I am trying to resolve an issue that is stopping my development.

I want to position an imageview so it is in the center of a frame layout using code.

I have been trying various solutions but do not seem to be able to achieve my goal.

Code

package com.example.testmovingobject

import android.content.Context
import android.os.Bundle
import android.util.DisplayMetrics
import android.widget.ImageView
import android.widget.TextView
import androidx.activity.enableEdgeToEdge
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    private lateinit var star: ImageView
    lateinit var directionText: TextView
    lateinit var background: ImageView
    lateinit var outMetrics : DisplayMetrics
    lateinit var context: Context

    private val testDirections = arrayOf(
        "North",
        "South",
        "East",
        "West",
        "North",
        "South",
        "East",
        "West"
    )
    private var topBorderHeight = 50f
    private var startX : Float = 0f
    private var startY : Float = 0f
    private var height = 13f
    private var width = 7f
    private var left = 0f
    private var top = 0f
    private var screenHeight = 0f
    private var screenWidth = 0f
    private var backgroundPos = IntArray(2)


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        context = getApplicationContext()
        setContentView(R.layout.main)


        Start()
    }



    private fun Start()
    {
        outMetrics = context.resources.displayMetrics
        screenHeight = outMetrics.heightPixels.toFloat()
        println("Start.metrics height="+screenHeight)
        screenWidth = outMetrics.widthPixels.toFloat()
        println("Start.metrics width="+screenWidth)
        background = findViewById(R.id.background)
        println("Start.background size="+background.getWidth()+" "+background.getHeight())
        star = findViewById(R.id.star)
        star.setBackgroundResource(R.drawable.star)
        println("Start.star parent="+star.parent)
        println("Start.star pos b4 x="+star.x+" star pos y="+star.y )

        background.getLocationOnScreen(backgroundPos)
        println("Start.background pos x="+backgroundPos[0]+" pos y="+backgroundPos[1])

        directionText = findViewById(R.id.messages)
        height = background.getHeight().toFloat()
        println("Start.background height="+height)
        width = background.getWidth().toFloat()
        println("Start.background width="+width)
        left = backgroundPos[0].toFloat()
        top = backgroundPos[1].toFloat()
        println("Start.background bounds left="+left+" top="+top+" width="+width+" height="+height)
        println("Start.star pos b4 x="+star.x+" star pos y="+star.y )
        startX = width / 2
        startY = height / 2
        star.x = startX
        star.y = startY
        println("Start.star pos aftr x="+star.x+" star pos y="+star.y )
        println("Start.bounds left="+left+" top="+top+" width="+width+" height="+height)
    }

}

XML

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/gameView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/grey_overlay"
    android:theme="@style/Base.Theme.TestMovingObject"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/TopBackground"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/light_blue_600"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent" />


    <ImageButton
        android:id="@+id/back_button"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:background="@color/grey_overlay"
        android:contentDescription="back"
        android:src="@drawable/ic_back"
        app:layout_constraintEnd_toEndOf="@+id/TopBackground"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="@+id/TopBackground"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/messages"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:layout_marginStart="40dp"
        android:layout_marginBottom="265dp"
        android:elevation="30dp"
        android:gravity="center"
        android:keepScreenOn="true"
        android:text="Messages"
        android:textColor="@color/black"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <FrameLayout
        android:id="@+id/frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="55dp"
        app:layout_constraintTop_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBottom_toBottomOf="parent">

        <ImageView
            android:id="@+id/background"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:contentDescription="background" />

        <ImageView
            android:id="@+id/star"
            android:layout_width="100dp"
            android:layout_height="120dp"
            android:layout_marginTop="372dp"
            android:background="@drawable/star"
            android:contentDescription="star"
            android:elevation="10dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.498"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/messages">
        </ImageView>

    </FrameLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

Screenshot when run

This image show the view of some of the xml and the device emulator and it can been seen that the star object is not postioned in the center.

Logcat output from printlns

-------------- PROCESS STARTED (5791) for package com.example.testmovingobject ----------------------------
2026-02-19 06:56:45.282  Start.metrics height=2028.0
2026-02-19 06:56:45.283  Start.metrics width=1080.0
2026-02-19 06:56:45.283  Start.background size=0 0
2026-02-19 06:56:45.283  Start.star parent=android.widget.FrameLayout{7f6878b V.E...... ......I. 0,0-0,0 #7f0800c8 app:id/frame}
2026-02-19 06:56:45.283  Start.star pos b4 x=0.0 star pos y=0.0
2026-02-19 06:56:45.283  Start.background pos x=0 pos y=0
2026-02-19 06:56:45.283  Start.background height=0.0
2026-02-19 06:56:45.283  Start.background width=0.0
2026-02-19 06:56:45.283  Start.background bounds left=0.0 top=0.0 width=0.0 height=0.0
2026-02-19 06:56:45.283  Start.star pos b4 x=0.0 star pos y=0.0
2026-02-19 06:56:45.283  Start.star pos aftr x=0.0 star pos y=0.0
2026-02-19 06:56:45.283  Start.bounds left=0.0 top=0.0 width=0.0 height=0.0
---------------- PROCESS ENDED (5791) for package com.example.testmovingobject ----------------------------