borderlayout.java

《移动Agent技术》一书的所有章节源代码。

     * <code>removeAll</code> methods. Most applications do not call this 
     * method directly. 
     * @param   comp   the component to be removed.
     * @see     java.awt.Container#remove(java.awt.Component)
     * @see     java.awt.Container#removeAll()
     * @since   JDK1.0
     */
    public void removeLayoutComponent(Component comp) {
      synchronized (comp.getTreeLock()) {
	if (comp == center) {
	    center = null;
	} else if (comp == north) {
	    north = null;
	} else if (comp == south) {
	    south = null;
	} else if (comp == east) {
	    east = null;
	} else if (comp == west) {
	    west = null;
	}
      }
    }

    /**
     * Determines the minimum size of the <code>target</code> container 
     * using this layout manager. 
     * <p>
     * This method is called when a container calls its 
     * <code>getMinimumSize</code> method. Most applications do not call 
     * this method directly. 
     * @param   target   the container in which to do the layout.
     * @return  the minimum dimensions needed to lay out the subcomponents 
     *          of the specified container.
     * @see     java.awt.Container  
     * @see     java.awt.BorderLayout#preferredLayoutSize
     * @see     java.awt.Container#getMinimumSize()
     * @since   JDK1.0
     */
    public Dimension minimumLayoutSize(Container target) {
      synchronized (target.getTreeLock()) {
	Dimension dim = new Dimension(0, 0);

	if ((east != null) && east.visible) {
	    Dimension d = east.getMinimumSize();
	    dim.width += d.width + hgap;
	    dim.height = Math.max(d.height, dim.height);
	}
	if ((west != null) && west.visible) {
	    Dimension d = west.getMinimumSize();
	    dim.width += d.width + hgap;
	    dim.height = Math.max(d.height, dim.height);
	}
	if ((center != null) && center.visible) {
	    Dimension d = center.getMinimumSize();
	    dim.width += d.width;
	    dim.height = Math.max(d.height, dim.height);
	}
	if ((north != null) && north.visible) {
	    Dimension d = north.getMinimumSize();
	    dim.width = Math.max(d.width, dim.width);
	    dim.height += d.height + vgap;
	}
	if ((south != null) && south.visible) {
	    Dimension d = south.getMinimumSize();
	    dim.width = Math.max(d.width, dim.width);
	    dim.height += d.height + vgap;
	}

	Insets insets = target.getInsets();
	dim.width += insets.left + insets.right;
	dim.height += insets.top + insets.bottom;

	return dim;
      }
    }
    
    /**
     * Determines the preferred size of the <code>target</code> 
     * container using this layout manager, based on the components
     * in the container. 
     * <p>
     * Most applications do not call this method directly. This method
     * is called when a container calls its <code>getPreferredSize</code> 
     * method.
     * @param   target   the container in which to do the layout.
     * @return  the preferred dimensions to lay out the subcomponents 
     *          of the specified container.
     * @see     java.awt.Container  
     * @see     java.awt.BorderLayout#minimumLayoutSize  
     * @see     java.awt.Container#getPreferredSize()
     * @since   JDK1.0
     */
    public Dimension preferredLayoutSize(Container target) {
      synchronized (target.getTreeLock()) {
	Dimension dim = new Dimension(0, 0);

	if ((east != null) && east.visible) {
	    Dimension d = east.getPreferredSize();
	    dim.width += d.width + hgap;
	    dim.height = Math.max(d.height, dim.height);
	}
	if ((west != null) && west.visible) {
	    Dimension d = west.getPreferredSize();
	    dim.width += d.width + hgap;
	    dim.height = Math.max(d.height, dim.height);
	}
	if ((center != null) && center.visible) {
	    Dimension d = center.getPreferredSize();
	    dim.width += d.width;
	    dim.height = Math.max(d.height, dim.height);
	}
	if ((north != null) && north.visible) {
	    Dimension d = north.getPreferredSize();
	    dim.width = Math.max(d.width, dim.width);
	    dim.height += d.height + vgap;
	}
	if ((south != null) && south.visible) {
	    Dimension d = south.getPreferredSize();
	    dim.width = Math.max(d.width, dim.width);
	    dim.height += d.height + vgap;
	}

