ConstraintLayout Weightsum

Question

i want to implement some thing like below image in constraint layout

Requirements :

1. Both buttons should have equal width
2. Between of buttons should be a margin
3. BTN 1 can be VISIBLE or GONE
4. If BTN 1 set to GONE , BTN 2 should remain width and move to center

I tried to use Chains but when BTN 1 gets GONE BTN 2 gets full width. Then i set layout_constraintWidth_percent="0.5" to both buttons but in this situation i can't set margin between two buttons. When is set margin , button moving out of screen. Any idea to solve this problem? Here is my code

<androidx.appcompat.widget.AppCompatButton
    android:id="@+id/btn_negative"
    style="?attr/borderlessButtonStyle"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginTop="@dimen/_24sdp"
    android:background="@drawable/btn_solid_white_round"
    android:ellipsize="end"
    android:gravity="center"
    android:maxLines="1"
    android:padding="@dimen/_8sdp"
    android:textColor="@color/darkTextColor"
    android:textSize="@dimen/_11ssp"
    app:fontFamily="@font/iran_yekan"
    app:layout_constraintEnd_toStartOf="@+id/btn_positive"
    app:layout_constraintHorizontal_bias="0.5"
    app:layout_constraintHorizontal_chainStyle="spread"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/txt_message"
    app:layout_constraintWidth_percent="0.5"
    tools:text="BTN 2" />

<androidx.appcompat.widget.AppCompatButton
    android:id="@+id/btn_positive"
    style="?attr/borderlessButtonStyle"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="@dimen/_12sdp"
    android:background="@drawable/btn_solid_accent_round"
    android:ellipsize="end"
    android:gravity="center"
    android:maxLines="1"
    android:padding="@dimen/_8sdp"
    android:textColor="@color/white"
    android:textSize="@dimen/_11ssp"
    app:fontFamily="@font/iran_yekan"
    app:layout_constraintBottom_toBottomOf="@+id/btn_negative"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.5"
    app:layout_constraintStart_toEndOf="@+id/btn_negative"
    app:layout_constraintTop_toTopOf="@+id/btn_negative"
    app:layout_constraintWidth_percent="0.5"
    tools:text="BTN 1" />

Answer 1

Don't use percent 0.5 and margin. User percent and chain only.

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/btn_negative"
        style="?attr/borderlessButtonStyle"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:background="@android:color/red"
        android:ellipsize="end"
        android:gravity="center"
        android:maxLines="1"
        android:padding="8dp"
        android:textColor="@android:color/white"
        android:textSize="11sp"
        android:visibility="gone"
        app:layout_constraintWidth_percent="0.4"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintEnd_toStartOf="@id/btn_positive"
        tools:text="BTN 2" />

    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/btn_positive"
        style="?attr/borderlessButtonStyle"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:background="@android:color/holo_green_dark"
        android:ellipsize="end"
        app:layout_constraintWidth_percent="0.4"
        android:gravity="center"
        android:maxLines="1"
        android:padding="8dp"
        android:textColor="@android:color/white"
        android:textSize="11sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toEndOf="@id/btn_negative"
        tools:text="BTN 1" />

</androidx.constraintlayout.widget.ConstraintLayout>