Relative Layout Manager for Java J2SE
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Point;
import java.util.StringTokenizer;
import java.util.Vector;
/**
* <p>
* RelativeLayout, a Relative Layout Manager for Java J2SE. Mainly for porting
* tired old code that uses x,y locations. You really can't just assign x,y
* locations to components in Java Java J2SE - it breaks badly when the user
* resizes (and you can <em>not</em> mandate that the user can't resize you --
* see any book on UI design for <em>that</em> little discussion -- and can
* also look bad due to resolution independance. Symantec Cafe 1.x, for example,
* used to spit out unfortunate (and unmaintainable) code like this:
*
* <pre>
* setLayout(null);
* setSize(331, 241);
* label1 = new Label("Info Applet", Label.CENTER);
* add(label1);
* label1.setBounds(91, 19, 107, 15);
* </pre>
*
* </p>
* <p>
* <em>Bleaarrgghh!!!</em> To make it work properly at all resolutions and
* survive user-initiated resize actions, change it to
*
* <pre>
*
* setLayout(new RelativeLayout(331,241,false);
* label1=new Label("Info Applet", Label.CENTER);
* add("91,19", label1);
*
* </pre>
*
* Note that it's actually <EM>less</EM> work to get it right. Symantec,
* Microsoft, and others, please take note!
* </p>
*
* @author Ian Darwin, http://www.darwinsys.com/
*/
public class RelativeLayout implements LayoutManager {
/** requested absolute width of canvas */
protected int reqWid;
/** requested absolute height of canvas */
protected int reqHgt;
/** actual size width when laid out */
protected int curWid;
/** actual size height when laid out */
protected int curHgt;
/** to track Components added by named add form. */
protected Vector curComps = new Vector();
/**
* Constructs an RelativeLayout, given original hard-coded size of panel.
*/
public RelativeLayout(int wid, int ht) {
this.reqWid = wid;
this.reqHgt = ht;
}
/**
* Called by AWT when the user uses the form add(name, Component). Adds the
* specified component with the specified name to the layout.
*
* @param name
* String with location for component c <EM>Note</EM>: the
* "name" <EM>must</EM> contain x, y location, ie., <BR>
* add("" + 320 + "," + 100, new Button("Quit")); <BR>
* or <BR>
* add("320,100", new Button("Quit"). <BR>
* This adds the Button at x=320, y=100 when the Panel is at its
* original full size.
* @param c
* Component to be added.
*/
public void addLayoutComponent(String name, Component c) {
int x, y;
StringTokenizer st = new StringTokenizer(name, ",");
x = Integer.parseInt(st.nextToken());
y = Integer.parseInt(st.nextToken());
// System.out.println("Adding: Name " + name +"; obj " + c
// + "; x " + x + "; y " + y);
Tracker t = new Tracker(x, y, c);
curComps.addElement(t);
}
/**
* Called by AWT to lay out the components in the target Container at its
* current size.
*
* @param target
* Container whose components are to be laid out.
*/
public void layoutContainer(Container target) {
Dimension targSize = target.getSize();
Insets ins = target.getInsets();
// System.out.println("layoutContainer: size " + targSize);
curWid = targSize.width;
curHgt = targSize.height;
float widRatio = (float) curWid / (float) reqWid;
float hgtRatio = (float) curHgt / (float) reqHgt;
for (int i = 0; i < curComps.size(); i++) {
int px, py, pw, ph;
Tracker t = (Tracker) curComps.elementAt(i);
Component tc = t.getComponent();
Dimension d = tc.getPreferredSize();
px = ins.right + (int) (t.getRequestedLoc().x * widRatio);
py = ins.top + (int) (t.getRequestedLoc().y * hgtRatio);
pw = d.width;
ph = d.height;
// System.out.println("layoutContainer["+i+"]: move " +
// tc + " to " + px + ", " + py);
tc.setBounds(px, py, pw, ph);
}
}
/**
* Called from AWT to calculate the minimum size dimensions for the target
* panel given the components in it. But we use our own list of named
* insertions, not the list of Components that the container keeps.
*
* @param target
* Container to calculate for
*/
public Dimension minimumLayoutSize(Container target) {
int minw = 0, minh = 0;
for (int i = 0; i < curComps.size(); i++) {
Tracker t = (Tracker) curComps.elementAt(i);
Component tc = t.getComponent();
Dimension d = tc.getMinimumSize();
Point rl = t.getRequestedLoc();
minw = Math.max(minw, rl.x + d.width);
minh = Math.max(minh, rl.y + d.height);
// System.out.println("minLay, minw = " + minw
// + "; minh = " + minh);
}
return new Dimension(minw, minw);
}
/**
* Called by AWT to compute the preferred size for the target panel given
* our list of the components that it contains.
*
* @param target
* Container to calculate for
*/
public Dimension preferredLayoutSize(Container target) {
int prefw = 0, prefh = 0;
for (int i = 0; i < curComps.size(); i++) {
Tracker t = (Tracker) curComps.elementAt(i);
Component tc = t.getComponent();
Dimension d = tc.getMinimumSize();
Point rl = t.getRequestedLoc();
prefw = Math.max(prefw, rl.x + d.width);
prefh = Math.max(prefh, rl.y + d.height);
// System.out.println("prefLay, prefw = " +
// prefw + "; prefh = " + prefh);
}
return new Dimension(prefw, prefh);
}
/**
* Called by AWT to remove a given component from the layout.
*
* @param c
* Component to be removed
*/
public void removeLayoutComponent(Component c) {
curComps.removeElement(c);
}
/**
* Tracker is a class used only by RelativeLayout, to track the original
* "requested" (hard-coded) x,y locations of each Component.
*/
class Tracker {
int absx, absy;
Component theComp;
/** Construct a tracker item given its location and Component. */
Tracker(int x, int y, Component c) {
this.absx = x;
this.absy = y;
this.theComp = c;
}
/** Extract the location as a Point. */
public Point getRequestedLoc() {
return new Point(absx, absy);
}
/** Extract the Component from this Tracker. */
public Component getComponent() {
return theComp;
}
}
}
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