添加一个自定义ListView 实现, 高效复用机制以及便捷的使用接口

ListViewJsDemo/assets/Script/HelloWorld.js

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+import ListView, {AbsAdapter} from "./ListView";
+
+const ListAdapter = require('./ListAdapter');
+
+cc.Class({
+    extends: cc.Component,
+
+    properties: {
+        listView: {
+            default: null,
+            type: ListView
+        },
+        tipLabel: {
+            type: cc.Label,
+            default: null
+        }
+    },
+
+    start() {
+        const adapter = new ListAdapter();
+        adapter.setDataSet([1, 2, 3, 4, 5, 6, 7, 8, 89, 9, 12, 1243, 45, 564, 6756, 876, 7988, 789, 78987, 978, 45, 6732, 423, 42]);
+        this.listView.setAdapter(adapter);
+    }
+});

ListViewJsDemo/assets/Script/HelloWorld.js.meta

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+{
+  "ver": "1.0.5",
+  "uuid": "280c3aec-6492-4a9d-9f51-a9b00b570b4a",
+  "isPlugin": false,
+  "loadPluginInWeb": true,
+  "loadPluginInNative": true,
+  "loadPluginInEditor": false,
+  "subMetas": {}
+}

ListViewJsDemo/assets/Script/ListAdapter.js

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+import {AbsAdapter} from "./ListView";
+
+const ListItem = require('./ListItem');
+
+cc.Class({
+    extends: AbsAdapter,
+    updateView(item, posIndex) {
+        let comp = item.getComponent(ListItem);
+        if (comp) {
+            comp.setData(this.getItem(posIndex));
+        }
+    }
+})

ListViewJsDemo/assets/Script/ListAdapter.js.meta

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+{
+  "ver": "1.0.5",
+  "uuid": "9ec2acad-d240-4e35-9106-069a09c2f73d",
+  "isPlugin": false,
+  "loadPluginInWeb": true,
+  "loadPluginInNative": true,
+  "loadPluginInEditor": false,
+  "subMetas": {}
+}

ListViewJsDemo/assets/Script/ListItem.js

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+cc.Class({
+    extends: cc.Component,
+    properties: {
+        label: {
+            default: null,
+            type: cc.Label
+        }
+    },
+
+    setData(data) {
+        this.label.string = `${data}`;
+    }
+});

ListViewJsDemo/assets/Script/ListItem.js.meta

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+{
+  "ver": "1.0.5",
+  "uuid": "f139de43-c595-4c6d-96b8-566361234e9c",
+  "isPlugin": false,
+  "loadPluginInWeb": true,
+  "loadPluginInNative": true,
+  "loadPluginInEditor": false,
+  "subMetas": {}
+}

ListViewJsDemo/assets/Script/ListView.ts

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+const {ccclass, property} = cc._decorator;
+
+@ccclass
+export default class ListView extends cc.Component {
+
+    @property(cc.Prefab)
+    private itemTemplate: cc.Prefab = null;
+
+    @property
+    private spacing: number = 1;
+
+    // 比可见元素多缓存3个, 缓存越多,快速滑动越流畅,但同时初始化越慢.
+    @property
+    private spawnCount: number = 2;
+
+    @property(cc.ScrollView)
+    private scrollView: cc.ScrollView = null;
+
+    private content: cc.Node = null;
+
+    private adapter: AbsAdapter = null;
+
+    private readonly _items: cc.NodePool = new cc.NodePool();
+    // 记录当前填充在树上的索引. 用来快速查找哪些位置缺少item了.
+    private readonly _filledIds: { [key: number]: number } = {};
+
+    private horizontal: boolean = false;
+
+    // 初始时即计算item的高度.因为布局时要用到.
+    private _itemHeight: number = 1;
+
+    private _itemWidth: number = 1;
+
+    private _itemsVisible: number = 1;
+
+    private lastStartIndex: number = -1;
+
+    private scrollTopNotifyed: boolean = false;
+    private scrollBottomNotifyed: boolean = false;
+
+    private pullDownCallback: () => void = null;
+    private pullUpCallback: () => void = null;
+
+    public onLoad() {
+        if (this.scrollView) {
+            this.content = this.scrollView.content;
+            this.horizontal = this.scrollView.horizontal;
+            if (this.horizontal) {
+                this.scrollView.vertical = false
+                this.content.anchorX = 0;
+                this.content.x = this.content.parent.width * this.content.parent.anchorX;
+            } else {
+                this.scrollView.vertical = true;
+                this.content.anchorY = 1;
+                this.content.y = this.content.parent.height * this.content.parent.anchorY;
+            }
+        } else {
+            console.error("ListView need a scrollView for showing.")
+        }
+        let itemOne = this._items.get() || cc.instantiate(this.itemTemplate);
+        this._items.put(itemOne);
+        this._itemHeight = itemOne.height || 10;
+        this._itemWidth = itemOne.width || 10;
+
+        if (this.horizontal) {
+            this._itemsVisible = Math.ceil(this.content.parent.width / this._itemWidth);
+        } else {
+            this._itemsVisible = Math.ceil(this.content.parent.height / this._itemHeight);
+        }
+        console.log("可见区域的item数量为:", this._itemsVisible);
+        this.adjustEvent();
+    }
+
+    public async setAdapter(adapter: AbsAdapter) {
+        this.adapter = adapter;
+        if (this.adapter == null) {
+            console.warn("adapter 为空.")
+            return
+        }
+        if (this.itemTemplate == null) {
+            console.error("Listview 未设置待显示的Item模板.");
+            return;
+        }
+
+        this.notifyUpdate();
+    }
+
+    public getItemIndex(height: number): number {
+        return Math.floor(Math.abs(height / ((this._itemHeight + this.spacing))));
+    }
+
+    public getPositionInView(item: cc.Node) {
+        let worldPos = item.parent.convertToWorldSpaceAR(item.position);
+        let viewPos = this.scrollView.node.convertToNodeSpaceAR(worldPos);
+        return viewPos;
+    }
+
+    // 数据变更了需要进行更新UI显示, 可只更新某一条.
+    public notifyUpdate(updateIndex?: number[]) {
+        if (this.adapter == null) {
+            return;
+        }
+        if (updateIndex && updateIndex.length > 0) {
+            updateIndex.forEach(i => {
+                if (this._filledIds.hasOwnProperty(i)) {
+                    delete this._filledIds[i];
+                }
+            })
+        } else {
+            Object.keys(this._filledIds).forEach(key => {
+                delete this._filledIds[key];
+            })
+        }
+        this.lastStartIndex = -1;
+        if (this.horizontal) {
+            this.content.width = this.adapter.getCount() * (this._itemWidth + this.spacing) + this.spacing;
+        } else {
+            this.content.height = this.adapter.getCount() * (this._itemHeight + this.spacing) + this.spacing; // get total content height
+        }
+        this.scrollView.scrollToTop()
+    }
+
+    public scrollToTop(anim: boolean = false) {
+        this.scrollView.scrollToTop(anim ? 1 : 0);
+    }
+
+    public scrollToBottom(anim: boolean = false) {
+        this.scrollView.scrollToBottom(anim ? 1 : 0);
+    }
+
+    public scrollToLeft(anim: boolean = false) {
+        this.scrollView.scrollToLeft(anim ? 1 : 0);
+    }
+
+    public scrollToRight(anim: boolean = false) {
+        this.scrollView.scrollToRight(anim ? 1 : 0);
+    }
+
+    // 下拉事件.
+    public pullDown(callback: () => void, this$: any) {
+        this.pullDownCallback = callback.bind(this$);
+    }
+
+    // 上拉事件.
+    public pullUp(callback: () => void, this$: any) {
+        this.pullUpCallback = callback.bind(this$);
+    }
+
+    protected update(dt) {
+        const startIndex = this.checkNeedUpdate();
+        if (startIndex >= 0) {
+            this.updateView(startIndex);
+        }
+    }
+
+    // 向某位置添加一个item.
+    private _layoutVertical(child: cc.Node, posIndex: number) {
+        this.content.addChild(child);
+        // 增加一个tag 属性用来存储child的位置索引.
+        child["_tag"] = posIndex;
+        this._filledIds[posIndex] = posIndex;
+        child.setPosition(0, -child.height * (0.5 + posIndex) - this.spacing * (posIndex + 1));
+    }
+
+    // 向某位置添加一个item.
