![\"LazyLayoutAlgorithm\u5de5\u7a0b\u5c01\u88c5\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/09\/20260921165656-6ab161d86dafc.png\")
<\/p>\n<\/p>\n
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\u8bf4\u660e：\u672c\u6587\u7528 LazyLayoutAlgorithm \u8ba8\u8bba\u5de5\u7a0b\u65b9\u6cd5，\u793a\u4f8b\u63a5\u53e3\u4e3a\u6559\u5b66\u62bd\u8c61，\u4e0d\u4ee3\u8868\u5f53\u524d HarmonyOS SDK \u7684\u5b8c\u6574\u771f\u5b9e\u7b7e\u540d\u3002\u7ec4\u4ef6\u80fd\u529b\u3001\u751f\u547d\u5468\u671f\u4e0e\u6d4b\u91cf\u89c4\u5219\u8bf7\u4ee5\u5b98\u65b9\u6587\u6863\u548c\u76ee\u6807 SDK \u4e3a\u51c6\u3002<\/p>\n
\u7b97\u6cd5\u8f93\u5165\u5305\u62ec\u7236\u7ea6\u675f\u3001\u6eda\u52a8\u504f\u79fb\u3001\u6570\u636e\u6570\u91cf\u3001\u95f4\u8ddd\u4e0e\u5df2\u77e5\u5c3a\u5bf8；\u8f93\u51fa\u662f\u9700\u8981\u7269\u5316\u7684\u7d22\u5f15\u8303\u56f4\u3001\u6bcf\u4e2a\u8282\u70b9\u7684\u4f4d\u7f6e\u548c\u6574\u4f53\u5185\u5bb9\u8303\u56f4\u3002\u4e1a\u52a1\u6570\u636e\u5185\u5bb9\u4e0d\u5e94\u8fdb\u5165\u51e0\u4f55\u8ba1\u7b97\u3002<\/p>\n
export interface LazyLayoutInput {
\n viewportWidth: number
\n viewportHeight: number
\n scrollOffset: number
\n itemCount: number
\n gap: number
\n overscan: number
\n}<\/p>\n
export interface ItemPlacement {
\n index: number
\n x: number
\n y: number
\n width: number
\n height: number
\n}<\/p>\n
\u8f93\u5165\u4fdd\u6301\u7eaf\u6570\u636e\u540e，\u6838\u5fc3\u7b97\u6cd5\u53ef\u4ee5\u8131\u79bb UI \u73af\u5883\u6d4b\u8bd5\u3002<\/p>\n
![\"LazyLayoutAlgorithm\u5206\u5c42\u67b6\u6784\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/09\/20260921165658-6ab161da87426.png\")
<\/p>\n
\u4e1a\u52a1\u7ec4\u4ef6\u58f0\u660e\u6570\u636e\u6e90\u3001\u7a33\u5b9a Key \u4e0e\u5e03\u5c40\u610f\u56fe；\u5e03\u5c40\u7b56\u7565\u8ba1\u7b97\u65b9\u5411\u3001\u5206\u7ec4\u548c\u4f4d\u7f6e；\u6d4b\u91cf\u9002\u914d\u5c42\u628a\u7236\u7ea6\u675f\u8f6c\u6362\u4e3a\u5b50\u9879\u7ea6\u675f\u5e76\u8c03\u7528\u5e73\u53f0\u6d4b\u91cf；\u5c3a\u5bf8\u4e0e\u7d22\u5f15\u7f13\u5b58\u7ef4\u62a4\u4f30\u7b97\u3001\u771f\u5b9e\u5c3a\u5bf8\u548c\u504f\u79fb\u6620\u5c04\u3002<\/p>\n
export interface ItemMeasurePort {
\n measure(index: number, constraint: ChildConstraint): Promise<ItemSize>
\n}<\/p>\n
export interface LayoutCache {
\n getSize(key: string): ItemSize | undefined
\n putSize(key: string, size: ItemSize): void
\n invalidate(keys: readonly string[]): void
\n}<\/p>\n
\u7b97\u6cd5\u4e0d\u76f4\u63a5\u8bfb\u53d6\u9875\u9762\u72b6\u6001，\u7f13\u5b58\u4e5f\u4e0d\u6301\u6709\u7ec4\u4ef6\u5b9e\u4f8b\u3002<\/p>\n
