angular
fix(cdk/overlay): scrolling broken in some overlay sizes
When the positioning of an overlay is calculated, the overlay pane is moved to the top right corner, and given an unbounded size. Based on the calculated size, a position is attempted where the entire element can fit next to the origin element without needing to scroll.
If an overlay pane is created with a size large enough that it needs scrolling in any valid position (top/bottom/left/right) but small enough that it can fit in the viewport without needing to scroll, the scrolling of that pane will break. When the pane is moved to the top left corner for size calculation, the pane will lose it's scroll position since it no longer has a scrollbar.
This fix introduces a maximum constraint on the size of the overlay pane during size calculation, where the maximum available vertical and horizontal space is used as the constraint.
This is a quick approach and there are probably some things I've missed. I haven't written any tests for this fix, and would like some help regarding how to best write those tests, as well as fix two tests that broke because of these changes.
Edit: Added a stackblitz with a reproduction
https://stackblitz.com/edit/components-issue-yusmdo?file=src/app/example-component.html
Open the 75vh overlay, scroll a bit in it and then scroll the body. The scroll in the overlay will reset to the top.
Open the 125vh overlay, scroll a bit in it and then scroll the body. The scroll in the overlay will not reset.
Yes, sorry should've added a stackblitz right away
https://stackblitz.com/edit/components-issue-yusmdo?file=src/app/example-component.html
Open the 75vh overlay, scroll a bit in it and then scroll the body. The scroll in the overlay will reset to the top.
Open the 125vh overlay, scroll a bit in it and then scroll the body. The scroll in the overlay will not reset.