CreateWindow

This function creates an overlapped, pop-up, or child window. It specifies the window class, window title, window style, and, optionally, the initial position and size of the window. This function also specifies the window's parent.

At a Glance

Header file:	Winuser.h
Windows CE versions:	1.0 and later

Syntax

HWND CreateWindow( LPCTSTR lpClassName, LPCTSTR lpWindowName, DWORD dwStyle, int x, int y, int nWidth, int nHeight, HWND hWndParent, HMENU hMenu, HANDLE hInstance, PVOID lpParam);

Parameters

lpClassName

Long pointer to a null-terminated string or an integer atom. If this parameter is an atom, it must be a global atom created by a previous call to the RegisterClass function. The atom, a 16-bit value less than 0xC000, must be in the low-order word of lpClassName; the high-order word must be zero.

If lpClassName is a string, it specifies the window class name. The class name can be any name registered with the RegisterClass function or any of the predefined control-class names. For a complete list, see the Remarks section.

lpWindowName

Long pointer to a null-terminated string that specifies the window name.

If the window style specifies a title bar, the window title pointed to by lpWindowName is displayed in the title bar. When using CreateWindow to create controls, such as buttons, check boxes, and static controls, use lpWindowName to specify the text of the control.

dwStyle

Specifies the style of the window being created. This parameter can be a combination of the following window styles, plus the control styles indicated in the Remarks section.

Value	Description
WS_BORDER	Creates a window that has a thin-line border.
WS_CAPTION	Creates a window that has a title bar (includes the WS_BORDER style).
WS_CHILD	Creates a child window. This style cannot be used with the WS_POPUP style.
WS_CLIPCHILDREN	Excludes the area occupied by child windows when drawing occurs within the parent window. This style is used when creating the parent window.
WS_CLIPSIBLINGS	Clips child windows relative to each other; that is, when a particular child window receives a WM_PAINT message, the WS_CLIPSIBLINGS style clips all other overlapping child windows out of the region of the child window to be updated. If WS_CLIPSIBLINGS is not specified and child windows overlap, it is possible, when drawing within the client area of a child window, to draw within the client area of a neighboring child window.
WS_DISABLED	Creates a window that is initially disabled. A disabled window cannot receive input from the user.
WS_DLGFRAME	Creates a window that has a border of a style typically used with dialog boxes. A window with this style cannot have a title bar.
WS_GROUP	Specifies the first control of a group of controls. The group consists of this first control and all controls defined after it, up to the next control with the WS_GROUP style. The first control in each group usually has the WS_TABSTOP style so that the user can move from group to group. The user can subsequently change the keyboard focus from one control in the group to the next control in the group by using the direction keys.
WS_HSCROLL	Creates a window that has a horizontal scroll bar.
WS_OVERLAPPED	Creates an overlapped window. An overlapped window has a title bar and a border. Same as the WS_TILED style.
WS_POPUP	Creates a pop-up window. This style cannot be used with the WS_CHILD style.
WS_SYSMENU	Creates a window that has a window-menu on its title bar. The WS_CAPTION style must also be specified.
WS_TABSTOP	Specifies a control that can receive the keyboard focus when the user presses the TAB key. Pressing the TAB key changes the keyboard focus to the next control with the WS_TABSTOP style.
WS_TILED	Creates an overlapped window. An overlapped window has a title bar and a border. Same as the WS_OVERLAPPED style.
WS_VISIBLE	Creates a window that is initially visible.
WS_VSCROLL	Creates a window that has a vertical scroll bar.

Specifies the initial horizontal position of the window. For an overlapped or pop-up window, the x parameter is the initial x-coordinate of the window’s upper-left corner, in screen coordinates. For a child window, x is the x-coordinate of the upper-left corner of the window relative to the upper-left corner of the parent window’s client area.

If this parameter is set to CW_USEDEFAULT, the system selects the default position for the window’s upper-left corner and ignores the y parameter. CW_USEDEFAULT is valid only for overlapped windows; if it is specified for a pop-up or child window, the x and y parameters are set to zero.