\u7d22\u5f15\u4f1a\u968f\u63d2\u5165\u3001\u5220\u9664\u548c\u6392\u5e8f\u53d8\u5316，\u4e0d\u80fd\u4f5c\u4e3a\u957f\u671f\u8eab\u4efd\u3002\u6570\u636e\u6e90\u4e3a\u6bcf\u9879\u63d0\u4f9b\u7a33\u5b9a\u4e14\u552f\u4e00\u7684 Key，\u5e03\u5c40\u7f13\u5b58\u4e0e\u7ec4\u4ef6\u72b6\u6001\u90fd\u56f4\u7ed5 Key \u5173\u8054\u3002<\/p>\n
export interface LazyDataSource<T> {
\n count(): number
\n keyAt(index: number): string
\n itemAt(index: number): T
\n}<\/p>\n
function assertUniqueKeys(source: LazyDataSource<unknown>): void {
\n const keys = new Set<string>()
\n for (let index = 0; index < source.count(); index += 1) {
\n const key = source.keyAt(index)
\n if (keys.has(key)) throw new Error('DUPLICATE_ITEM_KEY')
\n keys.add(key)
\n }
\n}<\/p>\n
\u91cd\u590d Key \u4f1a\u9020\u6210\u5c3a\u5bf8\u3001\u72b6\u6001\u548c\u52a8\u753b\u9519\u8bef，\u5e94\u5728\u5f00\u53d1\u4e0e\u6d4b\u8bd5\u9636\u6bb5\u7acb\u5373\u66b4\u9732\u3002<\/p>\n
\u7b49\u9ad8\u9879\u53ef\u4ee5\u76f4\u63a5\u6309\u504f\u79fb\u8ba1\u7b97\u7d22\u5f15；\u4e0d\u7b49\u9ad8\u9879\u5219\u4f7f\u7528\u7d2f\u8ba1\u5c3a\u5bf8\u7d22\u5f15\u6216\u533a\u95f4\u6811\u5b9a\u4f4d\u3002\u672a\u77e5\u5c3a\u5bf8\u5148\u7528\u5206\u7ec4\u4f30\u7b97\u503c，\u4e0d\u80fd\u4e3a\u4e86\u627e\u5230\u8d77\u70b9\u4ece\u7b2c\u96f6\u9879\u9010\u4e2a\u6d4b\u91cf\u3002<\/p>\n
export function estimateRange(
\n scrollOffset: number,
\n viewportHeight: number,
\n estimatedExtent: number,
\n itemCount: number,
\n overscan: number
\n): [number, number] {
\n const start = Math.max(0, Math.floor(scrollOffset \/ estimatedExtent) – overscan)
\n const end = Math.min(itemCount – 1,
\n Math.ceil((scrollOffset + viewportHeight) \/ estimatedExtent) + overscan)
\n return [start, end]
\n}<\/p>\n
\u4f30\u7b97\u53ea\u7528\u4e8e\u7f29\u5c0f\u5019\u9009\u8303\u56f4，\u771f\u5b9e\u653e\u7f6e\u4ecd\u4ee5\u6d4b\u91cf\u7ed3\u679c\u4e3a\u51c6\u3002<\/p>\n
![\"\u61d2\u5e03\u5c40\u8ba1\u7b97\u6d41\u7a0b\"](\"https:\/\/www.wsisp.com\/helps\/wp-content\/uploads\/2026\/09\/20260921165700-6ab161dc0d1d1.png\")
<\/p>\n
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export interface LayoutPassResult {
\n placements: readonly ItemPlacement[]
\n contentExtent: number
\n anchor: { key: string; offset: number }
\n measuredKeys: readonly string[]
\n}<\/p>\n
\u5e03\u5c40\u7ed3\u679c\u4fdd\u7559\u951a\u70b9，\u7528\u4e8e\u5c3a\u5bf8\u4fee\u6b63\u540e\u7a33\u5b9a\u89c6\u53e3\u3002<\/p>\n
