A layout must extend the org.eclipse.swt.widgets.Layout class.
org.eclipse.swt.widgets.Layout has only two abstract methods:
The computeSize method computes and returns the minimum size of the specified composite's client area according to this layout.
protected abstract Point computeSize(Composite composite,int wHint,int hHint, boolean flushCache)
Lay out the children of the composite.
protected abstract void layout(Composite composite, boolean flushCache)
/******************************************************************************
* Copyright (c) 1998, 2004 Jackwind Li Guojie
* All right reserved.
*
* Created on Jan 31, 2004 1:05:58 AM by JACK
* $Id$
*
* visit: http://www.asprise.com/swt
*****************************************************************************/
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Layout;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
public class BorderLayoutSWT {
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
shell.setLayout(new BorderLayout());
Button buttonWest = new Button(shell, SWT.PUSH);
buttonWest.setText("West");
buttonWest.setLayoutData(new BorderLayout.BorderData(BorderLayout.WEST));
Button buttonEast = new Button(shell, SWT.PUSH);
buttonEast.setText("East");
buttonEast.setLayoutData(new BorderLayout.BorderData(BorderLayout.EAST));
Button buttonNorth = new Button(shell, SWT.PUSH);
buttonNorth.setText("North");
buttonNorth.setLayoutData(new BorderLayout.BorderData(BorderLayout.NORTH));
Button buttonSouth = new Button(shell, SWT.PUSH);
buttonSouth.setText("South");
buttonSouth.setLayoutData(new BorderLayout.BorderData(BorderLayout.SOUTH));
Text text = new Text(shell, SWT.MULTI | SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL);
text.setText("Center");
text.setLayoutData(new BorderLayout.BorderData(BorderLayout.CENTER));
shell.pack();
shell.open();
// textUser.forceFocus();
// Set up the event loop.
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
// If no more entries in event queue
display.sleep();
}
}
display.dispose();
}
}
/*******************************************************************************
* Copyright (c) 1998, 2004 Jackwind Li Guojie All right reserved.
*
* Created on Jan 30, 2004 11:52:21 PM by JACK $Id$
*
* visit: http://www.asprise.com/swt
******************************************************************************/
/**
* Lays out a composite, arranging and resizing its components to fit in five
* regions: north, south, east, west, and center.
*/
class BorderLayout extends Layout {
// Region constants.
public static final int NORTH = 0;
public static final int SOUTH = 1;
public static final int CENTER = 2;
public static final int EAST = 3;
public static final int WEST = 4;
/**
* Indicates the region that a control belongs to.
*
*/
public static class BorderData {
public int region = CENTER; // default.
public BorderData() {
}
public BorderData(int region) {
this.region = region;
}
}
// Controls in all the regions.
public Control[] controls = new Control[5];
// Cached sizes.
Point[] sizes;
// Preferred width and height
int width;
int height;
/*
* (non-Javadoc)
*
* @see org.eclipse.swt.widgets.Layout#computeSize(org.eclipse.swt.widgets.Composite,
* int, int, boolean)
*/
protected Point computeSize(Composite composite, int wHint, int hHint, boolean flushCache) {
if (sizes == null || flushCache == true)
refreshSizes(composite.getChildren());
int w = wHint;
int h = hHint;
if (w == SWT.DEFAULT)
w = width;
if (h == SWT.DEFAULT)
h = height;
return new Point(w, h);
}
/*
* (non-Javadoc)
*
* @see org.eclipse.swt.widgets.Layout#layout(org.eclipse.swt.widgets.Composite,
* boolean)
*/
protected void layout(Composite composite, boolean flushCache) {
if (flushCache || sizes == null)
refreshSizes(composite.getChildren());
Rectangle clientArea = composite.getClientArea();
// Enough space for all.
if (controls[NORTH] != null) {
controls[NORTH].setBounds(clientArea.x, clientArea.y, clientArea.width, sizes[NORTH].y);
}
if (controls[SOUTH] != null) {
controls[SOUTH].setBounds(clientArea.x, clientArea.y + clientArea.height - sizes[SOUTH].y,
clientArea.width, sizes[SOUTH].y);
}
if (controls[WEST] != null) {
controls[WEST].setBounds(clientArea.x, clientArea.y + sizes[NORTH].y, sizes[WEST].x,
clientArea.height - sizes[NORTH].y - sizes[SOUTH].y);
}
if (controls[EAST] != null) {
controls[EAST].setBounds(clientArea.x + clientArea.width - sizes[EAST].x, clientArea.y
+ sizes[NORTH].y, sizes[EAST].x, clientArea.height - sizes[NORTH].y - sizes[SOUTH].y);
}
if (controls[CENTER] != null) {
controls[CENTER].setBounds(clientArea.x + sizes[WEST].x, clientArea.y + sizes[NORTH].y,
clientArea.width - sizes[WEST].x - sizes[EAST].x, clientArea.height - sizes[NORTH].y
- sizes[SOUTH].y);
}
}
private void refreshSizes(Control[] children) {
for (int i = 0; i < children.length; i++) {
Object layoutData = children[i].getLayoutData();
if (layoutData == null || (!(layoutData instanceof BorderData)))
continue;
BorderData borderData = (BorderData) layoutData;
if (borderData.region < 0 || borderData.region > 4) // Invalid.
continue;
controls[borderData.region] = children[i];
}
width = 0;
height = 0;
if (sizes == null)
sizes = new Point[5];
for (int i = 0; i < controls.length; i++) {
Control control = controls[i];
if (control == null) {
sizes[i] = new Point(0, 0);
} else {
sizes[i] = control.computeSize(SWT.DEFAULT, SWT.DEFAULT, true);
}
}
width = Math.max(width, sizes[NORTH].x);
width = Math.max(width, sizes[WEST].x + sizes[CENTER].x + sizes[EAST].x);
width = Math.max(width, sizes[SOUTH].x);
height = Math.max(Math.max(sizes[WEST].y, sizes[EAST].y), sizes[CENTER].y) + sizes[NORTH].y
+ sizes[SOUTH].y;
}
}
| 17.101.Custom Layout |
| 17.101.1. | Creating Your Own Layouts | |