[JAVA] Caricare e visualizzare un'immagine

[ugroppelli]

Ciao a tutti, sono un principiante di java e di programmazione in generale.
Sto facendo un un'applicazione nella quale devo caricare una immagine scegliendola con il filechooser e visualizzarla all'interno del pannello centrale. Quello che ho scritto...o meglio ho fatto qualche copia e incolla quà e là...mi visualizza l'immagine ma non riesce a centrarla correttamente..La mia idea era quella di creare una JLabel e caricare all'interno una ImageIcon che contenesse l' immagine da me scelta con il filechooser(in questo modo risolvevo il problema di ridimensionamento dell' immagine:lo fa in automatico): ed è quello che ho fatto. Purtroppo per me però non riesco a visualizzarla correttamente...

Vi scrivo il codice che ho fatto...
Spero qualcuno mi risonda...

package it.testimage;


import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SpringLayout;
import javax.swing.border.Border;


public class JFrameExample extends JFrame 
{
	
	String JFbanner="Simpatico";
	
	public JFrameExample() {
		//super(title);
        setTitle(JFbanner);
        //componente centrale
        JLabel labelIcon = new JLabel(new ImageIcon("C:/inverno.jpg"));
        labelIcon.setBorder(BorderFactory.createLineBorder(Color.black));

        //componente nord e sud
        JTextField northtextField = new JTextField("Premi OK");
        JTextField southtextField = new JTextField("Premi OK");
        northtextField.setEditable(false);
        southtextField.setEditable(false);
        
//      Pannello NORTH
        JPanel northPanel = new JPanel();
        northPanel.setLayout(new GridLayout(1,0));
        northPanel.setBorder(BorderFactory.createEmptyBorder(10,4,10,4));
        northPanel.add(northtextField);
        
        // Pannello CENTER
        centralPanel = new JPanel();
        centralPanel.setLayout(new BorderLayout());
        centralPanel.setBorder(
            BorderFactory.createEmptyBorder(3,4,3,4));
        centralPanel.add(BorderLayout.CENTER,labelIcon);

        //Pannello EAST
        JPanel eastPanel=new JPanel();
       // eastPanel.setLayout(new BorderLayout());
        
        
        // Pannello SOUTH
        JPanel southPanel = new JPanel();
        southPanel.setLayout(new GridLayout(0,1));
        southPanel.setBorder(BorderFactory.createEmptyBorder(10,4,10,4));
        southPanel.add(southtextField);
        
        
        JButton selectImageButton = new JButton("Select Image");
        selectImageButton.setPreferredSize(new Dimension(110, 20));
        selectImageButton.addActionListener(new ActionListener()
        		{
            public void actionPerformed(ActionEvent e) 
            		{
                		JFileChooser fc = new JFileChooser();
                		fc.addChoosableFileFilter(new ImageFilter());
                		fc.setFileView(new ImageFileView());
                		fc.setAccessory(new ImagePreview(fc));
                		int returnVal = fc.showDialog(JFrameExample.this, "Select Image");
                		if(returnVal==JFileChooser.APPROVE_OPTION)
                		{
                		if (fc.getSelectedFile() == null)
                		{ return; }
                		File file=fc.getSelectedFile();
                		String path=(String)file.getPath();
                		loadImage(path);
                		}
            		}
        		});
                      
        JButton selectFocusButton = new JButton("Select Focus");
        selectFocusButton.setPreferredSize(new Dimension(110, 20));
        JButton selectPointsButton = new JButton("Select Points" );
        selectPointsButton.setPreferredSize(new Dimension(112, 20));
        SpringLayout layout = new SpringLayout();
        
