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bug(virtual-scroll): scrollToIndex on viewport while inside cdkVirtualScrollingElement is wrong

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评估

难度
3/5
预计耗时
1-2 天
新手友好度
64/100
Issue 类型
缺陷
描述清晰度
基本清楚
活跃度
冷清
技术栈
angular, typescript
领域
frontend

调研方向

从 CDK 虚拟滚动 viewport 的实现和 scrollToIndex 入口点开始,然后将其行为与所提供的 StackBlitz 复现中的 measureViewportOffset('top') 进行比较。使用 regular viewport 和 cdkVirtualScrollingElement 两种情况验证更改:滚动到项目 50 时,两个部分都应选择项目 50,包括存在 100px header 偏移的情况。

由索引模型根据 Issue 内容生成。

描述

area: cdk/scrolling gemini-triaged P3
Is this a regression?
  • Yes, this behavior used to work in the previous version
The previous version in which this bug was not present was

No response

Description

When scrolling by index using scrollToIndex on the viewport it doesn't take into account any content around the viewport when using cdkVirtualScrollingElement.
The logic calculates the offset only based on the itemSize without taking into account the viewport offset.

Reproduction

StackBlitz link: https://stackblitz.com/edit/qmx1v9bc
Steps to reproduce:

  1. In the Regular section clicking on the button Scroll to item 50 correctly scrolls to item 50. This is a regular viewport without cdkVirtualScrollingElement.
  2. In the With cdkVirtualScrollingElement section clicking on the button Scroll to item 50 (not working) it scrolls to item 48 instead of 50 as there is a 100px header above the viewport while it should scroll to item 50.
  3. If the button Scroll to item 50 (fixed) is clicked the scrolling works as expected as I calculate the offset myself using viewport.measureViewportOffset('top') which is missing in scrollToIndex.
Expected Behavior

It should scroll to the correct item when using cdkVirtualScrollingElement

Actual Behavior

It scrolls without taking into account the viewport offset.

Environment
  • Angular: 21.2.6
  • CDK/Material: 21.1.2
  • Browser(s): Chrome 146
  • Operating System (e.g. Windows, macOS, Ubuntu): Windows 11
主要语言
TypeScript
星标
25k
派生
6.8k
平均合并
1 天 1 小时
30 天内合并 PR
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