Using bedit Controls in Dialog Boxes

Windows determines the number of box cells that can fit within a control window based on the window dimensions and the cell widths given in a GUIDE structure. Although the Pen API does not provide a way to explicitly set the number of boxes displayed in a bedit control, an application can imply the number by adjusting the size of the control window or the size of the cells. Under certain circumstances, however, Windows may change the dimensions of a bedit control in a dialog box, thus potentially decreasing or increasing the number of box cells within the bedit.

Usually, this makes no difference to the developer or the user. But if your application must always show a specific number of boxes within a bedit, this section explains how to forestall or handle any changes.

By default, Windows sizes a dialog box and its controls based on the system font. If the dialog template requests a different font with a FONT statement and the font is not available when Windows creates the dialog box, Windows selects an available font that best matches the requested font. It then scales the dialog box and the controls within it according to the size of the selected font, but does not also scale the bedit guides. Thus, although a bedit window may change in size because of new scaling, the size of the boxes within it remain the same. For this reason, the window may end up with fewer or more cells than the programmer expects.

To ensure a bedit window always displays a specific number of cells, use one of the following techniques:

  • Remove the FONT statement from the dialog template and let Windows use the system font in the dialog box controls.

  • Specify a font likely to be always available. However, this technique cannot guarantee correct results for an application that must run under many different configurations of Windows.

  • Readjust the size of the bedit window after Windows has changed it. When processing WM_INITDIALOG, an application can call the GetWindowRect function to see whether Windows has resized the bedit control window. If so, the application can restore the window's original size with either the MoveWindow or SetWindowPos function.

Note that this technique assumes a generous blank area surrounds the control, so that if your application enlarges the control window while Windows shrinks the rest of the dialog box, the various components of the dialog box do not overlap.

  • Recalculate the GUIDE values if Windows has changed the window size.

By default, all the controls within a dialog box use the font selected for the dialog box. An application can set a different font in bedit controls within the dialog box by sending a WM_SETFONT message when processing WM_INITDIALOG.

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