JavaFX drawing application with event filters

JavaFx Events and Event Handling: Exercise-12 with Solution

Write a JavaFX program to develop a drawing application with shapes. Implement event filters to detect and respond to user interactions with shapes.

Sample Solution:

JavaFx Code:

//Main.java

import javafx.application.Application;
import javafx.event.Event;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class Main extends Application {
    public static void main(String[] args) {
        // Launch the JavaFX application
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) {
        // Set the title for the drawing application window
        primaryStage.setTitle("Drawing Application");

        // Create a root pane
        Pane root = new Pane();

        // Create a rectangle for drawing
        Rectangle rectangle = createRectangle(100, 100, 100, 50, Color.BLUE);

        // Add an event filter to the rectangle to handle mouse events
        rectangle.addEventFilter(MouseEvent.MOUSE_PRESSED, event -> {
            // Handle mouse press event (e.g., start dragging)
            System.out.println("Mouse Pressed");
            event.consume();
        });

        rectangle.addEventFilter(MouseEvent.MOUSE_DRAGGED, event -> {
            // Handle mouse drag event (e.g., move or resize the rectangle)
            System.out.println("Mouse Dragged");
            event.consume();
        });

        rectangle.addEventFilter(MouseEvent.MOUSE_RELEASED, event -> {
            // Handle mouse release event (e.g., stop dragging)
            System.out.println("Mouse Released");
            event.consume();
        });

        // Add the rectangle to the root pane
        root.getChildren().add(rectangle);

        // Create the scene and set it on the stage
        Scene scene = new Scene(root, 400, 400);
        primaryStage.setScene(scene);

        // Show the drawing application window
        primaryStage.show();
    }

    // Helper method to create a rectangle
    private Rectangle createRectangle(double x, double y, double width, double height, Color color) {
        Rectangle rect = new Rectangle(x, y, width, height);
        rect.setFill(color);
        return rect;
    }
}

In the above exercise, we create a drawing application with a single blue rectangle that you can interact with. The rectangle responds to mouse events using event filters, and when you click and drag it, you'll see corresponding messages in the console.

Sample Output:

.............
Mouse Dragged
Mouse Dragged
Mouse Released
Mouse Pressed
Mouse Released
Mouse Pressed
Mouse Released
..............

Flowchart:

Java Code Editor:

Previous: JavaFX event propagation game.
Next: JavaFX Traffic light App with custom events.