canvas 和 camera 组件的层级优先级问题该怎么解决呢？

<view>   <canvas class="canvas" style="opacity: 0;width: 100%; height: 100%;" canvas-id="firstCanvas"></canvas>   <camera device-position="back" flash="off" binderror="error" style="position: absolute;top:0;left:0;z-index:999;width: 100%; height: 100%" bindstop="stopFn" class="camera">     <cover-view class="hallName">{{hallName}}</cover-view>     <cover-view class="recognition-container" bindtap="takePhoto">     </cover-view>   </camera> </view>

camera takePhoto 点击拍照，canvas 绘制相机拍照图片.

canvas 就盖住 camera了，页面效果就无法实时显示照相机里的内容。

我希望camera的层级一直是最高的该怎么弄呢？