ID Number: Q77551
3.00 3.10
WINDOWS
Summary:
The documentation for the ExtDeviceMode function on page 4-130 of the
"Microsoft Windows Software Development Kit Reference Volume 1" 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 function, see the
"Microsoft Windows Software Development Kit Guide to Programming,"
starting on page 17-6, in particular the paragraph on the bottom of
page 17-7:
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 instance, to validate some
fields in the structure). To do this, set the wMode parameter to
(DM_COPY | DM_MODIFY).
For more information about using the ExtDeviceMode function, query on
the words:
prod (winsdk) and ExtDeviceMode
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 reference words: 3.00 3.10 3.x DeviceMode printing