\u7236\u5bb9\u5668\u7ed9\u51fa\u53ef\u7528\u5bbd\u9ad8，\u5e03\u5c40\u7b56\u7565\u7ed3\u5408\u5217\u6570\u3001\u95f4\u8ddd\u4e0e\u8de8\u5217\u89c4\u5219\u751f\u6210\u5b50\u7ea6\u675f\u3002\u76f8\u540c\u8f93\u5165\u5fc5\u987b\u5f97\u5230\u76f8\u540c\u7ea6\u675f，\u907f\u514d\u6d4b\u91cf\u4e0e\u653e\u7f6e\u9636\u6bb5\u4f7f\u7528\u4e0d\u540c\u516c\u5f0f\u3002<\/p>\n
export interface ChildConstraint {
\n minWidth: number
\n maxWidth: number
\n minHeight: number
\n maxHeight: number
\n}<\/p>\n
function columnConstraint(width: number, columns: number, gap: number): ChildConstraint {
\n const itemWidth = (width – gap * (columns – 1)) \/ columns
\n return { minWidth: itemWidth, maxWidth: itemWidth, minHeight: 0, maxHeight: Infinity }
\n}<\/p>\n
\u5217\u6570\u53d8\u5316\u4f1a\u5f71\u54cd\u6240\u6709\u9879\u5bbd\u5ea6，\u5e94\u4f7f\u76f8\u5173\u5c3a\u5bf8\u7f13\u5b58\u6574\u4f53\u5931\u6548\u3002<\/p>\n
\u9996\u6b21\u51fa\u73b0\u7684\u8282\u70b9\u6ca1\u6709\u771f\u5b9e\u5c3a\u5bf8，\u53ef\u4ee5\u5148\u7528\u7c7b\u578b\u6216\u5206\u7ec4\u5e73\u5747\u503c\u4f30\u7b97\u3002\u8fdb\u5165\u9884\u53d6\u533a\u540e\u5b8c\u6210\u6d4b\u91cf\u5e76\u66f4\u65b0\u7d22\u5f15；\u82e5\u5c3a\u5bf8\u5dee\u5f02\u5f71\u54cd\u53ef\u89c6\u533a\u4e4b\u524d\u7684\u5185\u5bb9，\u5219\u901a\u8fc7\u951a\u70b9\u8865\u507f\u504f\u79fb\u3002<\/p>\n
export interface SizeEntry {
\n key: string
\n estimated: ItemSize
\n measured?: ItemSize
\n constraintHash: string
\n}<\/p>\n
function effectiveSize(entry: SizeEntry): ItemSize {
\n return entry.measured ?? entry.estimated
\n}<\/p>\n
\u7f13\u5b58\u952e\u5305\u542b\u7ea6\u675f\u6458\u8981，\u5c4f\u5e55\u5bbd\u5ea6\u6216\u5217\u6570\u53d8\u5316\u540e\u4e0d\u4f1a\u590d\u7528\u4e0d\u517c\u5bb9\u5c3a\u5bf8\u3002<\/p>\n
\u9884\u53d6\u80fd\u51cf\u5c11\u6eda\u52a8\u5230\u65b0\u533a\u57df\u65f6\u7684\u7a7a\u767d，\u4f46\u8fc7\u5927\u7a97\u53e3\u4f1a\u9000\u5316\u4e3a\u5168\u91cf\u5e03\u5c40\u3002\u9884\u7b97\u7ed3\u5408\u6eda\u52a8\u65b9\u5411\u3001\u901f\u5ea6\u3001\u8282\u70b9\u6210\u672c\u548c\u5185\u5b58\u538b\u529b\u52a8\u6001\u8c03\u6574\u3002<\/p>\n
export interface OverscanPolicy {
\n minItems: number
\n maxItems: number
\n velocityFactor: number
\n memoryPressure: 'normal' | 'high'
\n}<\/p>\n
function resolveOverscan(speed: number, policy: OverscanPolicy): number {
\n if (policy.memoryPressure === 'high') return policy.minItems
\n return Math.min(policy.maxItems,
\n policy.minItems + Math.floor(Math.abs(speed) * policy.velocityFactor))
\n}<\/p>\n
