DesktopScrollPane

/*
 * Copyright (c) 2013 DesktopScrollPane Pedro Duque Vieira. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  o Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 *  o Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 *  o Neither the name of DesktopScrollPane Pedro Duque Vieira nor the names of
 *    its contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package Modellus.WinUI.InternalFrames;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.ContainerEvent;
import java.awt.event.ContainerListener;

public class DesktopScrollPane extends JScrollPane {

    private JDesktopPane desktopPane;
    private InternalFrameComponentListener componentListener;

    /**
     * creates the DesktopScrollPane object
     *
     * @param desktopPane a reference to the JDesktopPane object
     */
    public DesktopScrollPane(JDesktopPane desktopPane) {

        componentListener = new InternalFrameComponentListener();

        this.desktopPane = desktopPane;
        desktopPane.addContainerListener(new ContainerListener() {
            @Override
            public void componentAdded(ContainerEvent e) {
                onComponentAdded(e);
            }

            @Override
            public void componentRemoved(ContainerEvent e) {
                onComponentRemoted(e);
            }
        });
        setViewportView(desktopPane);

        // set some defaults
        setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    }

    private void onComponentRemoted(ContainerEvent event) {
        Component removedComponent = event.getChild();
        if (removedComponent instanceof JInternalFrame)
            removedComponent.removeComponentListener(componentListener);

    }

    private void onComponentAdded(ContainerEvent event) {
        Component addedComponent = event.getChild();
        if (addedComponent instanceof JInternalFrame)
        {
            addedComponent.addComponentListener(componentListener);
            resizeDesktop();
        }
    }


    /**
     * returns all internal frames placed upon the desktop
     *
     * @return a JInternalFrame array containing references to the internal frames
     */
    public JInternalFrame[] getAllFrames() {
        return desktopPane.getAllFrames();
    }

    /**
     * sets the preferred size of the desktop
     *
     * @param dim a Dimension object representing the desired preferred size
     */
    public void setDesktopSize(Dimension dim) {
        desktopPane.setPreferredSize(dim);
        desktopPane.revalidate();
    }


    /**
     * resizes the desktop based upon the locations of its
     * internal frames. This updates the desktop scrollbars in real-time.
     */
    public void resizeDesktop() {

        SwingUtilities.invokeLater(new Runnable() {

            public void run(){

                // has to go through all the internal frames now and make sure none
                // off screen, and if so, add those scroll bars!

                Rectangle viewPort = getViewport().getViewRect();

                int maxX = viewPort.width + viewPort.x, maxY = viewPort.height + viewPort.y;
                int minX = viewPort.x, minY = viewPort.y;

                // determine the min/max extents of all internal frames

                JInternalFrame frame = null;
                JInternalFrame[] frames = getAllFrames();

                for (int i=0; i < frames.length; i++) {

                    frame = frames[i];

                    if (frame.getX() < minX) { // get minimum X
                        minX = frame.getX();
                    }
                    if ((frame.getX() + frame.getWidth()) > maxX)
                    {
                        maxX = frame.getX() + frame.getWidth();
                    }

                    if (frame.getY() < minY) { // get minimum Y
                        minY = frame.getY();
                    }
                    if ((frame.getY() + frame.getHeight()) > maxY)
                    {
                        maxY = frame.getY() + frame.getHeight();
                    }
                }

                // Don't count with frames that get off screen from the left side ant the top
                if (minX < 0) minX = 0;
                if (minY < 0) minY = 0;

                setVisible(false); // don't update the viewport
                // while we move everything (otherwise desktop looks 'bouncy')

                if (minX != 0 || minY != 0) {
                    // have to scroll it to the right or up the amount that it's off screen...
                    // before scroll, move every component to the right / down by that amount

                    for (int i=0; i < frames.length; i++) {
                        frame = frames[i];
                        frame.setLocation(frame.getX()-minX, frame.getY()-minY);
                    }

                    // have to scroll (set the viewport) to the right or up the amount
                    // that it's off screen...
                    JViewport view = getViewport();
                    view.setViewSize(new Dimension((maxX-minX),(maxY-minY)));
                    view.setViewPosition(new Point((viewPort.x-minX),(viewPort.y-minY)));
                    setViewport(view);

                }

                // resize the desktop
                setDesktopSize(new Dimension(maxX-minX, maxY-minY));

                setVisible(true); // update the viewport again


            }
        });
    }

  private class InternalFrameComponentListener implements ComponentListener
  {

      @Override
      public void componentResized(ComponentEvent e) {
          resizeDesktop();
      }

      @Override
      public void componentMoved(ComponentEvent e) {
          resizeDesktop();
      }

      @Override
      public void componentShown(ComponentEvent e) {
      }

      @Override
      public void componentHidden(ComponentEvent e) {
      }
  }
}