Android - Align view center to bottom of other view

Question

A picture tells more than a lengthy speech :

I want to align vertically the center of the red part with the middle of the black part. I have no constraint of contai

Answer 1

This is also possible using the ConstraintLayout. Similar to how aligning the start/end of a view to the parent centers it within the parent, we can use that concept to center along the edge of a View.

The key to this layout is two constraints on our bottom view:

app:layout_constraintTop_toBottomOf="@id/top_view"
app:layout_constraintBottom_toBottomOf="@id/top_view"

By constraining both the top/bottom of the lower view to the bottom of the upper view, the layout will adjust to center it along that bottom. Here is the full code and screenshot of the blueprint: