Microsoft KB Archive/77551

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INFO: Using ExtDeviceMode with DM_COPY

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Q77551

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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 &quot;Microsoft Windows Software Development Kit Guide to Programming,&quot; 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

Keywords : kbdocerr kb16bitonly _IK kbSDKWin16

Issue type : kbinfo

Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310