User Code: Image Browser

Here's the source code for creating a browser for viewing standard image files.

The ImageBrowser class, as the name suggests, is a simple image browser. You can view GIF and JPG, JPEG images using this browser. I have included the

main()

In addition, this code also teaches how to use menu items and menu bars. Moreover, viewers can benefit from the concepts of inner class (implementing ActionListner) and anonymous inner class (for trapping window events) presented in this code.

Comments are welcome :-)

/**
 * @author  Yasir Feroze Minhas
 * @version 1.0, 12/15/2000
 */

import java.awt.*;
import java.awt.event.*;
public class ImageBrowser extends Frame {

  //private variables to hold image and current directory name.
  private Image m = null;
  private String dir = null;


  //contants for Control-B and Control-X keys
  private static final int kControlB = 66;
  private static final int kControlX = 88;

  public static void main(String[] arg){
    ImageBrowser browser = new ImageBrowser();
    browser.setVisible(true);
  }

  public ImageBrowser() {
    try  {
      Init();
    }
    catch(Exception e) {
      e.printStackTrace();
    }

  }

  private void Init() throws Exception {

    //set title, background color and size of frame
    this.setTitle("Image Browser");
    this.setBackground(Color.darkGray);
    this.setSize(200,200);
    //create menubar for this frame
    MenuBar menuBar = new MenuBar();
    //attach image menu with menubar
    Menu menu = new Menu("Image");
    //include options in image menu
    menu.add(new MenuItem("Browse Image", new MenuShortcut(kControlB)));
    menu.add(new MenuItem("Quit", new MenuShortcut(kControlX)));
    menuBar.add(menu);
    //listen to the actions user performs on menu
    menu.addActionListener(new axnListener());
    this.setMenuBar(menuBar);
    //listen to window actions with anonymous inner class
    this.addWindowListener(new WindowAdapter(){
      public void windowClosing(WindowEvent e)
      {
        System.exit(0);
      }
    });
  }
  //opens a file dialog in LOAD mode and retrieves image file name
  public void loadImage()
  {
    FileDialog dlg = new FileDialog(this, "Choose Image", FileDialog.LOAD);
    //set current directory
    if(dir != null){
      dlg.setDirectory(dir);
    }
    dlg.setVisible(true);
    //get image name and path
    String imgFile = dlg.getDirectory()+dlg.getFile();
    dir = dlg.getDirectory();
    //create image using filename
    Toolkit tk = Toolkit.getDefaultToolkit();
    m = tk.getImage(imgFile);
    //call repaint to draw image
    repaint();
  }
  public void paint(Graphics g){
    //if image is not null, draw it and set the size of frame
    //according to the size of image
    if(m != null)
    {
      //The size of the frame includes any area designated for the border.
      //The dimensions of the border area can be obtained
      //using the getInsets method
      Insets insets = this.getInsets();
      g.drawImage(m, insets.left, insets.top, this);
      this.setSize(m.getWidth(this)+insets.left, m.getHeight(this)+insets.top);
    }
  }

  //inner class to listen menu actions
  class axnListener implements ActionListener{
    public void actionPerformed(ActionEvent e){
      if(e.getActionCommand().equalsIgnoreCase("Browse Image")){
        loadImage();
      }
      else System.exit(0);
    }
  }//end of inner class axnListener

}//end of ImageBrowser

Downloads

Download source = 2 Kb

About the Author

Yasir Feroze Minhas is a senior software engineer at KAPS Computing (pvt) Ltd. Pakistan. He hold a B.S. in computer science from FAST ICS Lahore, Pakistan. He describes himself as "a java fiend, with keen ineterest in server-side technologies." Currently, he is working on an Enterprise Resource Planning (ERP) system for KAPS.

[To contribute a code article to Gamelan, please contact kmurphy@internet.com.]