Develop Reference

Cannot align rows with chain restraints

I have a widget that, no matter what constraints I place upon it and other widgets, including the addition of barriers, always positions itself at the top of the layout.
This is a fairly simple arrangement of two rows of two elements each, not aligned column wise. The first element in each row is a TextView label, the second an input (Spinner).
There is also a lone TextView title above the first row stretching all the way across. By my understanding and previous experience with constraint layout, this shouldn't require a barrier between the rows, and that was my initial version.
This is the design view, where the selected element ("Credentials") is supposed to be in the second row but instead appears above the first row, over top of the title TextView ("PKIX"):
Actual result in the emulator looks much the same. The selected "Credentials" element is the fourth of five elements in the XML layout below. All of the other elements are in the right place.
<?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">
<TextView
android:id="#+id/addsrv_pkix_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#drawable/bottomborder"
android:text="PKIX"
android:textAlignment="center"
android:layout_marginHorizontal="10sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#+id/addsrv_trust_lbl"
/>
<TextView
android:id="#+id/addsrv_trust_lbl"
android:text="Trust"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#+id/addsrv_trust_spin"
app:layout_constraintTop_toBottomOf="#+id/addsrv_pkix_title"
app:layout_constraintBaseline_toBaselineOf="#+id/addsrv_trust_spin"
app:layout_constraintBottom_toTopOf="#+id/addsrv_cred_lbl"
/>
<Spinner
android:id="#+id/addsrv_trust_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toEndOf="#+id/addsrv_trust_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_pkix_title"
app:layout_constraintBottom_toTopOf="#+id/addsrv_cred_spin"
/>
<TextView
android:id="#+id/addsrv_cred_lbl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:paddingHorizontal="10sp"
android:text="Credentials"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#+id/addsrv_cred_spin"
app:layout_constraintTop_toBottomOf="#+id/addsrv_trust_lbl"
app:layout_constraintBaseline_toBaselineOf="#+id/addsrv_cred_spin"
/>
<Spinner
android:id="#+id/addsrv_cred_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toEndOf="#+id/addsrv_cred_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_trust_spin"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
I'm perplexed. The addsrv_cred_lbl TextView ("Credentials") is:
Start aligned with parent.
End aligned with the addsrv_cred_spin spinner, which appears correctly positioned;
this alignment is reciprocated to create a horizontal chain. They are also baseline
aligned.
Top aligned with the bottom of the TextView above it, addsrv_trust_lbl.
This alignment is also reciprocated.
There's no bottom alignment yet (there's another row to go); bottom aligning it with the parent makes no difference unless I bottom align the spinner from the same row, in which case the result goes from bad to worse.
Since this did not work, I tried to use a barrier between the rows. If I use it as a "top", with the second row widgets as the constraint referents, the barrier appears at the top, above the title, regardless of what constraints are used to position it below the first row. Used as a "bottom", with the first row widgets referenced and the second row chained below it (which is more logical), things are a little bit better in that the barrier appears in the right place -- but the "Credentials" widget is still up top.
The design view of this looks exactly the same as the previous one except the barrier is visible below the first row. In the XML, I aslo added optimizationLevel="none" after having read this can help with misbehaving barriers (but it made no difference). There's also a few stylistic elements added back here (such as font size) I removed for brevity before.
<?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"
app:layout_optimizationLevel="none"
>
<TextView
android:id="#+id/addsrv_pkix_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#drawable/bottomborder"
android:backgroundTint="#color/tbar"
android:text="PKIX"
android:textAlignment="center"
android:textSize="#dimen/addsrv_bigfont"
android:textColor="#color/titleText"
android:layout_marginHorizontal="10sp"
app:layout_constraintBottom_toTopOf="#+id/addsrv_trust_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
/>
<TextView
android:id="#+id/addsrv_trust_lbl"
android:text="Trust"
android:textSize="#dimen/addsrv_fontsz"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#+id/addsrv_trust_spin"
app:layout_constraintTop_toBottomOf="#+id/addsrv_pkix_title"
app:layout_constraintBaseline_toBaselineOf="#+id/addsrv_trust_spin"
app:layout_constraintBottom_toTopOf="#+id/addsrv_bar1"
app:layout_constraintHorizontal_chainStyle="packed"
/>
<Spinner
android:id="#+id/addsrv_trust_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toEndOf="#+id/addsrv_trust_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_pkix_title"
app:layout_constraintBottom_toTopOf="#+id/addsrv_bar1"
/>
<androidx.constraintlayout.widget.Barrier
android:id="#+id/addsrv_bar1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:barrierDirection="bottom"
app:constraint_referenced_ids="addsrv_trust_lbl,addsrv_trust_spin"
app:layout_constraintBottom_toTopOf="#+id/addsrv_cred_lbl"
/>
<TextView
android:id="#+id/addsrv_cred_lbl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
android:text="Credentials"
android:textSize="#dimen/addsrv_fontsz"
app:layout_constraintBaseline_toBaselineOf="#+id/addsrv_cred_spin"
app:layout_constraintEnd_toStartOf="#+id/addsrv_cred_spin"
app:layout_constraintHorizontal_chainStyle="packed"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_bar1" />
<Spinner
android:id="#+id/addsrv_cred_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toEndOf="#+id/addsrv_cred_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_bar1"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
Am I correct in observing that some of the constraints on addsrv_cred_lbl are being completely ignored? Doesn't topToBottom mean that the top of the widget is aligned with the bottom of the other? Instead, it seems simply to mean that they will be connected with a squiggly, potentially curved and convoluted line in the design view, and the spacial relation of the two widgets is arbitrary, such that the semantic logic might as well be inverted, "top = bottom, bottom = top", etc.
Please note that I do not want to use absolute values to position anything. If the only way to get this to work is to do that, constraint layout seems a complete waste of time even in this simple case, and I'd rather just stack some liner layouts.

