Stacked Dialog

Environment: VC6 SP2, NT4 SP5

Most common solution to organize a big amount of information in a dialog box
is to use a property sheet with a set of property pages. However, this approach
has several problems:

1. It is not easy to add controls to the property sheet (outside of property
   pages).
2. Things become fuzzy if some background process needs to change the currently
   active page.

The alternative solution is to use a stacked dialog with any number of stacked
pages. Stacked dialog is a simple dialog that contains any programmer defined
set of controls. One of these controls is designated as a placeholder control
(usually a picture control). Stacked page is a child dialog with any number
and type of controls. Stacked dialog will position and resize all stacked pages
according to the position and size of a placeholder control on a stacked dialog.
Only one stacked page may be visible and active at any moment of time. Active
stacked page is selected programmatically — this may be done either by clicking
on a dialog control (select page from a list box) or based on some event / trigger
from the application.

Using stacked dialog in your application, you will achieve the following:

1. Combine one of stacked pages with other controls.
2. Change active page either on user action or programmatically based on application’s
   internal state.
3. Simple class interface

Each TStackedPage derived class may implement any of the following virtual
functions:

• OnCreatePage called once after the page is created
• OnDestroyPage called once before the page is destroyed
• OnSetActive called once the page becomes active
• OnKillActive called once the page becomes inactive

TStackedDialog derived class must provide an implementation of the virtual
abstract function OnPageChanged(). This is an ideal place to modify the appereance
of the stacked dialog based on the deactivated/activated page.

Pictures from a demo application show a dialog box with 3 possibilities to
select a page: (1) from a listbox, (2) from a combobox and (3) clicking on a
push-like radio button. In the middle of the dialog are 2 pages: one with a
calendar control and the other with a tree control.

Step 1:

Create a dialog. Place a picture control (placeholder) where you want to have
stacked pages on your dialog. This control should be invisible and disabled.
Also, place a control that will enable a user to choose the active page (for
example, listbox or combobox).

Using class wizard, create a class for the new dialog. This class must be derived
from TStackedDialog. Since TStackedDialog is an abstract class, add an implementation
for the following TStackedDialog abstract virtual methods:

• TStackedPage *CreatePage(UINT nId)
• void OnPageChanged(UINT nId, BOOL bActivated)

Abstract virtual function CreatePage() is called to create a stacked page dialog
based on its resource ID.

Step 2:

Create a dialog for each stacked page that you need. Each dialog should have
the following properties:

• Child
• No border
• Not visible
• Disabled

Using class wizard, create a class for each stacked page. Each class must be
derived from TStackedPage.

Step 3:

Within OnInitDialog() function of the stacked dialog class, add stacked pages
to the stacked dialog.

...
AddPage(IDD_PAGE_1);
AddPage(IDD_PAGE_2);
...

Each AddPage() will execute the abstract virtual function of the base class
(implemented in derived class) CreatePage() that should have the following implementation:

TStackedPage *CreatePage(UINT nId)
{
 switch (nId) {
 case IDD_PAGE_1: return new CPageOneDialog;
 case IDD_PAGE_2: return new CPageTwoDialog;
 }
 return NULL;
}

Step 4:

After adding all the pages to the stacked dialog, activate the initial page
with the following line:

SetPage(IDD_PAGE_1);

Any previously activated page will be first deactivated. Use the same method
to activate the page as a response to a user action or based on internal application
state.

SetPage() function will call an abstract virtual function TStackedDialog::OnPageChanged()
implemented in derived class. This is the best place to update the stacked dialog
based on the currently active page.

Known problems

Manual movement through dialog controls (using Tab/Shift-Tab) is not working
properly. I have not actually had the time to work on it. Anybody interested
…

Latest version may be downloaded from www.scasoftware.com.
Any comments or suggestions regarding the known problem are welcomed.

Downloads

Download demo project – 17 Kb
Download source – 3 Kb