comboboxrenderer.java

FuncPlotter is a combined Java application and applet for displaying two-dimensional plots of explic

/*====================================================================*\

ComboBoxRenderer.java

Combo box renderer class.

------------------------------------------------------------------------

This file is part of FuncPlotter, a combined Java application and applet
for plotting explicit functions in one variable.
Copyright 2005-2007 Andy Morgan-Richards.

FuncPlotter 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 3 of the License, or (at your
option) 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, see <http://www.gnu.org/licenses/>.

\*====================================================================*/


// PACKAGE


package gui;

//----------------------------------------------------------------------


// IMPORTS


import java.awt.Component;
import java.awt.ComponentOrientation;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Rectangle;

import javax.swing.JComboBox;
import javax.swing.JComponent;
import javax.swing.JList;
import javax.swing.ListCellRenderer;

//----------------------------------------------------------------------


// COMBO BOX RENDERER CLASS


public class ComboBoxRenderer
    extends JComponent
    implements ListCellRenderer
{

////////////////////////////////////////////////////////////////////////
//  Constants
////////////////////////////////////////////////////////////////////////

    private static final    int TOP_MARGIN      = 1;
    private static final    int BOTTOM_MARGIN   = TOP_MARGIN;
    private static final    int LEADING_MARGIN  = 3;
    private static final    int TRAILING_MARGIN = 5;

////////////////////////////////////////////////////////////////////////
//  Constructors
////////////////////////////////////////////////////////////////////////

    public ComboBoxRenderer( JComboBox owner )
    {
        this.owner = owner;
        setOpaque( true );
    }

    //------------------------------------------------------------------

    public ComboBoxRenderer( JComboBox owner,
                             int       maxTextWidth )
    {
        this( owner );
        this.maxTextWidth = maxTextWidth;
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Instance methods : ListCellRenderer interface
////////////////////////////////////////////////////////////////////////

    public Component getListCellRendererComponent( JList   list,
                                                   Object  value,
                                                   int     index,
                                                   boolean isSelected,
                                                   boolean cellHasFocus )
    {
        setBackground( isSelected ? list.getSelectionBackground( ) : list.getBackground( ) );
        setForeground( isSelected ? list.getSelectionForeground( ) : list.getForeground( ) );
        text = (value == null) ? new String( ) : value.toString( );
        FontMetrics fontMetrics = getFontMetrics( list.getFont( ) );
        textWidth = fontMetrics.stringWidth( text );
        if ( (maxTextWidth > 0) && (textWidth > maxTextWidth) )
        {
            int maxWidth = maxTextWidth - fontMetrics.stringWidth( Constants.ELLIPSIS_STR );
            char[] chars = text.toCharArray( );
            int length = chars.length;
            while ( (length > 0) && (textWidth > maxWidth) )
                textWidth -= fontMetrics.charWidth( chars[--length] );
            text = new String( chars, 0, length ) + Constants.ELLIPSIS_STR;
        }
        textHeight = fontMetrics.getHeight( );
        return this;
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Instance methods : overriding methods
////////////////////////////////////////////////////////////////////////

    public Dimension getPreferredSize( )
    {
        int width = (maxTextWidth > 0) ? maxTextWidth : textWidth;
        return new Dimension( LEADING_MARGIN + width + TRAILING_MARGIN,
                              TOP_MARGIN + textHeight + BOTTOM_MARGIN );
    }

    //------------------------------------------------------------------

    protected void paintComponent( Graphics gr )
    {

        // Fill background

        Rectangle rect = gr.getClipBounds( );
        gr.setColor( getBackground( ) );
        gr.fillRect( rect.x, rect.y, rect.width, rect.height );

        // Draw text

        FontMetrics fontMetrics = gr.getFontMetrics( );
        int x = owner.getComponentOrientation( ).isLeftToRight( )
                                        ? LEADING_MARGIN
                                        : getWidth( ) - LEADING_MARGIN - fontMetrics.stringWidth( text );
        gr.setColor( getForeground( ) );
        gr.drawString( text, x, TOP_MARGIN + fontMetrics.getAscent( ) );

    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Instance variables
////////////////////////////////////////////////////////////////////////

    private JComboBox   owner;
    private int         maxTextWidth;
    private int         textWidth;
    private int         textHeight;
    private String      text;

}

//----------------------------------------------------------------------