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====== Mouse Events & Mouse Listeners ====== Κάθε φορά που μετακινείτε το ποντίκι ή πατάτε κάποιο κουμπί στο ποντίκι σας δημιουργείτε ένα //event// του τύπου [[http://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseEvent.html|MouseEvent]]. Αντίστοιχα, εάν μετακινείτε την ροδέλα του ποντικιού σας, τότε παράγεται ένα //event// του τύπου [[http://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseWheelEvent.html|MouseWheelEvent]]. Σε αυτή την ενότητα θα ασχοληθούμε αποκλειστικά με //MouseEvents//. Για να λάβετε ένα MouseEvent θα πρέπει να ορίσετε για τα //Components// που θέλετε να ακούν τα συγκεκριμένα //events// ένα αντικείμενο του τύπου [[http://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseListener.html|MouseListener]] ή [[http://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseMotionListener.html|MouseMotionListener]] ως //Listener//. Ο πρώτος τύπος //Listener// αφορά τα events που συνδέονται με τα πλήκτρα του ποντικιού, ενώ ο δεύτερος τύπος //Listener// αφορά την κίνηση του ποντικού. ===== MouseListener Interface ===== Ας δούμε αναλυτικότερα ποιες μεθόδους περιλαμβάνει το interface //MouseListener//. <code java> void mouseClicked(MouseEvent e) //Invoked when the mouse button has been clicked (pressed and released) on a component. void mouseEntered(MouseEvent e) //Invoked when the mouse enters a component. void mouseExited(MouseEvent e) //Invoked when the mouse exits a component. void mousePressed(MouseEvent e) //Invoked when a mouse button has been pressed on a component. void mouseReleased(MouseEvent e) //Invoked when a mouse button has been released on a component. </code> Παρακάτω δίνεται ένα παράδειγμα από το site της Oracle, που δείχνει την χρήση του συγκεκριμένου Listener. <code java MouseEventDemo.java> package events; /* * MouseEventDemo.java */ import java.awt.GridLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.event.MouseListener; import java.awt.event.MouseEvent; import javax.swing.*; public class MouseEventDemo extends JPanel implements MouseListener { BlankArea blankArea; JTextArea textArea; static final String NEWLINE = System.getProperty("line.separator"); public static void main(String[] args) { /* Use an appropriate Look and Feel */ try { //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); //UIManager.setLookAndFeel("com.sun.java.swing.plaf.gtk.GTKLookAndFeel"); UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel"); } catch (UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } /* Turn off metal's use of bold fonts */ UIManager.put("swing.boldMetal", Boolean.FALSE); //Schedule a job for the event dispatch thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event dispatch thread. */ private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("MouseEventDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. JComponent newContentPane = new MouseEventDemo(); newContentPane.setOpaque(true); //content panes must be opaque frame.setContentPane(newContentPane); //Display the window. frame.pack(); frame.setVisible(true); } public MouseEventDemo() { super(new GridLayout(0,1)); blankArea = new BlankArea(Color.YELLOW); add(blankArea); textArea = new JTextArea(); textArea.setEditable(false); JScrollPane scrollPane = new JScrollPane(textArea); scrollPane.setVerticalScrollBarPolicy( JScrollPane.VERTICAL_SCROLLBAR_ALWAYS); scrollPane.setPreferredSize(new Dimension(200, 75)); add(scrollPane); //Register for mouse events on blankArea and the panel. blankArea.addMouseListener(this); addMouseListener(this); setPreferredSize(new Dimension(450, 450)); setBorder(BorderFactory.createEmptyBorder(20,20,20,20)); } void eventOutput(String eventDescription, MouseEvent e) { textArea.append(eventDescription + " detected on " + e.getComponent().getClass().getName() + "." + NEWLINE); textArea.setCaretPosition(textArea.getDocument().getLength()); } public void mousePressed(MouseEvent