custom ViewGroup example?
I think the simplest example to look at is the source for AbsoluteLayout.java
You need to override onMeasure to measure the children and onLayout to position them.
I have strikingly more complicated ViewGroup code I can share as well if you want.
It't quite simple, all you need to do is to call super.onMeasure after calculate the exact dimentions of yout view.
class ProportionalConstraintLayout @JvmOverloads constructor( context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) : ConstraintLayout(context, attrs, defStyleAttr) { override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) { val exactWidth = 100 //do something to calculate the view widht val exactHeight = 100 //do something to calculate the view height setMeasuredDimension(exactWidth, exactHeight) super.onMeasure( MeasureSpec.makeMeasureSpec(exactWidth, MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(exactHeight, MeasureSpec.EXACTLY) ) }}