+    private _layoutHorizontal(child: cc.Node, posIndex: number) {
+        this.content.addChild(child);
+        // 增加一个tag 属性用来存储child的位置索引.
+        child["_tag"] = posIndex;
+        this._filledIds[posIndex] = posIndex;
+        child.setPosition(-child.width * (0.5 + posIndex) - this.spacing * (posIndex + 1), 0);
+    }
+
+    // 获取可回收item
+    private getRecycleItems(beginIndex: number, endIndex: number): cc.Node[] {
+        const children = this.content.children;
+        const recycles = []
+        children.forEach(item => {
+            if (item["_tag"] < beginIndex || item["_tag"] > endIndex) {
+                recycles.push(item);
+                delete this._filledIds[item["_tag"]];
+            }
+        })
+        return recycles;
+    }
+
+    // 填充View.
+    private updateView(startIndex) {
+        let itemStartIndex = startIndex;
+        // 比实际元素多3个.
+        let itemEndIndex = itemStartIndex + this._itemsVisible + (this.spawnCount || 2);
+        const totalCount = this.adapter.getCount();
+        if (itemStartIndex >= totalCount) {
+            return;
+        }
+
+        if (itemEndIndex > totalCount) {
+            itemEndIndex = totalCount;
+            if (!this.scrollBottomNotifyed) {
+                this.notifyScrollToBottom()
+                this.scrollBottomNotifyed = true;
+            }
+        } else {
+            this.scrollBottomNotifyed = false;
+        }
+
+        // 回收需要回收的元素位置.向上少收一个.向下少收2两.
+        const recyles = this.getRecycleItems(itemStartIndex - (this.spawnCount || 2), itemEndIndex);
+        recyles.forEach(item => {
+            this._items.put(item);
+        })
+
+        // 查找需要更新的元素位置.
+        const updates = this.findUpdateIndex(itemStartIndex, itemEndIndex)
+
+        // 更新相应位置.
+        for (let index of updates) {
+            let child = this.adapter._getView(this._items.get() || cc.instantiate(this.itemTemplate), index);
+            this.horizontal ?
+                this._layoutHorizontal(child, index) :
+                this._layoutVertical(child, index);
+        }
+    }
+
+    // 检测是否需要更新UI.
+    private checkNeedUpdate(): number {
+        if (this.adapter == null) {
+            return -1
+        }
+
+        let scroll = this.horizontal ? (this.content.x - this.content.parent.width * this.content.parent.anchorX)
+            : (this.content.y - this.content.parent.height * this.content.parent.anchorY);
+        let itemStartIndex = Math.floor(scroll / ((this.horizontal ? this._itemWidth : this._itemHeight) + this.spacing));
+        if (itemStartIndex < 0 && !this.scrollTopNotifyed) {
+            this.notifyScrollToTop();
+            this.scrollTopNotifyed = true;
+            return itemStartIndex;
+        }
+        // 防止重复触发topNotify.仅当首item不可见后才能再次触发
+        if (itemStartIndex > 0) {
+            this.scrollTopNotifyed = false;
+        }
+
+        if (this.lastStartIndex != itemStartIndex) {
+            this.lastStartIndex = itemStartIndex;
+            return itemStartIndex;
+        }
+
+        return -1;
+    }
+
+    // 查找需要补充的元素索引.
+    private findUpdateIndex(itemStartIndex: number, itemEndIndex: number): number[] {
+        const d = [];
+        for (let i = itemStartIndex; i < itemEndIndex; i++) {
+            if (this._filledIds.hasOwnProperty(i)) {
+                continue;
+            }
+            d.push(i);
+        }
+        return d;
+    }
+
+    private notifyScrollToTop() {
+        if (!this.adapter || this.adapter.getCount() <= 0) {
+            return;
+        }
+        if (this.pullDownCallback) {
+            this.pullDownCallback();
+        }
+    }
+
+    private notifyScrollToBottom() {
+        if (!this.adapter || this.adapter.getCount() <= 0) {
+            return;
+        }
+        if (this.pullUpCallback) {
+            this.pullUpCallback();
+        }
+    }
+
+    private adjustEvent() {
+        this.content.on(this.isMobile() ? cc.Node.EventType.TOUCH_END : cc.Node.EventType.MOUSE_UP, () => {
+            this.scrollTopNotifyed = false;
+            this.scrollBottomNotifyed = false;
+        },              this)
+        this.content.on(this.isMobile() ? cc.Node.EventType.TOUCH_CANCEL : cc.Node.EventType.MOUSE_LEAVE, () => {
+            this.scrollTopNotifyed = false;
+            this.scrollBottomNotifyed = false;
+        },              this);
+    }
+
+    private isMobile(): boolean {
+        return (cc.sys.isMobile || cc.sys.platform === cc.sys.WECHAT_GAME || cc.sys.platform === cc.sys.QQ_PLAY)
+    }
+}
+
+// 数据绑定的辅助适配器
+export abstract class AbsAdapter {
+
+    private dataSet: any[] = [];
+
+    public setDataSet(data: any[]) {
+        this.dataSet = data;
+    }
+
+    public getCount(): number {
+        return this.dataSet.length;
+    }
+
+    public getItem(posIndex: number): any {
+        return this.dataSet[posIndex];
+    }
+
+    public _getView(item: cc.Node, posIndex: number): cc.Node {
+        this.updateView(item, posIndex);
+        return item;
+    }
+
+    public abstract updateView(item: cc.Node, posIndex: number);
+}

ListViewJsDemo/assets/Script/ListView.ts.meta

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+{
+  "ver": "1.0.5",
+  "uuid": "8a20b952-8dfd-4538-aba8-d30cc2a55f00",
+  "isPlugin": false,
+  "loadPluginInWeb": true,
+  "loadPluginInNative": true,
+  "loadPluginInEditor": false,
+  "subMetas": {}
+}