import javafx.application.Application; import javafx.scene.Scene; import javafx.scene.layout.Pane; import javafx.stage.Stage; import javafx.scene.canvas.Canvas; import javafx.scene.canvas.GraphicsContext; import javafx.scene.input.KeyCode; import javafx.scene.input.KeyEvent; import javafx.scene.paint.Color; /** * This program demonstrates processing of KeyEvents. A colored square * is drawn on a canvas. By pressing the arrow keys, the user can move * the square up, down, left, or right. By pressing the keys * R, G, B, or K, the user can change the color of the square to red, * green, blue, or black, respectively. If the user types a lower case * r, g, b, or k, the square is filled; if upper case, only the outline * of the square is drawn. Pressing the space bar returns the square * to its original color, fill, and position. When the SHIFT key is down, * a thick cyan border is drawn around the canvas. */ public class KeyboardEventDemo extends Application { public static void main(String[] args) { launch(); } //------------------------------------------------------------------------ private static final int SQUARE_SIZE = 60; // Length of side of square. private Color squareColor = Color.RED; // The color of the square. private boolean filled = true; // Is the square filled as opposed to just outlined? private boolean border = false; // Is a border drawn on the canvas? private double squareTop = 170, squareLeft = 170; // Coordinates corner of square. private Canvas canvas; // The canvas on which everything is drawn. /** The start() method sets up the GUI and installs listeners for key events * on the scene. The scene gets a chance to handle key events that are not * consumed by other components. */ public void start(Stage stage) { canvas = new Canvas(400,400); draw(); // Draw the canvas in its initial state. Pane root = new Pane(canvas); Scene scene = new Scene(root); stage.setScene(scene); stage.setTitle("Keyboard Event Demo"); stage.setResizable(false); scene.setOnKeyPressed( e -> keyPressed(e) ); scene.setOnKeyTyped( e -> keyTyped(e) ); scene.setOnKeyReleased( e -> keyReleased(e) ); stage.show(); } //--------------- Key event handling methods -------------------- private void keyTyped(KeyEvent evt) { String ch = evt.getCharacter(); System.out.println("Char Typed: " + ch); // for testing switch (ch) { // (Note: Old switch statement syntax used here, just as an example.) case "r": squareColor = Color.RED; filled = true; draw(); break; case "g": squareColor = Color.GREEN; filled = true; draw(); break; case "b": squareColor = Color.BLUE; filled = true; draw(); break; case "k": squareColor = Color.BLACK; filled = true; draw(); break; case "R": squareColor = Color.RED; filled = false; draw(); break; case "G": squareColor = Color.GREEN; filled = false; draw(); break; case "B": squareColor = Color.BLUE; filled = false; draw(); break; case "K": squareColor = Color.BLACK; filled = false; draw(); break; } } // end keyTyped() /** * This is called each time the user presses a key while the window has * the input focus. If the key pressed was one of the arrow keys, * the square is moved (except that it is not allowed to move off the * edge of the canvas). If the SHIFT key is pressed, a border is added * to the canvas. The space bar restores the original settings. */ private void keyPressed(KeyEvent evt) { KeyCode key = evt.getCode(); // keyboard code for the pressed key System.out.println("Key Pressed: " + key); // for testing if (key == KeyCode.LEFT) { // left arrow key squareLeft -= 8; if (squareLeft < 3) squareLeft = 3; draw(); } else if (key == KeyCode.RIGHT) { // right arrow key squareLeft += 8; if (squareLeft > canvas.getWidth() - SQUARE_SIZE - 3) squareLeft = canvas.getWidth() - SQUARE_SIZE - 3; draw(); } else if (key == KeyCode.UP) { // up arrow key squareTop -= 8; if (squareTop < 3) squareTop = 3; draw(); } else if (key == KeyCode.DOWN) { // down arrow key squareTop += 8; if (squareTop > canvas.getHeight() - SQUARE_SIZE - 3) squareTop = canvas.getHeight() - SQUARE_SIZE - 3; draw(); } else if (key == KeyCode.SHIFT) { border = true; draw(); } else if (key == KeyCode.SPACE) { squareColor = Color.RED; filled = true; squareLeft = 170; squareTop = 170; draw(); } } // end keyPressed() /** * This is called each time the user releases a key while the window * has the input focus. Only the SHIFT key is handled here; when it is * released, the border is removed from the canvas. */ private void keyReleased(KeyEvent evt) { KeyCode key = evt.getCode(); System.out.println("Key Released: " + key); // for testing if (key == KeyCode.SHIFT) { border = false; draw(); } } // ------------------ the method for drawing the canvas content ----------- /** * Draws a square, message and maybe a border in the canvas. The border * is shown if the SHIFT key is held down. */ public void draw() { GraphicsContext g = canvas.getGraphicsContext2D(); g.setFill(Color.WHITE); g.fillRect(0,0,canvas.getWidth(),canvas.getHeight()); /* Draw the square. */ if (filled) { g.setFill(squareColor); g.fillRect(squareLeft, squareTop, SQUARE_SIZE, SQUARE_SIZE); } else { g.setStroke(squareColor); g.setLineWidth(10); g.strokeRect(squareLeft+5, squareTop+5, SQUARE_SIZE-10, SQUARE_SIZE-10); } /* Maybe draw a Cyan border around the edges of the canvas. */ if (border) { g.setStroke(Color.CYAN); g.setLineWidth(6); g.strokeRect(3,3,canvas.getWidth()-6,canvas.getHeight()-6); } /* Draw a message with instructions for using the keyboard. */ g.setFill(squareColor == Color.BLACK ? Color.MAGENTA : Color.BLACK); g.fillText("Arrow Keys Move Square.\n" + "k,r,g,b change color and fill the square.\n" + "K,R,G,B change color and outline the square.\n"+ "Hold down SHIFT to draw a border.\n" + "Space Bar restores original settings.", 20, 30); } // end draw() } // end class KeyboardEventDemo