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EMF Printer Spool File Viewer

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23 Apr 2014CPOL3 min read 806.9K   25.2K   92   181
A viewer application for EMF format spool files

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:

VB
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

  • 21st 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
Software Developer
Ireland Ireland
C# / SQL Server developer
Microsoft MVP (Azure) 2017
Microsoft MVP (Visual Basic) 2006, 2007

Comments and Discussions

 
GeneralCode difference? Pin
Skif7-Jun-11 13:14
Skif7-Jun-11 13:14 
GeneralLoading emf file .... nothing happens... Pin
tinvaltino15-Sep-10 12:28
tinvaltino15-Sep-10 12:28 
GeneralRe: Loading emf file .... nothing happens... Pin
Duncan Edwards Jones9-Dec-10 7:33
professionalDuncan Edwards Jones9-Dec-10 7:33 
GeneralRe: Loading emf file .... nothing happens... Pin
Loris Rinaldo10-Nov-11 4:31
Loris Rinaldo10-Nov-11 4:31 
GeneralRe: Loading emf file .... nothing happens... Pin
Loris Rinaldo18-Nov-11 10:21
Loris Rinaldo18-Nov-11 10:21 
GeneralRe: Loading emf file .... nothing happens... Pin
Loris Rinaldo18-Nov-11 10:23
Loris Rinaldo18-Nov-11 10:23 
QuestionExtract text from .spl file to .txt file Pin
BuzzardHawk24-Jul-10 9:06
BuzzardHawk24-Jul-10 9:06 
GeneralAdobe PDF Files Display Incorrectly [modified] Pin
tokfrans22-Mar-10 2:44
tokfrans22-Mar-10 2:44 
I really appreciate the hard work that has been put into this article and the source code especially.
I have found that viewing PDF files doesn't work correctly for some documents.
When loading the spooler file, the text looks scrambled and the underlying text is different to what's showing in the display.
To illustrate this I'm showing what I'm seeing.

In the original document when printed on paper you can find this text:
Hardware Requirements

The EMFViewer Application displays:
Ibsexbsf!Sfrvjsfnfout

When debugging the code, I find that this is the text in the EMF record:
,EVH[EVI6IUYMVIQIRXW

To me this seems like the EMF display has been shifted one byte up. H=I, a=b, r=s and so forth. And the same goes for the EMF record text, but the shift is 28 bytes, H=, a=E, r=V, d=H. You get the picture.

Some PDF files works without any problems and looks great, and others display problems like or similar to this.
Can anyone please try to explain why this is, and if there's anything I can do to handle this.

Thanks.
Timmy

GeneralRe: Adobe PDF Files Display Incorrectly Pin
Duncan Edwards Jones22-Mar-10 9:38
professionalDuncan Edwards Jones22-Mar-10 9:38 
GeneralDidn't get The Text From Spool Job using EmfTextRecord Pin
m.junaid8614-Jan-10 1:25
m.junaid8614-Jan-10 1:25 
GeneralRe: Didn't get The Text From Spool Job using EmfTextRecord Pin
Duncan Edwards Jones14-Jan-10 20:52
professionalDuncan Edwards Jones14-Jan-10 20:52 
GeneralRe: Didn't get The Text From Spool Job using EmfTextRecord Pin
mujahidcodeproject21-Jun-12 0:08
mujahidcodeproject21-Jun-12 0:08 
GeneralRead Text Printer output Pin
bardill19-Dec-08 4:17
bardill19-Dec-08 4:17 
GeneralPrint all pages Pin
Count.Zilch11-Dec-08 23:15
Count.Zilch11-Dec-08 23:15 
GeneralRe: Print all pages Pin
Duncan Edwards Jones12-Dec-08 22:18
professionalDuncan Edwards Jones12-Dec-08 22:18 
GeneralRe: Print all pages Pin
Count.Zilch13-Dec-08 0:05
Count.Zilch13-Dec-08 0:05 
GeneralRe: Print all pages Pin
Duncan Edwards Jones23-Apr-14 3:24
professionalDuncan Edwards Jones23-Apr-14 3:24 
GeneralIt's great, thanks. Where can I find the code of SpoolfileReaderBase.dll??? [modified] Pin
amanofsky10-Oct-08 6:40
amanofsky10-Oct-08 6:40 
GeneralRe: It's great, thanks. Where can I find the code of SpoolfileReaderBase.dll??? Pin
Dhanushkatr9-Jun-09 18:00
Dhanushkatr9-Jun-09 18:00 
QuestionProblem with GDI+ Pin
hsirc21-Sep-08 7:30
hsirc21-Sep-08 7:30 
AnswerRe: Problem with GDI+ Pin
Duncan Edwards Jones22-Sep-08 1:37
professionalDuncan Edwards Jones22-Sep-08 1:37 
GeneralRe: Problem with GDI+ Pin
hsirc23-Sep-08 20:09
hsirc23-Sep-08 20:09 
GeneralRe: Problem with GDI+ Pin
goyal mohit 3-Jun-14 21:27
goyal mohit 3-Jun-14 21:27 
GeneralRe: Problem with GDI+ Pin
Duncan Edwards Jones3-Jun-14 21:52
professionalDuncan Edwards Jones3-Jun-14 21:52 
GeneralRe: Problem with GDI+ Pin
goyal mohit 3-Jun-14 22:41
goyal mohit 3-Jun-14 22:41 

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