Accelerator Tables

An accelerator table consists of an array of ACCEL structures, each defining an individual accelerator. Each ACCEL structure includes the following information:

• The accelerator's keystroke combination
• The accelerator's identifier
• Various flags

To process accelerator keystrokes for a specified thread, call the TranslateAccelerator function in the message loop associated with the thread's message queue. This function monitors keyboard input to the message queue, checking for key combinations that match an entry in the accelerator table. When TranslateAccelerator finds a match, it translates the keyboard input, that is, the WM_KEYUP and WM_KEYDOWN messages, into a WM_COMMAND or WM_SYSCOMMAND message. It then sends the message to the window procedure of the specified window.

The WM_COMMAND message includes the identifier of the accelerator that caused TranslateAccelerator to generate the message. The window procedure examines the identifier to determine the source of the message and then processes the message accordingly.

Note Unlike Windows-based desktop platforms, Windows CE does not maintain a system-wide accelerator table that applies to all applications.

Windows CE maintains accelerator tables for each application. An application can define any number of accelerator tables for use with its own windows. A unique 32-bit handle, HACCEL, identifies each table. However, only one accelerator table can be active at a time for a specified thread. The handle of the accelerator table passed to the TranslateAccelerator function determines which accelerator table is active for a thread. The active accelerator table can be changed at any time by passing a different accelerator-table handle to TranslateAccelerator.

    To create an accelerator table

1. Use a resource compiler to create an accelerator table resource and to add it your executable file.
2. Call the LoadAccelerators function at run time to load the accelerator table and to retrieve the handle of the accelerator table.
3. Pass a handle to the accelerator table to the TranslateAccelerator function to activate the accelerator table.

You can create an accelerator table for an application at run time by passing an array of ACCEL structures to the CreateAcceleratorTable function. This method supports user-defined accelerators in the application. Like the LoadAccelerators function, CreateAcceleratorTable returns an accelerator-table handle that can be passed to TranslateAccelerator to activate the accelerator table.

Windows CE automatically destroys accelerator tables loaded by LoadAccelerators. An accelerator table created by CreateAcceleratorTable must be destroyed before an application closes. Use the DestroyAcceleratorTable function to destroy an accelerator table.