generating swt shell at the center of its parent shell

Question

I have SWT wizard page as my parent shell , for creating another shell on click of button i am writing following code

Shell permissionSetShell = new Shell(Display.getCurrent().getActiveShell(), SWT.CENTER|SWT.DIALOG_TRIM|SWT.APPLICATION_MODAL);
permissionSetShell.setText(PropertyClass.getPropertyLabel(QTLConstants.PERMISSION_SET_COLUMN_LABEL));

// Add shell to the center of parent wizard
permissionSetShell.setLayout(componentsRenderer.createGridLayout(1, false, 0, 5, 0, 0));    
Monitor primary = Display.getCurrent().getPrimaryMonitor ();
Rectangle bounds = primary.getBounds ();
Rectangle rect = Display.getCurrent().getActiveShell().getBounds ();
int x = bounds.x + (bounds.width - rect.width) / 2;
int y = bounds.y + (bounds.height - rect.height)/2;              
permissionSetShell.setLocation (x, y);

but as the child shell means this shell is not placed at the center of SWT wizard that is parent shell why?

Answer 1

Rectangle screenSize = display.getPrimaryMonitor().getBounds();
shell.setLocation((screenSize.width - shell.getBounds().width) / 2, (screenSize.height - shell.getBounds().height) / 2);

Answer 2

If you are writing a dialog or a child component you may want to use getParent instead of asking the display for the primary monitor so that the window is centered on the current screen for multiple monitor setups.

Rectangle parentSize = getParent().getBounds();
Rectangle shellSize = shell.getBounds();
int locationX = (parentSize.width - shellSize.width)/2+parentSize.x;
int locationY = (parentSize.height - shellSize.height)/2+parentSize.y;
shell.setLocation(new Point(locationX, locationY));