gridlayout.java

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/*
 * @(#)GridLayout.java	1.32 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, as published by the Free Software Foundation. 
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License version 2 for more details (a copy is
 * included at /legal/license.txt). 
 * 
 * You should have received a copy of the GNU General Public License
 * version 2 along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA 
 * 
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions. 
 *
 */

package java.awt;

/**
 * The <code>GridLayout</code> class is a layout manager that 
 * lays out a container's components in a rectangular grid. 
 * <p>
 * The container is divided into equal-sized rectangles, 
 * and one component is placed in each rectangle. 
 * <p>
 * For example, the following is an applet that lays out six buttons 
 * into three rows and two columns: 
 * <p>
 * <hr><blockquote><pre>
 * import java.awt.*;
 * import java.applet.Applet;
 * public class ButtonGrid extends Applet {
 *     public void init() {
 *         setLayout(new GridLayout(3,2));
 *         add(new Button("1"));
 *         add(new Button("2"));
 *         add(new Button("3"));
 *         add(new Button("4"));
 *         add(new Button("5"));
 *         add(new Button("6"));
 *     }
 * }
 * </pre></blockquote><hr>     
 * <p>
 * It produces the following output:
 * <p>
 * <img src="images-awt/GridLayout-1.gif" 
 * ALIGN=center HSPACE=10 VSPACE=7>
 * <p>
 * When both the number of rows and the number of columns have 
 * been set to non-zero values, either by a constructor or 
 * by the <tt>setRows</tt> and <tt>setColumns</tt> methods, the number of 
 * columns specified is ignored.  Instead, the number of 
 * columns is determined from the specified number or rows 
 * and the total number of components in the layout. So, for 
 * example, if three rows and two columns have been specified 
 * and nine components are added to the layout, then they will 
 * be displayed as three rows of three columns.  Specifying 
 * the number of columns affects the layout only when the 
 * number of rows is set to zero.
 *  
 * @version 1.28, 08/19/02
 * @since   JDK1.0
 */
public class GridLayout implements LayoutManager, java.io.Serializable {
    int hgap;
    int vgap;
    int rows;
    int cols;
    /**
     * Creates a grid layout with a default of one column per component,
     * in a single row.
     * @since JDK1.1
     */
    public GridLayout() {
        this(1, 0, 0, 0);
    }

    /**
     * Creates a grid layout with the specified number of rows and 
     * columns. All components in the layout are given equal size. 
     * <p>
     * One, but not both, of <code>rows</code> and <code>cols</code> can 
     * be zero, which means that any number of objects can be placed in a 
     * row or in a column. 
     * @param     rows   the rows, with the value zero meaning 
     *                   any number of rows.
     * @param     cols   the columns, with the value zero meaning 
     *                   any number of columns.
     * @since     JDK1.0
     */
    public GridLayout(int rows, int cols) {
        this(rows, cols, 0, 0);
    }

    /**
     * Creates a grid layout with the specified number of rows and 
     * columns. All components in the layout are given equal size. 
     * <p>
     * In addition, the horizontal and vertical gaps are set to the 
     * specified values. Horizontal gaps are placed at the left and 
     * right edges, and between each of the columns. Vertical gaps are 
     * placed at the top and bottom edges, and between each of the rows. 
     * <p>
     * One, but not both, of <code>rows</code> and <code>cols</code> can 
     * be zero, which means that any number of objects can be placed in a 
     * row or in a column. 
     * @param     rows   the rows, with the value zero meaning 
     *                   any number of rows.
     * @param     cols   the columns, with the value zero meaning 
     *                   any number of columns.
     * @param     hgap   the horizontal gap. 
     * @param     vgap   the vertical gap. 
     * @exception   IllegalArgumentException  if the of <code>rows</code> 
     *                   or <code>cols</code> is invalid.
     * @since     JDK1.0
     */
    public GridLayout(int rows, int cols, int hgap, int vgap) {
        if ((rows == 0) && (cols == 0)) {
            throw new IllegalArgumentException("rows and cols cannot both be zero");
        }
        this.rows = rows;
        this.cols = cols;
        this.hgap = hgap;
        this.vgap = vgap;
    }

