I have a horizontal RecyclerView inside a ConstraintLayout. I want to place a button at the end of the RecyclerView. When the recycler is empty, the button should expand to all available space. When items are added to the recycler, the button should squeeze down to a minimum.
There are some new additions to ConstraintLayout 1.1.0, like layout_constraintWidth_min, but I don't get it working. Is it supposed to work the way I intend?
Here are the relevant attributes, not including height:
<android.support.v7.widget.RecyclerView
android:id="#+id/horizontal_recycler"
android:layout_width="wrap_content"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#+id/add">
</android.support.v7.widget.RecyclerView>
and
<Button
android:id="#+id/add"
android:layout_width="0dp"
app:layout_constraintWidth_min="80dp"
app:layout_constraintStart_toEndOf="#+id/horizontal_recycler"
app:layout_constraintEnd_toEndOf="parent">
</Button>
So here is my solution.
<android.support.constraint.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.support.v7.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="wrap_content"
android:layout_height="200dp"
android:layout_marginEnd="80dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button"
android:layout_width="80dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text="ADD"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/recyclerView"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
Please note that in order to keep the recyclerView from squishing the button the margin end on the recycler should equal the button with plus any padding and margin you see fit to have.
Related
Hey I am working in constraint layout with recylerview. My bottom item is cut in the screen. I read this stack overflow post. I don't want to use relative layout or linear layout. Can someone guide me how to fix this in constraint layout.
abc.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"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.appcompat.widget.SearchView
android:id="#+id/searchView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="16dp"
app:closeIcon="#drawable/ic_cancel"
app:layout_constraintBottom_toTopOf="#+id/exploreScroll"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed"
app:layout_constraintVertical_bias="0.0" />
<HorizontalScrollView
android:id="#+id/exploreScroll"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:scrollbars="none"
app:layout_constraintBottom_toTopOf="#+id/exploreList"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/searchView">
<com.google.android.material.chip.ChipGroup
android:id="#+id/exploreChips"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:chipSpacingHorizontal="10dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:singleLine="true"
app:singleSelection="true" />
</HorizontalScrollView>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/exploreList"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="20dp"
android:paddingTop="10dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/exploreScroll" />
</androidx.constraintlayout.widget.ConstraintLayout>
My view cut from
UPDATE
#Zain after your suggestion i tried in my xml any my HorizontalScrollView is going behind my RV. I am adding my blueprint and you can see clearly that, HorizontalScrollView is going behind. After removing app:layout_constraintBottom_toTopOf="#+id/exploreList" from the HorizontalScrollView.
2nd suggestion try
Disclaimer Using a wrap_content height with vertical RecyclerView
can have impact on performance in terms of recycling views; specially
if the height is going to change frequently. Check this article
for more illustration.
So, the first step is to designate the RecyclerView height or to constraint it; from the constraints you want it to expand to the bottom; so use 0dp for that. But in order to make the minimum height to wrap content of the RecyclerView (in case that the items don't exceed the screen height); you can set the default height constraint to wrap with app:layout_constraintHeight_default="wrap" constraint.
Then remove app:layout_constraintBottom_toTopOf="#+id/exploreList" from the HorizontalScrollView, this actually made the bottom item of the RV hide (your main issue); because it is an over-constraint; the HorizontalScrollView tends to push the RV to the bottom while the RV tends to push the HorizontalScrollView to the top.
This will solve the main issue; but when the items are fully accommodated by the screen (no scrolling in the RV), then it will be biased in the middle; to fix this use the bias with app:layout_constraintVertical_bias="0.0" to be biased to the top.
Adding this in place into the 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"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.appcompat.widget.SearchView
android:id="#+id/searchView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="16dp"
app:closeIcon="#drawable/ic_cancel"
app:layout_constraintBottom_toTopOf="#+id/exploreScroll"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0"
app:layout_constraintVertical_chainStyle="packed" />
<HorizontalScrollView
android:id="#+id/exploreScroll"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:scrollbars="none"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/searchView">
<com.google.android.material.chip.ChipGroup
android:id="#+id/exploreChips"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:chipSpacingHorizontal="10dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:singleLine="true"
app:singleSelection="true" />
</HorizontalScrollView>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/exploreList"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginBottom="20dp"
android:paddingTop="10dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHeight_default="wrap"
app:layout_constraintVertical_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/exploreScroll" />
</androidx.constraintlayout.widget.ConstraintLayout>
I'm putting together a screen with 3 controls stacked vertically. Specifically, a RecyclerView sandwiched between two TextView. I have two situations I am trying to address.
