DialogBoxIndirectParamA function (winuser.h)

Article
02/09/2023

Creates a modal dialog box from a dialog box template in memory. Before displaying the dialog box, the function passes an application-defined value to the dialog box procedure as the lParam parameter of the WM_INITDIALOG message. An application can use this value to initialize dialog box controls.

Syntax

INT_PTR DialogBoxIndirectParamA(
  [in, optional] HINSTANCE       hInstance,
  [in]           LPCDLGTEMPLATEA hDialogTemplate,
  [in, optional] HWND            hWndParent,
  [in, optional] DLGPROC         lpDialogFunc,
  [in]           LPARAM          dwInitParam
);

Parameters

[in, optional] hInstance

Type: HINSTANCE

A handle to the module that creates the dialog box.

[in] hDialogTemplate

Type: LPCDLGTEMPLATE

The template that DialogBoxIndirectParam uses to create the dialog box. A dialog box template consists of a header that describes the dialog box, followed by one or more additional blocks of data that describe each of the controls in the dialog box. The template can use either the standard format or the extended format.

In a standard template for a dialog box, the header is a DLGTEMPLATE structure followed by additional variable-length arrays. The data for each control consists of a DLGITEMTEMPLATE structure followed by additional variable-length arrays.

In an extended template for a dialog box, the header uses the DLGTEMPLATEEX format and the control definitions use the DLGITEMTEMPLATEEX format.

[in, optional] hWndParent

Type: HWND

A handle to the window that owns the dialog box.

[in, optional] lpDialogFunc

Type: DLGPROC

A pointer to the dialog box procedure. For more information about the dialog box procedure, see DialogProc.

[in] dwInitParam

Type: LPARAM

The value to pass to the dialog box in the lParam parameter of the WM_INITDIALOG message.

Return value

Type: INT_PTR

If the function succeeds, the return value is the nResult parameter specified in the call to the EndDialog function that was used to terminate the dialog box.

If the function fails because the hWndParent parameter is invalid, the return value is zero. The function returns zero in this case for compatibility with previous versions of Windows. If the function fails for any other reason, the return value is –1. To get extended error information, call GetLastError.

Remarks

The DialogBoxIndirectParam function uses the CreateWindowEx function to create the dialog box. DialogBoxIndirectParam then sends a WM_INITDIALOG message to the dialog box procedure. If the template specifies the DS_SETFONT or DS_SHELLFONT style, the function also sends a WM_SETFONT message to the dialog box procedure. The function displays the dialog box (regardless of whether the template specifies the WS_VISIBLE style), disables the owner window, and starts its own message loop to retrieve and dispatch messages for the dialog box.

When the dialog box procedure calls the EndDialog function, DialogBoxIndirectParam destroys the dialog box, ends the message loop, enables the owner window (if previously enabled), and returns the nResult parameter specified by the dialog box procedure when it called EndDialog.

In a standard dialog box template, the DLGTEMPLATE structure and each of the DLGITEMTEMPLATE structures must be aligned on DWORD boundaries. The creation data array that follows a DLGITEMTEMPLATE structure must also be aligned on a DWORD boundary. All of the other variable-length arrays in the template must be aligned on WORD boundaries.

In an extended dialog box template, the DLGTEMPLATEEX header and each of the DLGITEMTEMPLATEEX control definitions must be aligned on DWORD boundaries. The creation data array, if any, that follows a DLGITEMTEMPLATEEX structure must also be aligned on a DWORD boundary. All of the other variable-length arrays in the template must be aligned on WORD boundaries.

All character strings in the dialog box template, such as titles for the dialog box and buttons, must be Unicode strings.

Note

The winuser.h header defines DialogBoxIndirectParam as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winuser.h (include Windows.h)
Library	User32.lib
DLL	User32.dll
API set	ext-ms-win-ntuser-dialogbox-l1-1-0 (introduced in Windows 8)