Specifies the initial vertical position of the window. For an overlapped or pop-up window, the y parameter is the initial y-coordinate of the window’s upper-left corner, in screen coordinates. For a child window, y is the initial y-coordinate of the upper-left corner of the child window relative to the upper-left corner of the parent window’s client area. For a list box, y is the initial y-coordinate of the upper-left corner of the list box’s client area relative to the upper-left corner of the parent window’s client area.

If an overlapped window is created with the WS_VISIBLE style bit set and the x parameter is set to CW_USEDEFAULT, the system ignores the y parameter.

nWidth

Specifies the width, in device units, of the window. For overlapped windows, nWidth is either the window’s width, in screen coordinates, or CW_USEDEFAULT. If nWidth is CW_USEDEFAULT, the system selects a default width and height for the window; the default width extends from the initial x-coordinate to the right edge of the screen, and the default height extends from the initial y-coordinate to the top of the icon area. CW_USEDEFAULT is valid only for overlapped windows; if CW_USEDEFAULT is specified for a pop-up or child window, nWidth and nHeight are set to zero.

nHeight

Specifies the height, in device units, of the window. For overlapped windows, nHeight is the window’s height, in screen coordinates. If nWidth is set to CW_USEDEFAULT, the system ignores nHeight.

hWndParent

Handle to the parent or owner window of the window being created. To create a child window or an owned window, supply a valid window handle. This parameter is optional for pop-up windows.

hMenu

Handle to a menu, or specifies a child-window identifier depending on the window style. For an overlapped or pop-up window, hMenu identifies the menu to be used with the window; it can be NULL if the class menu is to be used. For a child window, hMenu specifies the child-window identifier, an integer value used by a dialog box control to notify its parent about events. The application determines the child-window identifier; it must be unique for all child windows with the same parent window.

hInstance

Handle to the instance of the module to be associated with the window.

lpParam

Long pointer to a value to be passed to the window through the CREATESTRUCT structure passed in the lParam parameter the WM_CREATE message.

Return Values

A handle to the new window indicates success. NULL indicates failure. To get extended error information, call GetLastError.

Remarks

The CreateWindow function does not support the WM_NCDESTROY or the WM_PARENTNOTIFY message.

CreateWindow is implemented as a macro. It is defined as CreateWindowEx, but with the dwExStyle parameter set to 0L.

Menu bars are not supported. The hMenu parameter must be NULL, unless it is used as a child-window identifier.

The MDICLIENT window class is not supported.

The dwStyle parameter can be a combination of the window styles and control styles documented in Window and Message Box Styles and Control Styles.

The following dwStyle flags are not supported for windows:

WS_CHILDWINDOW	WS_ICONIC
WS_MAXIMIZE	WS_MAXIMIZEBOX
WS_MINIMIZE	WS_MINIMIZEBOX
WS_OVERLAPPEDWINDOW	WS_POPUPWINDOW
WS_SIZEBOX	WS_THICKFRAME
WS_TILED	WS_TILEDWINDOW

The following dwStyle flags are not supported for controls and dialog boxes:

Unsupported button styles	Unsupported static control styles
BS_LEFTTEXT	SS_BLACKFRAME
BS_MULTILINE	SS_GRAYFRAME
BS_TEXT	SS_METAPICT
BS_USERBUTTON	SS_SIMPLE
Unsupported combo box styles	SS_WHITERECT
CBS_OWNERDRAWFIXED	SS_BLACKRECT
CBS_OWNERDRAWVARIABLE	SS_GRAYRECT
CBS_SIMPLE	SS_RIGHTIMAGE
Unsupported list box control styles	SS_WHITEFRAME
LBS_NODATA	Unsupported dialog box styles
LBS_OWNERDRAWFIXED	DS_ABSALIGN
LBS_OWNERDRAWVARIABLE	DS_CENTERMOUSE
LBS_STANDARD	DS_CONTEXTHELP
Unsupported scroll bar styles	DS_FIXEDSYS
SBS_BOTTOMALIGN	DS_NOFAILCREATE
SBS_RIGHTALIGN	DS_NOIDLEMSG
SBS_SIZEBOXBOTTOMRIGHTALIGN	DS_SYSMODAL
SBS_SIZEGRIP

You can use the BS_OWNERDRAW style as a substitute for the BS_USERBUTTON style.

