Question

I am trying to ‘float’ a RelativeLayout to the bottom of a Window, and have the following layout:

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
    <com.my.activity.CanvasView
    android:id="@+id/canvas"
    android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:focusable="true" />
    <RelativeLayout
        android:id="@+id/toolbar_notification"
        android:layout_width="match_parent"
        android:layout_height="35dp"
        android:layout_alignParentBottom="true"
        android:gravity="bottom|center_vertical">
        <ImageView
            android:id="@+id/toolbar_notification_icon"
            android:layout_width="40dp"
            android:layout_height="match_parent"
            android:layout_alignParentBottom="true"
            android:layout_alignParentTop="true"
            android:layout_alignParentRight="true"
            android:contentDescription="@string/content_desc_save_icon"
            android:gravity="center|center_vertical" />
    </RelativeLayout>
</merge>

Unfortunately, the toolbar_notification RelativeLayout is not being bottom-aligned. Replacing the merge tag with a FrameLayout tag results in the desired effect, but in the name of efficiency I’d like to remove that if possible.

Anyone seen this issue, or have any suggestions? Is the fact that the merge element is not a ‘parent’ in the true sense resulting in the toolbar_notification element being unable to place itself?

Answer 1

android:gravity="bottom|center_vertical" is referred to children of RelativeLayout and not to RelativeLayout itself.

If you want to align RelativeLayout to the bottom of the parent (that is a FrameLayout) you have to use layout_gravity instead.

...
<RelativeLayout
        android:id="@+id/toolbar_notification"
        android:layout_width="match_parent"
        android:layout_height="35dp"
        android:layout_alignParentBottom="true"
        android:layout_gravity="bottom|center_vertical">
 ...