Programming Languages Suite/ProgLangD.iso/Java++/VJ/SAMPLES/JAVANOW/CHAP17/DIALOGWINDOW/DIALOGLAYOUT.JAVA

Java Source | 1996-06-13 | 5.3 KB | 188 lines

// This is a part of the Microsoft Jakarta library.
// Copyright (C) 1996 Microsoft Corporation
// All rights reserved.

//package java.awt;

import java.util.Hashtable;
import java.awt.LayoutManager;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.FontMetrics;
import java.awt.Insets;
import java.awt.Label;

//
// class DialogLayout
//
// DialogLayout is a simple layout manager which works with what the Win32
// API calls "dialog logical units" (DLUs).  DLUs are resolution independent
// coordinates which work well for laying out controls on a dialog box.  The
// mapping from DLUs to pixels is based on the font in use in the dialog box.
// An x-coordinate DLU is described as 1/4 (.25) of the of the average character
// width of the font used in the dialog.  A y-coordinate DLU is described as
// 1/8 (.125) of the character height used in the dialog.  One tricky issue to
// note: The average character width is not the average of all characters --
// rather it is the average of all alpha characters both uppercase and
// lowercase. That is, it is the extent of the string "a...zA...Z" divided
// by 52.
//
// This class allows you to associate a Rectangle (x, y, width, height) with a
// Component in a Container.  If called upon to layout the container, this
// layout manager will layout based on the translation of dialog units to
// pixels.
//

public class DialogLayout
    implements LayoutManager
{
    protected Hashtable m_map = new Hashtable();
    protected int m_width;
    protected int m_height;

    // DialogLayout methods

    public DialogLayout(Container parent, int width, int height)
    {
        //assert parent != null;
        Construct(parent, width, height);
    }

    public DialogLayout(Container parent, Dimension d)
    {
        //assert parent != null;
        Construct(parent, d.width, d.height);
    }

    public void setShape(Component comp, int x, int y, int width, int height)
    {
        //assert m_map != null;
        //assert comp != null;
        m_map.put(comp, new Rectangle(x, y, width, height));
    }

    public void setShape(Component comp, Rectangle rect)
    {
        //assert m_map != null;
        //assert comp != null;
        m_map.put(comp, new Rectangle(rect.x, rect.y, rect.width, rect.height));
    }

    public Rectangle getShape(Component comp)
    {
        //assert comp != null;
        Rectangle rect = (Rectangle)m_map.get(comp);
        //assert rect != null;
        return new Rectangle(rect.x, rect.y, rect.width, rect.height);
    }

    public Dimension getDialogSize()
    {
        return new Dimension(m_width, m_height);
    }

    // LayoutManager Methods

    public void addLayoutComponent(String name, Component comp) { }
    public void removeLayoutComponent(Component comp) { }

    public Dimension preferredLayoutSize(Container parent)
    {
        //assert parent != null;
        return new Dimension(m_width, m_height);
    }

    public Dimension minimumLayoutSize(Container parent)
    {
        //assert parent != null;
        return new Dimension(m_width, m_height);
    }

    public void layoutContainer(Container parent)
    {
        //assert parent != null;
        int count = parent.countComponents();
        Rectangle rect = new Rectangle();
        int charHeight = getCharHeight(parent);
        int charWidth = getCharWidth(parent);
        Insets insets = parent.insets();
        FontMetrics m = parent.getFontMetrics(parent.getFont());

        for (int i = 0; i < count; i++)
        {
            Component c = parent.getComponent(i);
            //assert c != null;
            Rectangle r = (Rectangle)m_map.get(c);
            if (r != null)
            {
                rect.x = r.x;
                rect.y = r.y;
                rect.height = r.height;
                rect.width = r.width;
                mapRectangle(rect, charWidth, charHeight);
                if (c instanceof Label)
                {
                    // REVIEW: Adjusts for space at left of Java labels.
                    //         Not sure what the space is for, but it seems
                    //         to be hard coded at 12 pixels, at least on Win95/NT,
                    //           and not related to the font.
                    rect.x     -= 12;
                    rect.width += 12;
                }

                rect.x += insets.left;
                rect.y += insets.top;
                c.reshape(rect.x, rect.y, rect.width, rect.height);
            }
        }
    }

    // Implementation Helpers

    protected void Construct(Container parent, int width, int height)
    {
        //assert m_map != null;
        Rectangle rect = new Rectangle(0, 0, width, height);
        mapRectangle(rect, getCharWidth(parent), getCharHeight(parent));
        m_width = rect.width;
        m_height = rect.height;
    }

    protected int getCharWidth(Container parent)
    {
        //assert parent != null;
        FontMetrics m = parent.getFontMetrics(parent.getFont());
        //assert m != null;
        String s     = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        int    width = m.stringWidth(s) / s.length();

        if (width <= 0)
            width = 1;
        return width;
    }

    protected int getCharHeight(Container parent)
    {
        //assert parent != null;
        FontMetrics m = parent.getFontMetrics(parent.getFont());
        //assert m != null;
        int height = m.getHeight();
        //assert height > 0;
        return height;
    }

    protected void mapRectangle(Rectangle rect, int charWidth, int charHeight)
    {
        //assert rect != null;
        //assert charWidth > 0;
        //assert charHeight > 0;
        rect.x      = (rect.x      * charWidth)  / 4;
        rect.y      = (rect.y      * charHeight) / 8;
        rect.width  = (rect.width  * charWidth)  / 4;
        rect.height = (rect.height * charHeight) / 8;
    }
}