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Applications can now modify printer settings (that is, DEVMODE values) while
printing a document. The ResetDC function lets applications update the
printer device context at each new page. This means applications can print
documents containing a mixture of page orientations, paper sources, and
other printing options without having to divide the document into smaller
documents.
 
To support ResetDC, a printer driver must provide code for the RESETDEVICE
escape. This escape, processed by the driver's Control function, copies
printer output state information from one physical device context (PDEVICE)
to another. GDI uses the escape to replace existing device contexts with new
ones.
 
When an application calls ResetDC, GDI first creates a new PDEVICE by
calling the driver's Enable function. This new PDEVICE receives the new
printer settings as specified by the application. GDI next uses the
RESETDEVICE escape to copy output state information from the existing
PDEVICE to the new one. The output state includes information such as job
number and list of downloaded fonts. The escape must copy the state
information without changing the printer settings in the new PDEVICE.
Finally, GDI substitutes the new PDEVICE for the old one in the
application's device context, discarding the old PDEVICE by calling the
Disable function.
 
When the printer driver receives the RESETDEVICE request, it must expect a
subsequent call to Disable with no intervening call to the ENDDOC escape.
The printer driver must also ensure that the new printer settings take
affect starting on the next printed page. If a printer driver allocated
bitmap or working buffers when it received the STARTDOC escape, the driver
should free the buffers for the old PDEVICE and allocate new buffers for the
new PDEVICE (an option is to reallocate the buffers).
 
The ResetDC function cannot be used to change the driver name, device name,
or the output port. When the user physically changes port connection or the
device name, the application must delete the original device context and
recreate a device context with the new device name and output port. Also the
application must cancel the selection of all objects in its device context
before calling ResetDC.
 
 
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