Here is the Constraintlayout with 3 views:
<?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/iv_profile_image"
android:layout_width="100dp"
android:layout_height="100dp"
app:layout_constraintBottom_toTopOf="#+id/tv_name"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<TextView
android:id="#+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/iv_profile_image" />
<TextView
android:id="#+id/tv_headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/tv_name" />
</android.support.constraint.ConstraintLayout>
The result:
As you can see, there is a big gap between each view. How can I remove those gaps and have them centered on the screen. I can achieve this easily using RelativeLayout or LinearLayout, but how can I do it in this ConstraintLayout? Is ConstraintLayout suppose to be a replacement for RelativeLayout?
When a view has two opposing constraints, ConstraintLayout will center the view between those constraints. This is what is happening in your layout.
If you want the views stacked one on top of another in the center of the screen, one way to do it is to used a packed chain.
Here is your layout using a vertical packed chain:
Here is the XML. Notice how the views are vertically constrained.
<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/iv_profile_image"
android:layout_width="100dp"
android:layout_height="100dp"
android:src="#mipmap/ic_launcher"
app:layout_constraintBottom_toTopOf="#+id/tv_name"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<TextView
android:id="#+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="tv_name"
app:layout_constraintBottom_toTopOf="#+id/tv_headline"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/iv_profile_image" />
<TextView
android:id="#+id/tv_headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="tv_headline"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tv_name" />
</android.support.constraint.ConstraintLayout>
ConstraintLayouts are said to give a flatter view hierarchy and better performance than normal RelativeLayouts.
I see some things that might cause wierd behaviour. For example in this view:
<TextView
android:id="#+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/iv_profile_image" />
You say that the top of this view should be aligned with the top of the #+id/iv_profile_image-view. Are you sure you don't mean that the top of this view should be aligned with the bottom of the #+id/iv_profile_image-view? And so on for the other views...
Try this it was helpful for you
we,ve to used all four constraints like left,right,top and bottom
you can implement like this also
I don'nt think you always prefer Drag and Drop you may go with the programmatic approarch also
<?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/iv_profile_image"
android:layout_width="100dp"
android:layout_height="100dp"
app:layout_constraintBottom_toTopOf="#+id/tv_name"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<TextView
android:id="#+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
app:layout_constraintTop_toBottomOf="#+id/iv_profile_image"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toTopOf="#+id/tv_headline" />
<TextView
android:id="#+id/tv_headline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tv_name" />
</android.support.constraint.ConstraintLayout>
Happy to help you
Related
I have 3 text views placed horizontally. Leftmost one and rightmost one are of fixed size, but middle one can vary in length significantly. Something like this:
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp">
<TextView
android:id="#+id/left"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingEnd="8dp"
android:text="LEFT"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/message"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:paddingEnd="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/right"
app:layout_constraintStart_toEndOf="#+id/left"
app:layout_constraintTop_toTopOf="parent"
tools:text="#tools:sample/lorem/random" />
<TextView
android:id="#+id/right"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="RIGHT"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/message"
app:layout_constraintTop_toTopOf="parent"
tools:visibility="visible" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
This results in following layout:
But if we have short text in the middle, like this:
tools:text="#tools:sample/lorem"
it will look:
Rightmost view is "glued" to the end.
I want it to follow the middle view, like this:
How can it be achieved?
You should use app:layout_constraintWidth_default="wrap" for the middle view and app:layout_constraintHorizontal_chainStyle="packed". Also don't forget to set app:layout_constraintHorizontal_bias="0.0" for the first view to align the whole layout to the start of the screen. Here how the whole layout should look:
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp">
<TextView
android:id="#+id/left"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
android:text="LEFT"
app:layout_constraintEnd_toStartOf="#id/message"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintHorizontal_chainStyle="packed"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/message"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:padding="8dp"
app:layout_constraintEnd_toStartOf="#id/apply_text"
app:layout_constraintStart_toEndOf="#id/left"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintWidth_default="wrap"
tools:text="#tools:sample/lorem" />
<TextView
android:id="#+id/apply_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
android:text="RIGHT"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#id/message"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
Here is the result:
It is quite a challenge. AFAIK, To do what you want, you have to change the width of the middle TextView to wrap_content and remove right TextView constraint with parent's right.
