How to adjust screen size for all android devices - android-layout

Question

I just can't seem to find a way to fit the photo onto my home page screen, I've tried many different ways but it wasn't successful. I have an image that pushes the layout that is under it and squeezes the buttons on the screen. Is there any way I can auto resize the height it for different screens? I only need the height since the width should be match_parent. Below is the xml file.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
android:orientation="vertical"
>
<RelativeLayout
android:id="#+id/headerLayout"
android:layout_width="match_parent"
android:layout_height="?android:attr/actionBarSize"
android:background="#drawable/nav_bar_homepage" >
<TextView
android:id="#+id/pageTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="WELCOME!" />
<ImageView
android:id="#+id/hiddenIcDrawer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="10dp"
android:src="#drawable/nav_icon"
android:visibility="invisible" />
</RelativeLayout>
<ImageView
android:id="#+id/horLine"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/headerLayout"
android:scaleType="center"
android:src="#drawable/line_big_white" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:scaleType="fitStart" >
<ImageView
android:id="#+id/image_homepage_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_gravity="center_horizontal"
android:src="#drawable/image_homepage"
/>
</RelativeLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentBottom="true"
android:layout_gravity="center"
android:layout_margin="10dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:background="#drawable/field_red_homepage"
android:orientation="vertical"
android:scaleType="fitXY" >
<ImageView
android:id="#+id/logo_homep"
android:layout_width="wrap_content"
android:layout_height="80dp"
android:layout_gravity="center"
android:layout_marginBottom="10dp"
android:layout_marginTop="5dp"
android:paddingBottom="10dp"
android:scaleType="fitXY"
android:src="#drawable/logo_homepage" />
<ImageView
android:id="#+id/redeembytton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_margin="10dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:background="#drawable/btn_redeemrewards"
android:scaleType="fitXY" >
</ImageView>
<ImageView
android:id="#+id/orderbutton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_margin="10dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="15dp"
android:background="#drawable/btn_orderonline"
android:scaleType="fitXY" >
</ImageView>
<ImageView
android:id="#+id/rewardsButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_margin="10dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="15dp"
android:background="#drawable/btn_earnrewards"
android:scaleType="fitXY" >
</ImageView>
<ImageView
android:id="#+id/referFriendButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_margin="10dp"
android:layout_marginBottom="5dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="15dp"
android:background="#drawable/btn_referafriend"
android:scaleType="fitXY" >
</ImageView>
</LinearLayout>
</LinearLayout>

Answer 1

Wrap you xml code into ScrollView if you are okay with scrolling down to reach your contents under ImageView. If you don't want to scroll down, it is best to use "weight" attribute. I am giving you an idea how to implement it in your code.
Let's say the height of the whole screen is 1. You have an image and a button to put on the screen for all devices. So split the screen into two parts... 0.8 for imageview and 0.2 for the button. You can use the code below to get this result.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="0dp" <!-- Important >
android:orientation="vertical"
android:layout_weight=".8" > <!-- 80% of your screen size>
<!-- Your ImageView >
</LinearLayout>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="0dp" <!-- Important >
android:orientation="vertical"
android:layout_weight=".2" > <!-- 20% of your screen size>
<!-- Your Button >
</LinearLayout>
</LinearLayout>

Answer 2

Try this
I think you should use
android:layout-weight="1" for adjusting the height according to different devices.use it in your <ImageLayout/>.