var copyDom = document.querySelector('.fenxiang1');
                    var width = copyDom.offsetWidth;//dom宽
                    var height = copyDom.offsetHeight;//dom高
                    console.log(JSON.stringify(copyDom));
                    console.log(width);
                    console.log(height);

                    var scale = 2;//放大倍数
                    html2canvas(copyDom, {
                        dpi: window.devicePixelRatio * 2,
                        scale: scale,
                        width: width,
                        heigth: height,
                    }).then(function (canvas) {
                        var dataURL = canvas.toDataURL();
                        console.log(dataURL);
                        that.canvas = dataURL.split(',')[1];
                        $(".i-d-canvas").attr('src', dataURL);
                        myApp.preloader.hide();

                        api.addEventListener({
                            name: 'longpress'
                        }, function (ret, err) {
                            ac5.open();
                        });
                    });

<div class="i-d-fenxiang-canvas" v-if="isfenxiang">
                <div class="i-d-fenxiang-close" @click="closeBanner"><i class="iconfont iconguanbi"></i></div>
//要放canvas的img

<img class="i-d-canvas" src=""> </div>

//要转化的弹窗开始
<!--分享弹窗开始-->
            <div id="win" class="i-d-fenxiang fenxiang1">
                <img class="i-d-fenxiang-pic" :src="fenxiang_pic" alt="">
                <div class="i-d-fenxiang-box">
                    <div class="i-d-fenxiang-info">
                        <div class="i-d-fenxiang-info-name">
                            <i v-if="type==1" class="iconfont iconxiangqing-tm"></i>
                            <i v-if="type==0" class="iconfont iconxiangqing-tb"></i>
                            <i v-if="isbaoyou" class="iconfont iconxiangqing-baoyou"></i>
                            {{name}}
                        </div>
                        <div class="i-d-fenxiang-price">现价：<span>￥{{yuan_price}}</span></div>
                        <div class="i-d-fenxiang-quan">
                            <div class="i-d-fenxiang-quan-left">
                                <div>券</div>
                                <div>{{quan}}</div>
                            </div>
                            <div class="i-d-fenxiang-quan-right">
                                券后价:<span>￥{{xian_price}}</span>
                            </div>
                        </div>
                    </div>
                    <div class="i-d-fenxiang-right">
                        <div class="i-d-fenxiang-qrcord">
                            <!--<img class="i-d-fenxiang-qrcord-pic" :src="erweima" alt="">-->
                            <div class="i-d-fenxiang-qrcord-pic" id="qrcode"></div>
                        </div>
                        <div class="i-d-fenxiang-qrcord-text">长按保存图片</div>
                        <!--<button class="i-d-fenxiang-qrcord-btn">复制文案-->
                        <!--</button>-->
                    </div>
                </div>
            </div>
            <!--分享弹窗结束-->

用到的js: 

<script src="http://html2canvas.hertzen.com/dist/html2canvas.min.js"></script>