add view ahead map in wechatapp

1.index.wxml

2.index.wxss

.canvas {
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 240rpx;
  display: block;
  background-color: #ff0000;
}

.canvasHide {
  display: none;
}

3.Postscript

any question comment below,i will reponse you.