Develop Reference

Constraint Layout Vertical Align Center - Two Child Views

I have two TextViews, one above the other. I would like the vertical middle of the two TextViews to be at the same position as the vertical middle of the ImageView. (This is so, regardless of the amount of text that may go into either TextView, everything will always look neat, vertically.)
I created what I need perfectly using two LinearLayouts (as the space above the title is the same as the space beneath the description):
But Android Studio was unable to covert it to ConstraintLayout successfully, as it just dumped the TextViews at the bottom of the layout. I've played with a lot of attributes, but could not quite arrive at the desired layout.
My question is similar to this one, except that I am trying to center_vertical align a pair of views rather than a single one - which means I have no view edge to align to the centre of the ImageView/container.
Is it possible to achieve what I'm after with ConstraintLayout? (I expect I may be able to do it with a single RelativeLayout, but I would like to use the layout_constraintDimensionRatio attribute on my ImageView which presumably leave me needing to use ConstraintLayout.)
In case it helps, here's the code for my aforementioned LinearLayout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
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="wrap_content"
android:orientation="horizontal">
<ImageView
android:id="#+id/imageView"
android:layout_width="#dimen/resources_list_image_size"
android:layout_height="#dimen/resources_list_image_size"
android:layout_marginEnd="#dimen/activity_horizontal_margin"
android:layout_marginRight="#dimen/activity_horizontal_margin"
android:layout_gravity="center_vertical"
android:contentDescription="#string/resource_image"
android:scaleType="centerCrop"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:orientation="vertical">
<TextView
android:id="#+id/textViewTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="#style/MyTextAppearanceMedium"
tools:text="Title" />
<TextView
android:id="#+id/textViewDescription"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="#style/MyTextAppearanceSmall"
tools:text="Description" />
</LinearLayout>
</LinearLayout>
Update: Solution
Thanks to Ben P's answer, this is my final code:
<?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="wrap_content">
<!-- Add guideline to align imageView to. -->
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.3" />
<ImageView
android:id="#+id/imageView"
android:layout_width="0dp"
android:layout_height="0dp"
android:contentDescription="#string/resource_image"
android:scaleType="centerCrop"
app:layout_constraintDimensionRatio="H,1:1"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#id/guideline"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
<TextView
android:id="#+id/textViewTitle"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="#dimen/activity_horizontal_margin"
android:layout_marginLeft="#dimen/activity_horizontal_margin"
app:layout_constraintBottom_toTopOf="#id/textViewDescription"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/imageView"
app:layout_constraintTop_toTopOf="parent"
android:textAppearance="#style/MyTextAppearanceMedium"
app:fontFamily="#font/roboto_slab_regular"
app:layout_constraintVertical_chainStyle="packed"
tools:text="#string/enter_title_colon" />
<TextView
android:id="#+id/textViewDescription"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="#dimen/activity_horizontal_margin"
android:layout_marginLeft="#dimen/activity_horizontal_margin"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/imageView"
app:layout_constraintTop_toBottomOf="#id/textViewTitle"
app:fontFamily="#font/roboto_slab_light"
android:textAppearance="#style/MyTextAppearanceSmall"
tools:text="Description" />
</androidx.constraintlayout.widget.ConstraintLayout>

It sounds like you could solve this problem by using a packed chain anchored to the top and bottom of the ImageView. You'll also need to use horizontal bias and a constrained width in order to get wrapping to work correctly.
<?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">
<View
android:id="#+id/anchor"
android:layout_width="80dp"
android:layout_height="80dp"
android:layout_margin="64dp"
android:background="#caf"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<TextView
android:id="#+id/one"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintVertical_chainStyle="packed"
app:layout_constraintHorizontal_bias="0"
app:layout_constrainedWidth="true"
app:layout_constraintTop_toTopOf="#id/anchor"
app:layout_constraintStart_toEndOf="#id/anchor"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toTopOf="#id/two"/>
<TextView
android:id="#+id/two"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintHorizontal_bias="0"
app:layout_constrainedWidth="true"
app:layout_constraintTop_toBottomOf="#id/one"
app:layout_constraintStart_toEndOf="#id/anchor"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="#id/anchor"/>
</androidx.constraintlayout.widget.ConstraintLayout>
The important attributes here are:
app:layout_constraintVertical_chainStyle="packed" on the first view, which causes the two textviews to stack right on top of each other
app:layout_constraintHorizontal_bias="0" on both views, which means that when the text is not long enough to reach the edge of the screen it will stick to the edge of the anchor view
app:layout_constrainedWidth="true" on both views, which prevents the textview from ever being wider than its constraints, and so the text wraps to a new line

