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Q77551: INFO: Using ExtDeviceMode() with DM_COPY

Article: Q77551
Product(s): Microsoft Windows Software Development Kit
Version(s): WINDOWS:3.1
Operating System(s): 
Keyword(s): kbdocerr kb16bitonly _IK kbSDKWin16
Last Modified: 04-JUL-1999

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The information in this article applies to:

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

The documentation for the ExtDeviceMode() API does not completely explain the
results of setting the wMode parameter to various values, in particular the
DM_COPY value. This function may produce unexpected results if the wMode
parameter is set incorrectly.

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

For a complete explanation of the ExtDeviceMode() API, see the "Microsoft
Windows Software Development Kit Guide to Programming," in particular, the
following paragraph

IMPORTANT: In order to change the settings, you must specify at least one input
value and one output value.... If you specify only output values (DM_COPY or
DM_UPDATE), the driver provides its current settings and ignores any input you
provide. If you specify only input values (DM_MODIFY or DM_PROMPT), calling
ExtDeviceMode generates no output, so your input has no real effect.

If the wMode parameter is set to DM_COPY only, the printer's default settings
will be copied into the output buffer -- even if an input buffer is specified.

In some cases, it is necessary to copy the print settings from the input buffer
to the output buffer (for example, to validate some fields in the structure). To
do this, set the wMode parameter to (DM_COPY | DM_MODIFY).

Note that DM_IN_BUFFER, DM_IN_PROMPT, DM_OUT_BUFFER, and DM_OUT_DEFAULT are
aliases for the DM_MODIFY, DM_PROMPT, DM_COPY, and DM_UPDATE constants,
respectively.


Additional query words: no32bit

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

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