The problem is that Spinner doesn't have a baseline. You were trying to tie it to the baseline of the item inside the Spinner is my guess - ConstraintLayout can't reach children of its children.
You can check it via the design tab with a right click. TextViews will show an option "Show baseline" but the Spinner doesn't.
Also snippet from the doc
Align the text baseline of a view to the text baseline of another
view.
That's what baselines are for, if you want two TextViews connect together so they don't have the height where the text starts messed up.
I think there is a tiny flaw in your approach to the chain. You were setting the top constraint of both elements in each row to the bottom of the previous row(or title in the first row). Even if the Spinner would have a baseline, this would make the label off-centered in relation to the Spinner(slightly higher because the baseline of a text is higher than the actual bottom of the view).
I think the best approach in these types of layouts is to have one guiding element(which is also the element of the chain) that represents the row and let other elements be positioned in relation to 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">
<TextView
android:id="#+id/addsrv_pkix_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="PKIX"
android:textAlignment="center"
android:layout_marginHorizontal="10sp"
app:layout_constraintVertical_chainStyle="spread"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#+id/addsrv_trust_spin"
/>
<TextView
android:id="#+id/addsrv_trust_lbl"
android:text="Trust"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#+id/addsrv_trust_spin"
app:layout_constraintTop_toTopOf="#+id/addsrv_trust_spin"
app:layout_constraintBottom_toBottomOf="#+id/addsrv_trust_spin"
/>
<Spinner
android:id="#+id/addsrv_trust_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toEndOf="#+id/addsrv_trust_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_pkix_title"
app:layout_constraintBottom_toTopOf="#+id/addsrv_cred_spin"
/>
<TextView
android:id="#+id/addsrv_cred_lbl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
android:text="Credentials"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toStartOf="#+id/addsrv_cred_spin"
app:layout_constraintTop_toTopOf="#+id/addsrv_cred_spin"
app:layout_constraintBottom_toBottomOf="#+id/addsrv_cred_spin"
/>
<Spinner
android:id="#+id/addsrv_cred_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintStart_toEndOf="#+id/addsrv_cred_lbl"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/addsrv_trust_spin"
app:layout_constraintBottom_toBottomOf="parent"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
NOTE: I added the last bottom constraint to the parent and "spread" to the chain for demonstration but also know that if you don't have the bottom of the last view constrained to something - it's not a chain.

