<template>
  <scroll-view @scroll="onScroll" class="page" show-scrollbar="false">
    <view ref="seatbar" class="seatbar"></view>

    <view class="content">
      <view class="content-item">
        <text class="text">1. 当前示例监听了 scroll-view 的 scroll 事件 ，滚动页面实时监听scrollTop。</text>
        <text class="text">2. 使用 ref 直接获取元素的节点，并在 scroll 事件中通过节点的 setProperty
          方法来修改搜索导航栏的高度、位置和背景颜色等样式，从而达到滚动折叠的效果。</text>
        <text class="text">3. 请向上\向下滚动页面观察效果。</text>
      </view>
      <view class="content-item" v-for="(item,index) in 20" :key="index">
        <text class="text">content-{{item}}</text>
      </view>
    </view>

    <view ref="navigatorbar" class="navigatorbar">
      <view class="titlebar">
        <view class="backview" @tap="back">
          <image class="back" src="/static/template/scroll-fold-nav/back.png" mode="widthFix"></image>
        </view>
        <text ref="title" class="title">DCloud 为开发者而生</text>
      </view>
      <view ref="searchbar" class="searchbar" @tap="search">
        <image class="searchimg" src="/static/template/scroll-fold-nav/search.png" mode="widthFix"></image>
        <text class="searchinput">请输入你要搜索的内容</text>
        <text class="searchbutton">搜索</text>
      </view>
    </view>
  </scroll-view>
</template>

<script>
  //导航栏高度
  const NAVIBARHEIGHT = 88;
  //搜索栏高度
  const SEARCHBARHEIGHT = 40;
  //返回键按钮宽度
  const BACKWIDTH = 32;
  export default {
    data() {
      return {
        statusBarHeight: 0,
        nviBarHeight: 0,
        naviElement: null as UniElement | null,
        titleElement: null as UniElement | null,
        searchElement: null as UniElement | null,
        seatElement: null as UniElement | null
      }
    },
    onLoad() {
      // #ifdef APP || MP
        this.statusBarHeight = uni.getWindowInfo().statusBarHeight;
      // #endif

      this.nviBarHeight = NAVIBARHEIGHT + this.statusBarHeight;
    },
    onReady() {
      this.naviElement = this.$refs['navigatorbar'] as UniElement;
      this.searchElement = this.$refs['searchbar'] as UniElement;
      this.titleElement = this.$refs['title'] as UniElement;
      this.seatElement = this.$refs['seatbar'] as UniElement;
      this.setStyle();
    },
    onResize(_ : OnResizeOptions) {
      // #ifdef APP-ANDROID
      // 监听多窗口模式
      this.statusBarHeight = uni.getWindowInfo().statusBarHeight;
      this.nviBarHeight = NAVIBARHEIGHT + this.statusBarHeight;
      this.setStyle();
      // #endif
    },
    methods: {
      onScroll(e : ScrollEvent) {
        let offset = e.detail.scrollTop>SEARCHBARHEIGHT?SEARCHBARHEIGHT:e.detail.scrollTop;//(e.detail.scrollTop<0?0:e.detail.scrollTop)
        this.naviElement?.style?.setProperty('height', (this.nviBarHeight -offset)+'px');
        this.titleElement?.style?.setProperty('opacity', (1-offset/SEARCHBARHEIGHT).toString());
        this.searchElement?.style?.setProperty('left', ((offset<0)?0:BACKWIDTH*offset/SEARCHBARHEIGHT)+'px');
      },
      back() {
        uni.navigateBack();
      },
      search() {
        uni.showToast({
          title: '暂不支持',
          icon: 'none'
        });
      },
      setStyle() {
        this.naviElement?.style?.setProperty('padding-top', this.statusBarHeight + 'px');
        this.naviElement?.style?.setProperty('height', (NAVIBARHEIGHT + this.statusBarHeight) + 'px');
        this.seatElement?.style?.setProperty('height', (NAVIBARHEIGHT + this.statusBarHeight) + 'px');
      }
    }
  }
</script>

<style>
.page {
  flex: 1;
  background-color: #f5f5f5;
}
.navigatorbar {
  position: fixed;
/* #ifdef APP */
  padding-top: 35px;
  height: 124px;
/* #endif */
/* #ifdef WEB */
  height: 88px;
/* #endif */
  border-bottom: 1px solid #efefef;
  width: 100%;
  background-color: #f5f5f5;
}
.titlebar {
  flex-direction: row;
  align-items: center;
  height: 44px;
}
.backview {
  width: 44px;
  height: 44px;
  justify-content: center;
  align-items: center;
}
.back {
  width: 20px;
}
.title {
  margin: 0px 2px;
}
.searchbar {
  position: absolute;
  bottom: 2px;
  left: 0px;
  right: 0px;
  background-color: #FFFFFF;
  border: 1px solid #fbdf0d;
  height: 32px;
  border-radius: 100px;
  margin: 6px 12px;
  padding: 8px;
  flex-direction: row;
  align-items: center;
  justify-content: center;
}
.searchimg {
  width: 15px;
}
.searchinput {
  flex-grow: 1;
  font-size: 12px;
  color: #666;
}
.searchbutton {
  font-size: 12px;
  background-color: #ff6900;
  color: #FFF;
  padding: 5px 8px;
  border-radius: 100px;
}
.seatbar {
/* #ifdef APP */
  height: 124px;
/* #endif */
/* #ifdef WEB */
  height: 88px;
/* #endif */
}
.content {
  padding: 5px 15px;
}
.content-item {
  padding: 15px;
  margin: 5px 0;
  background-color: #fff;
  border-radius: 5px;
}
.text {
  font-size: 14px;
  color: #666;
  line-height: 20px;
}

</style>