366 lines
9.9 KiB
Java
366 lines
9.9 KiB
Java
/* FlowLayout.java -- Grid-based layout engine
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Copyright (C) 1999, 2000, 2001, 2002, 2004 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt;
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import java.io.Serializable;
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/** This class implements a flow-based layout. Components are laid
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* out in order from left to right. When a component cannot be placed
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* without horizontal clipping, a new row is started. This class
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* supports horizontal and vertical gaps. These are used for spacing
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* between components.
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*
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* @author Tom Tromey (tromey@redhat.com)
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* @author Aaron M. Renn (arenn@urbanophile.com)
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*/
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public class FlowLayout implements LayoutManager, Serializable
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{
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/** Constant that specifies left alignment. */
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public static final int LEFT = 0;
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/** Constant that specifies center alignment. */
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public static final int CENTER = 1;
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/** Constant that specifies right alignment. */
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public static final int RIGHT = 2;
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/** Constant that specifies alignment to leading edge of container's
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* orientation. */
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public static final int LEADING = 3;
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/** Constant that specifies alignment to trailing edge of container's
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* orientation. */
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public static final int TRAILING = 4;
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// Serialization constant
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private static final long serialVersionUID = -7262534875583282631L;
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/**
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* Add a new component to the layout. This particular implementation
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* does nothing.
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*
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* @param name the name
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* @param comp the component
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*/
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public void addLayoutComponent (String name, Component comp)
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{
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// Nothing.
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}
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/**
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* Returns the current justification value for this object.
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*
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* @return The current justification value for this object.
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*/
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public int getAlignment ()
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{
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return align;
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}
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/**
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* Returns the horizontal gap between components.
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*
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* @return The horizontal gap between components.
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*/
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public int getHgap ()
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{
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return hgap;
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}
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/**
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* Returns the vertical gap between lines of components.
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*
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* @return The vertical gap between lines of components.
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*/
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public int getVgap ()
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{
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return vgap;
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}
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/**
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* Initializes a new instance of <code>FlowLayout</code> with a center
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* justification and a default horizontal and vertical gap of 5.
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*/
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public FlowLayout ()
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{
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this (CENTER, 5, 5);
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}
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/**
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* Initializes a new instance of <code>FlowLayout</code> with the specified
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* justification and a default horizontal and vertical gap of 5.
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*
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* @param align The justification setting, which should be one of the
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* contants in this class.
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*/
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public FlowLayout (int align)
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{
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this (align, 5, 5);
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}
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/**
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* Initializes a new instance of <code>FlowLayout</code> with the specified
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* justification and gap values
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* @param align Alignment
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* @param hgap The horizontal gap
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* @param vgap The vertical gap
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* @exception IllegalArgumentException If either gap is negative
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*/
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public FlowLayout (int align, int hgap, int vgap)
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{
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// Use methods to set fields so that we can have all the checking
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// in one place.
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setVgap (vgap);
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setHgap (hgap);
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setAlignment (align);
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}
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/** Lay out the container's components based on current settings.
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* @param parent The parent container
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*/
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public void layoutContainer (Container parent)
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{
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synchronized (parent.getTreeLock ())
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{
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int num = parent.getComponentCount ();
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// This is more efficient than calling getComponents().
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Component[] comps = parent.component;
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Dimension d = parent.getSize ();
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Insets ins = parent.getInsets ();
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ComponentOrientation orient = parent.getComponentOrientation ();
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boolean left_to_right = orient.isLeftToRight ();
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int y = ins.top + vgap;
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int i = 0;
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while (i < num)
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{
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// Find the components which go in the current row.
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int new_w = ins.left + hgap + ins.right;
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int new_h = 0;
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int j;
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boolean found_one = false;
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for (j = i; j < num; ++j)
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{
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// Skip invisible items.
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if (! comps[j].visible)
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continue;
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Dimension c = comps[j].getPreferredSize ();
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int next_w = new_w + hgap + c.width;
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if (next_w <= d.width || ! found_one)
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{
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new_w = next_w;
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new_h = Math.max (new_h, c.height);
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found_one = true;
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}
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else
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{
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// Must start a new row, and we already found an item
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break;
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}
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}
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// Set the location of each component for this row.
