attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
	<declare-styleable name="Graph">
		<attr name="gradientColorStart" format="color"/>
		<attr name="gradientColorEnd" format="color"/>

		<attr name="markerColor" format="color"/>
		<attr name="markerRadius" format="dimension" />

		<attr name="connectLinesColor" format="color"/>
		<attr name="connectLinesWidth" format="dimension" />

		<attr name="guidelinesFilledColor" format="color"/>
		<attr name="guidelinesFilledHeight" format="dimension" />
		<attr name="guidelinesEmptyHeight" format="dimension" />
		<attr name="guidelinesWidth" format="dimension"/>

		<attr name="graduationTextColor" format="color"/>
		<attr name="graduationTextSize" format="dimension" />
	</declare-styleable>
</resources>

layout.xml

<com.test.graphvisualizer.Graph
	android:id="@+id/graph"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	
    	app:layout_constraintBottom_toTopOf="parent"
	app:layout_constraintBottom_toBottomOf="parent"
	app:layout_constraintLeft_toLeftOf="parent"
	app:layout_constraintRight_toRightOf="parent"
	app:layout_constraintTop_toTopOf="parent"
	android:paddingLeft="35dp"
	android:paddingStart="35dp"
	android:paddingRight="35dp"
	android:paddingEnd="35dp"
	android:paddingTop="100dp"
	android:paddingBottom="100dp"
	
    	app:gradientColorStart="@color/greenDark"
	app:gradientColorEnd="@color/greenLight"
	app:markerColor="@color/greenDark"
	app:markerRadius="3dp"
	app:connectLinesColor="@color/greenDark"
	app:connectLinesWidth="2dp"
	app:guidelinesFilledColor="@color/gray"
	app:guidelinesFilledHeight="5dp"
	app:guidelinesEmptyHeight="5dp"
	app:guidelinesWidth="2dp"
	app:graduationTextColor="@color/gray"
	app:graduationTextSize="12sp" />