Working with ConstraintLayout is easy if you obey few simple rules:
Create one chain. That means Views hooking to each other reciprocally, all the way.
Now that you have a working chain, you can manipulate it with layout_constraintVertical_bias and layout_constraintVertical_chainStyle. If changing those does nothing, it means your chain is broken.
hook remaining Views to ones laid out by the chain
every control must have 4 constraints: top, bottom, start and end
do not create competing chains and try to force them into working together.
Spinner cannot have baseline, only TextView and its descendants have it. Spinner is AdapterView, so it can contain whatever you can imagine.
BTW: don't use #+id to refer to existing ids. Plus means creating new id, so if you make a typo it will create new id that refers to nothing instead of error "there's no such id".
Here's an example: top label and Spinners form the main chain and side labels are positioned each to their Spinner:
<?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"
>
<TextView
android:id="#+id/addsrv_pkix_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginHorizontal="10sp"
android:background=""
android:text="PKIX"
android:textAlignment="center"
app:layout_constraintBottom_toTopOf="#id/addsrv_trust_spin"
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"
/>
<TextView
android:id="#+id/addsrv_trust_lbl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
android:text="Trust"
app:layout_constraintBottom_toBottomOf="#id/addsrv_trust_spin"
app:layout_constraintEnd_toStartOf="#id/addsrv_trust_spin"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#id/addsrv_trust_spin"
app:layout_constraintVertical_bias="1.0"
/>
<Spinner
android:id="#+id/addsrv_trust_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="#id/addsrv_cred_spin"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/addsrv_trust_lbl"
app:layout_constraintTop_toBottomOf="#id/addsrv_pkix_title"
app:layout_constraintVertical_bias="0.0"
/>
<TextView
android:id="#+id/addsrv_cred_lbl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingHorizontal="10sp"
android:text="Credentials"
app:layout_constraintBottom_toBottomOf="#id/addsrv_cred_spin"
app:layout_constraintEnd_toStartOf="#id/addsrv_cred_spin"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#id/addsrv_cred_spin"
app:layout_constraintVertical_bias="1.0"
/>
<Spinner
android:id="#+id/addsrv_cred_spin"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/addsrv_cred_lbl"
app:layout_constraintTop_toBottomOf="#id/addsrv_trust_spin"
/>
</androidx.constraintlayout.widget.ConstraintLayout>

How to give vertical margin to constraint layout group?

So I have a few view that I group it using constraint layout group. I want to give vertical margin to the group as I do if I group it using linear/relative layout. add android:layout_marginVertical="100dp" doesn't seem to work.

Groups don't work like that. Take a look at ConstraintLayout's Layer widget available since version 2.0. You can search for tutorials on the use of Layer. In a nutshell, Layer will allow you to group widgets similar to a ViewGroup but will maintain a flat layout structure. If the views contained with the layer can be constrained to the layer itself, the whole layer will accept a top margin.
For example, take the following layout:
The blue is the background for the layer. The top/bottom, right/left views are contained within the layer and are constrained to it. The top margin of 100dp is set on the Layer. "Outside view" is a TextView that is constrained to the "Bottom right" TextVIew which is contained within the Layer something that can't be done if Layer is replaced by a ViewGroup.
The views may still be contained within a Group for group manipulations.
Here is the XML for this layout:
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.constraintlayout.helper.widget.Layer
android:id="#+id/layer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="100dp"
android:background="#android:color/holo_blue_light"
app:constraint_referenced_ids="topLeft,topRight,bottomLeft,bottomRight"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/topLeft"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
android:text="Top left"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
app:layout_constraintStart_toStartOf="#id/layer"
app:layout_constraintTop_toTopOf="#id/layer" />
<TextView
android:id="#+id/topRight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
android:text="Top right"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
app:layout_constraintStart_toStartOf="#+id/bottomRight"
app:layout_constraintTop_toTopOf="#id/layer" />
<TextView
android:id="#+id/bottomLeft"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
android:text="Bottom left"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
app:layout_constraintStart_toStartOf="#id/layer"
app:layout_constraintTop_toBottomOf="#+id/topLeft" />
<TextView
android:id="#+id/bottomRight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
android:text="Bottom right"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
app:layout_constraintStart_toEndOf="#+id/bottomLeft"
app:layout_constraintTop_toBottomOf="#+id/topRight" />
<TextView
android:id="#+id/outsideView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Outside view"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/bottomRight" />
</androidx.constraintlayout.widget.ConstraintLayout>

what you are trying to do is not correct.
ConstraintLayout Group can be used to "group" some references of different views or widgets and set their visibility (you can set the visibility of the group and all views will get it). It's not a fisical group like a LinearLayout can make.
Please, take a look at the documentation
https://developer.android.com/reference/androidx/constraintlayout/widget/Group
This class controls the visibility of a set of referenced widgets.
The visibility of the group will be applied to the referenced widgets. It's a convenient way to easily hide/show a set of widgets without having to maintain this set programmatically.
For what you want to do, you should use a Layout (LinearLayout, ConstraintLayout...) and group that views inside the layout and finally give the desired margin to this layout.

