bug(cdk/scrolling): scrollToIndex doesn't account for content before (when used with scrollWindow)

[Dador]

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

scrollToIndex doesn't account for content before scrollable (when used with scrollWindow).
Probably it should use measureViewportOffset or similar method to account for it.

Reproduction

Steps to reproduce:

1. Open https://stackblitz.com/edit/angular-ewgqzt?file=src/app/cdk-virtual-scroll-window-scrolling-example.ts
2. Click on button Scroll to index #1

Expected Behavior

Viewport should be scrolled so Scroll to index #1, so is the first element.

Actual Behavior

Viewport is scrolled but "Content before" is the first element. It's off by "content before" height.

Environment

• Angular: 15
• CDK/Material: 15.1.2
• Browser(s): Chrome 108
• Operating System (e.g. Windows, macOS, Ubuntu): macOS

[Dador]

Quick workaround for fixed size:

// let itemSize = 200; // Your item size
// let indexToScroll = 10; // To which index you want to scroll
// this.cdkScroll is CdkVirtualScrollViewport

const viewportOffset = this.cdkScroll.measureViewportOffset();
this.cdkScroll.scrollToOffset(Math.ceil(viewportOffset + indexToScroll * itemSize));