Java tutorial
/** THIS PROGRAM IS PROVIDED "AS IS" WITHOUT ANY WARRANTIES (OR CONDITIONS), EXPRESS OR IMPLIED WITH RESPECT TO THE PROGRAM, INCLUDING THE IMPLIED WARRANTIES (OR CONDITIONS) OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK ARISING OUT OF USE OR PERFORMANCE OF THE PROGRAM AND DOCUMENTATION REMAINS WITH THE USER. */ import java.awt.*; import java.util.*; /** * * A vertical layout manager similar to java.awt.FlowLayout. * Like FlowLayout components do not expand to fill available space except when the horizontal alignment * is <code>BOTH</code> * in which case components are stretched horizontally. Unlike FlowLayout, components will not wrap to form another * column if there isn't enough space vertically. VerticalLayout can optionally anchor components to the top or bottom * of the display area or center them between the top and bottom. * * Revision date 12th July 2001 * * @author Colin Mummery e-mail: colin_mummery@yahoo.com Homepage:www.kagi.com/equitysoft - * Based on 'FlexLayout' in Java class libraries Vol 2 Chan/Lee Addison-Wesley 1998 */ public class VerticalLayout implements LayoutManager { /** * The horizontal alignment constant that designates centering. Also used to designate center anchoring. */ public final static int CENTER = 0; /** * The horizontal alignment constant that designates right justification. */ public final static int RIGHT = 1; /** * The horizontal alignment constant that designates left justification. */ public final static int LEFT = 2; /** * The horizontal alignment constant that designates stretching the component horizontally. */ public final static int BOTH = 3; /** * The anchoring constant that designates anchoring to the top of the display area */ public final static int TOP = 1; /** * The anchoring constant that designates anchoring to the bottom of the display area */ public final static int BOTTOM = 2; private int vgap; //the vertical vgap between components...defaults to 5 private int alignment; //LEFT, RIGHT, CENTER or BOTH...how the components are justified private int anchor; //TOP, BOTTOM or CENTER ...where are the components positioned in an overlarge space private Hashtable comps; //Constructors /** * Constructs an instance of VerticalLayout with a vertical vgap of 5 pixels, horizontal centering and anchored to * the top of the display area. */ public VerticalLayout() { this(5, CENTER, TOP); } /** * Constructs a VerticalLayout instance with horizontal centering, anchored to the top with the specified vgap * * @param vgap An int value indicating the vertical seperation of the components */ public VerticalLayout(int vgap) { this(vgap, CENTER, TOP); } /** * Constructs a VerticalLayout instance anchored to the top with the specified vgap and horizontal alignment * * @param vgap An int value indicating the vertical seperation of the components * @param alignment An int value which is one of <code>RIGHT, LEFT, CENTER, BOTH</code> for the horizontal alignment. */ public VerticalLayout(int vgap, int alignment) { this(vgap, alignment, TOP); } /** * Constructs a VerticalLayout instance with the specified vgap, horizontal alignment and anchoring * * @param vgap An int value indicating the vertical seperation of the components * @param alignment An int value which is one of <code>RIGHT, LEFT, CENTER, BOTH</code> for the horizontal alignment. * @param anchor An int value which is one of <code>TOP, BOTTOM, CENTER</code> indicating where the components are * to appear if the display area exceeds the minimum necessary. */ public VerticalLayout(int vgap, int alignment, int anchor) { this.vgap = vgap; this.alignment = alignment; this.anchor = anchor; } //---------------------------------------------------------------------------- private Dimension layoutSize(Container parent, boolean minimum) { Dimension dim = new Dimension(0, 0); Dimension d; synchronized (parent.getTreeLock()) { int n = parent.getComponentCount(); for (int i = 0; i < n; i++) { Component c = parent.getComponent(i); if (c.isVisible()) { d = minimum ? c.getMinimumSize() : c.getPreferredSize(); dim.width = Math.max(dim.width, d.width); dim.height += d.height; if (i > 0) dim.height += vgap; } } } Insets insets = parent.getInsets(); dim.width += insets.left + insets.right; dim.height += insets.top + insets.bottom + vgap + vgap; return dim; } //----------------------------------------------------------------------------- /** * Lays out the container. */ public void layoutContainer(Container parent) { Insets insets = parent.getInsets(); synchronized (parent.getTreeLock()) { int n = parent.getComponentCount(); Dimension pd = parent.getSize(); int y = 0; //work out the total size for (int i = 0; i < n; i++) { Component c = parent.getComponent(i); Dimension d = c.getPreferredSize(); y += d.height + vgap; } y -= vgap; //otherwise there's a vgap too many //Work out the anchor paint if (anchor == TOP) y = insets.top; else if (anchor == CENTER) y = (pd.height - y) / 2; else y = pd.height - y - insets.bottom; //do layout for (int i = 0; i < n; i++) { Component c = parent.getComponent(i); Dimension d = c.getPreferredSize(); int x = insets.left; int wid = d.width; if (alignment == CENTER) x = (pd.width - d.width) / 2; else if (alignment == RIGHT) x = pd.width - d.width - insets.right; else if (alignment == BOTH) wid = pd.width - insets.left - insets.right; c.setBounds(x, y, wid, d.height); y += d.height + vgap; } } } //----------------------------------------------------------------------------- public Dimension minimumLayoutSize(Container parent) { return layoutSize(parent, false); } //----------------------------------------------------------------------------- public Dimension preferredLayoutSize(Container parent) { return layoutSize(parent, false); } //---------------------------------------------------------------------------- /** * Not used by this class */ public void addLayoutComponent(String name, Component comp) { } //----------------------------------------------------------------------------- /** * Not used by this class */ public void removeLayoutComponent(Component comp) { } //----------------------------------------------------------------------------- public String toString() { return getClass().getName() + "[vgap=" + vgap + " align=" + alignment + " anchor=" + anchor + "]"; } }