DEVMODE Members That Define or Select Page Size
Printer drivers store their default settings in a structure called the DEVMODE. When you define or select a page size, four members of this structure may be involved:
members contain values on all operating systems, but they can only be used to select or define a size on systems that are running Windows 95, Windows 98, or Windows Me. The dmFormName
member is only valid for systems that are running Windows NT or Windows 2000. The dmPaperSize
member can be used on any 32-bit Windows operating system, as long as the value that is assigned to it corresponds to a size or form that is defined on that system.
Thus, on systems that are running Windows 95, Windows 98, or Windows Me, you can define custom page sizes by height (length) and width or by a predefined paper size. Windows NT-based or Windows 2000-based systems only use defined forms for page sizes, which you can select in one of two ways:set dmFormName
or assign a valid "constant" value to dmPaperSize
To use a particular paper size on Windows NT or Windows 2000, you must define a form for it. The Visual Basic Printer
object has PageSize
, and Width
properties that expose the dmPaperSize
, and dmPaperWidth
members of the DEVMODE. However, the Printer
object does not expose a way to select a form by name, nor does it have a method to add a custom form at run time. We must use the Win32 application programming interface (API) to create a custom form and/or select a form by name.
How to Programmatically Select a Form
This article uses the EnumForms
basic process to list all forms that are supported for the current printer and to check the height and width of each form. If the specified size is found, it is selected. If it is not found, the code adds the form and then selects it.
There are three ways to programmatically select a form:
- Retrieve the printer's DEVMODE structure, set the dmFormName member, and use the ResetDC function to set this form as the current form for the Device Context (DC) of the printer. When this form is selected for the DC, it is only selected for the calling process and does not change the driver's default setting. This does not require any special permissions. This method is preferred for applications that change a printer's settings.
- Call the SetForm function to change the default form for the printer driver. This method requires full access permissions to the driver. When the default form is changed, it affects every application that uses this driver to print. If this is a network printer, most users do not have the necessary permissions to make this call.
- Assign the system-defined value for the custom form to Printer.PaperSize.
Only the first method is demonstrated in this article's sample code; the sample does not demonstrate the call to SetForm
or the value assignment to Printer.PaperSize
. The sample captures the system-assigned value of the new custom form by returning the value of its ordinal position in the list that EnumForms
returns. Note that this only works for custom forms. Predefined forms have constant values assigned to them that do not correspond to their ordinal position in this list.
When you use the AddForm
function to add your custom form, the form is given its own number, if available, which then remains consistent across all printers that use the form. In this case, the form is defined and given a "constant" value for the current system. You can then assign this value to Printer.PaperSize
to select it. However, because the number assignment is simply one more than the number of forms that is listed for the current printer when the form was added, this number may not be available because a predefined form is already using that number. Therefore, it is not recommended that you use this value to select a form, and this value is not demonstrated here. If you use this number assignment, and the value for it is unavailable, it will either select the wrong form or raise run-time error 380: "Invalid Property Value."
Form Sources and Functions
Most forms are defined by the operating system and are available to all local printers. However, forms for network printers are defined on the printer server. Some forms may be defined specifically for a given printer driver and only appear in the list for that driver. Another source for forms is custom-defined or user-defined forms, which can be created manually or through code and are available to all local printers on the system. Both printer-specific and user-defined forms are stored in the registry.