If you want to use ConstraintLayout you could use something like this:
<?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">
<ImageView
android:id="#+id/imageView"
android:layout_width="200dp"
android:layout_height="200dp"
android:contentDescription="description"
android:scaleType="centerCrop"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="#+id/imageView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/imageView"
app:layout_constraintTop_toTopOf="#+id/imageView">
<TextView
android:id="#+id/textViewTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:text="Title" />
<TextView
android:id="#+id/textViewDescription"
android:layout_width="match_parent"
android:layout_height="wrap_content"
tools:text="Description" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

You can use this layout:
<?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">
<TextView
android:id="#+id/textView2"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#color/colorAccent"
android:text="I am 5% of the screen height"
app:layout_constraintBottom_toTopOf="#+id/textView3"
app:layout_constraintEnd_toEndOf="#+id/textView3"
app:layout_constraintHeight_percent="0.05"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="#+id/textView3"
app:layout_constraintTop_toTopOf="#+id/imageView2" />
<TextView
android:id="#+id/textView3"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintHeight_percent="0.15"
android:layout_marginStart="8dp"
android:layout_marginEnd="8dp"
android:background="#color/colorPrimary"
android:text="I am 15% of the screen height (And the image is 20% screen size in height) "
app:layout_constraintBottom_toBottomOf="#+id/imageView2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/imageView2"
app:layout_constraintTop_toBottomOf="#+id/textView2" />
<ImageView
android:id="#+id/imageView2"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintHeight_percent="0.20"
app:layout_constraintDimensionRatio="1:1"
android:scaleType="fitXY"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/rose" />
</android.support.constraint.ConstraintLayout>
It will look like this:
One important thing about this layout:
You can control your aspect ratio (for the image) with app:layout_constraintDimensionRatio="x:y" and by passing "1:1" make it square
And by the way - I am using support library for no reason on this example, you can use androidx

Android - Constraint Layout - Alignment of Text and Icon

first of all I am new to Android-Development.
My question is regards alignment of different views in Android Studio/Development.
Specifically the properly height-alignment of an icon and text.
Icon-Text-Alignment
As you can see, I tried to align the text with the icon. However the result looks slightly different in the emulator.
Here is my .xml-file:
<?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=".DashboardActivity">
<TextView
android:id="#+id/textView3"
android:layout_width="0dp"
android:layout_height="50dp"
android:layout_marginStart="32dp"
android:layout_marginTop="32dp"
android:layout_marginBottom="352dp"
android:fontFamily="#font/poppins_medium"
android:text="Dashboard"
android:textAlignment="viewStart"
android:textColor="#color/colorText"
android:textSize="30sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/imageView10"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.04" />
<ImageView
android:id="#+id/imageView10"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_marginEnd="32dp"
app:layout_constraintBottom_toBottomOf="#+id/textView3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/textView3"
app:layout_constraintTop_toTopOf="#+id/textView3"
app:srcCompat="#drawable/ic_settings_black_24dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
My questions are:
1. How can i fix the alignment of these two views?
2. Why is the result in the emulator different?
3. Is there a best-practice to align views properly?

<?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=".DashboardActivity">
<TextView
android:id="#+id/textView3"
android:layout_width="0dp"
android:layout_height="50dp"
android:layout_marginStart="32dp"
android:layout_marginTop="32dp"
android:layout_marginBottom="352dp"
android:fontFamily="#font/poppins_medium"
android:text="Dashboard"
android:textAlignment="viewStart"
android:textColor="#color/colorText"
android:textSize="30sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toStartOf="#+id/imageView10" />
<ImageView
android:id="#id/imageView10"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_marginEnd="32dp"
app:srcCompat="#drawable/ic_settings_black_24dp"
app:layout_constraintTop_toTopOf="#id/textView3"
app:layout_constraintBottom_toBottomOf="#id/textView3"
app:layout_constraintEnd_toEndOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

You can do this simply by using a custom toolbar and adding a menu to it.

