Android Relativelayout, views don't overlay buttons

Question

I'm trying to implement simple view overlay using RelativeLayout but it seems like something is wrong, I want the last view in the layout to be rendered on top of the rest but it is actually rendered behind. can you spot whats wrong in my code?

edit: figured out it only happens if I want to overlay buttons with some other view

here is the view xml:

<RelativeLayout 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"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MyActivity">

<Button
    android:layout_alignParentTop="true"
    android:id="@+id/btn1"
    android:text="Normal View"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

<FrameLayout
    android:background="#ff0000"
    android:layout_width="match_parent"
        android:layout_height="match_parent"/>

 </RelativeLayout>

and of course you did tried to do internet search with "RelativeLayout z order" — Selvin, May 22 '17 at 14:56
@Selvin yeah, I know that the lower the view is defined in the layout the higher the z order that's why I expect the framelayout to be rendered on top of the button, not the other way around. — fire in the hole, May 22 '17 at 14:59
there is (Daniel Wilson's) explanation in the first link what is going on some API — Selvin, May 22 '17 at 15:00
ok, i was wrong but now try this: set android:elevation="0dp" for the Button. — from56, May 22 '17 at 15:13
@Selvin that explains it but offers no solution, as others might have this question as well, guess it is appropriate to keep this question and find the optimal solution/workaround ps. I edited my question — fire in the hole, May 22 '17 at 15:21
@Selvin can you please remove your downvote and upvote instead so it gets some attention? — fire in the hole, May 22 '17 at 15:57

score 1 · Answer 1 · answered May 22 '17 at 16:30

buttons and other elements in API 21 and greater have a high elevation, and therefore ignore the xml order of elements regardless of parent layout. thanks to this answer.

The solution to this bug is to set a higher elevation on the view which I want to be rendered over the button, the elevation value for the overlaying view should be higher than the button's.

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            view.setElevation(1000);
}

or in xml

<FrameLayout 
    android:elevation="1000"
...

Android Relativelayout, views don't overlay buttons

1 Answers1