How do I center a text inside a chain relative to the whole screen?

I want to create a user name centered TextView with an edit button to the right of the screen. If I specify the TextView to match the start/end of the parent, it will center. However, the text will overflow and paint over the button. I can chain one side of the text to the button, but then the text will not be centered. Here is the example code I have where tvName is not centered due to the button in the horizontal chain:
<TextView
android:id="#+id/tvName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="#dimen/pt_name_font_size"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="#id/tvUserMsisdn"
app:layout_constraintEnd_toStartOf="#id/ibChangeName"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/aivProfile"
tools:text="B"/>
<TextView
android:id="#+id/tvName2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="#dimen/pt_name_font_size"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="#id/tvUserMsisdn"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/tvName"
tools:text="A"/>
<ImageButton
android:id="#+id/ibChangeName"
android:layout_width="28dp"
android:layout_height="28dp"
android:layout_marginEnd="#dimen/default_margin"
app:layout_constraintBottom_toBottomOf="#id/tvName"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="#id/tvName"
android:background="#android:color/black"/>
This is what it looks like:
I can't use a horizontal bias, since the button has to remain with a static size, and the width of the screen may vary, as well as the size of the font. Ideally, I would be able to specify two app:layout_constraintEnd_toStartOf attributes, one for the whole width of the screen, so the text remains centered, and another one for the button, so it won't overflow.

Ideally, I would be able to specify two app:layout_constraintEnd_toStartOf attributes
I'm sure you already know this, but that is impossible.
The only thing you can do that is like that is to use a Barrier, but that's not helpful here because (in this case) that would be functionally identical to simply constraining the end to the start of the ImageButton.
The best thing you can do here, in my opinion, is to constrain the TextView's start and end to the parent, and then use padding to make sure that long text doesn't overlap the ImageButton. The button has a fixed width (28dp), and a fixed margin (#dimen/default_margin), so you can give the TextView left/right padding equal to 28dp + 2x default_margin. This will make sure that text wraps at least default_margin away from the left edge of the ImageButton.

Put both the TextView and the ImageButton inside a RelativeLayout:
<RelativeLayout
android:id="#+id/container"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<TextView
android:id="#+id/tvName2"
android:layout_alignParentStart="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toStartOf="#+id/ibChangeName"
android:textSize="#dimen/pt_name_font_size"
android:textStyle="bold"
tools:text="A"/>
<ImageButton
android:id="#+id/ibChangeName"
android:layout_alignParentEnd="true"
android:layout_width="28dp"
android:layout_height="28dp"
android:layout_marginEnd="#dimen/default_margin"
android:background="#android:color/black"/>
</RelativeLayout>
This attribute for the TextView
android:layout_toStartOf="#+id/ibChangeName"
ensures that the TextView won't overlap with the ImageButton
Now you have to center the relative layout

If the ImageButton always has a fixed size (28dp in this case) you can use a Space widget with the same dimensions as the button and place it on the left edge of the parent. You can then chain the three Views together and set the chain's style to spread_inside. The TextView's width can be set to match_constraint and its gravity to center or use wrap_content and app:layout_constrainedWidth="true" so it doesn't overlap the other Views if it gets too big.
Example XML to get the general idea:
<?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">
<Space
android:id="#+id/space"
android:layout_width="28dp"
android:layout_height="28dp"
app:layout_constraintHorizontal_chainStyle="spread_inside"
app:layout_constraintEnd_toStartOf="#id/textview"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="#+id/textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Textview"
app:layout_constrainedWidth="true"
app:layout_constraintEnd_toStartOf="#id/button"
app:layout_constraintStart_toEndOf="#id/space" />
<ImageButton
android:id="#+id/button"
android:layout_width="28dp"
android:layout_height="28dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/textview" />
</android.support.constraint.ConstraintLayout>

Is it possible to control the bias of both sides of a chain in Androids ConstraintLayout?

