Content Main

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="pro.izcali.u4drawing.MainActivity"
    tools:showIn="@layout/activity_main">

    <RelativeLayout
        android:id="@+id/canvasDrawing"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        ></RelativeLayout>

</LinearLayout>