CompoundIcon.java

import java.awt.*;
import javax.swing.*;

/**
 *  The CompoundIcon will paint two, or more, Icons as a single Icon. The
 *  Icons are painted in the order in which they are added.
 *  
 *  @author http://www.camick.com/java/source/CompoundIcon.java
 *
 *  The Icons are layed out on the specified axis:
 * <ul>
 * <li>X-Axis (horizontally)
 * <li>Y-Axis (vertically)
 * <li>Z-Axis (stacked)
 * </ul>
 *
 */
public class CompoundIcon implements Icon
{
    public enum Axis
    {
        X_AXIS,
        Y_AXIS,
        Z_AXIS;
    }

    public final static float TOP = 0.0f;
    public final static float LEFT = 0.0f;
    public final static float CENTER = 0.5f;
    public final static float BOTTOM = 1.0f;
    public final static float RIGHT = 1.0f;

    private Icon[] icons;

    private Axis axis;

    private int gap;

    private float alignmentX = CENTER;
    private float alignmentY = CENTER;

    /**
     *  Convenience contructor for creating a CompoundIcon where the
     *  icons are layed out on on the X-AXIS, the gap is 0 and the
     *  X/Y alignments will default to CENTER.
     *
     *  @param icons  the Icons to be painted as part of the CompoundIcon
     */
    public CompoundIcon(Icon... icons)
    {
        this(Axis.X_AXIS, icons);
    }

    /**
     *  Convenience contructor for creating a CompoundIcon where the
     *  gap is 0 and the X/Y alignments will default to CENTER.
     *
     *  @param axis   the axis used to lay out the icons for painting.
     *                Must be one of the Axis enums: X_AXIS, Y_AXIS, Z_Axis.
     *  @param icons  the Icons to be painted as part of the CompoundIcon
     */
    public CompoundIcon(Axis axis, Icon... icons)
    {
        this(axis, 0, icons);
    }

    /**
     *  Convenience contructor for creating a CompoundIcon where the
     *  X/Y alignments will default to CENTER.
     *
     *  @param axis   the axis used to lay out the icons for painting
     *                Must be one of the Axis enums: X_AXIS, Y_AXIS, Z_Axis.
     *  @param gap    the gap between the icons
     *  @param icons  the Icons to be painted as part of the CompoundIcon
     */
    public CompoundIcon(Axis axis, int gap, Icon... icons)
    {
        this(axis, gap, CENTER, CENTER, icons);
    }

    /**
     *  Create a CompoundIcon specifying all the properties.
     *
     *  @param axis        the axis used to lay out the icons for painting
     *                     Must be one of the Axis enums: X_AXIS, Y_AXIS, Z_Axis.
     *  @param gap         the gap between the icons
     *  @param alignmentX  the X alignment of the icons. Common values are
     *                     LEFT, CENTER, RIGHT. Can be any value between 0.0 and 1.0
     *  @param alignmentY  the Y alignment of the icons. Common values are
     *                     TOP, CENTER, BOTTOM. Can be any value between 0.0 and 1.0
     *  @param icons       the Icons to be painted as part of the CompoundIcon
     */
    public CompoundIcon(Axis axis, int gap, float alignmentX, float alignmentY, Icon... icons)
    {
        this.axis = axis;
        this.gap = gap;
        this.alignmentX = alignmentX > 1.0f ? 1.0f : alignmentX < 0.0f ? 0.0f : alignmentX;
        this.alignmentY = alignmentY > 1.0f ? 1.0f : alignmentY < 0.0f ? 0.0f : alignmentY;

        for (int i = 0; i < icons.length; i++)
        {
            if (icons[i] == null)
            {
                String message = "Icon (" + i + ") cannot be null";
                throw new IllegalArgumentException( message );
            }
        }

        this.icons = icons;
    }

    /**
     *  Get the Axis along which each icon is painted.
     *
     *  @return the Axis
     */
    public Axis getAxis()
    {
        return axis;
    }

