KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q112387: INFO: How GDI Sends Data to the Printer

Article: Q112387
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): kb16bitonly kbOSWin310 _IK kbSDKWin16
Last Modified: 09-JUL-1999

3.10
WINDOWS
kbprg

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Windows Software Development Kit (SDK) 3.1 
-------------------------------------------------------------------------------

SUMMARY
=======

If the "Fast Printing Direct to Port" option is enabled from the Microsoft
Windows Control Panel, print-job data will be sent directly to the printer port,
using COMM.drv. Otherwise, MS-DOS _lwrite() calls will be used to write data to
the port. The Fast Printing Direct to Port setting corresponds to the DosPrint
entry in the [Windows] section of WIN.ini.

MORE INFORMATION
================

When a print job is started by a printer driver, the printer driver will call
into GDI, using the OpenJob() function. Within OpenJob(), GDI uses the following
sequence of steps to determine whether to print directly to the port, or to use
MS-DOS _lwrite:

1. Attempts to call the network driver's WNetOpenJob() function, if that
  function exists. If WNetOpenJob succeeds, indicating that the port is a
  redirected network port, GDI will use _lwrite() to write to the port,
  regardless of the "Fast Printing Direct to Port" setting. Otherwise

2. Checks to see if "Fast Printing Direct to Port" is selected. If it is not
  selected, GDI will use _lwrite() to write to the port. Otherwise:

3. Calls OpenComm() for the selected port. If OpenComm() succeeds, the
  communications API, which call into COMM.drv, will be used to write to the
  port [WriteComm()]. Otherwise:

4. Uses _lwrite().

Additional query words: 3.10

======================================================================
Keywords          : kb16bitonly kbOSWin310 _IK kbSDKWin16 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1
Issue type        : kbinfo

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.