Technotes

Device-Independent Printing

Technote PR 02 May 1987

Revised by: March 1988
Written by: Ginger Jernigan May 1987

The Printing Manager was designed to give Macintosh applications a device- independent method of printing, but we have provided device-dependent information, such as the contents of the print record. Due to the large number of printer-type drivers becoming available (even for non-printer devices) device independence is more necessary than ever. What this means to you, as a developer, is that we will no longer be providing (or supporting) information regarding the internal structure of the print record.

We realize that there are situations where the application may know the best method for printing a particular document and may want to bypass our dialogs. Unfortunately, using your own dialogs or not using the dialogs at all, requires setting the necessary fields in the print record yourself. There are a number of problems:

* Many of the fields in the print record are undocumented, and, as we change the internal architecture of the Printing Manager to accommodate new devices, those undocumented fields are likely to change.

* Each driver uses the private, and many of the public, fields in the print record differently. The implications are that you would need intimate knowledge of how each field is used by each available driver, and you would have to set the fields in the record differently depending on the driver chosen. As the number of available printer-type drivers increases, this can become a cumbersome task.

Summary

To be compatible with future printer-like devices, it is essential that your application print in a device-independent manner. Avoid testing undocumented fields, setting fields in the print record directly and bypassing the existing print dialogs. Use the Printing Manager dialogs, PrintDefault and PrValidate to set up the print record for you.

Further Reference:

* The Printing Manager

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