You could try something like calculating width of left and right then if the total width of the device is more than or equal left + right + middle then you switch from
to this
I have 2 views which I need to center vertically (both).
I need to have fixed top margin between the 2 views (40 dp)
How can I do it with ConstraintLayout?
Thanks.
You need to use chains, in this case app:layout_constraintVertical_chainStyle="packed" will achieve what you're looking for.
Try something like this:
<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/text_view_1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView 1"
app:layout_constraintBottom_toTopOf="#+id/text_view_2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<TextView
android:id="#+id/text_view_2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="40dp"
android:text="TextView 2"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/text_view_1" />
</androidx.constraintlayout.widget.ConstraintLayout>
This is my layout file.
<?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">
<EditText
android:layout_width="150dp"
android:layout_height="50dp"
android:hint="please input test content"
android:inputType="phone"
android:textColorHint="#android:color/holo_red_light"
android:textSize="13sp"
app:layout_constraintBottom_toTopOf="parent"
app:layout_constraintRight_toLeftOf="parent" />
<TextView
android:layout_width="80dp"
android:layout_height="50dp"
android:gravity="center"
android:text="Hello"
android:textColor="#android:color/black"
app:layout_constraintBottom_toTopOf="parent"
app:layout_constraintHorizontal_bias="0.5" />
</android.support.constraint.ConstraintLayout>
Follow pic is preview view.
I want to move TextView to center_horizontal to parent view , but layout_constraintHorizontal_bias=0.5" seems not work.
Who has ideas for this problem ? Thanks for first !
Try 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">
<EditText
android:id="#+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:ems="10"
android:hint="please input test content"
android:inputType="phone"
android:textColorHint="#android:color/holo_red_light"
android:textSize="13sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:layout_width="80dp"
android:layout_height="50dp"
android:gravity="center"
android:text="Hello"
android:textColor="#android:color/black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
EDIT
to use bias you need to give constrained it to any parent.
Try this:
app:layout_constraintHorizontal_bias="0.5" is not working because
you haven't constrained it to any parent. Read more about bias.
<?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:layout_width="80dp"
android:layout_height="50dp"
android:gravity="center"
android:text="Hello"
android:textColor="#android:color/black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="#+id/editText2"
android:layout_width="150dp"
android:layout_height="50dp"
android:layout_marginBottom="16dp"
android:ems="10"
android:hint="please input test content"
android:inputType="phone"
android:textColorHint="#android:color/holo_red_light"
android:textSize="13sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
First of if i were you i would look at some guides explaining constraint layouts, since you seem to be missing some key elements. ConstraintLayout
When that is said, your problem is that you are asking your layout to constrain at a 0.5 bias to nothing. Your textView is not constrained to anything other than app:layout_constraintBottom_toTopOf="parent"
Which btw is a little wierd constraining the bottom of your textview to the top of your parent.
In order for bias to work, it needs to know which elements to be biased between. If you simple want it to be center of the parent then constrain the textview to the parent like so:
<TextView
android:layout_width="80dp"
android:layout_height="50dp"
android:gravity="center"
android:text="Hello"
android:textColor="#android:color/black"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintHorizontal_bias="0.5" />
Also at that point you wont need the bias, i left it in though since you could then use it to move it at other percentages.
There is no need of bias as bias used for spacing between elements since its not require one can constaint to parent from left right bottom and top
Thanks
I use the follow code to display buttons and ViewPager. I want to display ViewPager above of buttons but that it have wrap_content height and width.
