bug(cdk/overlay): BlockScrollStrategy is not working properly when overlay is called inside OnInit

[thekhegay]

Description

I didn't find any description in the documentation, but when Overlay creation called in OnInit, BlockScrollStrategy is not blocking scroll.

I noticed another behavior:

• height: 101vh applied as app-root styles, block is working fine (stackblitz)
• height: 101vh is applied as .root class with @HostBinding call - block is not working (stackblitz)

I think related: #19020, #22217

Reproduction

Everything works fine when called inside AfterViewInit: https://stackblitz.com/edit/stackblitz-starters-sp8ikj?file=src%2Fmain.ts

Environment

• Angular: 17.3.5
• CDK/Material: 17.3.5
• Browser(s): any
• Operating System (e.g. Windows, macOS, Ubuntu): any

[crisbeto]

The strategy needs to measure the sizes of elements in order to block scrolling. ngOnInit is likely too early for that to happen reliably. You can try either moving it to a later hook or wrapping it in a requestAnimationFrame.