Java tutorial
/* * * Copyright (c) 1998 Sun Microsystems, Inc. All Rights Reserved. * * Sun grants you ("Licensee") a non-exclusive, royalty free, license to use, * modify and redistribute this software in source and binary code form, * provided that i) this copyright notice and license appear on all copies of * the software; and ii) Licensee does not utilize the software in a manner * which is disparaging to Sun. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN AND ITS LICENSORS SHALL NOT BE * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE * POSSIBILITY OF SUCH DAMAGES. * * This software is not designed or intended for use in on-line control of * aircraft, air traffic, aircraft navigation or aircraft communications; or in * the design, construction, operation or maintenance of any nuclear * facility. Licensee represents and warrants that it will not use or * redistribute the Software for such purposes. */ import java.awt.Button; import java.awt.Component; import java.awt.Container; import java.awt.Dimension; import java.awt.Insets; import java.awt.LayoutManager; import java.awt.LayoutManager2; import java.awt.Rectangle; import java.util.Hashtable; import javax.swing.JFrame; /** * The <code>GraphPaperLayout</code> class is a layout manager that lays out a * container's components in a rectangular grid, similar to GridLayout. Unlike * GridLayout, however, components can take up multiple rows and/or columns. The * layout manager acts as a sheet of graph paper. When a component is added to * the layout manager, the location and relative size of the component are * simply supplied by the constraints as a Rectangle. * <P> * <code><pre> * import java.awt.*; * import java.applet.Applet; * * public class ButtonGrid extends Applet { * public void init() { * setLayout(new GraphPaperLayout(new Dimension(5, 5))); * // Add a 1x1 Rect at (0,0) * add(new Button("1"), new Rectangle(0, 0, 1, 1)); * // Add a 2x1 Rect at (2,0) * add(new Button("2"), new Rectangle(2, 0, 2, 1)); * // Add a 1x2 Rect at (1,1) * add(new Button("3"), new Rectangle(1, 1, 1, 2)); * // Add a 2x2 Rect at (3,2) * add(new Button("4"), new Rectangle(3, 2, 2, 2)); * // Add a 1x1 Rect at (0,4) * add(new Button("5"), new Rectangle(0, 4, 1, 1)); * // Add a 1x2 Rect at (2,3) * add(new Button("6"), new Rectangle(2, 3, 1, 2)); * } * } * </pre></code> * * @author Michael Martak */ class GraphPaperLayout implements LayoutManager2 { int hgap; // horizontal gap int vgap; // vertical gap Dimension gridSize; // grid size in logical units (n x m) Hashtable<Component, Rectangle> compTable; // constraints (Rectangles) /** * Creates a graph paper layout with a default of a 1 x 1 graph, with no * vertical or horizontal padding. */ public GraphPaperLayout() { this(new Dimension(1, 1)); } /** * Creates a graph paper layout with the given grid size, with no vertical or * horizontal padding. */ public GraphPaperLayout(Dimension gridSize) { this(gridSize, 0, 0); } /** * Creates a graph paper layout with the given grid size and padding. * * @param gridSize * size of the graph paper in logical units (n x m) * @param hgap * horizontal padding * @param vgap * vertical padding */ public GraphPaperLayout(Dimension gridSize, int hgap, int vgap) { if ((gridSize.width <= 0) || (gridSize.height <= 0)) { throw new IllegalArgumentException("dimensions must be greater than zero"); } this.gridSize = new Dimension(gridSize); this.hgap = hgap; this.vgap = vgap; compTable = new Hashtable<Component, Rectangle>(); } /** * @return the size of the graph paper in logical units (n x m) */ public Dimension getGridSize() { return new Dimension(gridSize); } /** * Set the size of the graph paper in logical units (n x m) */ public void setGridSize(Dimension d) { setGridSize(d.width, d.height); } /** * Set the size of the graph paper in logical units (n x m) */ public void setGridSize(int width, int height) { gridSize = new Dimension(width, height); } public void setConstraints(Component comp, Rectangle constraints) { compTable.put(comp, new Rectangle(constraints)); } /** * Adds the specified component with the specified name to the layout. This * does nothing in GraphPaperLayout, since constraints are required. */ public void addLayoutComponent(String name, Component comp) { } /** * Removes the specified component from the layout. * * @param comp * the component to be removed */ public void removeLayoutComponent(Component comp) { compTable.remove(comp); } /** * Calculates the preferred size dimensions for the specified panel given the * components in the specified parent container. * * @param parent * the component to be laid out * * @see #minimumLayoutSize */ public Dimension preferredLayoutSize(Container parent) { return getLayoutSize(parent, true); } /** * Calculates the minimum size dimensions for the specified panel given the * components in the specified parent container. * * @param parent * the component to be laid out * @see #preferredLayoutSize */ public Dimension minimumLayoutSize(Container parent) { return getLayoutSize(parent, false); } /** * Algorithm for calculating layout size (minimum or preferred). * <P> * The width of a graph paper layout is the largest cell width (calculated in * <code>getLargestCellSize()</code> times the number of columns, plus the * horizontal padding times the number of columns plus one, plus the left and * right insets of the target container. * <P> * The height of a graph paper layout is the largest