    /**
     *  Get the gap between each icon
     *
     *  @return the gap in pixels
     */
    public int getGap()
    {
        return gap;
    }

    /**
     *  Get the alignment of the icon on the x-axis
     *
     *  @return the alignment
     */
    public float getAlignmentX()
    {
        return alignmentX;
    }

    /**
     *  Get the alignment of the icon on the y-axis
     *
     *  @return the alignment
     */
    public float getAlignmentY()
    {
        return alignmentY;
    }

    /**
     *  Get the number of Icons contained in this CompoundIcon.
     *
     *  @return the total number of Icons
     */
    public int getIconCount()
    {
        return icons.length;
    }

    /**
     *  Get the Icon at the specified index.
     *
     *  @param index  the index of the Icon to be returned
     *  @return  the Icon at the specifed index
     *  @exception IndexOutOfBoundsException  if the index is out of range
     */
    public Icon getIcon(int index)
    {
        return icons[ index ];
    }
    //
    //  Implement the Icon Interface
    //
    /**
     *  Gets the width of this icon.
     *
     *  @return the width of the icon in pixels.
     */
    @Override
    public int getIconWidth()
    {
        int width = 0;

        //  Add the width of all Icons while also including the gap

        if (axis == Axis.X_AXIS)
        {
            width += (icons.length - 1) * gap;

            for (Icon icon : icons)
                width += icon.getIconWidth();
        }
        else  //  Just find the maximum width
        {
            for (Icon icon : icons)
                width = Math.max(width, icon.getIconWidth());
        }

        return width;
    }

    /**
     *  Gets the height of this icon.
     *
     *  @return the height of the icon in pixels.
     */
    @Override
    public int getIconHeight()
    {
        int height = 0;

        //  Add the height of all Icons while also including the gap

        if (axis == Axis.Y_AXIS)
        {
            height += (icons.length - 1) * gap;

            for (Icon icon : icons)
                height += icon.getIconHeight();
        }
        else  //  Just find the maximum height
        {
            for (Icon icon : icons)
                height = Math.max(height, icon.getIconHeight());
        }

        return height;
    }

    /**
     *  Paint the icons of this compound icon at the specified location
     *
     *  @param c The component on which the icon is painted
     *  @param g the graphics context
     *  @param x the X coordinate of the icon's top-left corner
     *  @param y the Y coordinate of the icon's top-left corner
     */
    @Override
    public void paintIcon(Component c, Graphics g, int x, int y)
    {
        if (axis == Axis.X_AXIS)
        {
            int height = getIconHeight();

            for (Icon icon : icons)
            {
                int iconY = getOffset(height, icon.getIconHeight(), alignmentY);
                icon.paintIcon(c, g, x, y + iconY);
                x += icon.getIconWidth() + gap;
            }
        }
        else if (axis == Axis.Y_AXIS)
        {
            int width = getIconWidth();

            for (Icon icon : icons)
            {
                int iconX = getOffset(width, icon.getIconWidth(), alignmentX);
                icon.paintIcon(c, g, x + iconX, y);
                y += icon.getIconHeight() + gap;
            }
        }
        else // must be Z_AXIS
        {
            int width = getIconWidth();
            int height = getIconHeight();

            for (Icon icon : icons)
            {
                int iconX = getOffset(width, icon.getIconWidth(), alignmentX);
                int iconY = getOffset(height, icon.getIconHeight(), alignmentY);
                icon.paintIcon(c, g, x + iconX, y + iconY);
            }
        }
    }

    /*
     *  When the icon value is smaller than the maximum value of all icons the
     *  icon needs to be aligned appropriately. Calculate the offset to be used
     *  when painting the icon to achieve the proper alignment.
     */
    private int getOffset(int maxValue, int iconValue, float alignment)
    {
        float offset = (maxValue - iconValue) * alignment;
        return Math.round(offset);
    }
}