[Ghoser777]

Maybe this already exists, but for as long as I've programmed in both pure Java and Cocoa separately, I wanted a Java LayoutManager that worked just like with Cocoa GUI components. So, I threw together the following 2 classes (never done a LayoutManager before, so I'm sure I'm breaking some conventions) and I kind of like how it works.

FahrenbacherLayout

Code:
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class FahrenbacherLayout implements LayoutManager2, HierarchyBoundsListener {

	private Container parent;
	private HashMap<Component,FahrenbacherConstraint> constraintsMap;
	
	private Dimension lastSize;

	public FahrenbacherLayout(Container c) {
		parent = c;
		parent.addHierarchyBoundsListener(this);
		
		constraintsMap = new HashMap<Component,FahrenbacherConstraint>();
	}

	public void addLayoutComponent(String name, Component comp){}
	
	public void addLayoutComponent(Component comp, Object constraints) {
		constraintsMap.put(comp, (FahrenbacherConstraint)constraints);
	}
	
	public void removeLayoutComponent(Component comp) {
		constraintsMap.remove(comp);
	}
	
	public Dimension minimumLayoutSize(Container parent) { 
		return parent.getMinimumSize(); 
	}
	
	public Dimension preferredLayoutSize(Container parent) { 
		return parent.getPreferredSize(); 
	}
	
	public Dimension maximumLayoutSize(Container target) { 
		return parent.getMaximumSize(); 
	}
	
	public float getLayoutAlignmentX(Container target){ return 0.0f; }
	public float getLayoutAlignmentY(Container target){ return 0.0f; }
	
	public void layoutContainer(Container parent) {
		if(parent.getWidth() == 0 || parent.getHeight() == 0)
			return;
		else if(lastSize == null)
			lastSize = parent.getSize();
	
		int count = parent.getComponentCount();
		for(int i = count-1; i>=0; i--) {
			Component c = parent.getComponent(i);
			FahrenbacherConstraint constr = constraintsMap.get(c);
			if(constr != null) {
			
				if(constr.propertyIsOn(FahrenbacherConstraint.STRETCH_HORIZONTALLY))
				{
					if(	constr.propertyIsOn(FahrenbacherConstraint.LEFT_FIXED_DISTANCE) && 
						constr.propertyIsOn(FahrenbacherConstraint.RIGHT_FIXED_DISTANCE))
					{
						c.setSize(parent.getWidth() - c.getX() - (lastSize.width - (c.getX() + c.getWidth())), c.getHeight());
					}
					else if(constr.propertyIsOn(FahrenbacherConstraint.LEFT_FIXED_DISTANCE))
					{
						double oldProp = c.getWidth() / (lastSize.getWidth() - c.getX());
						c.setSize((int)Math.round((parent.getWidth() - c.getX()) * oldProp), c.getHeight());
					}
					else if(constr.propertyIsOn(FahrenbacherConstraint.RIGHT_FIXED_DISTANCE))
					{
						int fromRight = lastSize.width - (c.getX() + c.getWidth());
						
						double oldProp = c.getWidth() / (lastSize.getWidth() - fromRight);
						int newWidth = (int)Math.round((parent.getWidth() - fromRight)*oldProp);
						int newX = parent.getWidth() - fromRight - newWidth;
						
						c.setSize(newWidth, c.getHeight());
						c.setLocation(newX, c.getY());
					}
					else
					{
						double midPercentFromLeft = (c.getX() + c.getWidth()/2) / lastSize.getWidth();
						double oldProp = c.getWidth() / lastSize.getWidth();
						
						int newWidth = (int)Math.round(parent.getWidth() * oldProp);
						int newX = (int)Math.round(parent.getWidth() * midPercentFromLeft - newWidth/2);
						
						c.setSize(newWidth, c.getHeight());
						c.setLocation(newX, c.getY());
					}
				}
				else
				{
					if(constr.propertyIsOn(FahrenbacherConstraint.LEFT_FIXED_DISTANCE)) //ignore right
					{
						//do nothing!  by default, that's how things will orient
					}
					else if(constr.propertyIsOn(FahrenbacherConstraint.RIGHT_FIXED_DISTANCE))
					{
						int fromRight = lastSize.width - (c.getX() + c.getWidth());
						c.setLocation(parent.getWidth() - fromRight - c.getWidth(), c.getY());
					}
					else //actually, more work to do in this case!
					{
						double midPercentFromLeft = (c.getX() + c.getWidth()/2) / lastSize.getWidth();						
						int newX = (int)Math.round(parent.getWidth() * midPercentFromLeft - c.getWidth()/2);						
						c.setLocation(newX, c.getY());
					}
				}
		
