2. Printer Driver Development in Windows 7
Felix Maxa Software Engineer Microsoft Corporation

3. Agenda New API and features in Windows 7 Print filter pipeline
Print Driver Isolation
XPS Print API
Plugin Execution Context API
Print filter pipeline
Updates
Performance
Point’n’print and Client Side Rendering

4. Print Driver Isolation
A driver can be loaded
in the spooler process, or
in a shared sandbox, or
isolated sandbox
Driver attributes and group policy
A print processor is isolated based on the policy of the driver that is associated with the queue that is printing the job
Isolation policies on client and server are unrelated

5. Print Driver Isolation
Client
Server
SANDBOX
SANDBOX
Windows 7 – CSR
Windows 7
Windows 7 – SSR
Windows Vista
Windows Server 2003
Windows XP
Windows Vista
Windows Server 2003
Windows XP
CSR – Client Side Rendering SSR – Server Side Rendering

6. XPS Print API Submits XPS documents to XPS and GDI printers
Sends document events to driver
Parity with WPF and GDI drivers
Runs in client application process
We’ll have a white paper about it – draft by WinHEC

7. Print Plug-in Context API
typedef enum {
PRINT_EXECUTION_CONTEXT_APPLICATION = 0,
PRINT_EXECUTION_CONTEXT_SPOOLER_SERVICE = 1,
PRINT_EXECUTION_CONTEXT_ISOLATION_HOST = 2,
PRINT_EXECUTION_CONTEXT_FILTER_PIPELINE = 3,
PRINT_EXECUTION_CONTEXT_WOW64 = 4 }
PRINT_EXECUTION_CONTEXT;
typedef struct
PRINT_EXECUTION_CONTEXT context;
DWORD clientAppPID;
PRINT_EXECUTION_DATA;
BOOL
WINAPI
GetPrintExecutionData(
__out PRINT_EXECUTION_DATA *pData );

8. Print Filter Pipeline – Optional Service Providers
“FilterServiceProvider” tag introduced in Windows Vista
“OptionalFilterServiceProvider” tag introduced in Windows 7
<Filters>
<Filter dll = “TestPrintFilters.dll" …
</Filter>
<FilterServiceProvider dll="unidrvui.dll"/>
<OptionalFilterServiceProvider dll=“somedll.dll"/>
</Filters>

9. Print Filter Pipeline - Updates
Property bag: XPS_FP_OUTPUT_FILE L"PrintOutputFileName"
Bypass print filter pipeline
Use XPS_PASS data type
Windows 7: enabled loading dependent DLLs from drivers directory
m_hModule = LoadLibraryEx(pszFile, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);

10. Print Filter Pipeline – Restricted Fonts
IPartFont interface introduced in Windows Vista
IPartFont2 interface introduced in Windows 7
typedef enum {
Xps_Restricted_Font_Installable = 0x0000,
Xps_Restricted_Font_NoEmbedding = 0x0002,
Xps_Restricted_Font_PreviewPrint = 0x0004,
Xps_Restricted_Font_Editable = 0x0008
} EXpsFontRestriction;
interface IPartFont2 : IPartFont
HRESULT
GetFontRestriction(
[out] EXpsFontRestriction *pRestriction ); }

11. Print Filter Pipeline - Performance
Performance issues with various types of documents
Thousands of pages
100 MB page or image associated with page
Pages with thousands of relationships
Fixed bugs in Vista SP1 and more in Windows 7
Fewer disk I/O operations
More efficient use of buffers and memory
More than 100% performance improvement in certain scenarios

12. Print Filter Pipeline - Discard Control
Microsoft XPS Document Converter (MXDC) produces discard control in Windows 7
Filters should be able to handle IPartDiscardControl
The physical location of discard data – close to sentinel page
Example of sequence of parts received by a filter when printing an XPS doc with 3 pages:
IXpsDocument
IFixedDocumentSequence
IFixedDocument
IFixedPage
IPartDiscardControl

13. Print Filter Pipeline - Best Practices Impersonation
Pipeline process runs a “local service”
Filters must impersonate when accessing user data
When using the printer handle
PTOpenProviderEx, PTMergeAndValidatePrintTicket, etc.

14. Print Filter Pipeline - Best Practices Global Variables
The same filters can be used in multiple pipelines at the same time
Pipeline process can call InitializeFilter and StartOperation concurrently
Protect global variables

15. Print Filter Pipeline – Best Practices Obfuscated Fonts
The Vista RTM WDK sample shows an unsupported method for using obfuscated fonts in the pipeline.
This is what we recommend:
1) Create the font and use a uniform resource identifier (URI) that includes "/", such as:
L"/21223d92-e614-48a5-925c-c6962b6a8124.odtff" (“/” is not needed on SP1 and later) 
2) Call the SetFontOptions method on the IPartFont. This method sets the appropriate content type and marks the font as obfuscated : pFont->SetFontOptions(Font_Obfusticate) 
3) Do not XOR manually the first bytes of the font data stream with the GUID which is part of the URI.

16. Client- and Server-Side Rendering
Filter pipeline is subject to client-side rendering (CSR)
SetPrinterData values
"ForceClientSideRendering“ in Windows 7
"EmfDespoolingSetting“ in Vista and later
Client – Server connectivity problems
Connection is switched to server-side rendering (SSR) in Vista
Connections stays CSR in Windows 7

17. Client-Side Rendering – GUID names
CSR uses local printer objects
Name like \\CSR|server\{GUID}
Possible to retrieve the printer connection name
Get the printer handle from the property bag
XPS_FP_PRINTER_HANDLE property
Key “dsspooler” and the value “UNCName“ in GetPrinterDataEx

18. Call To Action Review and follow best practices discussed in this deck
Continue adoption of new technologies in your driver and device development: XPS, WSD
Attend other print-related sessions

19. Related Sessions Session Day / Time
Best Practices for Developing Printer Drivers
Mon. 8:30-9:30 and Tues. 8:30-9:30
Printer Installation and Driver Management
Mon. 9:45-10:45 and
Tues. 2:45-3:45
Printer Verifier
Tues
Printer Driver Testing Tools
Tues. 9:45-10:45 and
Wed. 8:30-9:30
Printer Driver Testing and the Windows Logo Kit
Tues. 1:30-2:30
XPS Rasterization Services in Windows 7
Mon. 1:30-2:30 and
Tues. 5:15-6:15
Discussion: XPS Driver Development in Windows 7
Mon. 4-5 and
Wed. 1:30-2:30

20. Additional Resources
aliases for developer support: prninfo and xpsinfo
Print Devices on the WHDC Web Site:
XPS on the Microsoft Web site: