How to bind SWT objects to the center of the application window? - swt

Question

I am using SWT to create an application GUI, and I don't really need to resize the components, but it does bother me that when the window is maximized, the components stay left-aligned. Is there a way to fix this with SWT or do I need to utilize a different set of GUI tools?
Thanks in advance. I am using SWT 4.8 for this application.
EDIT: Images
Small: https://imgur.com/CPbAlaZ
Maximized: https://imgur.com/4d6YXcl
Provided images are a basic application using the following code
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
public class TestWindow {
protected Shell shlSwtApplicationExample;
private Text text;
/**
* Launch the application.
* #param args
*/
public static void main(String[] args) {
try {
TestWindow window = new TestWindow();
window.open();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Open the window.
*/
public void open() {
Display display = Display.getDefault();
createContents();
shlSwtApplicationExample.open();
shlSwtApplicationExample.layout();
while (!shlSwtApplicationExample.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
}
/**
* Create contents of the window.
*/
protected void createContents() {
shlSwtApplicationExample = new Shell();
shlSwtApplicationExample.setSize(705, 529);
shlSwtApplicationExample.setText("SWT Application Example");
Composite composite = new Composite(shlSwtApplicationExample, SWT.NONE);
composite.setBounds(10, 10, 669, 465);
text = new Text(composite, SWT.BORDER);
text.setBounds(22, 10, 334, 295);
Button btnNewButton = new Button(composite, SWT.NONE);
btnNewButton.setBounds(49, 384, 137, 26);
btnNewButton.setText("New Button");
Button button = new Button(composite, SWT.NONE);
button.setText("New Button");
button.setBounds(300, 384, 137, 26);
}
}

Answer 1

I would not recommend using setBounds since it does not resize the components when you resize the application. Use Layouts, like for example below I have used GridLayout for both the Shell and the Composite which will properly arrange the UI when resize happens.
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
public class TestWindow {
protected Shell shlSwtApplicationExample;
private Text text;
/**
* Launch the application.
* #param args
*/
public static void main(String[] args) {
try {
TestWindow window = new TestWindow();
window.open();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Open the window.
*/
public void open() {
Display display = Display.getDefault();
createContents(display);
shlSwtApplicationExample.open();
shlSwtApplicationExample.layout();
shlSwtApplicationExample.setLayout(new GridLayout(1, false));
while (!shlSwtApplicationExample.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
}
/**
* Create contents of the window.
* #param display
*/
protected void createContents(Display display) {
shlSwtApplicationExample = new Shell(display);
shlSwtApplicationExample.setLayout(new GridLayout(1, false));
Composite txtcomposite = new Composite(shlSwtApplicationExample, SWT.NONE);
txtcomposite.setLayout(new GridLayout(1, false));
txtcomposite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
Composite btncomposite = new Composite(shlSwtApplicationExample, SWT.NONE);
btncomposite.setLayout(new GridLayout(2, false));
btncomposite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, false));
text = new Text(txtcomposite, SWT.BORDER);
text.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
Button btnNewButton = new Button(btncomposite, SWT.NONE);
btnNewButton.setText("New Button");
Button button = new Button(btncomposite, SWT.NONE);
button.setText("New Button");
shlSwtApplicationExample.setText("SWT Application Example");
//shlSwtApplicationExample.setSize(705, 529);
}
}

Answer 2

Since you are using setBounds you will need to add a Control listener to the shell to be told about resize and move events. You will then have to recalculate the positions on each resize event.
shlSwtApplicationExample.addControlListener(
new ControlListener() {
#Override
public void controlMoved(ControlEvent event) {
// No action
}
#Override
public void controlResized(ControlEvent event) {
Rectangle rect = shlSwtApplicationExample.getClientArea();
// TODO Call new `setBounds` on each control based on the
// client area size
}
});
This might be a good time to learn about using Layouts instead of setBounds (see here). Layouts will automatically deal with resizes.