layer-list items dont appear with it's original sizes

I want to make several images layers .. i made a layer-list and used it as android:src of an ImageView .. the problem is all the layers fill the image view , is there any way to make every image in every layer appear with it's original size ?!

that's my layer-list code

<?xml version="1.0" encoding="utf-8"?>
<layer-list
    xmlns:android="http://ift.tt/nIICcg" >
     <item
        android:drawable="@drawable/dark"
        />
   <item
        android:drawable="@drawable/bg1"
        />
    <item
        android:drawable="@drawable/graphic_ring"
         android:layout_width="wrap_content"
        android:layout_height="wrap_content"
      />
</layer-list>

and thats my main layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://ift.tt/nIICcg"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="551dp"
        android:layout_height="265dp"
        android:layout_weight="0.70"
        android:src="@layout/test_layers" />

</LinearLayout>