ArcGIS Engine Developer Guide

VISUAL C++
For a general discussion of ATL, see the earlier
section ‘ATL in brief’.
interface ICommand;
}
};
ATL AND THE ACTIVEX CONTROLS
This section covers how to use ATL to add controls to a dialog box. Although
ATL is focused on providing COM support, it also supplies some useful Windows
programming wrapper classes. One of the most useful is CWindow, a wrapper
around a window handle (HWND). The method names on CWindow correspond
to the Win32 API functions. For example:
HWND buttonHWnd = GetDlgItem( IDC_BUTTON1 ); // Get window handle of
button.
CWindow myButtonWindow( buttonHWnd );
// Attach window handle
to CWindow class.
myButtonWindow.SetWindowText(_T("Button Title")); // Win32 function to
change button caption
CWindow is a generic wrapper for all window handles, so for specific Windows
messages to window common controls, such as buttons, tree views, or edit boxes,
one approach is to send window messages directly to the window, for example:
// Set button to be checked (pushed in or checkmarked, depending on button style)
myButtonWindow.SendMessage(BM_SETCHECK, BST_CHECKED);
However, there are some wrapper classes for these standard window common
controls in a header file atlcontrols.h. This is available as part of an ATL sample
ATLCON supplied in MSDN. See the article “HOWTO: Using Class Wrappers to
Access Windows Common Controls in ATL”, available for download from
Microsoft. This header file is an early version of Windows Template Libraries.
Visual Studio Resource Editor can be used to design and position Windows
common controls and ActiveX controls on a dialog box. To create and manipulate
the dialog box, a C++ class is typically created that inherits from CAxDialogImpl.
This class provides the plumbing to create and manage the ActiveX control on a
window. The ATL wizard can be used to supply the majority of the boilerplate
code. The steps to create a dialog box and add an ActiveX control in an ATL
project are discussed below.
1. Click the menu command Insert/New ATL Object.
2. Click the Miscellaneous category, then click the Dialog object.
3. A dialog box resource and a class inheriting from CAxDialogImpl will be
added to your project.
4. Right-click the dialog box in Resource view and click Insert ActiveX Control.
This will display a list of available ActiveX controls.
5. Double-click a control in the list to add that control to the dialog box.
6. Right-click the control and click Properties to set the control’s design-time
properties.
Chapter 4 • Developer environments • 123