Blank between two vertical ImageViews.

[vectorqi]

I set the margin as 1,and the horizontal layout seems good,but the why there is a blank between 2 ImageViews in vertical?

[DonLiangGit]

i think it depends on device, i try to set 0 and 1 dp it works fine.
make sure you set it right in your main activity xml: app:item_margin="?dp".