How to make ExpandItem fill all available vertical space? - swt

Question

This is the full working code:
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;
public static void main(String[] args) {
Display display = new Display();
Shell shell = new Shell(display);
shell.setSize(400, 300);
shell.setLayout(new GridLayout());
ExpandBar expandBar = new ExpandBar(shell, SWT.V_SCROLL);
expandBar.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
for (int i = 0; i < 3; i++) {
Group group = new Group(expandBar, SWT.NONE);
GridData layoutData = new GridData(GridData.FILL_BOTH);
layoutData.minimumHeight = 225;
layoutData.minimumWidth = 225;
layoutData.grabExcessVerticalSpace = true;
group.setLayoutData(layoutData);
group.setLayout(new GridLayout());
new Label(group, SWT.NONE).setText("Text " + i);
ExpandItem expandItem = new ExpandItem(expandBar, SWT.NONE);
expandItem.setControl(group);
expandItem.setText("Group " + i);
expandItem.setHeight(group.computeSize(SWT.DEFAULT, SWT.DEFAULT).y);
expandItem.setExpanded(true);
}
shell.open();
while (!shell.isDisposed()) {
if (!display.readAndDispatch()) {
display.sleep();
}
}
display.dispose();
}
If you run this program and try to resize the window, ExpandItems will be resized horizontally, but not vertically:
(Note the empty space at the bottom).
How to make them be resized vertically too?

Answer 1

The problem lies in this line:
expandItem.setHeight(group.computeSize(SWT.DEFAULT, SWT.DEFAULT).y);
Computed sized will be based on controls within a group + related layout information, like margins. So, since your group contains only one label, computed size height cannot be more then the size of the label. Even if you add more controls if will always compute the size to fit all the controls without adding any extra space.
What you could is could provide a height hint to computeSize method. Something like this:
expandItem.setHeight(group.computeSize(SWT.DEFAULT, 500).y);
Otherwise there is no way for SWT to understand how big you want your expand items to be.