jframeex.java

There a t least five Request for Enhancement s (RFE) in the JavaSoft bug database related to Mouse W

///////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2000 Davanum Srinivas ([e-mail])
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published by 
// the Free Software Foundation; either version 2 of the License, or 
// any later version. 
// 
// This program is distributed in the hope that it will be useful, but 
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details. 
//
// You should have received a copy of the GNU General Public License along with 
// this program; if not, write to the 
// Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 
///////////////////////////////////////////////////////////////////////////////

import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

// This is an undocumented package.
import sun.awt.*;

public class JFrameEx extends JFrame 
{
	static {
		//Load the library that contains the subclassing code.
		System.loadLibrary("MouseWheel");
	}

    // native entry point for subclassing the JFrame window
    public native void setHook(int hwnd);

    // native entry point for removing the hook.
    public native void resetHook(int hwnd);

	// this is the function which serves as a call back when 
	// a mouse wheel movement is detected.
	public void notifyMouseWheel(short fwKeys,short zDelta,long xPos, long yPos)
	{
		// Convert screen coordinates to component specific offsets.
		Point p = new Point((int)xPos,(int)yPos);
		SwingUtilities.convertPointFromScreen(p,this);

		// Find the embedded Swing component which should receive the scroll messages
		Component c = SwingUtilities.getDeepestComponentAt(this, p.x, p.y);
		try
		{
			// Get the scroll pane for the widget.
			JScrollPane scrollPane = (JScrollPane) c.getParent().getParent();

			// Get the vertical scrollbar for the scroll pane.
			JScrollBar scrollBar = scrollPane.getVerticalScrollBar();

			// Get the current value and set the new value depending on 
			// the direction of the mouse wheel.
			int nValue = scrollBar.getValue();
			nValue = nValue + ((zDelta > 0) ? 5 : -5);
			scrollBar.setValue(nValue);
		} catch (Exception e){
			// Ignore exceptions.
		}
	}

	// constructor which specifies the Title
    public JFrameEx(String strTitle)
    {
		super(strTitle);
    }

    // Returns the HWND for canvas. 
	// This is undocumented, but works on JDK1.1.8, JDK1.2.2 and JDK1.3 
    public int getHWND() 
    {
        DrawingSurfaceInfo drawingSurfaceInfo;
        Win32DrawingSurface win32DrawingSurface;
        int hwnd = 0;
     
        // Get the drawing surface 
        drawingSurfaceInfo =
            ((DrawingSurface)(getPeer())).getDrawingSurfaceInfo();
        
        if (null != drawingSurfaceInfo) {
            drawingSurfaceInfo.lock();
            // Get the Win32 specific information 
            win32DrawingSurface = 
                 (Win32DrawingSurface)drawingSurfaceInfo.getSurface();
            hwnd = win32DrawingSurface.getHWnd();
            drawingSurfaceInfo.unlock();
        }
        return hwnd;
    }

	// subclass the window once it has been created.
    public void addNotify()
    {
		super.addNotify();
		setHook(getHWND());
    }

	// remove the subclass-ing when the window is about to be destroyed.
    public void removeNotify()
    {
		resetHook(getHWND());
		super.removeNotify();
    }
}