cell height (calculated * in <code>getLargestCellSize()</code> times the number of rows, plus the * vertical padding times the number of rows plus one, plus the top and bottom * insets of the target container. * * @param parent * the container in which to do the layout. * @param isPreferred * true for calculating preferred size, false for calculating minimum * size. * @return the dimensions to lay out the subcomponents of the specified * container. * @see java.awt.GraphPaperLayout#getLargestCellSize */ protected Dimension getLayoutSize(Container parent, boolean isPreferred) { Dimension largestSize = getLargestCellSize(parent, isPreferred); Insets insets = parent.getInsets(); largestSize.width = (largestSize.width * gridSize.width) + (hgap * (gridSize.width + 1)) + insets.left + insets.right; largestSize.height = (largestSize.height * gridSize.height) + (vgap * (gridSize.height + 1)) + insets.top + insets.bottom; return largestSize; } /** * Algorithm for calculating the largest minimum or preferred cell size. * <P> * Largest cell size is calculated by getting the applicable size of each * component and keeping the maximum value, dividing the component's width by * the number of columns it is specified to occupy and dividing the * component's height by the number of rows it is specified to occupy. * * @param parent * the container in which to do the layout. * @param isPreferred * true for calculating preferred size, false for calculating minimum * size. * @return the largest cell size required. */ protected Dimension getLargestCellSize(Container parent, boolean isPreferred) { int ncomponents = parent.getComponentCount(); Dimension maxCellSize = new Dimension(0, 0); for (int i = 0; i < ncomponents; i++) { Component c = parent.getComponent(i); Rectangle rect = compTable.get(c); if (c != null && rect != null) { Dimension componentSize; if (isPreferred) { componentSize = c.getPreferredSize(); } else { componentSize = c.getMinimumSize(); } // Note: rect dimensions are already asserted to be > 0 when the // component is added with constraints maxCellSize.width = Math.max(maxCellSize.width, componentSize.width / rect.width); maxCellSize.height = Math.max(maxCellSize.height, componentSize.height / rect.height); } } return maxCellSize; } /** * Lays out the container in the specified container. * * @param parent * the component which needs to be laid out */ public void layoutContainer(Container parent) { synchronized (parent.getTreeLock()) { Insets insets = parent.getInsets(); int ncomponents = parent.getComponentCount(); if (ncomponents == 0) { return; } // Total parent dimensions Dimension size = parent.getSize(); int totalW = size.width - (insets.left + insets.right); int totalH = size.height - (insets.top + insets.bottom); // Cell dimensions, including padding int totalCellW = totalW / gridSize.width; int totalCellH = totalH / gridSize.height; // Cell dimensions, without padding int cellW = (totalW - ((gridSize.width + 1) * hgap)) / gridSize.width; int cellH = (totalH - ((gridSize.height + 1) * vgap)) / gridSize.height; for (int i = 0; i < ncomponents; i++) { Component c = parent.getComponent(i); Rectangle rect = compTable.get(c); if (rect != null) { int x = insets.left + (totalCellW * rect.x) + hgap; int y = insets.top + (totalCellH * rect.y) + vgap; int w = (cellW * rect.width) - hgap; int h = (cellH * rect.height) - vgap; c.setBounds(x, y, w, h); } } } } // LayoutManager2 ///////////////////////////////////////////////////////// /** * Adds the specified component to the layout, using the specified constraint * object. * * @param comp * the component to be added * @param constraints * where/how the component is added to the layout. */ public void addLayoutComponent(Component comp, Object constraints) { if (constraints instanceof Rectangle) { Rectangle rect = (Rectangle) constraints; if (rect.width <= 0 || rect.height <= 0) { throw new IllegalArgumentException( "cannot add to layout: rectangle must have positive width and height"); } if (rect.x < 0 || rect.y < 0) { throw new IllegalArgumentException("cannot add to layout: rectangle x and y must be >= 0"); } setConstraints(comp, rect); } else if (constraints != null) { throw new IllegalArgumentException("cannot add to layout: constraint must be a Rectangle"); } } /** * Returns the maximum size of this component. * * @see java.awt.Component#getMinimumSize() * @see java.awt.Component#getPreferredSize() * @see LayoutManager */ 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 target) { 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 target) { return 0.5f; } /** * Invalidates the layout, indicating that if the layout manager has cached * information it should be discarded. */ public void invalidateLayout(Container target) { // Do nothing } } public class Main { public static void main(String[] a) { JFrame frame = new JFrame(); frame.setLayout(new GraphPaperLayout(new Dimension(5, 5))); // Add a 1x1 Rect at (0,0) frame.add(new Button("1"), new Rectangle(0, 0, 1, 1)); // Add a 2x1 Rect at (2,0) frame.add(new Button("2"), new Rectangle(2, 0, 2, 1)); // Add a 1x2 Rect at (1,1) frame.add(new Button("3"), new Rectangle(1, 1, 1, 2)); // Add a 2x2 Rect at (3,2) frame.add(new Button("4"), new Rectangle(3, 2, 2, 2)); // Add a 1x1 Rect at (0,4) frame.add(new Button("5"), new Rectangle(0, 4, 1, 1)); // Add a 1x2 Rect at (2,3) frame.add(new Button("6"), new Rectangle(2, 3, 1, 2)); frame.pack(); frame.setVisible(true); } }