import org.eclipse.swt.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.events.*;


/**
 *  A tiny image viewer adapted from an example at :
 * 
 *  	http://www.cs.sbcc.net/~sstrenn/cs145/cs145.html
 *
 */
public class SwtImageViewer
{
    Shell shell;
    Composite clientArea;
    Image image;


    public static void main(String[] args)
    {

        new SwtImageViewer();
    }


    public SwtImageViewer()
    {
        createShell();
        shell.open();
        run();
        close();
    }


    /**
     *  Main processing method for the SWTImageViewerApp object
     */
    public void run()
    {
        Display display = shell.getDisplay();
        while (!shell.isDisposed())
        {
            if (!display.readAndDispatch())
            {
                display.sleep();
            }
        }
    }


    /*
     *  Free the allocated resources.
     */
    public void close()
    {
        if (shell != null && !shell.isDisposed())
        {
            shell.dispose();
        }
    }


    /**
     *  Setup the main window
     */
    private void createShell()
    {
        shell = new Shell();
        shell.setText("SWT Test Image Viewer");
        GridLayout layout = new GridLayout();
        layout.numColumns = 1;
        shell.setSize(500, 500);
        shell.setLayout(layout);

        createMenuBar(shell);
        createClientArea(shell);
        shell.layout(true);
    }


    void createClientArea(Shell shell)
    {
        clientArea = new Composite(shell, SWT.BORDER);
        GridData spec = new GridData();
        spec.horizontalAlignment = spec.FILL;
        spec.grabExcessHorizontalSpace = true;
        spec.verticalAlignment = spec.FILL;
        spec.grabExcessVerticalSpace = true;
        clientArea.setLayoutData(spec);
        GridLayout layout = new GridLayout();
        layout.numColumns = 1;
        clientArea.setLayout(layout);

        clientArea.addListener(SWT.Paint,
            new Listener()
            {
                public void handleEvent(Event e)
                {
                    if (image != null)
                    {
                        e.gc.drawImage(image, 0, 0);
                    }
                }
            });

    }


    private void createMenuBar(Shell shell)
    {
        Menu bar = new Menu(shell, SWT.BAR);
        shell.setMenuBar(bar);

        MenuItem fileItem = new MenuItem(bar, SWT.CASCADE);
        fileItem.setText("File");
        fileItem.setMenu(createFileMenu());
    }


    Menu createFileMenu()
    {
        Menu bar = shell.getMenuBar();
        Menu menu = new Menu(bar);

        MenuItem item = new MenuItem(menu, SWT.PUSH);
        item.setText("Open");
        item.addSelectionListener(
            new SelectionAdapter()
            {
                public void widgetSelected(SelectionEvent event)
                {
                    fileOpen_Click();
                }
            });

        new MenuItem(menu, SWT.SEPARATOR);

        item = new MenuItem(menu, SWT.PUSH);
        item.setText("Quit");
        item.addSelectionListener(
            new SelectionAdapter()
            {
                public void widgetSelected(SelectionEvent event)
                {
                    close();
                }
            });

        return menu;
    }


    void fileOpen_Click()
    {
        try
        {
            FileDialog fileChooser = new FileDialog(shell, SWT.OPEN);
            fileChooser.setFilterExtensions(new String[]{"*.bmp; *.gif; *.ico; *.jpg; *.pcx; *.png; *.tif", "*.bmp", "*.gif", "*.ico", "*.jpg", "*.pcx", "*.png", "*.tif"});
            fileChooser.setFilterNames(new String[]{" (bmp, gif, ico, jpg, pcx, png, tif)",
                    "BMP (*.bmp)", "GIF (*.gif)", "ICO (*.ico)", "JPEG (*.jpg)", "PCX (*.pcx)", "PNG (*.png)", "TIFF (*.tif)"});
            String filename = fileChooser.open();
            image = new Image(shell.getDisplay(), filename);
            clientArea.redraw();

        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }
    }
}