When few items are displayed in the RecyclerView the 3 items should be packed towards the top of the screen with blank space BELOW them.
When many items are displayed in the RecyclerView the full screen will be used with the last TextView along the bottom of the screen and scrolling in the center RecyclerView.
I'm struggling to get the position of the last TextView correct as it either gets pushed off the screen or buried behind the RecyclerView if there are many items in the RecyclerView. What I need is a way to tell the RecyclerView to wrap contents, but stop growing when it starts to push the TextView off of the screen.
Below is my layout, any suggestions?
<?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">
<TextView
android:id="#+id/topItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="#+id/middleItem"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/middleItem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="none"
app:layout_constraintBottom_toTopOf="#+id/bottomItem"
app:layout_constraintTop_toBottomOf="#+id/topItem" />
<TextView
android:id="#+id/bottomItem"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_horizontal|top"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#+id/middleItem" />
</androidx.constraintlayout.widget.ConstraintLayout>
Try the following:
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/topItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="This is the top item."
app:layout_constraintBottom_toTopOf="#+id/middleItem"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0"
app:layout_constraintVertical_chainStyle="packed" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/middleItem"
android:layout_width="0dp"
android:layout_height="0dp"
android:scrollbars="none"
app:layout_constrainedHeight="true"
app:layout_constraintBottom_toTopOf="#+id/bottomItem"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/topItem"
tools:itemCount="3" />
<TextView
android:id="#+id/bottomItem"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:gravity="center_horizontal|top"
android:text="This is the bottom item."
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/middleItem" />
</androidx.constraintlayout.widget.ConstraintLayout>
With three items in the RecyclerView:
With 50 items in the RecyclerView:
The key changes are:
Added app:layout_constraintVertical_bias="0.0" to the top TextView to position the chain always at the top;
Added app:layout_constrainedHeight="true" to the RecyclerView to make sure views don't go off-screen;
Changed match_parent to 0dp and set the horizontal constraints for direct children of the ConstraintLayout.
Changed the RecyclerView's height to '0dp'.
Update: Although the above works, it is a little overdone. As noted in the comments, the same effect can be accomplished by simply setting the height of the RecyclerView to 0dp.
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/topItem"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="This is the top item."
app:layout_constraintBottom_toTopOf="#+id/middleItem"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/middleItem"
android:layout_width="0dp"
android:layout_height="0dp"
android:scrollbars="none"
app:layout_constraintBottom_toTopOf="#+id/bottomItem"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/topItem"
tools:itemCount="3" />
<TextView
android:id="#+id/bottomItem"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:gravity="center_horizontal|top"
android:text="This is the bottom item."
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/middleItem" />
</androidx.constraintlayout.widget.ConstraintLayout>
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).
I have a simple side bar with 2 buttons vertical chained and i want my side bar to wrap largest button while smaller button expands to match largest one.