\u5feb\u901f\u6eda\u52a8\u53ea\u6269\u5927\u524d\u8fdb\u65b9\u5411\u7684\u9884\u53d6，\u907f\u514d\u4e24\u4fa7\u90fd\u65e0\u6548\u5de5\u4f5c\u3002<\/p>\n
\u62d6\u52a8\u6eda\u52a8\u6761\u6216\u8c03\u7528\u8df3\u8f6c\u65f6，\u76ee\u6807\u53ef\u80fd\u8ddd\u79bb\u5f53\u524d\u533a\u57df\u5f88\u8fdc\u3002\u7b97\u6cd5\u5229\u7528\u7d2f\u8ba1\u5c3a\u5bf8\u7d22\u5f15\u4f30\u7b97\u76ee\u6807\u504f\u79fb，\u76f4\u63a5\u6784\u5efa\u76ee\u6807\u9644\u8fd1\u8282\u70b9，\u518d\u6839\u636e\u771f\u5b9e\u5c3a\u5bf8\u5c0f\u5e45\u6821\u6b63\u3002<\/p>\n
export interface OffsetIndex {
\n offsetOf(index: number): number
\n indexAt(offset: number): number
\n update(index: number, oldExtent: number, newExtent: number): void
\n}<\/p>\n
\u7d22\u5f15\u7ed3\u6784\u628a\u5b9a\u4f4d\u590d\u6742\u5ea6\u4e0e\u6570\u636e\u89c4\u6a21\u89e3\u8026，\u907f\u514d\u957f\u8ddd\u79bb\u8df3\u8f6c\u51bb\u7ed3\u754c\u9762\u3002<\/p>\n
\u63d2\u5165\u3001\u5220\u9664\u3001\u79fb\u52a8\u548c\u5185\u5bb9\u5c3a\u5bf8\u53d8\u5316\u5f71\u54cd\u8303\u56f4\u4e0d\u540c\u3002\u6570\u636e\u6e90\u53d1\u9001\u5e26 Key \u7684\u53d8\u66f4\u96c6，\u7f13\u5b58\u53ea\u6e05\u7406\u53d7\u5f71\u54cd\u8282\u70b9\u53ca\u540e\u7eed\u504f\u79fb，\u800c\u4e0d\u662f\u6bcf\u6b21\u5168\u91cf\u91cd\u7b97\u3002<\/p>\n
export type DataMutation =
\n | { kind: 'insert'; index: number; keys: readonly string[] }
\n | { kind: 'remove'; index: number; keys: readonly string[] }
\n | { kind: 'move'; from: number; to: number; key: string }
\n | { kind: 'resize'; key: string }<\/p>\n
\u53d8\u66f4\u6279\u6b21\u5e26\u7248\u672c\u53f7，\u8fdf\u5230\u7684\u6d4b\u91cf\u7ed3\u679c\u4e0d\u80fd\u5199\u5165\u65b0\u7248\u672c\u5e03\u5c40\u3002<\/p>\n
\u4ec5\u4fdd\u5b58\u50cf\u7d20\u504f\u79fb\u5728\u5185\u5bb9\u53d8\u5316\u540e\u4e0d\u53ef\u9760\u3002\u4fdd\u5b58\u9876\u90e8\u53ef\u89c1\u9879\u7684 Key \u4e0e\u9879\u5185\u504f\u79fb，\u6062\u590d\u65f6\u5148\u5b9a\u4f4d Key，\u518d\u5e94\u7528\u76f8\u5bf9\u504f\u79fb；Key \u4e0d\u5b58\u5728\u65f6\u9009\u62e9\u90bb\u8fd1\u9879\u3002<\/p>\n
export interface ScrollAnchor {
\n key: string
\n innerOffset: number
\n dataVersion: number
\n}<\/p>\n
function restoreAnchor(anchor: ScrollAnchor, source: LazyDataSource<unknown>): number {
\n const index = findIndexByKey(source, anchor.key)
\n return index >= 0 ? offsetIndex.offsetOf(index) + anchor.innerOffset : 0
\n}<\/p>\n
\u8fd9\u80fd\u964d\u4f4e\u5f02\u6b65\u56fe\u7247\u52a0\u8f7d\u548c\u6570\u636e\u5237\u65b0\u5f15\u8d77\u7684\u89c6\u53e3\u8df3\u52a8\u3002<\/p>\n
