【ccc3.8】虚拟列表

一个简单的虚拟列表，没有任何其他东西。

原理就是向上滚动时，将下面离开屏幕的那一个item塞到上侧来：

主代码仅有两个：ScrollList对应的滚动容器，ScrollListItem对应单项的预制体

当前支持两种：竖向滚动、横线滚动。不支持那种横竖排版的。有需要自己添加

使用案例：https://github.com/EddyLwei/ccc3.8_VirtualList.git

ScrollList：

/**横向排布拖动*/
export const SCROLL_HORIZONTAL: number = 1;
/**竖向排布拖动*/
export const SCROLL_VERTICAL: number = 2;import { _decorator, Node, Prefab, instantiate, ScrollView, UITransform, Vec3, log } from 'cc';
import { ScrollListItem } from './ScrollListItem';const { ccclass, property } = _decorator;@ccclass('ScrollList')
export class ScrollList extends ScrollView {/**item子节点预制体*/@property({ type: Prefab, tooltip: "item子节点预制体" })itemPrefab: Prefab = null;/**单条记录高度*/private _itemSize: number;/**需要多少个记录组件 在可视范围内+2条*/private _numItem: number = 0;private _itemArr: Array<Node> = [];/**开始端下标*/private _itemIndex: number = 0;/**结束端下标*/private _dataIndex: number = 0;/**数据源*/private _dataArr: any[];/**滚动方向*/private _direction: number = 0;/**间隙 0=开始边框，1=结束边框，2=间隙*/private _gapNum: number[];/**子节点刷新绑定事件，或者使用item继承的模式*/public onItemRender: Function;start() {super.start();this.node.on('scrolling', this.scrollCheck, this);}onDestroy() {super.onDestroy();if (this.node) {this.node.off('scrolling', this.scrollCheck, this);}}/**设置数据* @param dataArr : 数据源* @param direction : 滚动方向，默认上下* @param gap : [开始边框距离，结束边框距离，每个之间空隙]*/public setDataList(dataArr: any[], direction: number = SCROLL_VERTICAL, gap?: number[]) {this._dataArr = dataArr;this._direction = direction;this._gapNum = gap;this.createItem();}/**获得数据后开始创建*/private createItem() {let _showSize = this.node.getComponent(UITransform).height;//获得预制体的高度if (!this._itemSize) {let pNode = instantiate(this.itemPrefab);if (this._direction == SCROLL_HORIZONTAL) {this._itemSize = pNode.getComponent(UITransform).contentSize.width;_showSize = this.node.getComponent(UITransform).width;}else {this._itemSize = pNode.getComponent(UITransform).contentSize.height;}pNode.destroy();// log("---_itemSize--", this._itemSize);}//可视范围，对应可以创建多少个实体单例itemthis._numItem = Math.floor(_showSize / this._itemSize) + 2;log(_showSize, "初始化获得数量：", this._numItem)if (this._dataArr.length < this._numItem) {this._numItem = this._dataArr.length;}this._itemArr.length = 0;for (let index = 0; index < this._numItem; index++) {let pNode = instantiate(this.itemPrefab);pNode.parent = this.content;this._itemArr.push(pNode);this.itemRender(pNode, index);}//设置容器大小let contentSize = this._itemSize * this._dataArr.length;//前面距离边框if (this._gapNum && this._gapNum[0]) {contentSize += this._gapNum[0];}//后面距离边框if (this._gapNum && this._gapNum[1]) {contentSize += this._gapNum[1];}//间隙距离if (this._gapNum && this._gapNum[2]) {contentSize += this._gapNum[2] * (this._dataArr.length - 1);}if (this._direction == SCROLL_HORIZONTAL) {this.content.getComponent(UITransform).width = contentSize;}else {this.content.getComponent(UITransform).height = contentSize;}this._itemIndex = this._dataIndex = this._itemArr.length - 1;log("初始化结束：", this._dataIndex, this._itemArr.length)}private scrollCheck() {let nowPos = this.getScrollOffset().y;let topPos = (this._dataIndex + 1 - this._numItem) * this._itemSize;//当前屏幕中靠近最开始的坐标//前面边框if (this._gapNum && this._gapNum[0]) {topPos += this._gapNum[0];}//间隙距离if (this._gapNum && this._gapNum[2]) {topPos += this._gapNum[2] * (this._dataIndex + 1 - this._numItem);}// let topPos = this.countPosByIndex(this._dataIndex + 1 - this._numItem);let size = this._itemSize;if (this._direction == SCROLL_HORIZONTAL) {nowPos = this.getScrollOffset().x;topPos = -topPos;size = -this._itemSize;}//判断向结束端滚动，滚动点和初始点对比if ((this._direction == SCROLL_VERTICAL && nowPos > size + topPos) ||(this._direction == SCROLL_HORIZONTAL && nowPos < size + topPos)) {let newIndex = this._dataIndex + 1;// Log.log(this._dataIndex, "-判断向结束端滚动 1 --将头部item转移到最后---", nowPos, topPos);if (newIndex >= this._dataArr.length) {return; //如果滚动到底部最后一条数据，不再进行写入}this._dataIndex = newIndex;let topItemIndex = this._itemIndex + 1;if (topItemIndex >= this._numItem) {topItemIndex = 0;}let item = this._itemArr[topItemIndex];if (item) {this.itemRender(item, newIndex);// Log.error(topItemIndex, "转移到最后", item.node.position);}this._itemIndex = topItemIndex;}//判断向开始端滚动else if ((this._direction == SCROLL_VERTICAL && nowPos < topPos) ||(this._direction == SCROLL_HORIZONTAL && nowPos > topPos)) {let newIndex = this._dataIndex + 1 - this._numItem - 1;// Log.log(this._dataIndex, "-判断向上滚动 2 -将最后item转移到头部----", newIndex);if (newIndex < 0) {// Log.warn("如果滚动到第一条数据，不再进行写入", newIndex)return; //如果滚动到第一条数据，不再进行写入}this._dataIndex--;// Log.error(this._itemIndex, "将最后item转移到头部", this._dataIndex, newIndex, newIndex * -this._itemSize);let item = this._itemArr[this._itemIndex];if (item) {this.itemRender(item, newIndex);// Log.error(this._itemIndex, "转移头部", item.node.position);}this._itemIndex--;if (this._itemIndex < 0) {this._itemIndex = this._numItem - 1;}}}/**刷新单项*/private itemRender(node: Node, newIndex: number) {//设置有全局得刷新事件if (this.onItemRender) {this.onItemRender(node, newIndex);}//没有全局，使用继承的itemelse {const item = node.getComponent(ScrollListItem)if (item) {item.onItemRender(this._dataArr[newIndex]);}}this.setPos(node, newIndex);}/**设置坐标*/private setPos(node: Node, index: number) {let pos = this.countPosByIndex(index);if (this._direction == SCROLL_HORIZONTAL) {node.setPosition(new Vec3(pos, 0));}else {node.setPosition(new Vec3(0, -pos));}}/**根据下标计算坐标*/private countPosByIndex(index: number): number {let pos = (1 / 2 + index) * this._itemSize;//前面距离边框if (this._gapNum && this._gapNum[0]) {pos += this._gapNum[0];}//间隙距离if (this._gapNum && this._gapNum[2]) {pos += this._gapNum[2] * index;}return pos;}}

ScrollListItem：（其实仅用一个接口的作用）

import { _decorator, Component, } from 'cc';const { ccclass, property } = _decorator;@ccclass('ScrollListItem')
export class ScrollListItem extends Component {/**滚动列表数据变更*/onItemRender(data, ...param: any[]) { }}

使用方式很简单：

import { _decorator, Component, Node } from 'cc';
import { SCROLL_HORIZONTAL, SCROLL_VERTICAL, ScrollList } from './ScrollList';
const { ccclass, property } = _decorator;@ccclass('TestScene')
export class TestScene extends Component {@property({ type: ScrollList, tooltip: "竖行滚动容器" })private vScroll: ScrollList;@property({ type: ScrollList, tooltip: "横向滚动容器" })private hScroll: ScrollList;start() {const dataArr = [];for (let index = 0; index < 50; index++) {dataArr.push(index)}this.hScroll.setDataList(dataArr, SCROLL_HORIZONTAL, [50, 50, 20]);this.vScroll.setDataList(dataArr, SCROLL_VERTICAL, [50, 50, 20]);}}

组件的设置注意：