Here is a capture where i want "AAA" button to match "VALIDATE" button width
Of course what poped my mind is to use match contraint width for both buttons but when using a wrap_content container this leads to:
my 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:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="bottom"
android:background="?attr/colorSurface"
android:padding="#dimen/screen_padding">
<com.google.android.material.button.MaterialButton
android:id="#+id/redo_button"
style="#style/AppStyle.Button.OutlinedButton.SecondaryVariantStroke"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="#dimen/spacing_normal"
android:text="aaa"
app:layout_constrainedWidth="false"
app:layout_constraintBottom_toTopOf="#+id/validate_button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<ImageView
android:layout_width="32dp"
android:layout_height="0dp"
android:layout_marginStart="8dp"
android:background="#drawable/shape_circle_secondary_variant"
android:padding="7dp"
android:src="#drawable/ic_camera"
android:tint="#android:color/white"
app:layout_constraintBottom_toBottomOf="#+id/redo_button"
app:layout_constraintDimensionRatio="h,1:1"
app:layout_constraintEnd_toEndOf="#+id/redo_button"
app:layout_constraintStart_toEndOf="#+id/redo_button"
app:layout_constraintTop_toTopOf="#+id/redo_button"
tools:ignore="ContentDescription" />
<com.google.android.material.button.MaterialButton
android:id="#+id/validate_button"
style="#style/AppStyle.Button.OutlinedButton"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="#string/global_valid"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/redo_button" />
</androidx.constraintlayout.widget.ConstraintLayout>
If you know which button is going to be wider, then you can make that button wrap_content and constrain the other button to it as follows:
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="bottom"
android:background="#android:color/darker_gray"
android:padding="16dp">
<Button
android:id="#+id/redo_button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="aaa"
app:layout_constrainedWidth="false"
app:layout_constraintBottom_toTopOf="#+id/validate_button"
app:layout_constraintEnd_toEndOf="#+id/validate_button"
app:layout_constraintStart_toStartOf="#+id/validate_button"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<Button
android:id="#+id/validate_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Validate"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/redo_button" />
</androidx.constraintlayout.widget.ConstraintLayout>
If this solves your problem, stop here.
Things get a little more complicated if you don't know in advance which button will be wider. (Maybe due to language changes.) In that case, you can check the sizes programmatically and explicitly expand the narrower button. You may consider this less than ideal.
As for accomplishing this in XML, I have looked at this type of problem in the past and the problem always reduces to some kind of circular reference issue. (In fact, this is the problem that you are having with match_constraints widgets in a wrap_content container. The widgets are as wide as the container and the container is as wide as the widgets! What?)
If you don't know which button will be wider, you can create an invisible button that has two lines of text that correspond to the labels of your buttons (assuming single line labels.)
Now that there is a dummy button that is the right width, constrain the sides of your buttons to the sides of the dummy button and make their width match_constraints.
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="bottom"
android:background="#android:color/darker_gray"
android:padding="16dp">
<Button
android:id="#+id/dummyForSizing"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="aaa\nValidate"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/redo_button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="aaa"
app:layout_constrainedWidth="false"
app:layout_constraintBottom_toTopOf="#+id/validate_button"
app:layout_constraintEnd_toEndOf="#+id/dummyForSizing"
app:layout_constraintStart_toStartOf="#+id/dummyForSizing"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<Button
android:id="#+id/validate_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Validate"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/dummyForSizing"
app:layout_constraintStart_toStartOf="#+id/dummyForSizing"
app:layout_constraintTop_toBottomOf="#+id/redo_button" />
</androidx.constraintlayout.widget.ConstraintLayout>
You would, of course, make the dummy button invisible.
I want to make the following design using ConstraintLayout. The screen should be devided into a top section (50% of screen), and a bottom section (50% of screen). The top section should be able to hide according to some application logic, making the bottom section use the remaining blank space on top.
My layout is as follows:
<ImageView
android:id="#+id/imageView"
android:layout_width="0dp"
android:layout_height="0dp"
android:visibility="visible"
app:layout_constraintBottom_toTopOf="#+id/guideline"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0"
app:srcCompat="#android:drawable/ic_input_add" />
<android.support.constraint.Guideline
android:id="#+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.5" />
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView" />
Comparison image showing on the left side how the layout looks with both sections visible. On the right side the top section is gone but the bottom RecyclerView does not stretch to use the top space. I added padding to the ImageView and RecyclerView to better illustrate the relationship between the views.
You can set equal vertical weights for both views in the chain so each occupies 50% of the space. If you set the top view's visibility to GONE in code or in XML, the bottom view will fill the remaining space.
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/recyclerView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#android:drawable/ic_input_add"
app:layout_constraintVertical_weight="1" />
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView"
app:layout_constraintVertical_weight="1" />
</android.support.constraint.ConstraintLayout>