EMF Printer Spool File Viewer

Duncan Edwards Jones

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23 Apr 2014CPOL3 min read

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A viewer application for EMF format spool files

Download source - 226.3 KB

What is an EMF Spool File?

When an application sends pages to a printer, they are held in an intermediary file which the application can write to and the printer driver can read from simultaneously. This speeds up the print process as control can return to the application before the printer has finished printing the document.

Usually, this spool file is held in the raw printer page definition language (which could be PCL, PostScript or one of many other options) but in Windows NT, 2000, XP and 2003, it is possible to make the spooler use a different, more device independent format known as an EMF spool file.

The file layout of an EMF spool file is not officially documented by Microsoft, but the newly released documentation reveals that it is a series of enhanced metafile records (one for each page) and a number of other record types which are specific to the business of printing these pages.

The EMF Spool File Record Types

The spool file is composed of the following record types:

Private Enum SpoolerRecordTypes
    SRT_EOF = &H0            ' // int32 zero
    SRT_RESERVED_1 = &H1     '*  1                               */
    SRT_FONTDATA = &H2       '  2 Font Data                      */
    SRT_DEVMODE = &H3        '  3 DevMode                        */
    SRT_FONT2 = &H4          '4 Font Data                        */
    SRT_RESERVED_5 = &H5     ' 5                                 */
    SRT_FONT_MM = &H6        ' 6 Font Data (Multiple Master)     */
    SRT_FONT_SUB1 = &H7      '   7 Font Data (SubsetFont 1)      */
    SRT_FONT_SUB2 = &H8      '   8 Font Data (SubsetFont 2)
    SRT_RESERVED_9 = &H9
    SRT_UNKNOWN = &H10       ' // int unknown...
    SRT_RESERVED_A = &HA
    SRT_RESERVED_B = &HB
    SRT_PAGE = &HC           ' 12  Enhanced Meta File (EMF)       */
    SRT_EOPAGE1 = &HD        ' 13  EndOfPage                      */
    SRT_EOPAGE2 = &HE        ' 14  EndOfPage                      */
    SRT_EXT_FONT = &HF       ' 15  Ext Font Data                  */
    SRT_EXT_FONT2 = &H10     ' 16  Ext Font Data                  */
    SRT_EXT_FONT_MM = &H11   ' 17  Ext Font Data (Multiple Master)
    SRT_EXT_FONT_SUB1 = &H12 ' 18  Ext Font Data (SubsetFont 1)   */
    SRT_EXT_FONT_SUB2 = &H13 '* 19  Ext Font Data (SubsetFont 2)  */
    SRT_EXT_PAGE = &H14      ' 20  Enhanced Meta File?
End Enum

Of these, the most important record types are:

SRT_PAGE

This record contains a Windows standard enhanced metafile, consisting of an EMF header and one or more EMF graphics record structures. The EMF header record gives you the dimensions of the boundary rectangle (the area inside the print margins), the number of graphics records that make up the page, and the file size of this single EMF page.

SRT_DEVMODE

This record contains the device settings that apply to the rest of the pages in the document (or until another DEVMODE record is encountered that overrides it). The DEVMODE structure holds details such as the number of copies, the page orientation (landscape versus portrait), the paper size and paper source, and so on.

SRT_EOF

This signifies the end of the spool file records.

Using the EMF Spoolfile Viewer

To view an EMF spool file, select the menu File -> Open. A dialog box will appear to allow you to browse to the spool file (extension .spl). These are typically held in your $winnt$\System32\spool\ directory. (I have included some samples with this application code as well.)

The viewer allows you to go to a particular page, zoom in and out, and even print the spool file using the following menu options:

File
- Open - Brings up a dialog box to find and open EMF spool files
- Print - Allows you to reprint the currently open EMF spool file
- Properties - Brings up a dialog box listing the print file properties
- Exit - Quits the application
Pages
- First Page - Goes to the beginning of the document
- Previous Page - Goes back one page
- Next Page - Goes to the next page
- Last Page - Goes to the end of the document
- Goto - Goes directly to the selected page
- Properties = Brings up a dialog with the properties of this page
View
- Zoom in enlarges the preview
- Zoom out reduces the size of the preview

Uses for EMF Spoolfiles

Since pretty much every application has a print function, the EMF spool file can serve as a quick and dirty portable document format (though much less featured than a PDF). Thus if you have an application and you want to send a file to someone who doesn't have that application to view, you simply use the application's print function and send them the spool file.

In addition, knowing the structure of the spool file means that it is possible to parse the file to extract information from it. You might want to extract just the text from a printed document for archival purposes, and you can do this by parsing the file and extracting the EMR_EXTTEXTOUTA and EMR_EXTTEXTOUTW records.

