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CreateCaret function

Creates a new shape for the system caret and assigns ownership of the caret to the specified window. The caret shape can be a line, a block, or a bitmap.

Syntax


BOOL WINAPI CreateCaret(
  _In_      HWND hWnd,
  _In_opt_  HBITMAP hBitmap,
  _In_      int nWidth,
  _In_      int nHeight
);

Parameters

hWnd [in]

Type: HWND

A handle to the window that owns the caret.

hBitmap [in, optional]

Type: HBITMAP

A handle to the bitmap that defines the caret shape. If this parameter is NULL, the caret is solid. If this parameter is (HBITMAP) 1, the caret is gray. If this parameter is a bitmap handle, the caret is the specified bitmap. The bitmap handle must have been created by the CreateBitmap, CreateDIBitmap, or LoadBitmap function.

If hBitmap is a bitmap handle, CreateCaret ignores the nWidth and nHeight parameters; the bitmap defines its own width and height.

nWidth [in]

Type: int

The width of the caret, in logical units. If this parameter is zero, the width is set to the system-defined window border width. If hBitmap is a bitmap handle, CreateCaret ignores this parameter.

nHeight [in]

Type: int

The height of the caret, in logical units. If this parameter is zero, the height is set to the system-defined window border height. If hBitmap is a bitmap handle, CreateCaret ignores this parameter.

Return value

Type: BOOL

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

The nWidth and nHeight parameters specify the caret's width and height, in logical units; the exact width and height, in pixels, depend on the window's mapping mode.

CreateCaret automatically destroys the previous caret shape, if any, regardless of the window that owns the caret. The caret is hidden until the application calls the ShowCaret function to make the caret visible.

The system provides one caret per queue. A window should create a caret only when it has the keyboard focus or is active. The window should destroy the caret before losing the keyboard focus or becoming inactive.

You can retrieve the width or height of the system's window border by using the GetSystemMetrics function, specifying the SM_CXBORDER and SM_CYBORDER values. Using the window border width or height guarantees that the caret will be visible on a high-resolution screen.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Winuser.h (include Windows.h)

Library

User32.lib

DLL

User32.dll

See also

Reference
DestroyCaret
HideCaret
ShowCaret
Conceptual
Carets
Other Resources
CreateBitmap
CreateDIBitmap
GetSystemMetrics
LoadBitmap

 

 

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