			
				if(constr.propertyIsOn(FahrenbacherConstraint.STRETCH_VERTICALLY)) {
					if(	constr.propertyIsOn(FahrenbacherConstraint.TOP_FIXED_DISTANCE) && 
						constr.propertyIsOn(FahrenbacherConstraint.BOTTOM_FIXED_DISTANCE))
					{
						c.setSize(c.getWidth(), parent.getHeight() - c.getY() - (lastSize.height - (c.getY() + c.getHeight())));
					}
					else if(constr.propertyIsOn(FahrenbacherConstraint.TOP_FIXED_DISTANCE))
					{
						double oldProp = c.getHeight() / (lastSize.getHeight() - c.getY());
						c.setSize(c.getWidth(), (int)Math.round((parent.getHeight() - c.getY()) * oldProp));
					}
					else if(constr.propertyIsOn(FahrenbacherConstraint.BOTTOM_FIXED_DISTANCE))
					{
						int fromBottom = lastSize.height - (c.getY() + c.getHeight());
						
						double oldProp = c.getHeight() / (lastSize.getHeight() - fromBottom);
						int newHeight = (int)Math.round((parent.getHeight() - fromBottom)*oldProp);
						int newY = parent.getHeight() - fromBottom - newHeight;
						
						c.setSize(c.getWidth(), newHeight);
						c.setLocation(c.getX(), newY);
					}
					else
					{
						double midPercentFromTop = (c.getY() + c.getHeight()/2) / lastSize.getHeight();
						double oldProp = c.getHeight() / lastSize.getHeight();
						
						int newHeight = (int)Math.round(parent.getHeight() * oldProp);
						int newY = (int)Math.round(parent.getHeight() * midPercentFromTop - newHeight/2);
						
						c.setSize(c.getWidth(), newHeight);
						c.setLocation(c.getX(), newY);
					}
				}
				else
				{
					if(constr.propertyIsOn(FahrenbacherConstraint.TOP_FIXED_DISTANCE)) //ignore bottom
					{
						//do nothing!  by default, that's how things will orient
					}
					else if(constr.propertyIsOn(FahrenbacherConstraint.BOTTOM_FIXED_DISTANCE))
					{
						int fromBottom = lastSize.height - (c.getY() + c.getHeight());
						c.setLocation(c.getX(), parent.getHeight() - fromBottom - c.getHeight());
					}
					else //actually, more work to do in this case!
					{
						double midPercentFromTop = (c.getY() + c.getHeight()/2) / lastSize.getHeight();						
						int newY = (int)Math.round(parent.getHeight() * midPercentFromTop - c.getHeight()/2);						
						c.setLocation(c.getX(), newY);
					}
				}
			}
		}
		
		lastSize = parent.getSize();
	}
	
	public void invalidateLayout(Container target){}
	
	public void ancestorMoved(HierarchyEvent e){}
	public void ancestorResized(HierarchyEvent e)
	{	
		layoutContainer(parent);
		parent.repaint();
	}
}

FahrenbacherConstraint

Code:
public class FahrenbacherConstraint {
	private int properties;
	
	public static final int NONE = 0;
	public static final int STRETCH_VERTICALLY = 1;
	public static final int STRETCH_HORIZONTALLY = 2;
	public static final int LEFT_FIXED_DISTANCE = 4;
	public static final int RIGHT_FIXED_DISTANCE = 8;
	public static final int TOP_FIXED_DISTANCE = 16;
	public static final int BOTTOM_FIXED_DISTANCE = 32;
	
	public FahrenbacherConstraint(int prop) {
		properties = prop;
	}
	
	public boolean propertyIsOn(int type) {
		return (properties & type) != 0;
	}
	
	public void setProperty(int type, boolean on) {
		if(on)
			properties = (properties | type);
		else if(propertyIsOn(type))
			properties -= type;
	}
}

Example usage:

Code:
JFrame frame = new JFrame();
frame.setSize(300,400);
Container c = getContentPane();
c.setLayout(new FahrenbacherLayout(c));

JButton butt = new JButton("Hi");
butt.setBounds(20,20,100,50);
c.add(butt, FahrenbacherConstraints.LEFT_FIXED_DISTANCE | 
                 FahrenbacherConstraints.RIGHT_FIXED_DISTANCE |
                 FahrenbacherConstraints.STRETCH_HORIZONTALLY);

[gperks]

Worth a look is Foam, Computers in Motion - Home. Also search for RelativeLayout.