You can use the SS_LEFT or SS_LEFTNOWORDWRAP style instead of the SS_SIMPLE style for static controls.

All windows implicitly have the WS_CLIPSIBLINGS and WS_CLIPCHILDREN styles.

Windows CE version 1.0 does not support owned windows, except for dialog boxes. If the hwndParent parameter is not NULL, the window is implicitly given the WS_CHILD style.

Windows CE version 1.0 does not support menu bars.

For Windows CE versions 2.10 and later, if nWidth and nHeight are set to CW_USEDEFAULT, the child window has dimensions of 0 x 0.

Before returning, CreateWindow sends a WM_CREATE message to the window procedure. For overlapped, pop-up, and child windows, CreateWindow sends WM_CREATE messages to the window. The lParam parameter of the WM_CREATE message contains a pointer to a CREATESTRUCT structure. If the WS_VISIBLE style is specified, CreateWindow sends the window all the messages required to activate and show the window.

The following predefined control classes can be specified in the lpClassName parameter. Note the corresponding control styles you can use in the dwStyle parameter.

BUTTON

Designates a small rectangular child window that represents a button the user can click to turn it on or off. Button controls can be used alone or in groups, and they can either be labeled or appear without text. Button controls typically change appearance when the user clicks them. For more information about buttons and the styles you can specify in the dwStyle parameter, see Control Styles.

COMBOBOX

Designates a control consisting of a list box and a selection field similar to an edit control. When using this style, an application should either display the list box at all times or enable a drop-down list box. If the list box is visible, typing characters into the selection field highlights the first list box entry that matches the characters typed. Conversely, selecting an item in the list box displays the selected text in the selection field. For more information about combo boxes and the styles you can specify in the dwStyle parameter, see Control Styles.

EDIT

Designates a rectangular child window into which the user can type text from the keyboard. The user selects the control and gives it the keyboard focus by clicking it or moving to it by pressing the TAB key. The user can type text when the edit control displays a flashing caret; use the mouse to move the cursor, select characters to be replaced, or position the cursor for inserting characters; or use the BACKSPACE key to delete characters. For more information about edit controls and the styles you can specify in the dwStyle parameter, see Control Styles.

LISTBOX

Designates a list of character strings. Specify this control whenever an application must present a list of names, such as filenames, from which the user can choose. The user can select a string by clicking it. A selected string is highlighted, and a notification message is passed to the parent window. For more information about list boxes and the styles you can specify in the dwStyle parameter, see Control Styles.

MDICLIENT

Designates an MDI client window. This window receives messages that control the MDI application’s child windows. The recommended style bits are WS_CLIPCHILDREN and WS_CHILD. Specify the WS_HSCROLL and WS_VSCROLL styles to create an MDI client window that allows the user to scroll MDI child windows into view.

RichEdit

Designates a Rich Edit version 1.0 control. This window lets the user view and edit text with character and paragraph formatting, and can include embedded COM objects.

RICHEDIT_CLASS

Designates a Rich Edit version 2.0 control. This controls let the user view and edit text with character and paragraph formatting, and can include embedded COM objects.

SCROLLBAR

Designates a rectangle that contains a scroll box and has direction arrows at both ends. The scroll bar sends a notification message to its parent window whenever the user clicks the control. The parent window is responsible for updating the position of the scroll box, if necessary. For more information about scroll bars and the styles you can specify in the dwStyle parameter, see Control Styles.

STATIC

Designates a simple text field, box, or rectangle used to label, box, or separate other controls. Static controls take no input and provide no output. For more information about static controls and the styles you can specify in the dwStyle parameter, see Creating Controls.

Note

If you specify Windows version 4.x when linking your application, its windows cannot have caption buttons unless they also have window menus. This is not a requirement if you specify Windows version 3.x when linking your application.