zhangmeng
2024-04-19 e3ba120cb766a17e098e58d11c39ffc600a3070c
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<template>
    <!-- #ifdef APP-NVUE -->
    <cell>
        <!-- #endif -->
        <view
            class="u-list-item"
            :ref="`u-list-item-${anchor}`"
            :anchor="`u-list-item-${anchor}`"
            :class="[`u-list-item-${anchor}`]"
        >
            <slot />
        </view>
        <!-- #ifdef APP-NVUE -->
    </cell>
    <!-- #endif -->
</template>
 
<script>
    import props from './props.js';
    // #ifdef APP-NVUE
    const dom = uni.requireNativePlugin('dom')
    // #endif
    /**
     * List 列表
     * @description 该组件为高性能列表组件
     * @tutorial https://www.uviewui.com/components/list.html
     * @property {String | Number}    anchor    用于滚动到指定item
     * @example <u-list-ite v-for="(item, index) in indexList" :key="index" ></u-list-item>
     */
    export default {
        name: 'u-list-item',
        mixins: [uni.$u.mpMixin, uni.$u.mixin,props],
        data() {
            return {
                // 节点信息
                rect: {},
                index: 0,
                show: true,
                sys: uni.$u.sys()
            }
        },
        computed: {
 
        },
        inject: ['uList'],
        watch: {
            // #ifndef APP-NVUE
            'uList.innerScrollTop'(n) {
                const preLoadScreen = this.uList.preLoadScreen
                const windowHeight = this.sys.windowHeight
                if(n <= windowHeight * preLoadScreen) {
                    this.parent.updateOffsetFromChild(0)
                } else if (this.rect.top <= n - windowHeight * preLoadScreen) {
                    this.parent.updateOffsetFromChild(this.rect.top)
                }
            }
            // #endif
        },
        created() {
            this.parent = {}
        },
        mounted() {
            this.init()
        },
        methods: {
            init() {
                // 初始化数据
                this.updateParentData()
                this.index = this.parent.children.indexOf(this)
                this.resize()
            },
            updateParentData() {
                // 此方法在mixin中
                this.getParentData('u-list')
            },
            resize() {
                this.queryRect(`u-list-item-${this.anchor}`).then(size => {
                    const lastChild = this.parent.children[this.index - 1]
                    this.rect = size
                    const preLoadScreen = this.uList.preLoadScreen
                    const windowHeight = this.sys.windowHeight
                    // #ifndef APP-NVUE
                    if (lastChild) {
                        this.rect.top = lastChild.rect.top + lastChild.rect.height
                    }
                    if (size.top >= this.uList.innerScrollTop + (1 + preLoadScreen) * windowHeight) this.show =
                        false
                    // #endif
                })
            },
            // 查询元素尺寸
            queryRect(el) {
                return new Promise(resolve => {
                    // #ifndef APP-NVUE
                    this.$uGetRect(`.${el}`).then(size => {
                        resolve(size)
                    })
                    // #endif
 
                    // #ifdef APP-NVUE
                    const ref = this.$refs[el]
                    dom.getComponentRect(ref, res => {
                        resolve(res.size)
                    })
                    // #endif
                })
            }
        }
    }
</script>
 
<style lang="scss" scoped>
    @import "../../libs/css/components.scss";
 
    .u-list-item {}
</style>