The sample in this article uses a few function calls that are related to forms. Briefly, the key functions are as follows:
|EnumForms||Returns information about all of the forms that are supported for the current printer.|
|AddForm||Adds a custom form to the system. The data on this form is stored in the registry. Thus, custom forms are available for all printers, not just the printer that was current when the form was added. The numeric value that the system assigns to this form is simply one number higher than the number of forms that EnumForms returns for the current printer. You must have full rights to the driver to call this function. If you cannot add a form manually, this function call also fails for you. For this reason, you usually cannot use this function on network printers.|
|DeleteForm||Removes a custom form. However, this function does not delete the standard forms that the operating system defines and returns error code 87 if this is attempted. This function also requires the same rights as AddForm.|
Although the sample does not use the following functions, it does include the Declares for these functions:
|GetForm||Retrieves information about a specific form.|
|SetForm||Sets the default form information for the specified printer. This function requires full rights, just as changing any printer driver setting does.|
It must be emphasized that some of these functions require Full Control permissions on the printer. Therefore, the SetForm
, and DeleteForm
functions almost never work for printers that are installed as "network printers." This is because the drivers for network printers are not installed locally but reside on the printer server, and your User account is unlikely to have Administrator rights on the printer server. This differs from systems that are running Windows 95, Windows 98, or Windows Me, in which all printer drivers (even network printers) are always installed locally. However, you can install network printers as local printers in Windows NT or Windows 2000 and set the Port to the printer queue. Then you can use these functions to make changes without affecting other users who share the printer.
Steps to Add a Local Printer Driver for a Network Printer
- On the Start menu, point to Settings, and then click Printers. Double-click Add Printer to start the Add Printer Wizard.
- When prompted, make sure that you click Local printer or My Computer and NOT Network printer. Although you will connect to a network printer, you want to use a driver on My Computer. Click Next to continue.
- On Windows NT, click Add Port. On Windows 2000, click Create a new port.
- In the drop-down list box, click Local Port. On Windows NT, click New Port. On Windows 2000, click Next, and you are prompted for a Port Name.
- Type the location of the printer on the network. For example:
\\printserver\printernamewhere you use the exact path name to the printer.
- Click OK, and complete the wizard.
If you change the printer properties for the active printer, you still affect all applications that use that printer, but only for the local system.IMPORTANT
When you use custom page sizes, the behavior differs between Laser or Ink Jet printers and Dot Matrix or impact printers. Obviously, no printer accepts a page size that is wider than it can physically accommodate. But printers that use continuous feed paper can be flexible on page sizes because they print one line at a time. Alternately, Laser and Ink Jet printers print one page at a time. Thus, for example, when you print to a Dot Matrix printer (which uses continuous feed paper), you can easily see the page length during a form feed because the printer advances to the place where it expects the top of the next page to start, regardless of the physical size of the paper that it is using. On Laser and Ink Jet printers, a form feed always ejects a full physical page regardless of the page size it expects. Also, on most Laser printers, the display reads "Load Custom" (or similar) when you ask the printer to print on a user-defined page size.
- Set a local printer as the default printer. To do this, follow these steps:
- On the Start menu, point to Settings, and then click Printers.
- Right-click the icon for a local printer, and then click Set as default.
- Start a new Standard EXE project in Visual Basic. Form1 is created by default.
- Add three CommandButtons and a ListBox control to Form1.
