Background
I was tasked to work on an app that has android:supportsRtl="false" in its manifest. Not sure why it was set as such, but it seems that in some places the user can choose the direction. Also in some cases it's floating (using system-alert-window permission).
The problem
I wanted to have some ConstraintLayout that I will be able to change its direction at runtime, as indeed in this app I have to let the user choose the direction.
For this, I made a small POC, combining all basic cases that I could find, to make sure all will be affected:
<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="match_parent" android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView1" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="bias=0"
app:layout_constraintBottom_toTopOf="@id/textView2" app:layout_constraintHorizontal_bias="0"
app:layout_constraintStart_toStartOf="parent" app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/textView2" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="aligned to start alone"
app:layout_constraintBottom_toTopOf="@id/textView3"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/textView1" />
<TextView
android:id="@+id/textView3" android:layout_width="0px" android:layout_height="wrap_content"
android:text="take whole row" app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/textView2" />
</androidx.constraintlayout.widget.ConstraintLayout>
On LTR, they are all aligned to the left, as expected.
The problem here is that with or without trying to change the direction of the layout, it seems to be affecting only the first 2 cases (and worse in case of the flag being set to false, as it causes nothing to occur).
What I've tried
First I wanted to see how it works without setting the flag of android:supportsRtl="false". I tried changing the layout direction of the ContstraintLayout, and sadly it affected only 2 of the TextViews:
val container = findViewById<ConstraintLayout>(R.id.container)
container.layoutDirection = View.LAYOUT_DIRECTION_RTL
This occurs when changing the locale to RTL language too (Hebrew for example).
Adding the flag, as I wrote, made them all be as if it's still on LTR : All were aligned to the left.
I also tried to call container.requestLayout() . It didn't help.
I want to work only on this layout, without changing the behavior for other places, which could cause visual bugs there. So I don't want to change the flag (I've already noticed it causes many issues when the locale of the device is set to RTL language).
The questions
- How come only for 2 cases it gets affected by the direction? How can I let the other be affected too?
- How can I force the direction to be changed even if the flag is set (
android:supportsRtl="false") ? I want it to work just for this layout (at least for now), and not affecting anywhere on the app.