I created two rows of ImageButtons through chains and used the packed style to close the gap between the two rows. However there is a lot of extra space surrounding the overall ImageButtons rows on the top and bottom.
When I try to use layout_constraintVertical_bias="0.1" on the top row buttons and layout_constraintVertical_bias="0.9" on the bottom row buttons to remove the gap it only shifts the rows up to the top of the layout. I know chain constraint details should be in the parent view but is there anyway to get the children of the chain to adapt a bias as well? I know this can be done by changing the width to 0dp but when I do that the images on the bottom become wider than the images at the top due to an uneven number of buttons.
<?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="wrap_content">
<ImageButton
android:id="#+id/button1"
android:layout_width="80dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#id/button4"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#id/button2"
app:layout_constraintVertical_chainStyle="packed"/>
<ImageButton
android:id="#+id/button2"
android:layout_width="80dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#id/button4"
app:layout_constraintLeft_toRightOf="#+id/button1"
app:layout_constraintRight_toLeftOf="#id/button3"
app:layout_constraintVertical_bias="1"/>
<ImageButton
android:id="#+id/button3"
android:layout_width="80dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="#id/button5"
app:layout_constraintLeft_toRightOf="#id/button2"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintVertical_chainStyle="packed"/>
<ImageButton
android:id="#+id/button4"
android:layout_width="80dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/button1"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#id/button5"
app:layout_constraintBottom_toBottomOf="parent"/>
<ImageButton
android:id="#+id/button5"
android:layout_width="80dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/button3"
app:layout_constraintLeft_toRightOf="#id/button4"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
</android.support.constraint.ConstraintLayout>
Edit:
This is what I'm trying to accomplish below. I basically want the arrows to push up to the red line while the ImageButtons stay in the place they are at right now so there is a gap between the buttons and the top and bottom edge of the layout. I attempted to shrink the gap in the second image using vertical bias but as you can see it only worked for the top row of buttons and not the buttons on the bottom row.

So, the question is really "why is my ConstraintLayout so tall?" If you can use a later release of ConstraintLayout (1.1.0-beta3 is the latest), this problem will go away. If you can't use a beta release, there is a work-around but upgrading is the best solution. Ping back if you can't use a beta release.

How to achieve overlap/negative margin on Constraint Layout?

Is it possible to achieve negative margin on constraint layout to achieve overlap?
I am trying to have a image centered on the layout and have a Text view such that it overlaps a by x dp. I tried setting negative margin value but no luck.
It would be great if there is a way to achieve this.

