CTRLTEST

The CTRLTEST sample demonstrates several techniques for implementing and using custom controls.

• CParsedEdit is a specialized edit control that illustrates two methods of using custom controls.
• The spin control has small up-arrow and down-arrow buttons for incrementing or decrementing a value.
• The bitmapped button illustrates how to implement custom menu commands by using the CBitmapButton class.

Implementing and Using Custom Controls

You can implement a custom control from scratch by deriving from CWnd, but it is much easier if you can borrow functionality from one of the standard Windows controls by deriving from its control class in the library. CTRLTEST does this to implement a specialized edit control, CParsedEdit. This edit control accepts only specified sets of characters as user input -- numeric, alphabetic, and other non-control characters. CParsedEdit is derived from CEdit. It has an OnChar message handler to filter the characters.

The implementation of the commands in the Simple menu illustrates two methods for using a custom control. The methods are distinguished according to how the application associates instances of the control in the dialog box with the CParsedEdit class. Each Simple menu command displays a dialog box with four instances of the CParsedEdit control. Data entered in the dialog box is sent to the debug port as TRACE output. The two Simple menu commands are:

Test C++ Derived Class:

The CParsedEdit controls are data members of the dialog class. The controls are explicitly created in the dialog's OnInitDialog function by calling CParsedEdit::CreateSet. See DERTEST.CPP.

Test Dynamic Subclassing:

The controls are laid out in a dialog template resource (IDD_SUB_EDIT in CTRLTEST.RC) as standard edit controls. The controls are declared as CParsedEdit data members in the dialog class. The dialog's OnInitDialog function calls CParsedEdit::SubClassEdit, which in turn calls CWnd::SubclassDlgItem, to associate each specific instance of the edit control with the CParsedEdit class. See PAREDIT.CPP.

Example: Spin Control

The CTRLTEST sample includes an implementation of a spin control. The spin control has a small up-arrow and a small down-arrow button for incrementing or decrementing a value.

The Spin Control command calls a dialog box that has four CParsedEdit controls, each associated with a spin control. You can enter numeric data by either typing the value into the CParsedEdit control and selecting OK or by selecting the up or down arrow. Data entered in the CParsedEdit controls in this dialog box is filtered to accept only nonnegative integers. The CParsedEdit control treats all invalid values as 0. If you enter a negative or invalid number, an error message pops up when you select OK.

Example: Bitmap Button

The implementation of the following Custom menu commands illustrates ways to use CBitmapButton:

• Bitmap Button 1: The dialog constructor explicitly loads the bitmap resources for each of the three states (up, down, and focus) of the button by calling CBitmapButton::LoadBitmaps.
• Bitmap Button 2: The dialog's OnInitDialog function calls CBitmapButton::Autoload to load the bitmap resources based on the following naming convention. The window text of the control serves as the base resource name, and the letters U, D, and F are appended to create the names of the resources for each of the three bitmap images for, respectively, up, down, and focus. For example, the three bitmap resources for the OK button are named OKU, OKD, and OKF.
• Bitmap Button 3: The dialog box is an extension of the second dialog box above, using a fourth possible button state, disabled. To use this dialog, click the left- or right-arrow bitmap button until the displayed number reaches 1, the lowest number, or 10, the highest number. When the limit is reached, the button is disabled and a fourth bitmap image is displayed. The naming convention for the bitmap resource for the disabled state is an X suffix, as is reflected in the resource names PREVX and NEXTX.

This sample demonstrates the following keywords:

You can find the CTRLTEST project files in the Wce\Samples\Mfc\CTRLTEST directory.

For information on the Windows CE platforms that support this sample, see MFC for Windows CE Samples.