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fix:当子节点过多时,滚动到最底部时,会产生闪烁 #116

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fix:当子节点过多时,滚动到最底部时,会产生闪烁 #116

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56 changes: 41 additions & 15 deletions src/hooks/useVirtualList.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -47,26 +47,37 @@ export const useVirtualList = (nonReactive: INonReactiveData, props: IUseVirtual
/**
* 计算渲染的节点，基于 scrollTop 计算当前应该渲染哪些节点
*/
const updateRenderNodes = (isScroll: boolean = false): void => {
function updateRenderNodes(isScroll: boolean = false): void {
// 添加边界检查,防止无效更新
if (blockLength.value === 0) return;

if (blockLength.value > renderAmount.value) {
const scrollTop = Math.max(scrollArea.value.scrollTop, 0)
/** 当前滚动了多少节点 */
const scrollNodeAmount = Math.floor(scrollTop / props.nodeMinHeight)
renderStart.value =
Math.floor(scrollNodeAmount / props.bufferNodeAmount) *
props.bufferNodeAmount
const scrollTop = scrollArea.value.scrollTop
const maxScrollTop = blockAreaHeight.value - scrollArea.value.clientHeight

// 添加滚动到底部的判断
if (scrollTop >= maxScrollTop) {
renderStart.value = Math.max(0, blockLength.value - renderAmount.value)
} else {
const scrollNodeAmount = Math.floor(scrollTop / props.nodeMinHeight)
renderStart.value = Math.floor(scrollNodeAmount / props.bufferNodeAmount) * props.bufferNodeAmount
}
} else {
renderStart.value = 0
}

// 避免不必要的更新
if (
isScroll &&
renderAmountCache.value === renderAmount.value &&
renderStartCache.value === renderStart.value
)
) {
return
}

renderNodes.value = nonReactive.blockNodes
.slice(renderStart.value, renderStart.value + renderAmount.value)
.map(blockNode => {
.map((blockNode: TreeNode) => {
return Object.assign({}, blockNode, {
_parent: null,
children: []
Expand Down Expand Up @@ -105,15 +116,30 @@ export const useVirtualList = (nonReactive: INonReactiveData, props: IUseVirtual
blockAreaHeight.value = props.nodeMinHeight * blockLength.value
}

const handleTreeScroll = (): void => {
//#endregion Calculate nodes
const isThrottled = ref(false)

function handleTreeScroll(): void {
if (debounceTimer.value) {
window.cancelAnimationFrame(debounceTimer.value)
}
renderAmountCache.value = renderAmount.value
renderStartCache.value = renderStart.value
debounceTimer.value = window.requestAnimationFrame(
updateRenderNodes.bind(null, true)
)

// 添加节流
if (!isThrottled.value) {
isThrottled.value = true

renderAmountCache.value = renderAmount.value
renderStartCache.value = renderStart.value

debounceTimer.value = window.requestAnimationFrame(() => {
updateRenderNodes(true)

// 重置节流状态
setTimeout(() => {
isThrottled.value = false
}, 16) // 约60fps
})
}
}

/**
Expand Down