Update
ConstraintLayout now supports negative margins with version 2.1.0-alpha2. Simply state
android:layout_marginTop="-25dp"
for a negative 25dp margin. (This will only work if the top of the view is constrained. A margin has no effect in ConstraintLayout if the margin's side is not constrained.)
Clarification: The answer below remains valid, but I want to clarify a couple of things. The original solution will place a view with a de facto negative offset with respect to another view as stated and will appear in the layout as shown.
Another solution is to use the translationY property as suggested by Amir Khorsandi here. I prefer that solution as simpler with one caveat: The translation occurs post-layout, so views that are constrained to the displaced view will not follow the translation.
For example, the following XML displays two TextViews immediately below the image. Each view is constrained top-to-bottom with the view that appears immediately above it.
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView"
android:layout_width="150dp"
android:layout_height="150dp"
android:tint="#388E3C"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/ic_action_droid" />
<TextView
android:id="#+id/sayName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Say my name."
android:textAppearance="#style/TextAppearance.AppCompat.Large"
app:layout_constraintTop_toBottomOf="#+id/imageView"
app:layout_constraintEnd_toEndOf="#+id/imageView"
app:layout_constraintStart_toStartOf="#+id/imageView" />
<TextView
android:id="#+id/sayIt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Say it."
android:textAppearance="#style/TextAppearance.AppCompat.Large"
app:layout_constraintEnd_toEndOf="#+id/sayName"
app:layout_constraintStart_toStartOf="#+id/sayName"
app:layout_constraintTop_toBottomOf="#id/sayName" />
</androidx.constraintlayout.widget.ConstraintLayout>
Now, let's translate the "Say my name" TextView up by 50dp by specifying
android:translationY="-50dp"
This produces the following:
The "Say my name" TextView has shifted up as expected, but the "Say it" TextView has not followed it up as we might expect. This is because the translation occurs post-layout. Although the view moves post-layout, it can still be made clickable in the new position.
So, IMO, go with translationX and translationY for negative margins in ConstraintLayout if the caveat above doesn't affect your layout; otherwise, go with the space widget as outlined below.
Another caveat: As stated by Salam El-Banna in a comment to another answer, translationX will not be a good solution for RTL layouts since the sign of the translation will dictate the direction of the shift (left/right) regardless of the RTL or LTR nature of the layout.
Original answer
Although it doesn't appear that negative margins will be supported in ConstraintLayout, there is a way to accomplish the effect using the tools that are available and supported. Here is an image where the image title is overlapped 22dp from the bottom of the image - effectively a -22dp margin:
This was accomplished by using a Space widget with a bottom margin equal to the offset that you want. The Space widget then has its bottom constrained to the bottom of the ImageView. Now all you need to do is to constrain the top of the TextView with the image title to the bottom of the Space widget. The TextView will be positioned at the bottom of the Space view ignoring the margin that was set.
The following is the XML that accomplishes this effect. I will note that I use Space because it is lightweight and intended for this type of use, but I could have used another type of View and made it invisible. (You will probably need to make adjustments, though.) You could also define a View with zero margins and the height of the inset margin you want, and constrain the top of the TextView to the top of the inset View.
Yet another approach would be to overlay the TextView on top of the ImageView by aligning tops/bottoms/lefts/right and make suitable adjustments to margins/padding. The benefit of the approach demonstrated below is that a negative margin can be created without a lot of computation. That is all to say that there are several ways to approach this.
Update: For a quick discussion and demo of this technique, see the Google Developers Medium blog post.
Negative Margin for ConstraintLayout XML
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#mipmap/ic_launcher" />
<android.support.v4.widget.Space
android:id="#+id/marginSpacer"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="22dp"
app:layout_constraintBottom_toBottomOf="#+id/imageView"
app:layout_constraintLeft_toLeftOf="#id/imageView"
app:layout_constraintRight_toRightOf="#id/imageView" />
<TextView
android:id="#+id/editText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Say my name"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/marginSpacer" />
</android.support.constraint.ConstraintLayout>

Another way is using translationX or translationY like this:
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:translationX="25dp"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
it will work like android:layout_marginRight="-25dp"

Negative margins have never been officially supported in RelativeLayout. Negative margins will not be supported in ConstraintLayout. [...]
-- Romain Guy on Jun 8, 2016
Follow these two issues:
https://code.google.com/p/android/issues/detail?id=212499
https://code.google.com/p/android/issues/detail?id=234866

This is what I figured out after hours of trying to find a solution.
Let us consider two images, image1 and image2. Image2 is to be placed on top of image1 positioned to the bottom-right side.
Overlapping Views Example
We can use Space widget for overlapping views.
Constraint the Space widget's four sides with the four sides of the image1 respectively. For this example, constraint the image2's left side with the Space widget's right side and the image2's top side with the Space widget's bottom side. This will tie image2 with the Space widget and since the Space widget is constrained from all the sides, we can define required horizontal or vertical bias which will move image2 as required.
<?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"
tools:context=".Player">
<ImageView
android:id="#+id/image1"
android:layout_width="250dp"
android:layout_height="167dp"
android:src="#android:color/holo_green_dark"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Space
android:id="#+id/space"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="#+id/image1"
app:layout_constraintEnd_toEndOf="#+id/image1"
app:layout_constraintHorizontal_bias="0.82"
app:layout_constraintStart_toStartOf="#+id/image1"
app:layout_constraintTop_toTopOf="#+id/image1"
app:layout_constraintVertical_bias="0.62" />
<ImageView
android:id="#+id/image2"
android:layout_width="82dp"
android:layout_height="108dp"
android:src="#android:color/holo_green_light"
app:layout_constraintStart_toEndOf="#+id/space"
app:layout_constraintTop_toBottomOf="#+id/space" />
</android.support.constraint.ConstraintLayout>
Additionally, to position image2 on the center-bottom of image1, we can constraint image2's left and right sides with Space widget's left and right sides respectively. Similarly, we can place image2 anywhere by changing image2's constraints with Space widget.

