Middle of the button isn't placed to the bottom of another view

Question

I have the following situation: I want to place my button to the bottom of ImageView (situation is the same as you can see in this question). I have the following xml layout:

<?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=".ui.profile.ProfileFragment">

    <androidx.coordinatorlayout.widget.CoordinatorLayout
        android:id="@+id/coordinator_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <ImageView
            android:id="@+id/iv_background_avatar"
            android:layout_width="match_parent"
            android:layout_height="350dp"
            android:scaleType="centerCrop"
            android:src="@drawable/profile_background"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:ignore="ContentDescription" />


        <com.google.android.material.floatingactionbutton.FloatingActionButton
            android:id="@+id/btn_log_out"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_marginEnd="@dimen/base_margin"
            android:src="@drawable/logout"
            app:layout_anchor="@+id/iv_background_avatar"
            app:layout_anchorGravity="end|bottom" />

    </androidx.coordinatorlayout.widget.CoordinatorLayout>

    <de.hdodenhof.circleimageview.CircleImageView
        android:id="@+id/iv_avatar"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_marginTop="@dimen/base_margin"
        app:civ_border_color="#000000"
        app:civ_border_width="2dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:src="@tools:sample/avatars" />

    <TextView
        android:id="@+id/tv_login"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/base_margin"
        android:layout_marginTop="@dimen/base_margin"
        android:layout_marginEnd="@dimen/base_margin"
        android:text="@string/login"
        android:textAlignment="center"
        app:layout_constraintTop_toBottomOf="@id/coordinator_layout" />

    <TextView
        android:id="@+id/tv_id"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/base_margin"
        android:layout_marginTop="@dimen/base_margin"
        android:layout_marginEnd="@dimen/base_margin"
        android:text="@string/id"
        android:textAlignment="center"
        app:layout_constraintTop_toBottomOf="@id/tv_login" />

    <TextView
        android:id="@+id/tv_email"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginStart="@dimen/base_margin"
        android:layout_marginTop="@dimen/base_margin"
        android:layout_marginEnd="@dimen/base_margin"
        android:autoLink="email"
        android:clickable="true"
        android:focusable="true"
        android:text="@string/email"
        android:textAlignment="center"
        app:layout_constraintTop_toBottomOf="@id/tv_id" />


</androidx.constraintlayout.widget.ConstraintLayout>

As in the question, which is higher, I added Coordinator Layout, but it allows me only to place FAB in the corners and middles of the sides of avatar while I need to place it to the bottom|end corner of background iv and I specified it in attribute.But unfortunately FAB isn't placed as it need to be (sorry for such a background color):

So, how can I solve this problem?

Answer 1

You can use ConstraintLayout to achieve this "view over view" look.

Here is an example using ConstraintLayout without using fixed sizes:

<?xml version="1.0" encoding="utf-8"?>


<android.support.constraint.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"
  android:orientation="vertical">

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="8dp"
    android:text="FAB"
    app:layout_constraintBottom_toBottomOf="@+id/imageView"
    app:layout_constraintEnd_toEndOf="@+id/imageView"
    app:layout_constraintStart_toStartOf="@+id/imageView"
    app:layout_constraintTop_toBottomOf="@+id/imageView" />

<ImageView
    android:id="@+id/imageView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.5"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:srcCompat="@tools:sample/avatars[7]" />

</android.support.constraint.ConstraintLayout>

And it will look like this:

And now if you want to change the position of your button horizontally all you need to do is change one constraint and you got it.

---

For example - if you want your button to be aligned to the right side you can do something like this:

<?xml version="1.0" encoding="utf-8"?>


<android.support.constraint.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"
  android:orientation="vertical"
 >

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="FAB"
    app:layout_constraintBottom_toBottomOf="@+id/imageView"
    app:layout_constraintEnd_toEndOf="@+id/imageView"
    app:layout_constraintTop_toBottomOf="@+id/imageView" />

<ImageView
    android:id="@+id/imageView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="8dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    tools:srcCompat="@tools:sample/avatars[7]" />

</android.support.constraint.ConstraintLayout>

And it will look like this:

---

Please notice:

Different phones got different screen size, in your layout you are using fixed-size on your views and the result is that what may look good on one screen will not look good on another screen.

In my examples, I was using wrap_content instead of fixed sizes.

I know that using wrap_content is not ideal as well for responsive layout, if you want your layout to be responsive to all screen sizes I can recommend to use Guidelines