IssueTracker

Component used: StaggeredGridLayoutManager

Version used: 1.3.2

Devices/Android versions reproduced on: Pixel 7, API 34

When using a top/bottom decoration with a vertical StaggeredGridLayoutManager (with RV height match_parent), and child item views with fixed heights, the child heights are decreased from what they are defined as by the offsets.

It seems the decoration offsets are being double counted (i.e. added below/above the item, and then also subtracted from the item height). This is opposed to the standard GridLayoutManager where this works correctly and the item heights are not altered.

The problem may be related to this bug fix in GridLayoutManager: https://github.com/androidx/androidx/commit/de8a5de43b647f9b61f4859a22a0ce59155f442a

StaggeredGridLayoutManager still retains the updateSpecWithExtra method, and skipping the calls to this method in StaggeredGridLayoutManager (as was done in the GridLayoutManager fix) seems to fix the issue (however I assume an actual fix would probably be slightly more involved than that).

The screenshots attached show the problem in StaggeredGridLayoutManager with various item decoration bottom offset sizes, with GridLayoutManager showing the correct behaviour. The sample project from which the screenshots were taken is also attached.