    /**
     * Gets the number of rows in this layout.
     * @return    the number of rows in this layout.
     * @since     JDK1.1
     */
    public int getRows() {
        return rows;
    }

    /**
     * Sets the number of rows in this layout to the specified value.
     * @param        rows   the number of rows in this layout.
     * @exception    IllegalArgumentException  if the value of both 
     *               <code>rows</code> and <code>cols</code> is set to zero.
     * @since        JDK1.1
     */
    public void setRows(int rows) {
        if ((rows == 0) && (this.cols == 0)) {
            throw new IllegalArgumentException("rows and cols cannot both be zero");
        }
        this.rows = rows;
    }

    /**
     * Gets the number of columns in this layout.
     * @return     the number of columns in this layout.
     * @since      JDK1.1
     */
    public int getColumns() {
        return cols;
    }

    /**
     * Sets the number of columns in this layout to the specified value. 
     * Setting the number of columns has no affect on the layout 
     * if the number of rows specified by a constructor or by 
     * the <tt>setRows</tt> method is non-zero. In that case, the number 
     * of columns displayed in the layout is determined by the total 
     * number of components and the number of rows specified.
     * @param        cols   the number of columns in this layout.
     * @exception    IllegalArgumentException  if the value of both 
     *               <code>rows</code> and <code>cols</code> is set to zero.
     * @since        JDK1.1
     */
    public void setColumns(int cols) {
        if ((cols == 0) && (this.rows == 0)) {
            throw new IllegalArgumentException("rows and cols cannot both be zero");
        }
        this.cols = cols;
    }

    /**
     * Gets the horizontal gap between components.
     * @return       the horizontal gap between components.
     * @since        JDK1.1
     */
    public int getHgap() {
        return hgap;
    }
    
    /**
     * Sets the horizontal gap between components to the specified value.
     * @param        hgap   the horizontal gap between components.
     * @since        JDK1.1
     */
    public void setHgap(int hgap) {
        this.hgap = hgap;
    }
    
    /**
     * Gets the vertical gap between components.
     * @return       the vertical gap between components.
     * @since        JDK1.1
     */
    public int getVgap() {
        return vgap;
    }
    
    /**
     * Sets the vertical gap between components to the specified value.
     * @param         vgap  the vertical gap between components.
     * @since        JDK1.1
     */
    public void setVgap(int vgap) {
        this.vgap = vgap;
    }

    /**
     * Adds the specified component with the specified name to the layout.
     * @param name the name of the component.
     * @param comp the component to be added.
     * @since JDK1.0
     */
    public void addLayoutComponent(String name, Component comp) {}

    /**
     * Removes the specified component from the layout. 
     * @param comp the component to be removed.
     * @since JDK1.0
     */
    public void removeLayoutComponent(Component comp) {}

    /** 
     * Determines the preferred size of the container argument using 
     * this grid layout. 
     * <p>
     * The preferred width of a grid layout is the largest preferred 
     * width of any of the widths in the container 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 preferred height of a grid layout is the largest preferred 
     * height of any of the widths in the container times the number of 
     * rows, plus the vertical padding times the number of rows plus one, 
     * plus the top and left insets of the target container. 
     * 
     * @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.GridLayout#minimumLayoutSize 
     * @see       java.awt.Container#getPreferredSize()
     * @since     JDK1.0
     */
    public Dimension preferredLayoutSize(Container parent) {
        synchronized (parent.getTreeLock()) {
            Insets insets = parent.getInsets();
            int ncomponents = parent.getComponentCount();
            int nrows = rows;
            int ncols = cols;
            if (nrows > 0) {
                ncols = (ncomponents + nrows - 1) / nrows;
            } else {
                nrows = (ncomponents + ncols - 1) / ncols;
            }
            int w = 0;
            int h = 0;
            for (int i = 0; i < ncomponents; i++) {
                Component comp = parent.getComponent(i);
                Dimension d = comp.getPreferredSize();
                if (w < d.width) {
                    w = d.width;
                }
                if (h < d.height) {
                    h = d.height;
                }
            }
            return new Dimension(insets.left + insets.right + ncols * w + (ncols - 1) * hgap, 
                    insets.top + insets.bottom + nrows * h + (nrows - 1) * vgap);
        }
    }

