dialog_tool_img.xml

<?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:gravity="center_vertical">

    <ImageView
        android:id="@+id/iv_img"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>