    layer.open(setting);
                }
            });