JavaFX pane doesn't draw shapes on a resized area - javafx

Question

I want to create a bouncer app using JavaFX. I used Pane to show moving shapes (circle, Rectange) on it. The problem happens when I resize the window to a larger area. When I do that, then the newly created area doesn't show moving shapes properly. What happens in this new area: shapes change color from black to white and they leave a white trace.
The shapes are moved using the setTranslateX (and Y) methods.
I also included a sample code below the screen shots. The code isn't the same as the one on the recorded screens, but it produces the same problem.
window with original size
resized window with an area where the shapes are not drawn properly
The FXML document named view.fxml
<?import javafx.scene.shape.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.AnchorPane?>
<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.company.bouncer.Controller">
<center>
<Pane fx:id="paneField" prefHeight="344.0" prefWidth="600.0" BorderPane.alignment="CENTER" />
</center>
<top>
<HBox alignment="CENTER_LEFT" prefHeight="56.0" prefWidth="600.0" spacing="30.0" BorderPane.alignment="CENTER">
<children>
<Button fx:id="btnLaunch" mnemonicParsing="false" onAction="#handleBtn" text="Launch" />
</children>
<opaqueInsets>
<Insets />
</opaqueInsets>
<BorderPane.margin>
<Insets />
</BorderPane.margin>
<padding>
<Insets left="30.0" />
</padding>
</HBox>
</top>
</BorderPane>
Main class that extends Application
package com.company.bouncer;
import java.io.IOException;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;
public class Main extends Application {
#Override
public void start(Stage primaryStage) throws IOException {
Parent root = FXMLLoader.load(getClass().getResource("/view.fxml"));
primaryStage.setTitle("Bouncer");
primaryStage.setScene(new Scene(root, 600, 400));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
/**
* called when the window is closed
*/
#Override
public void stop() throws Exception {
Controller.stopExecutor();
super.stop();
}
}
** Controller **
package com.company.bouncer;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.ResourceBundle;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.geometry.Insets;
import javafx.scene.control.Button;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.shape.Shape;
public class Controller implements Initializable {
#FXML
private Button btnLaunch;
#FXML
private Pane paneField;
private ShapePlatform shapeRunnable;
private static ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
#Override
public void initialize(URL location, ResourceBundle resources) {
shapeRunnable = new ShapePlatform();
paneField.setBackground(new Background(new BackgroundFill(Color.web("#aaaaaa"), CornerRadii.EMPTY, Insets.EMPTY)));
executor.scheduleAtFixedRate(shapeRunnable, 0, 10, TimeUnit.MILLISECONDS);
}
#FXML
private void handleBtn(){
shapeRunnable.generateShapeMover();
}
public static void stopExecutor(){
executor.shutdown();
}
public class ShapePlatform implements Runnable {
private List<ShapeMover> shapeList = new ArrayList<>();
/**
* Constructor
* #param parentPane Pane on which the shapes will be displayed
*/
public ShapePlatform(){
}
/**
* creates a new shape and adds it to the shapeList
*/
public void generateShapeMover(){
Shape newShape = new Rectangle(0, 0, 100, 80);
paneField.getChildren().add(newShape);
//position the object in some random location on the pane
newShape.setTranslateX(300);
newShape.setTranslateY(300);
//wrap it in shape mover
ShapeMover shapeMover = new ShapeMover(newShape);
shapeList.add(shapeMover);
}
/**
* executes one frame of moving objects
*/
private void moveAllOnce(){
shapeList.forEach(sm -> sm.move());
}
/**
* moves all objects, checks any intersections between objects
* and changes their direction if there is an intersection
*/
#Override
public void run() {
moveAllOnce();
}
public class ShapeMover {
private Shape shape;
private int xDir = 1;
private int yDir = 1;
private int periodSpeed = 1;
private int periodSpeedCountDown = periodSpeed;
/**
* constructs the object
* #param shape - shape to be moved
*/
public ShapeMover(Shape shape){
this.shape = shape;
}
/**
* moves object for one iteration
*/
public void move(){
if(periodSpeedCountDown == 0){
shape.setTranslateX(shape.getTranslateX() + xDir);
shape.setTranslateY(shape.getTranslateY() + yDir);
periodSpeedCountDown = periodSpeed;
} else {
periodSpeedCountDown--;
}
}
}
}
}

Answer 1

So, the problem was actually that I was running the movement handling background thread which probably produced my problem. With a suggestion from #James_D I implemented the movement handling using extention of AnimationTimer, and now the menitoned problem is gone.
The new code is int under the text. I still have to implement a mechanism to handle the right timing as now there are no periods defined in AnimationTimer
public class Controller implements Initializable {
#FXML
private Button btnLaunch;
#FXML
private Pane paneField;
private ShapePlatform shapeAnimTimer;
private static ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
#Override
public void initialize(URL location, ResourceBundle resources) {
paneField.setBackground(new Background(new BackgroundFill(Color.web("#aaaaaa"), CornerRadii.EMPTY, Insets.EMPTY)));
shapeAnimTimer = new ShapePlatform();
shapeAnimTimer.start();
}
#FXML
private void handleBtn(){
shapeAnimTimer.generateShapeMover();
}
public static void stopExecutor(){
executor.shutdown();
}
public class ShapePlatform extends AnimationTimer {
private List<ShapeMover> shapeList = new ArrayList<>();
/**
* creates a new shape and adds it to the shapeList
*/
public void generateShapeMover(){
Shape newShape = new Rectangle(0, 0, 100, 80);
paneField.getChildren().add(newShape);
//position the object in some random location on the pane
newShape.setTranslateX(300);
newShape.setTranslateY(300);
//wrap it in shape mover
ShapeMover shapeMover = new ShapeMover(newShape);
shapeList.add(shapeMover);
}
/**
* executes one frame of moving objects
*/
private void moveAllOnce(){
shapeList.forEach(sm -> sm.move());
}
/**
* moves all objects, checks any intersections between objects
* and changes their direction if there is an intersection
* #param now current frame
*/
#Override
public void handle(long now) {
System.out.println(now);
moveAllOnce();
}
public class ShapeMover {
private Shape shape;
private int xDir = 1;
private int yDir = 1;
private int periodSpeed = 1;
private int periodSpeedCountDown = periodSpeed;
/**
* constructs the object
* #param shape - shape to be moved
*/
public ShapeMover(Shape shape){
this.shape = shape;
}
/**
* moves object for one iteration
*/
public void move(){
if(periodSpeedCountDown == 0){
shape.setTranslateX(shape.getTranslateX() + xDir);
shape.setTranslateY(shape.getTranslateY() + yDir);
periodSpeedCountDown = periodSpeed;
} else {
periodSpeedCountDown--;
}
}
}
}
}