e) { eventOutput("Mouse pressed (# of clicks: " + e.getClickCount() + ")", e); } public void mouseReleased(MouseEvent e) { eventOutput("Mouse released (# of clicks: " + e.getClickCount() + ")", e); } public void mouseEntered(MouseEvent e) { eventOutput("Mouse entered", e); } public void mouseExited(MouseEvent e) { eventOutput("Mouse exited", e); } public void mouseClicked(MouseEvent e) { eventOutput("Mouse clicked (# of clicks: " + e.getClickCount() + ")", e); } } </code> Από τις μεθόδους του παραπάνω interface, αλλά και από το παράδειγμα ίσως παρατηρήσατε ότι δεν μπορείτε να εξάγεται άμεσα καμία πληροφορία **α)** για τον αριθμό των clicks **β)** για το button το οποίο πατήθηκε. Την πληροφορία για τα δύο παραπάνω μπορείτε να την δείτε στην κλάση [[http://docs.oracle.com/javase/7/docs/api/java/awt/event/MouseEvent.html|MouseEvent]] και συγκεκριμένα στις μεθόδους <code java> int getButton() //Returns which, if any, of the mouse buttons has changed state. int getClickCount() //Returns the number of mouse clicks associated with this event. </code> ===== MouseMotionListener Interface ===== Οι μέθοδοι που πρέπει να υποστηρίζει κάθε αντικείμενο που υλοποιεί το interface //MouseMotionListener// είναι οι παρακάτω. <code java> void mouseDragged(MouseEvent e) //Invoked when a mouse button is pressed on a component and then dragged. void mouseMoved(MouseEvent e) //Invoked when the mouse cursor has been moved onto a component but no buttons have been pushed. </code> Παρακάτω δίνεται ένα παράδειγμα από το site της Oracle, που δείχνει την χρήση του συγκεκριμένου Listener. <code java MouseMotionEventDemo.java> package events; /* * MouseMotionEventDemo.java * */ import java.awt.Color; import java.awt.Dimension; import java.awt.event.MouseMotionListener; import java.awt.event.MouseEvent; import java.awt.GridLayout; import javax.swing.*; public class MouseMotionEventDemo extends JPanel implements MouseMotionListener { BlankArea blankArea; JTextArea textArea; static final String NEWLINE = System.getProperty("line.separator"); public static void main(String[] args) { /* Use an appropriate Look and Feel */ try { //UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel"); //UIManager.setLookAndFeel("com.sun.java.swing.plaf.gtk.GTKLookAndFeel"); UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel"); } catch (UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } /* Turn off metal's use of bold fonts */ UIManager.put("swing.boldMetal", Boolean.FALSE); //Schedule a job for the event dispatch thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event-dispatching thread. */ private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("MouseMotionEventDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. JComponent newContentPane = new MouseMotionEventDemo(); newContentPane.setOpaque(true); //content panes must be opaque frame.setContentPane(newContentPane); //Display the window. frame.pack(); frame.setVisible(true); } public MouseMotionEventDemo() { super(new GridLayout(0,1)); blankArea = new BlankArea(Color.YELLOW); add(blankArea); textArea = new JTextArea(); textArea.setEditable(false); JScrollPane scrollPane = new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED); scrollPane.setPreferredSize(new Dimension(200, 75)); add(scrollPane); //Register for mouse events on blankArea and panel. blankArea.addMouseMotionListener(this); addMouseMotionListener(this); setPreferredSize(new Dimension(450, 450)); setBorder(BorderFactory.createEmptyBorder(20,20,20,20)); } void eventOutput(String eventDescription, MouseEvent e) { textArea.append(eventDescription + " (" + e.getX() + "," + e.getY() + ")" + " detected on " + e.getComponent().getClass().getName() + NEWLINE); textArea.setCaretPosition(textArea.getDocument().getLength()); } public void mouseMoved(MouseEvent e) { eventOutput("Mouse moved", e); } public void mouseDragged(MouseEvent e) { eventOutput("Mouse dragged", e); } } </code>