        
      //  center.setLayout(layout);
        //nter.add(immagine);
        eastPanel.setLayout(layout);
        eastPanel.add(selectImageButton);
        eastPanel.add(selectFocusButton);
        eastPanel.add(selectPointsButton);
        
        layout.putConstraint(SpringLayout.NORTH,  selectImageButton,    3, SpringLayout.NORTH,  northPanel);
        layout.putConstraint(SpringLayout.NORTH,  selectFocusButton,   10, SpringLayout.SOUTH,  selectImageButton);
        layout.putConstraint(SpringLayout.NORTH,  selectPointsButton,  10, SpringLayout.SOUTH,  selectFocusButton);
        layout.putConstraint(SpringLayout.EAST,   eastPanel,          5, SpringLayout.EAST,   selectFocusButton);
        layout.putConstraint(SpringLayout.EAST,   eastPanel,           5, SpringLayout.EAST,   selectImageButton);
        //layout.putConstraint(SpringLayout.EAST,   selectImageButton,   10, SpringLayout.WEST,   eastPanel);
        //layout.putConstraint(SpringLayout.EAST, centralPanel,               20, SpringLayout.EAST,   eastPanel);
        
       
          
          JFrame f = new JFrame(JFbanner);
          f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
          f.getContentPane().setLayout(new BorderLayout());
          f.getContentPane().add(BorderLayout.NORTH,northPanel);
          f.getContentPane().add(BorderLayout.CENTER,centralPanel);
          f.getContentPane().add(BorderLayout.SOUTH,southPanel);
          f.getContentPane().add(BorderLayout.EAST,eastPanel);
          f.pack();
          f.setVisible(true);
        
	}
	
	public JPanel centralPanel;
	public BufferedImage mBufferedImage;	
	
	public void loadImage(String fileName)
	{
		Image image = Toolkit.getDefaultToolkit().getImage(fileName);
		MediaTracker mt = new MediaTracker(this);
		mt.addImage(image, 0);
		try { mt.waitForID(0); }
		catch (InterruptedException ie) { return; }
		if (mt.isErrorID(0)) return;
	
//		mBufferedImage = new BufferedImage(image.getWidth(null),
//		image.getHeight(null),
//		BufferedImage.TYPE_INT_RGB);
		Graphics g = centralPanel.getGraphics();
		g.drawImage(image, 0, 0, null);
	
		validate();
		repaint();
		setTitle(JFbanner + ": " + fileName);
	}
	
	public void paint(Graphics g)
	{
	super.paint(g);
	if (mBufferedImage == null) return;
	Insets insets = getInsets();
	g.drawImage(mBufferedImage, insets.left, insets.top, this);
	}

	public static void main(String[] args) 
	{
		
		 JFrameExample ex=new JFrameExample();
		 //ex.setSize(500,300);
		 //ex.show();
	}


}






package it.testimage;
import java.io.File;
import javax.swing.*;
import javax.swing.filechooser.*;

public class ImageFileView extends FileView {
    ImageIcon jpgIcon = new ImageIcon("images/jpgIcon.gif");
    ImageIcon gifIcon = new ImageIcon("images/gifIcon.gif");
    ImageIcon tiffIcon = new ImageIcon("images/tiffIcon.gif");
    
    public String getName(File f) {
        return null; // let the L&F FileView figure this out
    }
    
    public String getDescription(File f) {
        return null; // let the L&F FileView figure this out
    }
    
    public Boolean isTraversable(File f) {
        return null; // let the L&F FileView figure this out
    }
    
    public String getTypeDescription(File f) {
        String extension = getExtension(f);
        String type = null;

        if (extension != null) {
            if (extension.equals("jpeg") ||
                extension.equals("jpg")) {
                type = "JPEG Image";
            } else if (extension.equals("gif")){
                type = "GIF Image";
            } else if (extension.equals("tiff") ||
                       extension.equals("tif")) {
                type = "TIFF Image";
            } 
        }
        return type;
    }
    
    public Icon getIcon(File f) {
        String extension = getExtension(f);
        Icon icon = null;
        if (extension != null) {
            if (extension.equals("jpeg") ||
                extension.equals("jpg")) {
                icon = jpgIcon;
            } else if (extension.equals("gif")) {
                icon = gifIcon;
            } else if (extension.equals("tiff") ||
                       extension.equals("tif")) {
                icon = tiffIcon;
            } 
        }
        return icon;
    }
    
    // Get the extension of this file. Code is factored out
    // because we use this in both getIcon and getTypeDescription
    private String getExtension(File f) {

