Windows API Guide: CompareString Function

Declare Function DeleteDC Lib "gdi32.dll" (ByVal hdc As Long) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Requires Windows CE 1.0 or later.

Description & Usage

DeleteDC destroys a device context which was created by CreateDC. Your program should delete a device context once it has finished using it in order to conserve resources. Do not use this function to close a device context gotten from GetDC -- for those, use ReleaseDC instead.

Return Value

If an error occured, the function returns 0 (Windows NT, 2000: use GetLastError to get the error code). If successful, the function returns a non-zero value.

Visual Basic-Specific Information

None.

Parameters

hdc: A handle to the device context to delete.

Example

' This code is licensed according to the terms and conditions listed here. ' Print out a page with an ellipse drawn with a thickened black ' pen on it.  The page is printed on the computer's default printer. ' The following are special declarations needed to allow string ' manipulation functions to use pointers to strings. Declare Function lstrcpy Lib "kernel32.dll" Alias "lstrcpyA" (ByVal lpString1 As String, ByVal lpString2 As Long) As Long Declare Function lstrlen Lib "kernel32.dll" Alias "lstrlenA" (ByVal lpString As Long) As Long ' Variable declarations Dim hPrintDC As Long  ' handle to the printer's device context Dim di As DOCINFO  ' information about the document to print Dim hPen As Long  ' handle to the pen to draw the ellipse with Dim hOldPen As Long  ' handle to the printer's previously selected pen Dim buffer(0 To 3076 / 4) As Long  ' 3076-byte buffer Dim pi2 As PRINTER_INFO_2  ' receives info about the default printer Dim printret As Long  ' receives the number of printers returned from EnumPrinters Dim spaceneeded As Long  ' receives space requires for EnumPrinters Dim retval As Long  ' return value ' Get the device and driver names of the default printer.  For a more detailed ' description of the semi-confusing code below, consult the ' EnumPrinters page. retval = EnumPrinters(PRINTER_ENUM_DEFAULT, "", 2, buffer(0), 3076, spaceneeded, printret) If retval = 0 Then   Debug.Print "No default printer is configured."   End  ' abort the program End If ' Copy the device and driver names to the structure.  All the ' other information retrieved is not needed and is omitted here. pi2.pPrinterName = Space(lstrlen(buffer(1))) retval = lstrcpy(pi2.pPrinterName, buffer(1)) pi2.pDriverName = Space(lstrlen(buffer(4))) retval = lstrcpy(pi2.pDriverName, buffer(4)) ' Create a device context to the printer, using its default initialization. hPrintDC = CreateDC("", pi2.pPrinterName, 0, ByVal CLng(0)) ' Create a solid black brush with a thickness of 5. hPen = CreatePen(PS_SOLID, 5, RGB(0, 0, 0)) ' Load information about the document to print into the structure. di.cbSize = Len(di)  ' size of structure di.lpszDocName = "Printer API Demonstration"  ' name of document di.lpszOutput = 0  ' do not print to a file di.lpszDatatype = ""  ' data type of file doesn't apply di.fwType = 0  ' no additional information ' Begin the print job. retval = StartDoc(hPrintDC, di) ' Begin the first and only page to print. retval = StartPage(hPrintDC) ' Select the pen for use with the printer. hOldPen = SelectObject(hPrintDC, hPen) ' Draw an ellipse with bounding rectangle corners (1000,1500)-(2000,3000) retval = Ellipse(hPrintDC, 1000, 1500, 2000, 3000) ' Restore the printer's previously selected pen. retval = SelectObject(hPrintDC, hOldPen) ' End information about the first and only page. retval = EndPage(hPrintDC) ' End information about the document. retval = EndDoc(hPrintDC) ' The printer will now begin printing the document. ' Delete the pen created for drawing. retval = DeleteObject(hPen) ' Delete the device context to the printer. retval = DeleteDC(hPrintDC)