- Paste the following code into the module of Form1:
Option ExplicitPrivate Sub Command1_Click()Dim FormName As StringFormName = "MyCustomForm" ' Use special, user-defined form.UseForm FormNameEnd SubPrivate Sub Command2_Click()Dim FormName As String' Get FormName from the ListBox.On Error GoTo ListBoxERR ' Trap for no selection.FormName = Mid(List1.Text, 1, InStr(1, List1.Text, " -") - 1)On Error GoTo 0 ' Turn off Error trap.UseForm FormNameExit SubListBoxERR:MsgBox "Select a printer from the ListBox before using this option.", _ vbExclamationEnd SubPrivate Sub Command3_Click()Dim RetVal As LongDim PrinterHandle As Long ' Handle to printerDim PrinterName As StringDim FormName As StringDim Continue As Long' Delete form that is selected in ListBox.PrinterName = Printer.DeviceName ' Current printerIf OpenPrinter(PrinterName, PrinterHandle, 0&) Then On Error GoTo ListBoxERR ' Trap for no selection. FormName = Mid(List1.Text, 1, InStr(1, List1.Text, " -") - 1) On Error GoTo 0 ' Turn off Error trap. Continue = MsgBox("Are you sure you want to permanently remove " & _ FormName & " from " & PrinterName & "?", vbYesNo) If Continue = vbYes Then RetVal = DeleteForm(PrinterHandle, FormName & Chr(0)) If RetVal <> 0 Then ' DeleteForm succeeded. List1.Clear ' Reflect the deletion in the ListBox. Form_Load ' Rebuild the list. MsgBox FormName & " deleted!", vbInformation, "Success!" Else MsgBox FormName & " not deleted!" & vbCrLf & vbCrLf & _ "Error code: " & Err.LastDllError, vbInformation, "Failure!" End If End If ClosePrinter (PrinterHandle)End IfExit SubListBoxERR:MsgBox "Select a printer from the ListBox before using this option.", _ vbExclamationClosePrinter (PrinterHandle)End SubPrivate Sub Form_Load()Dim NumForms As Long, I As LongDim FI1 As FORM_INFO_1Dim aFI1() As FORM_INFO_1 ' Working FI1 arrayDim Temp() As Byte ' Temp FI1 arrayDim BytesNeeded As LongDim PrinterName As String ' Current printerDim PrinterHandle As Long ' Handle to printerDim FormItem As String ' For ListBoxDim RetVal As LongDim FormSize As SIZEL ' Size of desired formPrinterName = Printer.DeviceName ' Current printerIf OpenPrinter(PrinterName, PrinterHandle, 0&) Then With FormSize ' Desired page size .cx = 214000 .cy = 216000 End With ReDim aFI1(1) RetVal = EnumForms(PrinterHandle, 1, aFI1(0), 0&, BytesNeeded, _ NumForms) ReDim Temp(BytesNeeded) ReDim aFI1(BytesNeeded / Len(FI1)) RetVal = EnumForms(PrinterHandle, 1, Temp(0), BytesNeeded, _ BytesNeeded, NumForms) Call CopyMemory(aFI1(0), Temp(0), BytesNeeded) For I = 0 To NumForms - 1 With aFI1(I) ' List name and size including the count (index). FormItem = PtrCtoVbString(.pName) & " - " & .Size.cx / 1000 & _ " mm X " & .Size.cy / 1000 & " mm (" & I + 1 & ")" List1.AddItem FormItem End With Next I ClosePrinter (PrinterHandle)End IfEnd SubPrivate Sub UseForm(FormName As String)Dim RetVal As IntegerRetVal = SelectForm(FormName, Me.hwnd)Select Case RetVal Case FORM_NOT_SELECTED ' 0 ' Selection failed! MsgBox "Unable to retrieve From name", vbExclamation, _ "Operation halted!" Case FORM_SELECTED ' 1 ' Selection succeeded! PrintTest ' Comment this line to avoid printing Case FORM_ADDED ' 2 ' Form added and selected. List1.Clear ' Reflect the addition in the ListBox Form_Load ' by rebuilding the list.End SelectEnd Sub
- From the Project menu, add a new Module, Module1.
