Java-based panel function for selecting and dragging images [Based on the swing component], Drag and Drop swing

Java-based panel function for selecting and dragging images [Based on the swing component], Drag and Drop swing

This example describes the selectable and drag-and-drop panel functions implemented by Java. We will share this with you for your reference. The details are as follows:

I saw a post on the forum today, hoping to drag images in Swing like a map. This is the simplest implementation and provides a basic idea.

Import javax. swing. *; import javax. swing. filechooser. fileNameExtensionFilter; import java. awt. *; import java. awt. event. mouseEvent; import java. awt. event. mouseListener; import java. awt. event. mouseMotionListener; import java. io. file;/*** drag an image on the form. Usage: double-click the blank area of the form to open the image dialog box. After opening the image, you can drag the image on the form. */@ SuppressWarnings ("serial") public class DragingFrame extends JFrame {/*** constructor ** @ throws HeadlessException ??? */Public DragingFrame () throws HeadlessException {this. setdefaclocloseoperation (EXIT_ON_CLOSE); getContentPane (). setLayout (new BorderLayout (); getContentPane (). add (new ImagePanel (), BorderLayout. CENTER);} // program entry public static void main (String [] args) throws Exception {UIManager. setLookAndFeel (UIManager. getSystemLookAndFeelClassName (); DragingFrame = new DragingFrame (); frame. setSize (4 00,300); frame. setLocation (300,300); frame. setResizable (false); frame. setTitle ("www.jb51.net double-click to open the image and drag it"); frame. setVisible (true) ;}}/*** can drag the image panel */@ SuppressWarnings ("serial") class ImagePanel extends JPanel {private DragStatus status = DragStatus. ready; // Drag and Drop status private Image image; // private Point imagePosition = new Point (0, 0) of the Image to be displayed ), // The current position of the image imageStartposition = new Point (0, 0 ), // The position of the image at the start of the secondary drag (that is, the position after the last drag) mouseStartposition; // The Position of the mouse at the start of each drag ImagePanel () {addMouseListener (new MouseListener () {// double-click the mouse to open the public void mouseClicked (MouseEvent e) {if (e. getClickCount () = 2) {openImage () ;}// when you press the mouse, the status is changed and the start position of the drag and drop operation is recorded. Public void mousePressed (MouseEvent e) {if (status = DragStatus. ready) {status = DragStatus. dragging; mouseStartposition = e. getPoint (); imageStartposition. setLocation (imagePosition. getLocation () ;}}// change the public void mouseReleased (MouseEvent e) {if (status = DragStatus. dragging) {status = DragStatus. ready ;}} public void mouseEntered (MouseEvent e) {} public void mouseExited (Mouse Event e) {}}); addMouseMotionListener (new MouseMotionListener () {// Java has a drag Event. In this Event, move the image position public void mouseDragged (MouseEvent e) {if (status = DragStatus. dragging) {moveImage (e. getPoint () ;}} public void mouseMoved (MouseEvent e) {}}) ;}/ *** move the image. In fact, drawing is performed in paintComponent (). Here, we only calculate the image position and call this method. ** @ Param point current mouse position */private void moveImage (Point point) {// the current position of the image is equal to the starting position of the image plus the offset of the mouse position. ImagePosition. setLocation (imageStartposition. getX () + (point. getX ()-mouseStartposition. getX (), imageStartposition. getY () + (point. getY ()-mouseStartposition. getY (); repaint ();} // open the image private void openImage () {System. out. println ("Opening image... "); File file = createFileChooser (). getSelectedFile (); if (file! = Null) {image = Toolkit. getdefatooltoolkit (). getImage (file. getAbsolutePath (); if (image! = Null) {this. repaint () ;}}// create open file dialog box private JFileChooser createFileChooser () {JFileChooser chooser = new JFileChooser (); chooser. setDialogTitle ("select an image file... "); chooser. addChoosableFileFilter (new FileNameExtensionFilter ("common image formats", "jpg", "jpeg", "gif", "png"); chooser. showOpenDialog (this); return chooser;} @ Override protected void paintComponent (Graphics g) {super. paintComponent (g); if (I Mage! = Null) {g. drawImage (image, (int) imagePosition. getX (), (int) imagePosition. getY (), this) ;}} private enum DragStatus {Ready, Dragging }}

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