Acknowledgements

The source code in this application draws heavily on the work of Feng Yuan and Christophe Lindemann as well as numerous others on the various forums and news groups.

Portions of this article are based on www.undocprint.org/formats/winspool/spl. These portions are subject to the GNU Free Documentation License and are copyright © 2003-2005 Free Software Foundation, Inc.

History

21^st August, 2006: Code updated to .NET 2.0 and page navigation improved

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Written By

Duncan Edwards Jones

Software Developer

Ireland

C# / SQL Server developer
Microsoft MVP (Azure) 2017
Microsoft MVP (Visual Basic) 2006, 2007

'\\ --[DevMode]------------------------------------------------------------ '\\ Represnts a DEVMODE structure stored in a file (shadow or spool...) '\\ ----------------------------------------------------------------------- Public Class DevMode #Region "Private properties" Private dmDeviceName(64) As Char Private dmSpecVersion As Short Private dmDriverVersion As Short Private dmSize As Short Private dmDriverExtra As Short Private dmFields As Integer Private dmOrientation As Short Private dmPaperSize As Short Private dmPaperLength As Short Private dmPaperWidth As Short Private dmScale As Short Private dmCopies As Short Private dmDefaultSource As Short Private dmPrintQuality As Short Private dmColor As Short Private dmDuplex As Short Private dmYResolution As Short Private dmTTOption As Short Private dmCollate As Short Private dmFormName(32) As Char Private dmUnusedPadding As Short Private dmBitsPerPel As Integer Private dmPelsWidth As Integer Private dmPelsHeight As Integer Private dmDisplayFlags As Integer Private dmDisplayFrequency As Integer Private dmICMMethod As Integer Private dmICMIntent As Integer Private dmMediaType As Integer Private dmDitherType As Integer Private dmReserved1 As Integer Private dmReserved2 As Integer Private dmPanningWidth As Integer Private dmPanningHeight As Integer #End Region #Region "Public properties" #Region "Copies" Public ReadOnly Property Copies() As Short Get If dmCopies < 1 Then dmCopies = 1 End If Return dmCopies End Get End Property #End Region #Region "Collate" Public ReadOnly Property Collate() As Boolean Get Return (dmCollate > 0) End Get End Property #End Region #End Region #Region "Public constructors" Public Sub New(ByVal FileReader As System.IO.BinaryReader) dmDeviceName = FileReader.ReadChars(64) 'FileReader.BaseStream.Seek(64, IO.SeekOrigin.Current) dmSpecVersion = FileReader.ReadInt16 dmDriverVersion = FileReader.ReadInt16 dmSize = FileReader.ReadInt16 dmDriverExtra = FileReader.ReadInt16 dmFields = FileReader.ReadInt32 dmOrientation = FileReader.ReadInt16 dmPaperSize = FileReader.ReadInt16 dmPaperLength = FileReader.ReadInt16 dmPaperWidth = FileReader.ReadInt16 dmScale = FileReader.ReadInt16 dmCopies = FileReader.ReadInt16 dmDefaultSource = FileReader.ReadInt16 dmPrintQuality = FileReader.ReadInt16 dmColor = FileReader.ReadInt16 dmDuplex = FileReader.ReadInt16 dmYResolution = FileReader.ReadInt16 dmTTOption = FileReader.ReadInt16 dmCollate = FileReader.ReadInt16 dmFormName = FileReader.ReadChars(32) '32 chars dmUnusedPadding = FileReader.ReadInt16 dmBitsPerPel = FileReader.ReadInt32 dmPelsWidth = FileReader.ReadInt32 dmPelsHeight = FileReader.ReadInt32 dmDisplayFlags = FileReader.ReadInt32 dmDisplayFrequency = FileReader.ReadInt32 dmICMMethod = FileReader.ReadInt32 dmICMIntent = FileReader.ReadInt32 dmMediaType = FileReader.ReadInt32 dmDitherType = FileReader.ReadInt32 dmReserved1 = FileReader.ReadInt32 dmReserved2 = FileReader.ReadInt32 dmPanningWidth = FileReader.ReadInt32 dmPanningHeight = FileReader.ReadInt32 End Sub #End Region End Class

'--8<--------------------------- ElseIf .iType = SpoolerRecordTypes.SRT_DEVMODE Then '\\ Spool job DEVMODE Dim _dmThis As New DevMode(SpoolBinaryReader) _Copies = _dmThis.Copies SpoolBinaryReader.BaseStream.Seek(.Seek + 8 + .nSize, SeekOrigin.Begin) '--8<---------------------------

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.