import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import java.awt.event.MouseEvent;

import java.awt.event.AdjustmentListener;

import java.awt.event.AdjustmentEvent;

import javax.swing.ToolTipManager;

/**

* This class is used to help generate tooltips on components added to a

* scrollpane. Generally tooltips are generated as the mouse if moved over

* components that display tooltips. On complex component, like a JTable

* the component can generate multiple tooltips depending on which cell the

* mouse is positioned over.

*

* However, when the viewport of the scrollpane is moved and the mouse is

* not moved the tooltip is not updated even though the mouse is positioned

* over a different cell. This might happen for example when the mouse wheel

* is used to scroll the viewport.

*

* To force updating of the tooltip, this class will generate a phantom

* mouseMoved event which is passed to the ToolTipManager.

*

* This class is actually a 3 in 1 listener and will work slightly different

* depending on how it is being used. When used as a:

*

* a) MouseWheelListener - it is added to the scrollpane. In this case the

* mouseMoved events are only generated by scrolling of the mouse wheel

* and therefore only supports vertical movement of the viewport

* b) AdjustmentListener - is added to the vertical and/or horizontal scrollbar.

* In this case the viewport can be scrolled by using the mouse wheel or

* the keyboard and mouseMoved events will be generated.

* c) ComponentListener - it is added to the component. In this case all forms

* of viewport movement as well as changes in the component size will cause

* the mouseMoved event to be generated.

*

*/

public class ToolTipListener

implements ComponentListener, MouseWheelListener, AdjustmentListener

{

/**

* Create a mouseMoved event to pass to the ToolTipManager.

*/

private void phantomMouseMoved(Component component)

{

if (component == null) return;

// Mouse is in the bounds of the component, generate phantom

// mouseMoved event for the ToolTipManager

Point mouseLocation = component.getMousePosition();

if (mouseLocation != null)

{

MouseEvent phantom = new MouseEvent(

component,

MouseEvent.MOUSE_MOVED,

System.currentTimeMillis(),

0,

mouseLocation.x,

mouseLocation.y,

0,

false);

ToolTipManager.sharedInstance().mouseMoved(phantom);

}

}

// Implement ComponentListener

public void componentMoved(ComponentEvent e)

{

Component component = e.getComponent();

phantomMouseMoved( component );

}

public void componentResized(ComponentEvent e)

{

Component component = e.getComponent();

phantomMouseMoved( component );

}

public void componentHidden(ComponentEvent e) {}

public void componentShown(ComponentEvent e) {}

// Implement MouseWheelListener

public void mouseWheelMoved(MouseWheelEvent e)

{

JScrollPane scrollPane = (JScrollPane)e.getSource();

Component component = scrollPane.getViewport().getView();

phantomMouseMoved( component );

}

// Implement AdjustmentListener

public void adjustmentValueChanged(AdjustmentEvent e)

{

JScrollBar scrollBar = (JScrollBar)e.getSource();

JScrollPane scrollPane = (JScrollPane)scrollBar.getParent();

Component component = scrollPane.getViewport().getView();

phantomMouseMoved( component );

}

}