feat: 添加滚动隐藏搜索框和回到顶部功能

- 滚动时搜索框自动隐藏/显示
- 添加回到顶部按钮
- 优化滚动交互体验

pages/index/index.js

@@ -21,6 +21,15 @@ Page({
     sidebarBtnTop: 500,
     sidebarBtnHidden: false,
     
+    // 搜索区域相关
+    searchSectionVisible: true,
+    lastScrollTop: 0,
+    isScrollLocked: false,
+    
+    // 回到顶部按钮
+    showBackToTop: false,
+    scrollTop: 0,
+    
     // 搜索相关
     searchKeyword: '',
     selectedRegion: '全国',
@@ -772,7 +781,42 @@ Page({
   
   // 滚动事件处理
   onScroll: function(e) {
-    const { scrollTop, scrollHeight, clientHeight } = e.detail;
+    const { scrollTop } = e.detail;
+    
+    if (this.data.isScrollLocked) {
+      this.setData({ lastScrollTop: scrollTop });
+      return;
+    }
+    
+    const scrollDirection = scrollTop > this.data.lastScrollTop ? 'down' : 'up';
+    const scrollDelta = Math.abs(scrollTop - this.data.lastScrollTop);
+    
+    if (scrollDelta < 10) {
+      this.setData({ lastScrollTop: scrollTop });
+      return;
+    }
+    
+    if (scrollDirection === 'down' && scrollTop > 100 && this.data.searchSectionVisible) {
+      this.setData({ searchSectionVisible: false, isScrollLocked: true });
+      setTimeout(() => {
+        this.setData({ isScrollLocked: false });
+      }, 300);
+    } else if (scrollDirection === 'up' && !this.data.searchSectionVisible && scrollTop < 50) {
+      this.setData({ searchSectionVisible: true, isScrollLocked: true });
+      setTimeout(() => {
+        this.setData({ isScrollLocked: false });
+      }, 300);
+    }
+    
+    if (scrollTop > 300 && !this.data.showBackToTop) {
+      this.setData({ showBackToTop: true });
+    } else if (scrollTop <= 300 && this.data.showBackToTop) {
+      this.setData({ showBackToTop: false });
+    }
+    
+    this.setData({ lastScrollTop: scrollTop });
+    
+    const { scrollHeight, clientHeight } = e.detail;
     const distanceToBottom = scrollHeight - scrollTop - clientHeight;
     
     const app = getApp();
@@ -783,6 +827,15 @@ Page({
     app.globalData.showTabBar = true;
   },
   
+  // 回到顶部
+  scrollToTop: function() {
+    this.setData({ 
+      scrollTop: 0,
+      searchSectionVisible: true,
+      showBackToTop: false
+    });
+  },
+  
   // 上拉加载更多
   onReachBottom: function() {
     if (this.data.hasMoreData && !this.data.loadingMore) {

pages/index/index.wxml

@@ -1,9 +1,9 @@
 <view class="container">
   <!-- 标题 -->
-  <view class="title">专业的鸡蛋现货交易平台</view>
+  <view class="title {{searchSectionVisible ? '' : 'title-hidden'}}">专业的鸡蛋现货交易平台</view>
   
   <!-- 搜索区域 -->
-  <view class="search-section">
+  <view class="search-section {{searchSectionVisible ? 'search-visible' : 'search-hidden'}}">
     <view class="search-bar">
       <view class="search-input-wrapper">
         <!-- 将地区选择器放在最左边 -->
@@ -107,6 +107,15 @@
   
   <!-- 侧边栏弹出层 -->
   <view wx:if="{{showSidebar}}" class="sidebar-overlay" bindtap="toggleSidebar"></view>
+  
+  <!-- 回到顶部按钮 -->
+  <view 
+    class="back-to-top-btn {{showBackToTop ? 'visible' : ''}}" 
+    bindtap="scrollToTop"
+  >
+    <text class="back-to-top-icon">↑</text>
+    <text class="back-to-top-text">顶部</text>
+  </view>
   <view wx:if="{{showSidebar}}" class="sidebar">
     <view class="sidebar-title">招商合作</view>
     <view class="sidebar-menu">
@@ -155,9 +164,11 @@
   <view class="goods-section">
     <scroll-view 
       class="goods-list" 
+      id="goodsScrollView"
       bindscrolltolower="onReachBottom" 
       bindscroll="onScroll"
       scroll-y="true"
+      scroll-top="{{scrollTop}}"
       refresher-enabled="{{true}}"
       refresher-default-style="none"
       refresher-background="#f8f8f8"

pages/index/index.wxss

@@ -26,7 +26,36 @@ page {
   margin: 20rpx;
   color: #333;
   text-align: center;
-  flex: 0 1 auto;
+  flex-shrink: 0;
+  transition: all 0.3s ease;
+}
+
+.title-hidden {
+  opacity: 0;
+  transform: translateY(-20rpx);
+  height: 0;
+  margin: 0;
+  padding: 0;
+  overflow: hidden;
+}
+
+/* 搜索区域样式 */
+.search-section {
+  flex-shrink: 0;
+  transition: all 0.3s ease;
+}
+
+.search-visible {
+  opacity: 1;
+  transform: translateY(0);
+  height: auto;
+}
+
+.search-hidden {
+  opacity: 0;
+  transform: translateY(-100%);
+  height: 0;
+  overflow: hidden;
 }
 
 /* 搜索区域样式 */
@@ -1326,3 +1355,42 @@ wx-button:not([size=mini]) {
   font-size: 24rpx;
   color: #ccc;
 }
+
+/* 回到顶部按钮 */
+.back-to-top-btn {
+  position: fixed;
+  right: 30rpx;
+  bottom: 200rpx;
+  width: 100rpx;
+  height: 100rpx;
+  background: linear-gradient(135deg, #1677ff 0%, #4096ff 100%);
+  border-radius: 50%;
+  display: flex;
+  flex-direction: column;
+  justify-content: center;
+  align-items: center;
+  box-shadow: 0 4rpx 16rpx rgba(22, 119, 255, 0.4);
+  opacity: 0;
+  transform: translateY(20rpx);
+  transition: all 0.3s ease;
+  z-index: 999;
+  pointer-events: none;
+}
+
+.back-to-top-btn.visible {
+  opacity: 1;
+  transform: translateY(0);
+  pointer-events: auto;
+}
+
+.back-to-top-icon {
+  font-size: 36rpx;
+  color: white;
+  font-weight: bold;
+}
+
+.back-to-top-text {
+  font-size: 18rpx;
+  color: white;
+  margin-top: 2rpx;
+}