feat: 模板页面增加自行实现长列表示例

pages.json

@@ -1270,6 +1270,14 @@
       	"navigationBarTitleText": "ad",
       	"backgroundColor": "#F8F8F8"
       }
+    },
+    {
+      "path" : "pages/template/custom-long-list/custom-long-list",
+      "style" : 
+      {
+        "navigationBarTitleText" : "",
+        "enablePullDownRefresh" : false
+      }
     }
     // #endif
   ],

pages/tabBar/template.uvue

@@ -110,6 +110,13 @@
               },
             ] as Page[],
           },
+          {
+            id: 'custom-long-list',
+            url: 'custom-long-list',
+            name: '自行实现长列表组件',
+            open: false,
+            pages: [] as Page[],
+          },
           // #ifdef APP
           {
             id: 'custom-refresher',

pages/template/custom-long-list/custom-list-item.uvue

+<template>
+  <view ref="box" class="custom-list-item-box">
+    <slot></slot>
+  </view>
+</template>
+
+<script>
+  export default {
+    name: "custom-list-item",
+    props: {
+      item: {
+        type: Object as PropType<any>,
+        required: true
+      }
+    },
+    inject: {
+      cachedSize: {
+        type: Map as PropType<Map<any, number>>,
+        default: () : Map<any, number> => {
+          return new Map<any, number>()
+        }
+      },
+    },
+    mounted() {
+      nextTick(() => {
+        uni.createSelectorQuery().in(this).select('.custom-list-item-box').boundingClientRect().exec((ret) => {
+          (this.cachedSize as Map<any, number>).set(this.item, (ret[0] as NodeInfo).height!)
+        })
+      })
+    }
+  }
+</script>
+
+<style>
+
+</style>

pages/template/custom-long-list/custom-list-view.uvue

+<template>
+  <scroll-view class="custom-list-view-scoll-view" v-bind="$attrs" ref="scroll" @scroll="onScroll">
+    <view class="custom-list-view-placeholder" :style="{ height: placeholderHeight + 'px' }">
+      <view class="custom-list-view-container" :style="{ top: containerTop + 'px' }">
+        <slot :items="items"></slot>
+      </view>
+    </view>
+  </scroll-view>
+</template>
+
+<script>
+  /**
+   * 使用限制
+   * - 容器大小变动时未刷新缓存的子元素大小
+   * - 不支持设置初始滚动位置
+   * - list数据内每一项不可以是基础类型
+   * - item不支持设置margin，会导致计算位置不准确
+   */
+  export default {
+    name: "custom-list-view",
+    props: {
+      list: {
+        type: Array as PropType<any[]>,
+        default: [] as any[]
+      }
+    },
+    watch: {
+      list: {
+        handler(list : any[]) {
+          this.cachedSize.forEach((_ : number, key : any) => {
+            if (!list.includes(key)) {
+              this.cachedSize.delete(key)
+            }
+          })
+        },
+        deep: true
+      }
+    },
+    data() {
+      return {
+        items: [] as any[],
+        containerTop: 0,
+        scrollElementHeight: 0,
+        placeholderHeight: 0,
+        offsetThreshold: [0, 0, 0, 0], // -5, -3, 3, 5 屏对应的offset
+        cachedSize: new Map<any, number>(),
+        initialized: false,
+        hasDefaultSize: false,
+        defaultItemSize: 40,
+      };
+    },
+    provide() {
+      return {
+        cachedSize: this.cachedSize
+      }
+    },
+    created() {
+      this.placeholderHeight = this.list.length * this.defaultItemSize
+    },
+    mounted() {
+      nextTick(() => {
+        uni.createSelectorQuery().in(this).select('.custom-list-view-scoll-view').boundingClientRect().exec((ret) => {
+          this.scrollElementHeight = (ret[0] as NodeInfo).height!
+          this.rearrange(0)
+          this.initialized = true
+        })
+      })
+    },
+    methods: {
+      onScroll(e : UniScrollEvent) {
+        if (!this.initialized) {
+          return
+        }
+        const scrollTop = e.detail.scrollTop
+        if (scrollTop < this.offsetThreshold[1] || scrollTop > this.offsetThreshold[2]) {
+          this.rearrange(scrollTop)
+        }
+      },
+      rearrange(scrollTop : number) {
+        this.offsetThreshold[0] = Math.max(scrollTop - this.scrollElementHeight * 5, 0)
+        this.offsetThreshold[1] = Math.max(scrollTop - this.scrollElementHeight * 3, 0)
+        this.offsetThreshold[2] = Math.min(scrollTop + this.scrollElementHeight * 4, this.placeholderHeight)
+        this.offsetThreshold[3] = Math.min(scrollTop + this.scrollElementHeight * 6, this.placeholderHeight)
+        const items = [] as any[]
+        let tempTotalHeight = 0
+        let containerTop = 0
+        for (let i = 0; i < this.list.length; i++) {
+          const item = this.list[i]
+          let itemSize = this.defaultItemSize
+          const cachedItemSize = this.cachedSize.get(item)
+          if (cachedItemSize != null) {
+            itemSize = cachedItemSize
+            if (!this.hasDefaultSize) {
+              this.defaultItemSize = itemSize
+              this.hasDefaultSize = true
+            }
+          }
+          tempTotalHeight += itemSize
+          if (tempTotalHeight >= this.offsetThreshold[0] && tempTotalHeight <= this.offsetThreshold[3]) {
+            items.push(item)
+          } else if (tempTotalHeight < this.offsetThreshold[0]) {
+            containerTop = tempTotalHeight
+          }
+        }
+        this.placeholderHeight = tempTotalHeight
+        this.items = items
+        this.containerTop = containerTop
+      }
+    }
+  }
+</script>
+
+<style>
+
+</style>

pages/template/custom-long-list/custom-long-list.uvue

+<template>
+  <custom-list-view style="flex: 1;" :list="list" @scrolltoupper="scrolltoupper" @scroll="scroll">
+    <template v-slot:default="{items}">
+      <custom-list-item v-for="item in (items as Item[])" :item="item" :key="item.id" style="padding: 5px; 10px">
+        <view style="background-color: aqua;">{{item.title}}</view>
+        <view>{{item.content}}</view>
+      </custom-list-item>
+    </template>
+  </custom-list-view>
+</template>
+
+<script>
+  type Item = {
+    id : number
+    title : string
+    content : string
+  }
+  import CustomListView from "./custom-list-view"
+  import CustomListItem from "./custom-list-item"
+  export default {
+    components: {
+      CustomListView,
+      CustomListItem
+    },
+    data() {
+      return {
+        list: [] as Item[]
+      }
+    },
+    created() {
+      for (let i = 0; i < 1000; i++) {
+        this.list.push({
+          id: i,
+          title: `title-` + i,
+          content: `Content-${i}: Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.`
+        } as Item)
+      }
+    },
+    methods: {
+      scrolltoupper() {
+        console.log('scroll top upper')
+      },
+      scroll(e : UniScrollEvent) {
+        console.log('scroll', e)
+      }
+    }
+  }
+</script>
+
+<style>
+
+</style>