增加一个 grid-layout 网格布局

list-3x/assets/lib/grid-layout.ts

@@ -0,0 +1,140 @@
+import { math, UITransform, warn } from "cc";
+import { YXCollectionView, YXIndexPath, YXLayout, YXLayoutAttributes } from "./yx-collection-view";
+
+export class GridLayout extends YXLayout {
+
+    /**
+     * 节点大小  
+     */
+    itemSize: math.Size = new math.Size(100, 100)
+
+    /**
+     * 垂直间距  
+     */
+    horizontalSpacing: number = 0
+
+    /**
+     * 水平间距  
+     */
+    verticalSpacing: number = 0
+
+    /**
+     * 整体对齐方式  
+     * 0靠左 1居中 2靠右  
+     */
+    alignment: number = 1
+
+    /**
+     * 获取每行最多可以容纳多少个节点  
+     */
+    protected getMaxItemsPerRow(collectionView: YXCollectionView): number {
+        if (this._maxItemsPerRow == null) {
+            let num = 1
+            const width = collectionView.node.getComponent(UITransform).contentSize.width
+            while ((num * this.itemSize.width + (num - 1) * this.horizontalSpacing) <= width) { num++ }
+            num = Math.max(1, num - 1)
+            this._maxItemsPerRow = num
+        }
+        return this._maxItemsPerRow
+    }
+    protected _maxItemsPerRow: number = null
+
+    prepare(collectionView: YXCollectionView): void {
+        if (collectionView.scrollDirection === YXCollectionView.ScrollDirection.VERTICAL) {
+            this._prepare_vertical(collectionView)
+            return
+        }
+        if (collectionView.scrollDirection === YXCollectionView.ScrollDirection.HORIZONTAL) {
+            warn(`GridLayout 仅支持垂直方向排列`)
+            this._prepare_vertical(collectionView)
+            return
+        }
+    }
+
+    protected _prepare_vertical(collectionView: YXCollectionView) {
+        collectionView.scrollView.horizontal = false
+        collectionView.scrollView.vertical = true
+
+        let attrs: YXLayoutAttributes[] = []
+        let contentSize = collectionView.node.getComponent(UITransform).contentSize.clone()
+
+        // 容器宽度
+        const width = contentSize.width
+
+        // 计算每行最多可以放多少个节点
+        this._maxItemsPerRow = null
+        let num = this.getMaxItemsPerRow(collectionView)
+
+        // 根据设置的对齐方式计算左边距
+        let left = 0
+        if (this.alignment == 1) {
+            let maxWidth = (num * this.itemSize.width + (num - 1) * this.horizontalSpacing) // 每行节点总宽度
+            left = (width - maxWidth) * 0.5
+        }
+        if (this.alignment == 2) {
+            let maxWidth = (num * this.itemSize.width + (num - 1) * this.horizontalSpacing) // 每行节点总宽度
+            left = width - maxWidth
+        }
+
+        const numberOfSections = collectionView.getNumberOfSections()
+        if (numberOfSections > 1) { warn(`GridLayout 暂时不支持分区模式`) }
+
+        const numberOfItems = collectionView.getNumberOfItems(0)
+        for (let index = 0; index < numberOfItems; index++) {
+
+            // 计算这个节点是第几行
+            let row = Math.floor(index / num)
+
+            // 计算这个节点是第几列
+            let column = index % num
+
+            // 计算节点 origin
+            let x = left + (this.itemSize.width + this.horizontalSpacing) * column
+            let y = (this.itemSize.height + this.verticalSpacing) * row
+
+            let attr = YXLayoutAttributes.layoutAttributesForCell(new YXIndexPath(0, index))
+            attr.frame.x = x
+            attr.frame.y = y
+            attr.frame.width = this.itemSize.width
+            attr.frame.height = this.itemSize.height
+            attrs.push(attr)
+
+            // 更新内容高度
+            contentSize.height = Math.max(contentSize.height, attr.frame.yMax)
+        }
+
+        this.attributes = attrs
+        this.contentSize = contentSize
+    }
+
+    initOffset(collectionView: YXCollectionView): void {
+        collectionView.scrollView.scrollToTop()
+    }
+
+    layoutAttributesForElementsInRect(rect: math.Rect, collectionView: YXCollectionView): YXLayoutAttributes[] {
+        return this.visibleElementsInRect(rect, collectionView)
+    }
+
+    /**
+     * 抽出来一个方法用来优化列表性能  
+     * 在优化之前，可以先看一下 @see YXLayout.layoutAttributesForElementsInRect 关于返回值的说明  
+     */
+    protected visibleElementsInRect(rect: math.Rect, collectionView: YXCollectionView) {
+        if (this.attributes.length <= 100) { return this.attributes } // 少量数据就不查了，直接返回全部  
+
+        // 根据当前范围直接计算出一个区间  
+        const startRow = Math.floor(rect.y / (this.itemSize.height + this.verticalSpacing))
+        const endRow = Math.ceil(rect.yMax / (this.itemSize.height + this.verticalSpacing))
+
+        // 计算每行最多可以放多少个节点
+        let num = this.getMaxItemsPerRow(collectionView)
+
+        // 计算索引区间
+        const startIdx = startRow * num
+        const endIdx = endRow * num
+
+        // 只返回区间节点的布局属性
+        return this.attributes.slice(startIdx, endIdx)
+    }
+}
+

list-3x/assets/lib/grid-layout.ts.meta

@@ -0,0 +1,9 @@
+{
+  "ver": "4.0.23",
+  "importer": "typescript",
+  "imported": true,
+  "uuid": "02a96aac-8c52-4201-b8af-c7ed49aae6d4",
+  "files": [],
+  "subMetas": {},
+  "userData": {}
+}