Grab and Drag scrolling on a JPanel filled with drawn shapes

OK, so I have made this JPanel filled with 20 x 20 hexagons in a diamond shape. They are pretty big, so you can't see all of them at the same time, but since this is supposed to be the map in a game, I would like to have grab'n'drag scrolling.

The actual moving works - but when I move the panel, I only move the tiles that I could already see away, the tiles that should be just outside the window borders doesn't show. It's like I'm moving an image. However, if I resize the window, I get to see more of the hexagons.

I've tried forcing repaints after mouseDragged was finished, but without success. Anyone who has any ideas are very welcome to share them!

This is where I show everything in the Interface-class:

            ComponentMover comp = new ComponentMover();
        comp.registerComponent(gameTiles,this);
        main.add(gameTiles, "Game");
        cardLayout.show(main, "Game");

and this is the ComponentMover-class (borrowed from http://tips4java.wordpress.com/2009/06/14/moving-windows/ with a few mods)

public class ComponentMover extends MouseAdapter {

private Class destinationClass;
private Component destinationComponent;
private Component destination;
private Component source;

private ArrayList<Component>comps;

private boolean changeCursor = true;

private Point pressed;
private Point location;

private Cursor originalCursor;
private boolean autoscrolls;

private Insets dragInsets = new Insets(0, 0, 0, 0);
private Dimension snapSize = new Dimension(1, 1);

/**
 *  Constructor for moving individual components. The components must be
 *  regisetered using the registerComponent() method.
 */
public ComponentMover()
{ comps = new ArrayList<Component>();
}

/**
 *  Constructor to specify a Class of Component that will be moved when
 *  drag events are generated on a registered child component. The events
 *  will be passed to the first ancestor of this specified class.
 *
 *  @param destinationClass  the Class of the ancestor component
 *  @param component         the Components to be registered for forwarding
 *                           drag events to the ancestor Component.
 */
public ComponentMover(Class destinationClass, Component... components)
{
    this.destinationClass = destinationClass;
    registerComponent( components );
}

/**
 *  Constructor to specify a parent component that will be moved when drag
 *  events are generated on a registered child component.
 *
 *  @param destinationComponent  the component drage events should be forwareded to
 *  @param components    the Components to be registered for forwarding drag
 *                       events to the parent component to be moved
 */
public ComponentMover(Component destinationComponent, Component... components)
{
    this.destinationComponent = destinationComponent;
    registerComponent( components );
}

/**
 *  Get the change cursor property
 *
 *  @return  the change cursor property
 */
public boolean isChangeCursor()
{
    return changeCursor;
}

/**
 *  Set the change cursor property
 *
 *  @param  changeCursor when true the cursor will be changed to the
 *                       Cursor.MOVE_CURSOR while the mouse is pressed
 */
public void setChangeCursor(boolean changeCursor)
{
    this.changeCursor = changeCursor;
}

/**
 *  Get the drag insets
 *
 *  @return  the drag insets
 */
public Insets getDragInsets()
{
    return dragInsets;
}

/**
 *  Set the drag insets. The insets specify an area where mouseDragged
 *  events should be ignored and therefore the component will not be moved.
 *  This will prevent these events from being confused with a
 *  MouseMotionListener that supports component resizing.
 *
 *  @param  dragInsets
 */
public void setDragInsets(Insets dragInsets)
{
    this.dragInsets = dragInsets;
}

/**
 *  Remove listeners from the specified component
 *
 *  @param component  the c开发者_如何学Component the listeners are removed from
 */
public void deregisterComponent(Component... components)
{
    for (Component component : components)
        component.removeMouseListener( this );
}

/**
 *  Add the required listeners to the specified component
 *
 *  @param component  the component the listeners are added to
 */
public void registerComponent(Component... components)
{
    for (Component component : components) {
        component.addMouseListener( this );
        comps.add(component);
    }
}

/**
 *  Get the snap size
 *
 *  @return the snap size
 */
public Dimension getSnapSize()
{
    return snapSize;
}

/**
 *  Set the snap size. Forces the component to be snapped to
 *  the closest grid position. Snapping will occur when the mouse is
 *  dragged half way.
 */
public void setSnapSize(Dimension snapSize)
{
    this.snapSize = snapSize;
}

/**
 *  Setup the variables used to control the moving of the component:
 *
 *  source - the source component of the mouse event
 *  destination - the component that will ultimately be moved
 *  pressed - the Point where the mouse was pressed in the destination
 *      component coordinates.
 */
@Override
public void mousePressed(MouseEvent e)
{
    source = e.getComponent();
    int width  = source.getSize().width  - dragInsets.left - dragInsets.right;
    int height = source.getSize().height - dragInsets.top - dragInsets.bottom;
    Rectangle r = new Rectangle(dragInsets.left, dragInsets.top, width, height);

    if (r.contains(e.getPoint()))
        setupForDragging(e);
}

private void setupForDragging(MouseEvent e)
{
    source.addMouseMotionListener( this );

    //  Determine the component that will ultimately be moved

    if (destinationComponent != null)
    {
        destination = destinationComponent;
    }
    else if (destinationClass == null)
    {
        destination = source;
    }
    else  //  forward events to destination component
    {
        destination = SwingUtilities.getAncestorOfClass(destinationClass, source);
    }

    pressed = e.getLocationOnScreen();
    location = destination.getLocation();

    if (changeCursor)
    {
        originalCursor = source.getCursor();
        source.setCursor( Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR) );
    }

    //  Making sure autoscrolls is false will allow for smoother dragging of
    //  individual components

    if (destination instanceof JComponent)
    {
        JComponent jc = (JComponent)destination;
        autoscrolls = jc.getAutoscrolls();
        jc.setAutoscrolls( false );
    }
}

/**
 *  Move the component to its new location. The dragged Point must be in
 *  the destination coordinates.
 */
@Override
public void mouseDragged(MouseEvent e)
{
    destination.repaint();
    Point dragged = e.getLocationOnScreen();
    int dragX = getDragDistance(dragged.x, pressed.x, snapSize.width);
    int dragY = getDragDistance(dragged.y, pressed.y, snapSize.height);
    destination.setLocation(location.x + dragX, location.y + dragY);
    for(Component c : comps)
        c.repaint();
}

/*
 *  Determine how far the mouse has moved from where dragging started
 *  (Assume drag direction is down and right for positive drag distance)
 */
private int getDragDistance(int larger, int smaller, int snapSize)
{
    int halfway = snapSize / 2;
    int drag = larger - smaller;
    drag += (drag < 0) ? -halfway : halfway;
    drag = (drag / snapSize) * snapSize;

    return drag;
}

/**
 *  Restore the original state of the Component
 */
@Override
public void mouseReleased(MouseEvent e)
{
    for(Component c : comps)
        c.repaint();
    System.out.println("Repainted!");

    source.removeMouseMotionListener( this );

    if (changeCursor)
        source.setCursor( originalCursor );

    if (destination instanceof JComponent)
    {
        ((JComponent)destination).setAutoscrolls( autoscrolls );
    }

}

}

ComponentMover is used to change the location of components on a panel.

It sounds to me like you want to scroll the panel contained in the viewport of a scrollpane. If so, I suggest you check out the JComponent.setAutoScrolls() method which has some example code for scrolling a component in a scrollpane.