如果 ImageView 包含在不覆盖整个屏幕的 ViewPager 的片段中，是否可以使 ImageView 覆盖整个屏幕？

Question

I am using a ViewPager in an activity layout which is a ConstraintLayout . This ViewPager is constrained in order to be displayed below a sibling widget. This ViewPager , so, doesn't cover the whole screen.

However, in the fragments of this ViewPager , there is an ImageView that must be displayed covering the whole screen. This ImageView is unique per fragment of this ViewPager (implying that each ImageView must actually be contained in each ViewPager 's fragments).

The problem is: since this ImageView is within the fragments of the ViewPager that doesn't cover the whole screen, then it's impossible to use something like match_parent for this ImageView , since it will match the ViewPager which, obviously, doesn't cover all the screen (since it's shown below a sibling widget).

What could I do to make the ImageView fill the whole screen?

Answer 1

When you show the imageView fragment in view pager you can change your constraints programmatically. Here there is simple example for this

ConstraintLayout: change constraints programmatically

Answer 2

fragment.xml

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <androidx.viewpager2.widget.ViewPager2
            android:id="@+id/viewPagerImage"
            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_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

viewpger_item.xml

<androidx.constraintlayout.widget.ConstraintLayout
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <androidx.appcompat.widget.AppCompatImageView
                android:id="@+id/imgPool"
                android:layout_width="0dp"
                android:layout_height="0dp"
                android:scaleType="fitXY"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>