Try using Custom toolbar :
<LinearLayout 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"
tools:context=".terminalShortActivity">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#4EACE2"
app:popupTheme="#style/ThemeOverlay.AppCompat">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:orientation="horizontal">
<TextView
style="#style/TextAppearance.AppCompat.Widget.ActionBar.Title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Terminal Shortcuts"
android:textColor="#FFFFFF" />
</LinearLayout>
</androidx.appcompat.widget.Toolbar>
</LinearLayout>

So I dig into the alignment issue a little further and came up with a few "solutions". Generally speaking and to answer my questions the "Custom Toolbar" is not the right solution to align the views.
The problem lies in the padding of fonts. Android take the whole view to align views and not as assumed the "text" only. Therefore the alignment looks off.
Different paddings/fonts
Poppinsmedium: without padding
Poppinsmedium: with padding; normal state
Android-Font: with padding; normal state
The bottom-padding can be eliminated with the following code:
android:includeFontPadding="false"
Or check this thread for more in-depth knowledge of the issues of font-padding.
To align views, now I am using Chain-Constraints and do it without padding. It looks like the best-way to align views, especially Text-Views. However, I have to say that despite the deleting of the bottom padding it is necessary to adjust the alignment a littlebit with the vertical-bias.
For reference:
constraintlayout.com
Android-Doc: constrain-chain

Android Studio - Why does my recycler-view get stuck without letting me scrolling to its bottom?

Description
I am using a recycler view that has more items inside than screen´s height, so to see them we should scroll down. The problem is that I can only scroll some dps down (like 10 or 20 dps).
What do I need?
I need to scroll to it´s bottom in order to see all recycler´s views.
My design is private so I am going to show you a graphic:
The blue box is my recycler view. It has ten views loaded, but we can only see two and a half. I can slide so that I can see "Daddy Yankee" full name, but not more than that.
My fragment XML code (in which I have my recycler)
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:contentDescription="#string/ayuda">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/constraint_bar"
android:layout_width="match_parent"
android:layout_height="50dp"
android:elevation="2dp"
android:contentDescription="#string/ayuda"
android:paddingTop="5dp"
android:paddingBottom="5dp"
android:background="#8d6e63"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<ImageButton
android:id="#+id/imgbt_back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:contentDescription="#string/ayuda"
android:background="?selectableItemBackgroundBorderless"
android:src="#drawable/icon_back_negro"
android:tint="#ffffff"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/txt_lobby"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="15dp"
android:contentDescription="#string/ayuda"
android:text="Lobby"
android:textColor="#ffffff"
android:textSize="15.5sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toEndOf="#+id/imgbt_back"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
<TextView
android:id="#+id/txt_names"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginTop="20dp"
android:text="(10) names"
android:fontFamily="#font/arimo"
android:textColor="#000000"
android:textSize="16sp"
app:layout_constraintTop_toBottomOf="#id/constraint_bar"
app:layout_constraintLeft_toLeftOf="parent"
android:contentDescription="#string/ayuda"/>
<View
android:id="#+id/view_barra0"
android:layout_width="match_parent"
android:layout_height="1.5dp"
android:layout_marginTop="5dp"
android:background="#eeeeee"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#id/txt_names"
android:contentDescription="#string/ayuda"/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycler_names"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/view_barra0"
app:layout_constraintLeft_toLeftOf="parent"
android:contentDescription="#string/ayuda"/>
</androidx.constraintlayout.widget.ConstraintLayout>
What can I do to slide my recycler to the bottom to be able to see all the other views?

Add this constraint on your id/recycler_names:
app:layout_constraintBottom_toBottomOf="parent"
and then set layout_height to 0dp (match constraint).

