The Net: Ultimate Internet Guide/WWLCD1.ISO/pc/java/un2maiq4/pjjava/src/pj/awt/pjbuttonlayout.java

Java Source | 1996-08-14 | 7.1 KB | 237 lines

/*---------------------------------------------------------------------------

    Written by the Personal Journal developers of Dow Jones & Company, Inc.

    Dow Jones makes no representations or warranties about
    the suitability of this software, either express or
    implied, including but not limited to the implied warranties
    of merchantability, fitness for a particular purpose,
    or non-infringement.  Dow Jones will not be liable for
    any damages suffered by a user as a result of using,
    modifying or distributing this software or its derivatives.


    @(#)PjButtonLayout.java   0.00 8-Feb-96

        A PjButtonLayout that manages the eaual size buttons layout.

    Authors:

        jlee        James Lee

    Version Ident:

        $Header$

    History:

         8-Feb-96    jlee   Initial creation.
        15-Feb-96    jlee   Added and used PjFinals class for all size info.
        25-Mar-96    jlee   Modified layoutCOntainer so that it dosn't repeat the same layout change.
---------------------------------------------------------------------------*/

package pj.awt;

import pj.awt.PjFinals;

import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Rectangle;

/**
 * PjButtonLayout is used to layout equal size buttons in a panel.
 * <P>
 * This custom layout places the equal size buttons horizontally,
 * regardless of the length of caption of individual button.
 * <pre>
 *      ____________________________________________
 *      |     Button1       |       Button2         |
 *      ---------------------------------------------
 * </pre>
 * @version     0.00, 8/2/96
 * @author      James Lee
 */
public class PjButtonLayout implements LayoutManager
    {

    // Instance variables

    //widthFixed: wether or not the width of buttons are bound.
    private boolean bWidthFixed = true;

    private int   hgap;
    private int   vgap;

    private final Dimension dimButtonSize  = new Dimension( PjFinals.nPjMinimumPageViewWidth, PjFinals.nPjButtonHeight );
    private       Rectangle recLast        = new Rectangle(0, 0, 0, 0);


    // --- Public constructors
    /**
     * Constructs a new Flow Layout with a centered alignment.
     * Default value for hgap and vgap is 0.
     */
    public PjButtonLayout()
        {
        this(0, 0);
        }

    /**
     * Constructs a new Flow Layout with the specified alignment and gap
     * values.
     * @param fixed the constraint flag for button width
     */
    public PjButtonLayout(boolean fixed)
        {
        this(0, 0);
        this.bWidthFixed = fixed;
        }

    /**
     * Constructs a new Flow Layout with the specified alignment and gap
     * values.
     * @param hgap the horizontal gap variable
     * @param vgap the vertical gap variable
     */
    public PjButtonLayout(int hgap, int vgap)
        {
        this.hgap = hgap;
        this.vgap = vgap;
        }

    /**
     * Constructs a new Flow Layout with the specified alignment and gap
     * values.
     * @param hgap  the horizontal gap variable
     * @param vgap  the vertical gap variable
     * @param fixed the constraint flag for button width
     */
    public PjButtonLayout(int hgap, int vgap, boolean fixed)
        {
        this.hgap = hgap;
        this.vgap = vgap;
        this.bWidthFixed = fixed;
        }

    // --- Public operations
    /**
     * Adds the specified component to the layout. Not used by this class.
     * @param name the name of the component
     * @param comp the the component to be added
     */
    public void addLayoutComponent(String name, Component comp)
        {
        }

    /**
     * Removes the specified component from the layout. Not used by
     * this class.
     * @param comp the component to remove
     */
    public void removeLayoutComponent(Component comp)
        {
        }

    /**
     * Returns the preferred dimensions for this layout given the components
     * in the specified target container.
     * @param target the component which needs to be laid out
     * @see Container
     * @see #minimumLayoutSize
     */
    public Dimension preferredLayoutSize(Container target)
        {
        Dimension dim = new Dimension(dimButtonSize.width + hgap, dimButtonSize.height);
        int nmembers = target.countComponents();

        Insets insets = target.insets();
        dim.width += insets.left + insets.right + hgap*2;
        dim.height += insets.top + insets.bottom + vgap*2;

        return dim;
        }

    /**
     * Returns the minimum dimensions needed to layout the components
     * contained in the specified target container.
     * @param target the component which needs to be laid out
     * @see #preferredLayoutSize
     */
    public Dimension minimumLayoutSize(Container target)
        {
        Dimension dim = new Dimension(dimButtonSize.width + hgap, dimButtonSize.height);

        Insets insets = target.insets();
        dim.width += insets.left + insets.right + hgap*2;
        dim.height += insets.top + insets.bottom + vgap*2;

        return dim;
        }


    /**
     * Lays out the container. This method will actually reshape the
     * components in the target in order to satisfy the constraints of
     * the PjAdViewLayout object.
     * @param target the specified component being laid out.
     * @see Container
     */
    public void layoutContainer(Container target)
        {
        Insets insets = target.insets();
        Rectangle rec = target.bounds();

        if ( target.isValid() &&
            rec.x == recLast.x && rec.y == recLast.y &&
            rec.width == recLast.width && rec.height == recLast.height  )

            return;
        else
            recLast = rec;

        int maxwidth = rec.width - (insets.left + insets.right + hgap*2);
        int nmembers = target.countComponents();

        int width;
        int btnWidth;

        if ( bWidthFixed )
            {
            width = maxwidth - dimButtonSize.width;
            btnWidth = ( dimButtonSize.width - (nmembers - 1) * hgap ) / nmembers;
            }
        else
            {
            width = hgap*2;
            btnWidth = ( maxwidth - (nmembers - 1) * hgap ) / nmembers;
            }

        int x = width / 2;
        int y = (rec.height - dimButtonSize.height - vgap*2) / 2;

        for (int i = 0 ; i < nmembers ; i++)
            {
            Component m = target.getComponent(i);

            if ( m.isVisible() )
                m.reshape( x, y, btnWidth, PjFinals.nPjButtonHeight );

            x += btnWidth + hgap;
            }
        }

    /**
     * Returns the String representation of this PjButtonLayout's values.
     */
    public String toString()
        {
        return  getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + "]" +
                "[width=" + dimButtonSize.width + ",height=" + dimButtonSize.height + "]";
        }
}