<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:id="#+id/linearLayout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#color/transparent_hd_image_scrim">
<android.support.v4.view.ViewPager
android:id="#+id/view_pager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<LinearLayout
android:id="#+id/buttons_bottom_layout"
android:layout_width="0dp"
android:layout_height="#dimen/hd_preview_buttons_height"
android:layout_marginEnd="#dimen/basic_keyline"
android:layout_marginRight="#dimen/basic_keyline"
android:orientation="horizontal"
android:layout_marginBottom="16dp"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#id/view_pager"
app:layout_constraintBottom_toBottomOf="parent">
<Button
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible" />
<View
android:id="#+id/stubBottom"
android:layout_width="#dimen/basic_keyline"
android:layout_height="wrap_content" />
<Button
android:id="#+id/send_button"
style="#style/HDPreviewButtonStyle"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="#color/colorAccent"
android:text="#string/send"
android:textAllCaps="true" />
</LinearLayout>
What I see on preview.
But on practice on emulator I get this screen.
What I do incorrect?
From the XML code you posted there are several issues that ConstraintLayout might have problem with.
Also ConstraintLayout can help you with nesting layout, which you also mentioned in comments you want to avoid.
I am not sure you want the view pager to behave as wrap rather than match it's constraints.
I created what I think is what you want using what ConstraintLayout has to offer to ease pain of previous layouts.
<android.support.constraint.ConstraintLayout android:id="#+id/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:background="#color/transparent_hd_image_scrim">
<android.support.v4.view.ViewPager
android:id="#+id/view_pager"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toTopOf="#+id/barrier"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="16dp"
android:layout_marginStart="16dp"
android:visibility="invisible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/send_button"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view_pager" />
<Button
android:id="#+id/send_button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginEnd="16dp"
android:layout_marginStart="8dp"
android:background="#color/colorAccent"
android:textAllCaps="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="#+id/button"
app:layout_constraintTop_toBottomOf="#+id/view_pager"
tools:text="Send" />
<android.support.constraint.Barrier
android:id="#+id/barrier"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:barrierDirection="top"
app:constraint_referenced_ids="send_button, button"
app:layout_constraintBottom_toBottomOf="parent" />
</android.support.constraint.ConstraintLayout>
Bottom buttons are chained horizontally together - this is basically replacement of the previous LinearLayout and the weight usage.
Also added barrier for height of the bottom buttons - this will make sure the height of the view pager will always accomodate to the height of any of them.
If you will actually want to the view pager to have wrap content add these
app:layout_constraintWidth_max="wrap"
app:layout_constraintHeight_max="wrap"
I'm trying to put a Button at the top of the screen and under it an ImageView which need to fill the screen (all screen sizes).
In RelativeLayout it's seems to be easy to do, but in the ConstraintLayout I don't succeed to get it done.
Here is an example of what it's look like in RelativeLayout:
and the XML Code:
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Download Image"
android:id="#+id/button"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true"
android:onClick="downloadImage" />
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/imageView"
android:layout_below="#+id/button"
android:layout_alignParentStart="true" />
Thanks for your help,
Shay.
Maybe I've not understod your question completely but this is what I did to recreate the image you gave as example:
<?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">
<Button
android:id="#+id/button2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:text="Button"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView27"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.59"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/button2"
app:srcCompat="#drawable/common_google_signin_btn_icon_dark" />
</android.support.constraint.ConstraintLayout>
and the result:
Actually fill_parent property is deprecated. so use 0dp to fill available space of the ConstraintLayout
For your question use following code to show Button at the top of the screen and under it an ImageView which will definitely fill the screen (for all screen sizes).
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:onClick="downloadImage"
android:text="Download Image"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/imageView"
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/button" />
</android.support.constraint.ConstraintLayout>
Note: If you want to add margin/padding then apply to the layout or any view as per your requirement. but when you are adding any margin to the view inside to the ConstraintLayout, that view need to have Constraint for that particulate side.
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Download Image"
android:id="#+id/button"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true"
android:onClick="downloadImage"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="#+id/imageView"
android:layout_below="#+id/button"
android:layout_alignParentStart="true"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/button"
app:layout_constraintBottom_toBottomOf="parent"/>
Button needs to have left, right and top constraints with parent.
And ImageView needs to have left, right , bottom constraints with parent and top constraint with button's bottom.