How to place the controls of an Exoplayer outside of the PlayerView

I'm using Exoplayer2 to show videos in my application. I need the controls to be visible at all time. I can archive this by setting app:show_timeout="0". But when the controls are always visible they take up space in the PlayerView.
I would like to show the controls beneath the PlayerView, so that I can always show to whole video.
This is my layout file:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".MediaPlayerActivity"
android:theme="#android:style/Theme.NoTitleBar"
android:contentDescription="hf_hide_help">
<com.google.android.exoplayer2.ui.PlayerView
android:id="#+id/playerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:use_controller="true"
app:rewind_increment="0"
app:fastforward_increment="0"
app:repeat_toggle_modes="none"
app:show_timeout="0"
/>
</RelativeLayout>
And this is my exo_player_control_view.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:layoutDirection="ltr"
android:background="#CC000000"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:paddingTop="4dp"
android:orientation="horizontal">
<ImageButton android:id="#id/exo_play"
style="#style/ExoMediaButton.Play"/>
<ImageButton android:id="#id/exo_pause"
style="#style/ExoMediaButton.Pause"/>
<TextView android:id="#id/exo_position"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="14sp"
android:textStyle="bold"
android:paddingLeft="4dp"
android:paddingRight="4dp"
android:includeFontPadding="false"
android:textColor="#FFBEBEBE"/>
<com.google.android.exoplayer2.ui.DefaultTimeBar
android:id="#id/exo_progress"
android:layout_width="0dp"
android:layout_weight="1"
android:layout_height="26dp"/>
<TextView android:id="#id/exo_duration"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="14sp"
android:textStyle="bold"
android:paddingLeft="4dp"
android:paddingRight="4dp"
android:includeFontPadding="false"
android:textColor="#FFBEBEBE"/>
</LinearLayout>
</LinearLayout>
This is what it looks like:
And this is what it looks like, when I click on the player - the controls hide.

Your use-case is not something general and ExoPlayer doesn't support it. In your case, you will need to disable the default controls and add your own custom controls beneath the player view. It would be very easy to build the layout and add the actions to them.
Update: (To answer Gyan's comment about time-bar)
Two approaches: (I explain the strategies since thousands of code examples are available already on SO and other sites)
1 - My suggestion which has worked perfectly for my needs:
override default controls view of the exoplayer (having a view with the same name in your layouts folder would do the job). Then remove all unnecessary buttons which you brought down in your custom view but just keep the time bar in overridden view. By doing that, all the appearing / disappearing behaviors are automatically kept for the time bar and you will have the rest in your own view. You wouldn't need to worry about handling the time bar if you liked that approach.
2- Just in case you insist on bringing the time bar out under the player window, what you need is a horizontal progressbar (Notice that you can customize the look of progress view to match your design). Then write a listener on exoplayer to take the timings (passed / remaining / current play-time) and calculate and update the progress of the bar based upon them. Remember that the progress bar needs to be touchable (and focusable) so that the user could drag it back and forth. Then you would need to re-calculate playtime when user drags the progress. (lots of coding and calculations obviously but almost easy stuff). Hope it works for you. If you needed code samples please let me know.

Here I have play/pause button on the video and other controls under the video, here is how to do it.
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.google.android.exoplayer2.ui.StyledPlayerView
android:id="#+id/video_view"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_gravity="center"
app:auto_show="true"
app:controller_layout_id="#layout/custom_exo_overlay_controller_view"
app:layout_constraintBottom_toTopOf="#id/exoBottomControls"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0"
app:repeat_toggle_modes="none"
app:resize_mode="fixed_width"
app:surface_type="surface_view"
app:use_controller="true" />
<com.google.android.exoplayer2.ui.StyledPlayerControlView
android:id="#+id/exoBottomControls"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
app:controller_layout_id="#layout/custom_exo_bottom_controller_view"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/video_view"
app:show_timeout="0" />
</androidx.constraintlayout.widget.ConstraintLayout>
here i am using both use_controller=true and StyledPlayerControlView.
controls which should appear on the video should go in your custom_exo_overlay_controller_view other views which should appear under the video should go in custom_exo_bottom_controller_view.
here is custom_exo_overlay_controller_view.xml
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageButton
android:id="#id/exo_play_pause"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#android:color/transparent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
and custom_exo_bottom_controller_view.xml
<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="wrap_content">
<View
android:id="#id/exo_controls_background"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#color/color_secondary_black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#id/exo_position"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginBottom="8dp"
android:textColor="#color/colorWhite"
android:textSize="14sp"
app:layout_constraintBottom_toTopOf="#+id/exo_progress"
app:layout_constraintStart_toStartOf="parent"
tools:text="00:50" />
<TextView
android:id="#id/exo_duration"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:textColor="#color/colorWhite"
android:textSize="14sp"
app:layout_constraintBottom_toTopOf="#+id/exo_progress"
app:layout_constraintEnd_toEndOf="parent"
tools:text="02:50" />
<ImageButton
android:id="#+id/exo_sound_on"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginBottom="32dp"
android:background="#android:color/transparent"
android:src="#drawable/ic_sound_on"
app:layout_constraintBottom_toTopOf="#+id/exo_duration"
app:layout_constraintEnd_toEndOf="parent" />
<ImageButton
android:id="#+id/exo_sound_off"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginBottom="32dp"
android:background="#android:color/transparent"
android:src="#drawable/ic_sound_off"
android:visibility="gone"
app:layout_constraintBottom_toTopOf="#+id/exo_duration"
app:layout_constraintEnd_toEndOf="parent" />
<com.google.android.exoplayer2.ui.DefaultTimeBar
android:id="#id/exo_progress"
android:layout_width="0dp"
android:layout_height="52dp"
app:buffered_color="#android:color/transparent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:played_color="#android:color/transparent"
app:scrubber_drawable="#drawable/ic_scrubber"
app:touch_target_height="52dp"
app:unplayed_color="#android:color/transparent" />
</androidx.constraintlayout.widget.ConstraintLayout>
also you should assign your controller like this
player = ExoPlayer.Builder(binding.root.context).build().also {
binding.videoView.player = it
binding.exoBottomControls.player = it
val mediaItem = MediaItem.fromUri(video.url)
it.setMediaItem(mediaItem)
it.seekTo(video.currentWindow, video.playbackPosition)
it.prepare()
}