\u6d4b\u8bd5\u8986\u76d6\u7a7a\u6570\u636e\u3001\u5355\u9879\u3001\u4e07\u7ea7\u6570\u636e\u3001\u7b49\u9ad8\u4e0e\u4e0d\u7b49\u9ad8\u3001\u63d2\u5165\u5220\u9664\u3001\u5feb\u901f\u8df3\u8f6c\u3001\u6b63\u53cd\u5411\u6eda\u52a8\u3001\u5bbd\u5ea6\u53d8\u5316\u548c\u5927\u5b57\u4f53\u3002\u9a8c\u8bc1\u53ea\u6d4b\u91cf\u53ef\u89c6\u4e0e\u9884\u53d6\u533a\u3001Key \u552f\u4e00\u3001\u7f13\u5b58\u6309\u7ea6\u675f\u5931\u6548\u3001\u65e7\u6d4b\u91cf\u4e0d\u6c61\u67d3\u65b0\u7248\u672c\u3001\u6062\u590d\u951a\u70b9\u7a33\u5b9a\u3002\u6027\u80fd\u68c0\u67e5\u540c\u65f6\u89c2\u5bdf\u5e03\u5c40\u8017\u65f6\u3001\u8282\u70b9\u6570\u91cf\u3001\u5185\u5b58\u548c\u6eda\u52a8\u5e27\u7a33\u5b9a\u6027\u3002<\/p>\n
LazyLayoutAlgorithm \u7684\u5de5\u7a0b\u6838\u5fc3\u662f\u628a\u5e03\u5c40\u5de5\u4f5c\u9650\u5236\u5728\u5f53\u524d\u771f\u6b63\u9700\u8981\u7684\u533a\u57df\u3002\u901a\u8fc7\u7a33\u5b9a Key\u3001\u533a\u95f4\u7d22\u5f15\u3001\u4f30\u7b97\u4e0e\u771f\u5b9e\u6d4b\u91cf\u534f\u4f5c\u3001\u65b9\u5411\u6027\u9884\u53d6\u3001\u5c40\u90e8\u5931\u6548\u548c\u951a\u70b9\u6062\u590d，\u81ea\u5b9a\u4e49\u5e03\u5c40\u624d\u80fd\u5728\u6570\u636e\u89c4\u6a21\u6269\u5927\u540e\u4ecd\u4fdd\u6301\u6b63\u786e\u3001\u6d41\u7545\u4e14\u53ef\u7ef4\u62a4\u3002<\/p><\/p>\n","protected":false},"excerpt":{"rendered":"
\u3010HarmonyOS 7\u65b0\u80fd\u529b｜045\u3011LazyLayoutAlgorithm\u5de5\u7a0b\u5c01\u88c5：\u628a\u63a5\u5165\u903b\u8f91\u653e\u8fdb\u53ef\u7ef4\u62a4\u7684\u5206\u5c42\u7ed3\u6784\u5e38\u89c4\u5217\u8868\u80fd\u8986\u76d6\u591a\u6570\u573a\u666f，\u4f46\u7011\u5e03\u6d41\u3001\u65f6\u95f4\u8f74\u3001\u5206\u7ec4\u5361\u7247\u6216\u4e0d\u89c4\u5219\u753b\u5eca\u5f80\u5f80\u9700\u8981\u81ea\u5b9a\u4e49\u5e03\u5c40\u3002\u6570\u636e\u91cf\u4e0a\u5347\u540e，\u5982\u679c\u4e00\u6b21\u6d4b\u91cf\u5e76\u653e\u7f6e\u5168\u90e8\u8282\u70b9，\u9996\u5c4f\u3001\u6eda\u52a8\u548c\u5185\u5b58\u90fd\u4f1a\u627f\u53d7\u4e0d\u5fc5\u8981\u5f00\u9500\u3002\u61d2\u5e03\u5c40\u7684\u5173\u952e\u4e0d\u662f\u201c\u5c11\u521b\u5efa\u7ec4\u4ef6\u201d\u8fd9\u4e00\u53e5\u8bdd，\u800c\u662f\u53ea\u5bf9\u53ef\u89c6\u533a\u53ca\u5408\u7406\u9884\u53d6\u8303\u56f4\u505a\u5de5\u4f5c，\u540c\u65f6\u7ef4\u6301\u7a33\u5b9a\u7d22\u5f15\u3001\u6b63\u786e\u5c3a\u5bf8\u548c<\/p>\n","protected":false},"author":2,"featured_media":108512,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[12384,4362,5534,280,56],"topic":[],"class_list":["post-108515","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-server","tag-12384","tag-arkts","tag-arkui","tag-harmonyos","tag-56"],"yoast_head":"\n