- Paste the following code into Module1:
Option ExplicitPublic Declare Function EnumForms Lib "winspool.drv" Alias "EnumFormsA" _ (ByVal hPrinter As Long, ByVal Level As Long, ByRef pForm As Any, _ ByVal cbBuf As Long, ByRef pcbNeeded As Long, _ ByRef pcReturned As Long) As LongPublic Declare Function AddForm Lib "winspool.drv" Alias "AddFormA" _ (ByVal hPrinter As Long, ByVal Level As Long, pForm As Byte) As LongPublic Declare Function DeleteForm Lib "winspool.drv" Alias "DeleteFormA" _ (ByVal hPrinter As Long, ByVal pFormName As String) As Long Public Declare Function OpenPrinter Lib "winspool.drv" _ Alias "OpenPrinterA" (ByVal pPrinterName As String, _ phPrinter As Long, ByVal pDefault As Long) As LongPublic Declare Function ClosePrinter Lib "winspool.drv" _ (ByVal hPrinter As Long) As LongPublic Declare Function DocumentProperties Lib "winspool.drv" _ Alias "DocumentPropertiesA" (ByVal hwnd As Long, _ ByVal hPrinter As Long, ByVal pDeviceName As String, _ pDevModeOutput As Any, pDevModeInput As Any, ByVal fMode As Long) _ As LongPublic Declare Function ResetDC Lib "gdi32" Alias "ResetDCA" _ (ByVal hdc As Long, lpInitData As Any) As LongPublic Declare Sub CopyMemory Lib "KERNEL32" Alias "RtlMoveMemory" _ (hpvDest As Any, hpvSource As Any, ByVal cbCopy As Long)Public Declare Function lstrcpy Lib "KERNEL32" Alias "lstrcpyA" _ (ByVal lpString1 As String, ByRef lpString2 As Long) As Long ' Optional functions not used in this sample, but may be useful.Public Declare Function GetForm Lib "winspool.drv" Alias "GetFormA" _ (ByVal hPrinter As Long, ByVal pFormName As String, _ ByVal Level As Long, pForm As Byte, ByVal cbBuf As Long, _ pcbNeeded As Long) As Long Public Declare Function SetForm Lib "winspool.drv" Alias "SetFormA" _ (ByVal hPrinter As Long, ByVal pFormName As String, _ ByVal Level As Long, pForm As Byte) As Long' Constants for DEVMODEPublic Const CCHFORMNAME = 32Public Const CCHDEVICENAME = 32Public Const DM_FORMNAME As Long = &H10000Public Const DM_ORIENTATION = &H1&' Constants for PRINTER_DEFAULTS.DesiredAccessPublic Const PRINTER_ACCESS_ADMINISTER = &H4Public Const PRINTER_ACCESS_USE = &H8Public Const STANDARD_RIGHTS_REQUIRED = &HF0000Public Const PRINTER_ALL_ACCESS = (STANDARD_RIGHTS_REQUIRED Or _ PRINTER_ACCESS_ADMINISTER Or PRINTER_ACCESS_USE) ' Constants for DocumentProperties() callPublic Const DM_MODIFY = 8Public Const DM_IN_BUFFER = DM_MODIFYPublic Const DM_COPY = 2Public Const DM_OUT_BUFFER = DM_COPY' Custom constants for this sample's SelectForm functionPublic Const FORM_NOT_SELECTED = 0Public Const FORM_SELECTED = 1Public Const FORM_ADDED = 2Public Type RECTL Left As Long Top As Long Right As Long Bottom As LongEnd TypePublic Type SIZEL cx As Long cy As LongEnd TypePublic Type SECURITY_DESCRIPTOR Revision As Byte Sbz1 As Byte Control As Long Owner As Long Group As Long Sacl As Long ' ACL Dacl As Long ' ACLEnd Type' The two definitions for FORM_INFO_1 make the coding easier.Public Type FORM_INFO_1 Flags As Long pName As Long ' String Size As SIZEL ImageableArea As RECTLEnd TypePublic Type sFORM_INFO_1 Flags As Long pName As String Size As SIZEL ImageableArea As RECTLEnd TypePublic Type DEVMODE dmDeviceName As String * CCHDEVICENAME dmSpecVersion As Integer dmDriverVersion As Integer dmSize As Integer dmDriverExtra As Integer dmFields As Long dmOrientation As Integer dmPaperSize As