Pass canvas to DrawingThread

src/main/java/lab/App.java

@@ -38,10 +38,7 @@ public class App extends Application {
 			
 			//Exit program when main window is closed
 			primaryStage.setOnCloseRequest(this::exitProgram);
-			//graphic context is used for a painting
-			GraphicsContext gc = canvas.getGraphicsContext2D();
-		
-			timer = new DrawingThread(gc);
+			timer = new DrawingThread(canvas);
 			timer.start();
 		} catch (Exception e) {
 			e.printStackTrace();

src/main/java/lab/DrawingThread.java

 package lab;
 
 import javafx.animation.AnimationTimer;
+import javafx.scene.canvas.Canvas;
 import javafx.scene.canvas.GraphicsContext;
-import javafx.scene.paint.Color;
 
 public class DrawingThread extends AnimationTimer {
 
+	private final Canvas canvas;
 	private final GraphicsContext gc;
 
-	public DrawingThread(GraphicsContext gc) {
-		this.gc = gc;
+	public DrawingThread(Canvas canvas) {
+		this.canvas = canvas;
+		this.gc = canvas.getGraphicsContext2D();
+		
 	}
 
 	/**
@@ -18,9 +21,9 @@ public class DrawingThread extends AnimationTimer {
 	@Override
 	public void handle(long now) {
 		// put your code here
-		gc.setFill(Color.AQUA);
-		gc.setStroke(Color.BLACK);
-		gc.fillOval(10, 10, 20, 20);
+		//gc.setFill(Color.AQUA);
+		//gc.setStroke(Color.BLACK);
+		//gc.fillOval(10, 10, 20, 20);
 
 	}