        String ext = null;
        String s = f.getName();
        int i = s.lastIndexOf('.');

        if (i > 0 &&  i < s.length() - 1) {
            ext = s.substring(i+1).toLowerCase();
        }
        return ext;
    }
}




package it.testimage;
import java.io.File;
import javax.swing.*;
import javax.swing.filechooser.*;

public class ImageFilter extends FileFilter {
    final static String jpeg = "jpeg";
    final static String jpg = "jpg";
    final static String gif = "gif";
    final static String tiff = "tiff";
    final static String tif = "tif";
    
    // Accept all directories and all gif, jpg, or tiff files.
    public boolean accept(File f) {

        if (f.isDirectory()) {
            return true;
        }

        String s = f.getName();
        int i = s.lastIndexOf('.');

        if (i > 0 &&  i < s.length() - 1) {
            String extension = s.substring(i+1).toLowerCase();
            if (tiff.equals(extension) ||
                tif.equals(extension) ||
                gif.equals(extension) ||
                jpeg.equals(extension) ||
                jpg.equals(extension)) {
                    return true;
            } else {
                return false;
            }
        }

        return false;
    }
    
    // The description of this filter
    public String getDescription() {
        return "Just Images";
    }
}





package it.testimage;
import javax.swing.*;
import java.beans.*;
import java.awt.*;
import java.io.File;

public class ImagePreview extends JComponent 
                          implements PropertyChangeListener {
    ImageIcon thumbnail = null;
    File file = null;
                             
    public ImagePreview(JFileChooser fc) {
        setPreferredSize(new Dimension(100, 50));
        fc.addPropertyChangeListener(this);
    }

    public void loadImage() {
        if (file == null)
            return;
 
        ImageIcon tmpIcon = new ImageIcon(file.getPath());
        if (tmpIcon.getIconWidth() > 90) {
            thumbnail = new ImageIcon(tmpIcon.getImage().
                                      getScaledInstance(90, -1,
                                                        Image.SCALE_DEFAULT));
        } else {
            thumbnail = tmpIcon;
        }
    }

    public void propertyChange(PropertyChangeEvent e) {
        String prop = e.getPropertyName();
        if (prop.equals(JFileChooser.SELECTED_FILE_CHANGED_PROPERTY)) {
            file = (File) e.getNewValue();
            if (isShowing()) {
                loadImage();
                repaint();
            }
        }
    }

    public void paintComponent(Graphics g) {
        if (thumbnail == null) {
            loadImage();
        }
        if (thumbnail != null) {
            int x = getWidth()/2 - thumbnail.getIconWidth()/2;
            int y = getHeight()/2 - thumbnail.getIconHeight()/2;

            if (y < 0) {
                y = 0;
            }

            if (x < 5) {
                x = 5;
            }
            thumbnail.paintIcon(this, g, x, y);
        }
    }
}

Spero di non essere stato troppo confuso.

[Andrea1979]

ti dico la verità che tutto quel codice non l'ho nemmeno provato ...
Questo va però... vedi se magari riesci a tirarne fuori qualcosa di utile anche per la tua applicazione.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;


public class displayImages extends JFrame implements ActionListener {
  
  
  File f;
  JLabel img;
  JScrollPane sc;
  
  private ImageIcon createImageIcon(String path) {
    try {
      
       return new ImageIcon(path);
    }
    catch (Exception e) {
      System.out.println(e.toString());
      return null;
    }
  }

  
  public void actionPerformed (ActionEvent ae) {
    try {
      JFileChooser fc = new JFileChooser();
      fc.showDialog(this, "Choose Image");
      f = fc.getSelectedFile();
      try {
        img.setVisible(false);
        sc.setVisible(false);
      }
      catch (Exception ex) {}
      img = new JLabel(createImageIcon(f.getAbsolutePath()));
      sc = new JScrollPane(img);
      this.getContentPane().add(sc, BorderLayout.CENTER);
      this.validate();
    }
    catch (Exception e) {}
  }
  
  public displayImages() {
    super("Image display");
    JButton open = new JButton("Open...");
    this.getContentPane().setLayout(new BorderLayout());
    this.getContentPane().add(open, BorderLayout.NORTH);
    open.addActionListener(this);
    this.setSize(300, 300);
    this.setVisible(true);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
  }
  
  public static void main (String[] args) {
    displayImages d = new displayImages();
  }
}

[ugroppelli]

Grazie Andrea1979 mi sei stato molto utile...