How to resize a WizardDialog depending on the WizardPage? - resize

Question

I am creating a JFace WizardDialog including a single WizardPage that is changing its contents (controls) depending on user selection. In short:
final PageAccess page = new PageAccess(...);
WizCreate wiz = new WizCreate() {
#Override
public boolean performFinish() {
page.performFinish();
return true;
}
};
wiz.addPage(page);
Shell shell = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
WizardDialog dialog = new WizardDialog(shell, wiz);
dialog.open();
PageAccess extends WizardPage, and WizCreate extends Wizard.
All the Composites in the page use GridLayout.
The page implements a SelectionListener and redraws its contents.
When the page changes its size (expand its width because of new controls), the dialog is not resized so that the page is cut off.
So how to resize the dialog depending on the page?

Answer 1

WizardDialog implements IWizardContainer2 which has an updateSize method that you can call to recalculate the size.
In your page you can use
if (getContainer() instanceof IWizardContainer2 container) {
container.updateSize();
}
(code uses Java 16 instanceof type patterns, for older releases it would be a bit more complicated).
Note that WizardDialog only ever increases the size, it won't reduce the size.

Answer 2

I managed by calculating the preferred size of the main control, and then resizing the dialog shell:
Point preferredSize = getControl().computeSize(SWT.DEFAULT, SWT.DEFAULT, true);
WizardDialog dialog = (WizardDialog) getContainer();
dialog.getShell().setSize(preferredSize.x+..., preferredSize.y+...);