BtnBar.exe Demonstrates a Button Bar (74999)

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For the button bar to correctly interact with the Multiple Document Interface (MDI) functions of Windows, the client window must be resized to avoid painting problems. The code in the BTNBAR file is designed to be merged into the MULTIPAD sample application that is provided with the Windows SDK.

The remainder of this article provides some information on the design of this button bar implementation.

Each button on the button bar is defined in an array of TOOL structures, which is defined as follows:

   typedef struct tagTOOL

    {
    HICON     hIcon;             // 2
    WORD      CommandID;         // 2
    BOOL      bEnabled;          // 2
    WORD      x, y, dx, dy;      // 8
    }                            // --

  TOOL;                          // 14 bytes total
				

To conserve system resources, the determination that a given button has been pressed is done by performing hit testing, instead of creating separate buttons. Hit testing is demonstrated in Charles Petzold's "Checkers" program, presented in the "Microsoft Systems Journal."

This implementation of the button bar uses icons to label the buttons. The DrawTool() function draws a plain button with a gray face and dark edges, to simulate a three-dimensional object. Then, the icon specified in the structure is drawn over the button. This icon must use the "screen" color for its background color. This places the icon image on the button with minimal coding effort.

When the user clicks on a button, the button bar code sends a WM_COMMAND message to the main window (ghWnd). The wParam parameter of this message is set to the CommandID value.