Integer dmPaperLength As Integer dmPaperWidth As Integer dmScale As Integer dmCopies As Integer dmDefaultSource As Integer dmPrintQuality As Integer dmColor As Integer dmDuplex As Integer dmYResolution As Integer dmTTOption As Integer dmCollate As Integer dmFormName As String * CCHFORMNAME dmUnusedPadding As Integer dmBitsPerPel As Long dmPelsWidth As Long dmPelsHeight As Long dmDisplayFlags As Long dmDisplayFrequency As LongEnd TypePublic Type PRINTER_DEFAULTS pDatatype As String pDevMode As Long ' DEVMODE DesiredAccess As LongEnd TypePublic Type PRINTER_INFO_2 pServerName As String pPrinterName As String pShareName As String pPortName As String pDriverName As String pComment As String pLocation As String pDevMode As DEVMODE pSepFile As String pPrintProcessor As String pDatatype As String pParameters As String pSecurityDescriptor As SECURITY_DESCRIPTOR Attributes As Long Priority As Long DefaultPriority As Long StartTime As Long UntilTime As Long Status As Long cJobs As Long AveragePPM As LongEnd TypePublic Function GetFormName(ByVal PrinterHandle As Long, _ FormSize As SIZEL, FormName As String) As IntegerDim NumForms As Long, I As LongDim FI1 As FORM_INFO_1Dim aFI1() As FORM_INFO_1 ' Working FI1 arrayDim Temp() As Byte ' Temp FI1 arrayDim FormIndex As IntegerDim BytesNeeded As LongDim RetVal As LongFormName = vbNullStringFormIndex = 0ReDim aFI1(1)' First call retrieves the BytesNeeded.RetVal = EnumForms(PrinterHandle, 1, aFI1(0), 0&, BytesNeeded, NumForms)ReDim Temp(BytesNeeded)ReDim aFI1(BytesNeeded / Len(FI1))' Second call actually enumerates the supported forms.RetVal = EnumForms(PrinterHandle, 1, Temp(0), BytesNeeded, BytesNeeded, _ NumForms)Call CopyMemory(aFI1(0), Temp(0), BytesNeeded)For I = 0 To NumForms - 1 With aFI1(I) If .Size.cx = FormSize.cx And .Size.cy = FormSize.cy Then ' Found the desired form FormName = PtrCtoVbString(.pName) FormIndex = I + 1 Exit For End If End WithNext IGetFormName = FormIndex ' Returns non-zero when form is found.End FunctionPublic Function AddNewForm(PrinterHandle As Long, FormSize As SIZEL, _ FormName As String) As StringDim FI1 As sFORM_INFO_1Dim aFI1() As ByteDim RetVal As LongWith FI1 .Flags = 0 .pName = FormName With .Size .cx = FormSize.cx .cy = FormSize.cy End With With .ImageableArea .Left = 0 .Top = 0 .Right = FI1.Size.cx .Bottom = FI1.Size.cy End WithEnd WithReDim aFI1(Len(FI1))Call CopyMemory(aFI1(0), FI1, Len(FI1))RetVal = AddForm(PrinterHandle, 1, aFI1(0))If RetVal = 0 Then If Err.LastDllError = 5 Then MsgBox "You do not have permissions to add a form to " & _ Printer.DeviceName, vbExclamation, "Access Denied!" Else MsgBox "Error: " & Err.LastDllError, "Error Adding Form" End If AddNewForm = "none"Else AddNewForm = FI1.pNameEnd IfEnd FunctionPublic Function PtrCtoVbString(ByVal Add As Long) As StringDim sTemp As String * 512, x As Longx = lstrcpy(sTemp, ByVal Add)If (InStr(1, sTemp, Chr(0)) = 0) Then PtrCtoVbString = ""Else PtrCtoVbString = Left(sTemp, InStr(1, sTemp, Chr(0)) - 1)End IfEnd FunctionPublic Function SelectForm(FormName As String, ByVal MyhWnd As Long) _ As IntegerDim nSize As Long ' Size of DEVMODEDim pDevMode As DEVMODEDim PrinterHandle As Long ' Handle to printerDim hPrtDC As Long ' Handle to Printer DCDim PrinterName As StringDim aDevMode() As Byte ' Working DEVMODEDim FormSize As SIZELPrinterName = Printer.DeviceName ' Current