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Q75471: INFO: Basics of Banding Printing in Windows

Article: Q75471
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): kb16bitonly kbOSWin310 _IK kbOSWin300 kbSDKWin16
Last Modified: 04-JUL-1999

3.00 3.10
WINDOWS
kbprg

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The information in this article applies to:

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

Banding is a technique used to implement the full functionality of the Windows
Graphics Device Interface (GDI) in printer drivers that can only print bitmaps
for graphics. An application that is aware of the banding process can enhance
its printing performance.

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

Most dot-matrix printers and many laser printers cannot print graphics such as
polygons and lines. They can print only bitmaps and text. These printers require
special support in GDI to implement the full range of GDI functionality.

When an application prints to such a device, the printer driver does not send
output directly to the printer. Rather, the printer driver generates a bitmap in
memory. When all graphics have been rendered into the bitmap, the bitmap itself
is printed.

For most printers, the bitmap can be very large. For example, a 300 dots-per-inch
(dpi) laser printer requires nearly a megabyte to render a single letter-size
page. To reduce memory requirements, the image is broken into a sequence of
smaller rectangles, called bands, which cover the page. Each of these individual
rectangles is rendered and downloaded to the printer separately.

There are two ways that the graphics calls can be duplicated on each band. If the
application is unaware of the banding process, GDI will capture all graphics
calls for a page into a metafile. When the application calls the NEWFRAME (next
page) escape, GDI plays the entire metafile into each band. Alternatively, the
application may request a band from the printer driver and produce the output
itself. A significant optimization results since GDI will not need to create,
write, and reread a disk-based metafile.

Whether GDI or the application requests the band from the driver, the process is
very similar. Banding printer drivers implement an escape called NEXTBAND. The
escape causes the printer driver to download the previous band to the printer
(if any) and to initialize itself to render the new band. It also returns a
rectangle defining the bounds of the band bitmap relative to the whole page.
Output calls made to the driver's Device Context (DC) after NEXTBAND go directly
to the printer driver.

GDI, or the banding application, calls NEXTBAND after each band is rendered to
download the band and also to retrieve the next band from the driver. When all
bands have been printed, NEXTBAND causes the printer driver to eject the page
and return an empty rectangle to indicate the end of a page.

For more information on how to implement banding, query on the following words:

  prod(winsdk) and banding

Additional query words: 3.00 3.10

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Keywords          : kb16bitonly kbOSWin310 _IK kbOSWin300 kbSDKWin16 
Technology        : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310
Version           : WINDOWS:3.1
Issue type        : kbinfo

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