pk8f3pmu2/miniprogram/course/components/index-list/index-list.js

import {throttle} from "../../../js/utils";

Component({
    options: {
        addGlobalClass: true,
        pureDataPattern: /^_/
    },
    properties: {
        list: {
            type: Array,
            value: [],
            observer: function observer(newVal) {
                var _this = this;

                if (newVal.length === 0) return;
                var data = this.data;
                var alphabet = data.list.map(function (item) {
                    return item.letter;
                });
                alphabet.unshift("↑");
                this.setData({
                    alphabet: alphabet,
                    current: alphabet[0]
                }, function () {
                    _this.computedSize();
                });
            }
        },
        ext:{
            type:Object
        },
        vibrated: {
            type: Boolean,
            value: true
        }
    },
    data: {
        current: 'A',
        intoView: '',
        touching: false,
        alphabet: [],
        _tops: [],
        _anchorItemH: 0,
        _anchorTop: 0
    },
    lifetimes: {
        created: function created() {},
        attached: function attached() {
            this.__scrollTo = throttle(this._scrollTo, 100, {});
            this.__onScroll = throttle(this._onScroll, 100, {});
        }
    },
    methods: {
        choose: function choose(e) {
            ;
            var item = e.target.dataset.item;
            this.triggerEvent('choose', { item: item });
        },
        scrollTo: function scrollTo(e) {
            this.__scrollTo(e);
        },
        _scrollTo: function _scrollTo(e) {
            var data = this.data;
            var clientY = e.changedTouches[0].clientY;
            ;
            var index = Math.floor((clientY - data._anchorTop) / data._anchorItemH);
            if(index<0||index>=data.alphabet.length)
                return;
            var current = data.alphabet[index];
            if(current=='↑')
                this.setData({current, scrollTop:0, touching:true});
            else
                this.setData({ current: current, intoView: current=='#'?'hash':current, touching: true });
            if (data.vibrated) wx.vibrateShort();
        },
        computedSize: function computedSize() {
            var data = this.data;
            var query = this.createSelectorQuery();
            query.selectAll('.index_list_item').boundingClientRect();
            query.select(".top-view").boundingClientRect();
            query.select('.anchor-list').boundingClientRect(function (rect) {
                data._anchorItemH = rect.height / data.alphabet.length;
                data._anchorTop = rect.top;
                ;
            });
            query.exec(res=>{
                data._tops = res[0].map(function (item) {
                    return item.top-res[1].top;
                });
                ;
            });
        },
        removeTouching: function removeTouching() {
            var _this2 = this;

            setTimeout(function () {
                _this2.setData({ touching: false });
            }, 150);
        },
        onScroll: function onScroll(e) {
            this.__onScroll(e);
        },
        _onScroll: function _onScroll(e) {
            if(this.data.touching)
                return;
            var data = this.data;
            var _tops = data._tops,
                alphabet = data.alphabet;
            ;
            var pageTop = e.detail.scrollTop;
            var current = '';
            if (pageTop < _tops[0]) {
                current = alphabet[0];
            } else {
                for (var i = 0, len = _tops.length; i < len - 1; i++) {
                    if (pageTop >= _tops[i] && pageTop < _tops[i + 1]) {
                        current = alphabet[i+1];
                    }
                }
            }
            if (!current) current = alphabet[alphabet.length - 1];
            this.setData({ current: current });
        }
    }
});