set width and height as percentage in relative layout

Question

I would like to have this: a ViewPager overlaid by 2 arrows

And I get what I want by this code. However, I got these warnings of lint :

• this layout is useless (for dummy layouts)
• nested weights are bad for performance.

I wonder if there is a better way to get this UI as I want.

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<android.support.v4.view.ViewPager
    android:id="@+id/dialog_instruction_pager"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >
</android.support.v4.view.ViewPager>

<!-- this LinearLayout  overlays the ViewPager -->
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical" >

    <!-- This is just the container for the left and right arrows , it is allocated with only 20% of screen height-->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight=".2"
        android:orientation="horizontal" >

        <!-- I want to align this to the left and set width only 5% of the parent -->
        <ImageButton
            android:id="@+id/instruction_dialog_left_arrow"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight=".05"
            android:background="?android:attr/selectableItemBackground"
            android:scaleType="fitCenter"
            android:src="@drawable/arrow_left_grey" />

        <!-- This is the dummy layout, standing in the middle of 2 arrows so they can be align to the left and right of the parent -->
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight=".8" >
        </LinearLayout>

        <!-- I want to align this to the right and set width only 5% of the parent-->
        <ImageButton
            android:id="@+id/instruction_dialog_right_arrow"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight=".05"
            android:background="?android:attr/selectableItemBackground"
            android:scaleType="fitCenter"
            android:src="@drawable/arrow_right_grey" />
    </LinearLayout>
</LinearLayout>

P.S: Is there any layout that allows align children left, right, bottom (like RelativeLayout) and also allows set width, height as percentage (like "weight" attribute in LinearLayout)?

Thank you !

Answer 1

Try the below code and see whether it works, 
This code will get the layout what you have attached

      <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical" >

  <android.support.v4.view.ViewPager
    android:id="@+id/dialog_instruction_pager"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@color/theme_blue" >
</android.support.v4.view.ViewPager>

<ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentLeft="true"
    android:layout_centerInParent="true"
    android:background="@drawable/ic_launcher" />

  <ImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentRight="true"
    android:layout_centerInParent="true"
    android:background="@drawable/ic_launcher" />

 </RelativeLayout>