Windows DEVICEDATA Escape Usage

The information in this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows versions 3.1 and 3.0

SUMMARY

The following provides information about the usage of the DEVICEDATA escape.

MORE INFORMATION

The term "#define DEVICEDATA 19" was previously called PASSTHROUGH; however, it was later renamed. Using the DEVICEDATA escape, which is essentially a "pass-through" to the device, will make an application absolutely device dependent.

The primary use of the DEVICEDATA escape is to download information that needs to be in the printer (that is, information that should be there, however, the programmer knows is not there) or to set the printer state. The DEVICEDATA escape will not interact with the GDI in a reasonable way; however, it allows device-driver writers to provide escapes directly into a printer for functions supported there. In particular, if the state in a printer is set to something other than what GDI thinks it to be, the results could be unpredictable. For example, a simple dump of text strings could be sent to a device. However, the programmer must be sure that the printer is in text mode (that is, not in graphics mode) before the programmer attempts this procedure.

A better way to perform a "quick and dirty" print is to set the requested print quality to Draft. Time-conscious drivers would probably use intrinsic fonts for draft-quality printing (no assertion has been made that there are any drivers out there that actually do this; it is part of the semantics of draft-quality printing).

To summarize this information, the DEVICEDATA escape provides a simple way to send a string of bytes to a device; however, it does not provide a simple way to print to the device. It is device-dependent as to whether those bytes get printed, are interpreted as a downloaded font, reset printer characteristics, and so on. The DEVICEDATA escape should not be considered a substitute for using the GDI interface. For these reasons, Microsoft recommends that this escape never be used by well-behaved applications.