How to center vertically the ConstraintLayout content in Android Studio?

I'm begginer with Android Studio and I'm trying to center vertically content of ConstraintLayout, but without success. I've tried to use android:gravity="center" and I removed the app:layout_editor_absoluteY of all the elements, but not happens... So, how can I centralize 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:background="#layout/gradient"
android:gravity="center"
tools:context="com.test.test.MainActivity"
tools:layout_editor_absoluteY="81dp"
tools:layout_editor_absoluteX="0dp">
<EditText
android:id="#+id/txtEmail"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:ems="10"
android:hint="#string/lblEmail"
android:inputType="textEmailAddress"
android:textColorHint="#color/colorGray"
android:background="#color/colorWhite"
android:padding="15dp" />
<EditText
android:id="#+id/txtSenha"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:ems="10"
android:hint="#string/lblSenha"
android:inputType="textPassword"
android:textColorHint="#color/colorGray"
android:background="#color/colorWhite"
android:padding="15dp"
app:layout_constraintTop_toBottomOf="#+id/txtEmail" />
<Button
android:id="#+id/btnEntrar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:text="#string/lblEntrar"
app:layout_constraintTop_toBottomOf="#+id/txtSenha" />
</android.support.constraint.ConstraintLayout>

ConstraintLayout is pretty flexible in the arrangements you can make, but from your description I think a "Packed Chain" would fit what your asking for.
A "Chain" means that all the Views in a line constrain to each other in both directions, so the top view constrains to the next view down and that next view constrains back up to the top view and so on down the chain. You then have some options for how the chain behaves. So in your example(extra stuff removed for simplicity):
<android.support.constraint.ConstraintLayout
....
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="#+id/txtEmail"
android:layout_width="match_parent"
android:layout_height="wrap_content"
...
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#+id/txtSenha"
app:layout_constraintVertical_chainStyle="packed" />
<EditText
android:id="#+id/txtSenha"
android:layout_width="match_parent"
android:layout_height="wrap_content"
...
app:layout_constraintTop_toBottomOf="#+id/txtEmail"
app:layout_constraintBottom_toTopOf="#+id/btnEntrar"/>
<Button
android:id="#+id/btnEntrar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
...
app:layout_constraintTop_toBottomOf="#+id/txtSenha"
app:layout_constraintBottom_toBottomOf="parent"/>
</android.support.constraint.ConstraintLayout>
In a chain, the top view(or left for horizontal chains) is the "head" where you can change the behaviour of the chain, in this case the chainStyle is packed meaning the views all cram together. By default they will be packed in the centre of the screen, but you can change this by altering the attributes in the "head" view, eg app:layout_constraintVertical_bias="0.9" would put them 90% of the way down the screen instead.
More about chains (including diagrams) in the ConstraintLayout guidance here.