I found a way to do it much simpler.
Basically have the ImageView, then on the Text View add top constraint to match the top constraint of the image and just add the margin top of the TextView to match to achieve the -ve margin type behavior.

This will help many
In my case i want my design like this:
Means i want my image is display half of their width so the basically i need negative margin of half of the actual image width but my whole layout in constraint layout and constraint layout does not allowed negative margin so i achieved this with below code
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="100dp"
android:layout_height="100dp"
android:scaleType="centerCrop"
android:src="#drawable/ic_launcher_background"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#id/guideline"
app:layout_constraintTop_toTopOf="parent" />
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_begin="50dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
So that ImageView will end at the starting of the guideline. and the effect is same as like negative margin at the start of 50dp.
And also if your view's width is not fixed and it's in percentage so that you can place guideline with percentage and achieve whatever effect you want
Happy Coding:)

You only need to use Space widget in your layout
<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">
<Space
android:id="#+id/negative_margin"
android:layout_width="16dp"
android:layout_height="16dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toLeftOf="parent"/>
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Widget who needs negative margin"
app:layout_constraintTop_toBottomOf="#+id/negative_margin"
app:layout_constraintLeft_toLeftOf="#+id/negative_margin" />

Place Background View Behind Subject View
I wanted to use negative margin to add a view behind a subject view that is proportionally bigger than the subject view. The solution I found was to scale android:scaleX="1.2" and android:scaleY="1.2" the background view while constraining it to all sides of the subject.
<View
android:id="#+id/subjectBackground"
android:layout_width="0dp"
android:layout_height="0dp"
android:scaleY="1.2"
android:scaleX="1.2"
app:layout_constraintBottom_toBottomOf="#+id/subjectView"
app:layout_constraintEnd_toEndOf="#+id/subjectView"
app:layout_constraintStart_toStartOf="#+id/subjectView"
app:layout_constraintTop_toTopOf="#+id/subjectView" />

This is an old question yet very much asked, the fastest way to achieve this is by constraining the top and bottom to the side of the view you want to anchor to, like so:
<androidx.appcompat.widget.AppCompatImageView
android:layout_width="55dp"
android:layout_height="55dp"
app:layout_constraintBottom_toBottomOf="#+id/parent_view_id"
app:layout_constraintTop_toBottomOf="#+id/parent_view_id"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent" />
This will center it in the bottom line of the view, centered horizontally.

One can try this way, this is much simpler
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".MyProfileFragment">
<ImageView
android:id="#+id/imageViewUserPic"
android:layout_width="#dimen/dp60"
android:src="#mipmap/ic_launcher"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:layout_margin="20dp"
android:layout_height="wrap_content">
</ImageView>
<ImageView
android:id="#+id/imageViewEdit"
app:layout_constraintBottom_toBottomOf="#+id/imageViewUserPic"
android:src="#drawable/ic_edit_red_round"
app:layout_constraintEnd_toEndOf="#+id/imageViewUserPic"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</ImageView>
</androidx.constraintlayout.widget.ConstraintLayout>
The layout will be like this..

this is my soluation
<com.oven.test.avatar
android:id="#+id/imageview_a"
android:layout_width="128dp"
android:layout_height="128dp"
android:layout_marginTop="28dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<com.oven.test.smallicon
android:id="#+id/small_icon_overlap_a"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="30dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="#+id/imageview_a"
app:layout_constraintTop_toTopOf="#+id/imageview_a"
app:layout_constraintVertical_bias="1"
android:layout_marginBottom="20dp"/>

Using translationX and translationY may works for your situation.
<TextView
android:id="#+id/tvText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="text"
android:translationX="-15dp"
android:translationY="10dp"
app:layout_constraintEnd_toEndOf="#+id/imageView"
app:layout_constraintTop_toTopOf="#+id/imageView" />

A Simple Way.
I'm not sure best way.
Just wrap using LinearLayout
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
<View
android:layout_width="wrap_content"
android:layout_marginLeft="-20dp"
android:layout_height="wrap_content"/>
</LinearLayout>