CreateDC

Article
11/18/2015

A version of this page is also available for

4/8/2010

This function creates a device context (DC) for a device.

Syntax

HDC CreateDC( 
  LPCTSTR lpszDriver, 
  LPCTSTR lpszDevice, 
  LPCTSTR lpszOutput, 
  CONST DEVMODE* lpInitData
);

Parameters

lpszDriver
[in] Long pointer to a null-terminated string that specifies the file name of a driver. If this parameter is set to NULL, the system returns a screen DC.

lpszDevice
[in] Long pointer to a null-terminated string that specifies the name of the specific output device being used, as shown by the Print Manager. It is not the printer model name. The lpszDevice parameter must be used.

In Windows CE 2.0 and later, this parameter is ignored.

lpszOutput
[in] Long pointer to an output destination.

It can be one of the following values, and the colon is required when specifying a port.

Value	Description
COMx:	Serial ports; x is a number from 1 to 9.
LPTx:	Parallel ports; x is a number from 1 to 9.
IRDA:	IRDA port. For Windows CE 2.0 and 2.01, use COM3: to specify the IRDA port.
\\servername\sharename	Universal naming convention (UNC) that identifies a network printer server.

lpInitData
[in] Long pointer to a DEVMODE structure containing device-specific initialization data for the device driver.

The lpInitData parameter must be NULL if the device driver is to use the default initialization (if any) specified by the user.

Return Value

The handle to a device context for the specified device indicates success.

NULL indicates failure.

To get extended error information, call GetLastError.

Code Example

In the following code example, CreateDC is used to obtain a device context for the display driver.

Note

To make the following code example easier to read, error checking is not included. This code example should not be used in a release configuration unless it has been modified to include secure error handling.

typedef struct _tagUIEXTRA{
    HIMC     hIMC;
    UICHILD  uiStatus;
    UICHILD  uiCand;
    DWORD    dwCompStyle;
    HFONT    hFont;
    BOOL     bVertical;
    UICHILD  uiDefComp;
    UICHILD2 uiComp[MAXCOMPWND];
    UICHILD  uiGuide;
} UIEXTRA, NEAR *PUIEXTRA, FAR *LPUIEXTRA;
INT
GetCompFontHeight(
    IN LPUIEXTRA lpUIExtra      // IME UI extra information.
    )
{
    HDC hIC;
    HFONT hOldFont = 0;
    SIZE sz;
    hIC = CreateDC(TEXT("DISPLAY"),NULL,NULL,NULL);
    if (lpUIExtra->hFont)
        hOldFont = SelectObject(hIC,lpUIExtra->hFont);
    GetTextExtentPoint(hIC,TEXT("A"),1,&sz);
    if (hOldFont)
        SelectObject(hIC,hOldFont);
    DeleteDC(hIC);
    return sz.cy;
}

Remarks

Windows Embedded CE passes the lpInitData and lpszOutput parameters to the driver without modification.

The lpszOutput parameter must contain a colon after the port — that is, use LPT1: or COM1:. Otherwise, the connection fails.

When you no longer need the device context, call the DeleteDC function to delete it.

Requirements

Header	windows.h
Library	coredll.lib
Windows Embedded CE	Windows CE 2.0 and later
Windows Mobile	Windows Mobile Version 5.0 and later

Partager via