printerhPrtDC = Printer.hdc ' hDC for current PrinterSelectForm = FORM_NOT_SELECTED ' Set for failure unless reset in code.' Get a handle to the printer.If OpenPrinter(PrinterName, PrinterHandle, 0&) Then ' Retrieve the size of the DEVMODE. nSize = DocumentProperties(MyhWnd, PrinterHandle, PrinterName, 0&, _ 0&, 0&) ' Reserve memory for the actual size of the DEVMODE. ReDim aDevMode(1 To nSize) ' Fill the DEVMODE from the printer. nSize = DocumentProperties(MyhWnd, PrinterHandle, PrinterName, _ aDevMode(1), 0&, DM_OUT_BUFFER) ' Copy the Public (predefined) portion of the DEVMODE. Call CopyMemory(pDevMode, aDevMode(1), Len(pDevMode)) ' If FormName is "MyCustomForm", we must make sure it exists ' before using it. Otherwise, it came from our EnumForms list, ' and we do not need to check first. Note that we could have ' passed in a Flag instead of checking for a literal name. If FormName = "MyCustomForm" Then ' Use form "MyCustomForm", adding it if necessary. ' Set the desired size of the form needed. With FormSize ' Given in thousandths of millimeters .cx = 214000 ' width .cy = 216000 ' height End With If GetFormName(PrinterHandle, FormSize, FormName) = 0 Then ' Form not found - Either of the next 2 lines will work. 'FormName = AddNewForm(PrinterHandle, FormSize, "MyCustomForm") AddNewForm PrinterHandle, FormSize, "MyCustomForm" If GetFormName(PrinterHandle, FormSize, FormName) = 0 Then ClosePrinter (PrinterHandle) SelectForm = FORM_NOT_SELECTED ' Selection Failed! Exit Function Else SelectForm = FORM_ADDED ' Form Added, Selection succeeded! End If End If End If ' Change the appropriate member in the DevMode. ' In this case, you want to change the form name. pDevMode.dmFormName = FormName & Chr(0) ' Must be NULL terminated! ' Set the dmFields bit flag to indicate what you are changing. pDevMode.dmFields = DM_FORMNAME ' Copy your changes back, then update DEVMODE. Call CopyMemory(aDevMode(1), pDevMode, Len(pDevMode)) nSize = DocumentProperties(MyhWnd, PrinterHandle, PrinterName, _ aDevMode(1), aDevMode(1), DM_IN_BUFFER Or DM_OUT_BUFFER) nSize = ResetDC(hPrtDC, aDevMode(1)) ' Reset the DEVMODE for the DC. ' Close the handle when you are finished with it. ClosePrinter (PrinterHandle) ' Selection Succeeded! But was Form Added? If SelectForm <> FORM_ADDED Then SelectForm = FORM_SELECTED Else SelectForm = FORM_NOT_SELECTED ' Selection Failed!End IfEnd FunctionPublic Sub PrintTest() ' Print two test pages to confirm the page size. Printer.Print "Top of Page 1." Printer.NewPage ' Spacing between lines should reflect the chosen page height. Printer.Print "Top of Page 2. - Check the page Height (Length.)" Printer.EndDoc MsgBox "Check Printer " & Printer.DeviceName, vbInformation, "Done!"End Sub
- Run the project. The ListBox shows all of the forms that the current printer supports.
- Click Command1. This adds "MyCustomForm - 214 mm X 216 mm (xxx)" to the end of the list, where "xxx" is the number that is assigned to the new form.
- Click a form in the ListBox, and then click Command2. This prints a test page to the current printer using the selected form.
- Click the new custom form in the ListBox, and then click Command3. You are prompted to confirm the deletion of the form. If you click Yes, it removes the custom form. If you try this with a predefined form, it raises error 87 because only custom forms can be deleted.