title: The android layout lacks proportion when I set the background of Imagebutton.
body: <p>The  <code>android layout</code> lacks proportion when I set the background of <code>Imagebutton</code>.  </p>
  
  <p><img src="https://i.stack.imgur.com/Vt6qe.png" alt="enter image description here"></p>
  
  <p>And the code of xml is like the following:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:baselineAligned="false"
      android:orientation="vertical" &gt;
  
      &lt;FrameLayout
          android:id="@+id/player_frame"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:layout_above="@+id/buttonLayout" &gt;
  
          &lt;FrameLayout
              android:id="@+id/player_surface_frame"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent"
              android:layout_gravity="center" &gt;
  
              &lt;SurfaceView
                  android:id="@+id/player_surface"
                  android:layout_width="fill_parent"
                  android:layout_height="fill_parent"
                  android:layout_gravity="center" /&gt;
          &lt;/FrameLayout&gt;
      &lt;/FrameLayout&gt;
  
      &lt;LinearLayout
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_alignParentTop="true"
          android:orientation="vertical" &gt;
  
          &lt;LinearLayout
              android:layout_width="fill_parent"
              android:layout_height="wrap_content" &gt;
  
              &lt;Button
                  android:id="@+id/findCameraButton"
                  android:layout_width="0dp"
                  android:layout_height="match_parent"
                  android:layout_weight="4"
                  android:text="@string/label_find_camera" /&gt;
  
              &lt;Button
                  android:id="@+id/SettingButton"
                  android:layout_width="0dp"
                  android:layout_height="match_parent"
                  android:layout_weight="4"
                  android:text="@string/Camera_WiFi_setup" /&gt;
  
              &lt;ImageButton
                  android:id="@+id/FileSavebutton"
                  android:layout_width="0dp"
                  android:layout_height="match_parent"
                  android:layout_weight="4"
                  android:background="@drawable/save_in_camera" /&gt;
          &lt;/LinearLayout&gt;
  
          &lt;LinearLayout
              android:layout_width="match_parent"
              android:layout_height="wrap_content" &gt;
                  &lt;TextView
                  android:id="@+id/TimeStampLabel"
                  android:layout_width="wrap_content"
                  android:layout_height="wrap_content"
                  android:layout_margin="10dip"
                  android:text=""
                  android:textColor="#ffff00"
                  android:textAppearance="?android:attr/textAppearanceMedium" /&gt;
          &lt;/LinearLayout&gt; 
  
      &lt;/LinearLayout&gt;
  
      &lt;LinearLayout
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_alignParentBottom="true"
          android:orientation="vertical" &gt;
  
          &lt;LinearLayout
              android:layout_width="fill_parent"
              android:layout_height="wrap_content" &gt;
  
              &lt;Button
                  android:id="@+id/snapshotButton"
                  android:layout_width="0dp"
                  android:layout_height="wrap_content"
                  android:layout_weight="4"
                  android:text="@string/label_app_snapshot" /&gt;
  
              &lt;Button
                  android:id="@+id/recordButton"
                  android:layout_width="0dp"
                  android:layout_height="wrap_content"
                  android:layout_weight="4"
                  android:text="@string/label_app_record" /&gt;
  
               &lt;ImageButton
                  android:id="@+id/photo_record_mode"
                  android:layout_width="0dp"
                  android:layout_height="match_parent"
                  android:layout_weight="4"
                  android:background="@drawable/turn_to_photomode"/&gt;
  
          &lt;/LinearLayout&gt;
      &lt;/LinearLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>How to setup can make the top of <code>LinearLayout</code> no deformation like the <code>LinearLayout</code> of bottom ?</p>