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int x;
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int myalign = align;
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if (align == LEADING)
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myalign = left_to_right ? LEFT : RIGHT;
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else if (align == TRAILING)
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myalign = left_to_right ? RIGHT : LEFT;
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if (myalign == RIGHT)
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x = ins.left + (d.width - new_w) + hgap;
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else if (myalign == CENTER)
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x = ins.left + (d.width - new_w) / 2 + hgap;
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else // LEFT and all other values of align.
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x = ins.left + hgap;
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for (int k = i; k < j; ++k)
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{
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if (comps[k].visible)
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{
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Dimension c = comps[k].getPreferredSize ();
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comps[k].setBounds (x, y + (new_h - c.height) / 2,
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c.width, c.height);
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x += c.width + hgap;
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}
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}
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// Advance to next row.
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i = j;
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y += new_h + vgap;
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}
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}
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}
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/**
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* Returns the minimum layout size for the specified container using
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* this layout.
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* @param cont The parent container
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* @return The minimum layout size.
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*/
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public Dimension minimumLayoutSize (Container cont)
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{
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return getSize (cont, true);
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}
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/**
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* Returns the preferred layout size for the specified container using
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* this layout.
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* @param cont The parent container
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* @return The preferred layout size.
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*/
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public Dimension preferredLayoutSize (Container cont)
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{
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return getSize (cont, false);
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}
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/** Remove the indicated component from this layout manager.
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* This particular implementation does nothing.
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* @param comp The component to remove
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*/
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public void removeLayoutComponent (Component comp)
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{
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// Nothing.
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}
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/**
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* Sets the justification value for this object to the specified value.
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*
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* @param align The new justification value for this object, which must
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* be one of the constants in this class.
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*/
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public void setAlignment (int align)
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{
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// The JDK accepts invalid values and treats them as
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// LEFT during layout, so do we. The invalid value is even stored,
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// getAlignment() returns the same invalid value.
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this.align = align;
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}
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/**
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* Sets the horizontal gap between lines of components to the specified value.
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* No Exception is thrown if hgap < 0.
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*
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* @param hgap The new horizontal gap between components.
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*/
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public void setHgap (int hgap)
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{
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this.hgap = hgap;
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}
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/**
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* Sets the vertical gap between lines of components to the specified value.
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* No Exception is thrown if vgap < 0.
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*
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* @param vgap The new vertical gap.
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*/
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public void setVgap (int vgap)
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{
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this.vgap = vgap;
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}
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/** Return String description of this object.
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* @return A string representation of this object.
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*/
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public String toString ()
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{
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return ("[" + getClass ().getName () + ",hgap=" + hgap + ",vgap=" + vgap
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+ ",align=" + align + "]");
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}
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// This method is used to compute the various sizes.
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private Dimension getSize (Container parent, boolean is_min)
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{
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synchronized (parent.getTreeLock ())
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{
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int w, h, num = parent.getComponentCount ();
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// This is more efficient than calling getComponents().
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Component[] comps = parent.component;
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w = 0;
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h = 0;
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for (int i = 0; i < num; ++i)
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{
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if (! comps[i].visible)
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continue;
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// FIXME: can we just directly read the fields in Component?
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// Or will that not work with subclassing?
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Dimension d;
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if (is_min)
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d = comps[i].getMinimumSize ();
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else
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d = comps[i].getPreferredSize ();
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w += d.width;
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h = Math.max (d.height, h);
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}
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Insets ins = parent.getInsets ();
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if (num == 0)
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w += 2 * hgap + ins.left + ins.right;
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else
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w += (num + 1) * hgap + ins.left + ins.right;
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h += 2 * vgap + ins.top + ins.bottom;
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return new Dimension (w, h);
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}
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}
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/**
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* @serial The justification alignment of the lines of components, which
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* will be one of the constants defined in this class.
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*/
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private int align;
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/**
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* @serial The horizontal gap between components.
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*/
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private int hgap;
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/**
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* @serial The vertical gap between lines of components.
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*/
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private int vgap;
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}
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