    /**
     * Determines the minimum size of the container argument using this 
     * grid layout. 
     * <p>
     * The minimum width of a grid layout is the largest minimum width 
     * of any of the widths in the container 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 minimum height of a grid layout is the largest minimum height 
     * of any of the widths in the container times the number of rows, 
     * plus the vertical padding times the number of rows plus one, plus 
     * the top and left insets of the target container. 
     *  
     * @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.GridLayout#preferredLayoutSize
     * @see         java.awt.Container#doLayout
     * @since       JDK1.0
     */
    public Dimension minimumLayoutSize(Container parent) {
        synchronized (parent.getTreeLock()) {
            Insets insets = parent.getInsets();
            int ncomponents = parent.getComponentCount();
            int nrows = rows;
            int ncols = cols;
            if (nrows > 0) {
                ncols = (ncomponents + nrows - 1) / nrows;
            } else {
                nrows = (ncomponents + ncols - 1) / ncols;
            }
            int w = 0;
            int h = 0;
            for (int i = 0; i < ncomponents; i++) {
                Component comp = parent.getComponent(i);
                Dimension d = comp.getMinimumSize();
                if (w < d.width) {
                    w = d.width;
                }
                if (h < d.height) {
                    h = d.height;
                }
            }
            return new Dimension(insets.left + insets.right + ncols * w + (ncols - 1) * hgap, 
                    insets.top + insets.bottom + nrows * h + (nrows - 1) * vgap);
        }
    }

    /** 
     * Lays out the specified container using this layout. 
     * <p>
     * This method reshapes the components in the specified target 
     * container in order to satisfy the constraints of the 
     * <code>GridLayout</code> object. 
     * <p>
     * The grid layout manager determines the size of individual 
     * components by dividing the free space in the container into 
     * equal-sized portions according to the number of rows and columns 
     * in the layout. The container's free space equals the container's 
     * size minus any insets and any specified horizontal or vertical 
     * gap. All components in a grid layout are given the same size. 
     *  
     * @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 parent) {
        synchronized (parent.getTreeLock()) {
            Insets insets = parent.getInsets();
            int ncomponents = parent.getComponentCount();
            int nrows = rows;
            int ncols = cols;
            if (ncomponents == 0) {
                return;
            }
            if (nrows > 0) {
                ncols = (ncomponents + nrows - 1) / nrows;
            } else {
                nrows = (ncomponents + ncols - 1) / ncols;
            }
            int w = parent.width - (insets.left + insets.right);
            int h = parent.height - (insets.top + insets.bottom);
            w = (w - (ncols - 1) * hgap) / ncols;
            h = (h - (nrows - 1) * vgap) / nrows;
            for (int c = 0, x = insets.left; c < ncols; c++, x += w + hgap) {
                for (int r = 0, y = insets.top; r < nrows; r++, y += h + vgap) {
                    int i = r * ncols + c;
                    if (i < ncomponents) {
                        parent.getComponent(i).setBounds(x, y, w, h);
                    }
                }
            }
        }
    }
    
    /**
     * Returns the string representation of this grid layout's values.
     * @return     a string representation of this grid layout.
     * @since      JDK1.0
     */
    public String toString() {
        return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap + 
            ",rows=" + rows + ",cols=" + cols + "]";
    }
}