	Insets insets = target.getInsets();
	dim.width += insets.left + insets.right;
	dim.height += insets.top + insets.bottom;

	return dim;
      }
    }

    /**
     * Returns the maximum 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
     * @see #preferredLayoutSize
     */
    public Dimension maximumLayoutSize(Container target) {
	return new Dimension(Integer.MAX_VALUE, Integer.MAX_VALUE);
    }

    /**
     * Returns the alignment along the x axis.  This specifies how
     * the component would like to be aligned relative to other 
     * components.  The value should be a number between 0 and 1
     * where 0 represents alignment along the origin, 1 is aligned
     * the furthest away from the origin, 0.5 is centered, etc.
     */
    public float getLayoutAlignmentX(Container parent) {
	return 0.5f;
    }

    /**
     * Returns the alignment along the y axis.  This specifies how
     * the component would like to be aligned relative to other 
     * components.  The value should be a number between 0 and 1
     * where 0 represents alignment along the origin, 1 is aligned
     * the furthest away from the origin, 0.5 is centered, etc.
     */
    public float getLayoutAlignmentY(Container parent) {
	return 0.5f;
    }

    /**
     * Invalidates the layout, indicating that if the layout manager
     * has cached information it should be discarded.
     */
    public void invalidateLayout(Container target) {
    }
				      
    /**
     * Lays out the container argument using this border layout. 
     * <p>
     * This method actually reshapes the components in the specified
     * container in order to satisfy the constraints of this 
     * <code>BorderLayout</code> object. The <code>North</code> 
     * and <code>South</code>components, if any, are placed at 
     * the top and bottom of the container, respectively. The 
     * <code>West</code> and <code>East</code> components are 
     * then placed on the left and right, respectively. Finally, 
     * the <code>Center</code> object is placed in any remaining 
     * space in the middle. 
     * <p>
     * Most applications do not call this method directly. This method 
     * is called when a container calls its <code>doLayout</code> method. 
     * @param   target   the container in which to do the layout.
     * @see     java.awt.Container  
     * @see     java.awt.Container#doLayout()
     * @since   JDK1.0
     */
    public void layoutContainer(Container target) {
      synchronized (target.getTreeLock()) {
	Insets insets = target.getInsets();
	int top = insets.top;
	int bottom = target.height - insets.bottom;
	int left = insets.left;
	int right = target.width - insets.right;

	if ((north != null) && north.visible) {
	    north.setSize(right - left, north.height);
	    Dimension d = north.getPreferredSize();
	    north.setBounds(left, top, right - left, d.height);
	    top += d.height + vgap;
	}
	if ((south != null) && south.visible) {
	    south.setSize(right - left, south.height);
	    Dimension d = south.getPreferredSize();
	    south.setBounds(left, bottom - d.height, right - left, d.height);
	    bottom -= d.height + vgap;
	}
	if ((east != null) && east.visible) {
	    east.setSize(east.width, bottom - top);
	    Dimension d = east.getPreferredSize();
	    east.setBounds(right - d.width, top, d.width, bottom - top);
	    right -= d.width + hgap;
	}
	if ((west != null) && west.visible) {
	    west.setSize(west.width, bottom - top);
	    Dimension d = west.getPreferredSize();
	    west.setBounds(left, top, d.width, bottom - top);
	    left += d.width + hgap;
	}
	if ((center != null) && center.visible) {
	    center.setBounds(left, top, right - left, bottom - top);
	}
      }
    }
    
    /**
     * Returns a string representation of the state of this border layout.
     * @return    a string representation of this border layout.
     * @since     JDK1.0
     */
    public String toString() {
	return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + "]";
    }
}