public OverlayLayout(Container target) 
{
        this.target = target;
}

Constructs a layout manager that performs overlay arrangement of the children. The layout manager created is dedicated to the given container.

Parameters:

target - the container to do layout against

 public  void addLayoutComponent(String name,
    Component comp) 
{
        invalidateLayout(comp.getParent());
}

Adds the specified component to the layout. Used by this class to know when to invalidate layout.

 public  void addLayoutComponent(Component comp,
    Object constraints) 
{
        invalidateLayout(comp.getParent());
}

Adds the specified component to the layout, using the specified constraint object. Used by this class to know when to invalidate layout.

  void checkContainer(Container target) 
{
        if (this.target != target) {
            throw new AWTError("OverlayLayout can't be shared");
        }
}

  void checkRequests() 
{
        if (xChildren == null || yChildren == null) {
            // The requests have been invalidated... recalculate
            // the request information.
            int n = target.getComponentCount();
            xChildren = new SizeRequirements[n];
            yChildren = new SizeRequirements[n];
            for (int i = 0; i <  n; i++) {
                Component c = target.getComponent(i);
                Dimension min = c.getMinimumSize();
                Dimension typ = c.getPreferredSize();
                Dimension max = c.getMaximumSize();
                xChildren[i] = new SizeRequirements(min.width, typ.width,
                                                    max.width,
                                                    c.getAlignmentX());
                yChildren[i] = new SizeRequirements(min.height, typ.height,
                                                    max.height,
                                                    c.getAlignmentY());
            }
            xTotal = SizeRequirements.getAlignedSizeRequirements(xChildren);
            yTotal = SizeRequirements.getAlignedSizeRequirements(yChildren);
        }
}

 public float getLayoutAlignmentX(Container target) 
{
        checkContainer(target);
        checkRequests();
        return xTotal.alignment;
}

Returns the alignment along the x axis for the container.

 public float getLayoutAlignmentY(Container target) 
{
        checkContainer(target);
        checkRequests();
        return yTotal.alignment;
}

Returns the alignment along the y axis for the container.

 public final Container getTarget() 
{
        return this.target;
}

Returns the container that uses this layout manager.

 public  void invalidateLayout(Container target) 
{
        checkContainer(target);
        xChildren = null;
        yChildren = null;
        xTotal = null;
        yTotal = null;
}

Indicates a child has changed its layout related information, which causes any cached calculations to be flushed.

 public  void layoutContainer(Container target) 
{
        checkContainer(target);
        checkRequests();
        int nChildren = target.getComponentCount();
        int[] xOffsets = new int[nChildren];
        int[] xSpans = new int[nChildren];
        int[] yOffsets = new int[nChildren];
        int[] ySpans = new int[nChildren];
        // determine the child placements
        Dimension alloc = target.getSize();
        Insets in = target.getInsets();
        alloc.width -= in.left + in.right;
        alloc.height -= in.top + in.bottom;
        SizeRequirements.calculateAlignedPositions(alloc.width, xTotal,
                                                   xChildren, xOffsets,
                                                   xSpans);
        SizeRequirements.calculateAlignedPositions(alloc.height, yTotal,
                                                   yChildren, yOffsets,
                                                   ySpans);
        // flush changes to the container
        for (int i = 0; i <  nChildren; i++) {
            Component c = target.getComponent(i);
            c.setBounds(in.left + xOffsets[i], in.top + yOffsets[i],
                        xSpans[i], ySpans[i]);
        }
}

Called by the AWT when the specified container needs to be laid out.

 public Dimension maximumLayoutSize(Container target) 
{
        checkContainer(target);
        checkRequests();
        Dimension size = new Dimension(xTotal.maximum, yTotal.maximum);
        Insets insets = target.getInsets();
        size.width += insets.left + insets.right;
        size.height += insets.top + insets.bottom;
        return size;
}

Returns the maximum dimensions needed to lay out the components contained in the specified target container. Recomputes the layout if it has been invalidated, and factors in the inset setting returned by getInset.

 public Dimension minimumLayoutSize(Container target) 
{
        checkContainer(target);
        checkRequests();
        Dimension size = new Dimension(xTotal.minimum, yTotal.minimum);
        Insets insets = target.getInsets();
        size.width += insets.left + insets.right;
        size.height += insets.top + insets.bottom;
        return size;
}

Returns the minimum dimensions needed to lay out the components contained in the specified target container. Recomputes the layout if it has been invalidated, and factors in the current inset setting.

 public Dimension preferredLayoutSize(Container target) 
{
        checkContainer(target);
        checkRequests();
        Dimension size = new Dimension(xTotal.preferred, yTotal.preferred);
        Insets insets = target.getInsets();
        size.width += insets.left + insets.right;
        size.height += insets.top + insets.bottom;
        return size;
}

Returns the preferred dimensions for this layout given the components in the specified target container. Recomputes the layout if it has been invalidated. Factors in the current inset setting returned by getInsets().

 public  void removeLayoutComponent(Component comp) 
{
        invalidateLayout(comp.getParent());
}

Removes the specified component from the layout. Used by this class to know when to invalidate layout.