All Databases develop - 1996

September 96 - Print Hints: The All-New LaserWriter Driver Version 8.4

Print Hints: The All-New LaserWriter Driver

Version 8.4

Dave Polaschek

By the time you read this, version 8.4 of the LaserWriter 8 printer driver will have

shipped. This driver -- LaserWriter version 8.4, for short -- is not the same old

LaserWriter driver: it has new features that developers have been asking for, sports a

new user interface, and beats earlier versions of the driver in the quarter mile.

Here I'll outline some of the changes -- a few minor, a few major -- that you need to

be aware of for compatibility reasons. Even if you don't want to take advantage of any of

the great new features, you'll at least need to address compatibility issues if any of the

changes cause problems with your application.

To help you implement the new features, this column is backed up with detailed

documentation on this issue's CD.

THE EXTENDED PRINT RECORD

The 120-byte print record in the previous driver version doesn't have as many free

bits available as some programmers would like. So to let you save all possible printing

information about a document, Apple decided to allow for extensible print records.

If all you want to do is maintain compatibility with the new driver version, you

shouldn't need to change your application at all. But if you want to take advantage of the

extended print record -- and implement attractive features such as access to a larger

number of paper sizes, tray handling that works with the PrJobMerge function, and

the ability to reliably save more user settings from the Page Setup dialog -- you do

need to make some minor changes, along the following lines:

• Because the extended print record can be any size larger than 120 bytes,

your application must not make any assumptions about the record's size.

• Although the locations of fields that are currently defined within the

TPrint structure won't change, you should use PrGeneral with the extended

print record opcodes (described below) to access any additional fields.

• When using an extended print record, you'll need to call the

extendPrDefault and extendPrValidate functions where you previously would

have called the functions PrintDefault and PrValidate. (The new extend

functions really just call PrGeneral with specific opcodes, but are more

convenient to use than PrGeneral itself.) See "Extending the Print Record" on

this issue's CD for more information on the extend functions and how they use

the new PrGeneral opcodes.

Those who break the rules might need to make more changes. See the Print Hints

column in develop Issue 26 ("The Top 10 Printing Crimes Revisited") for more

information.

NEW PRGENERAL OPCODES

LaserWriter version 8.4 adds three new PrGeneral opcodes for dealing with the

extended print record: kExtendPrintRecOp (which extends the print record),

kGetExtendedPrintRecOp, and kSetExtendedPrintRecOp.

Table 1 gives a complete list of all the PrGeneral opcodes as of June 1996 (but be

aware that printing in Mac OS 8 might not implement all of these). These opcodes are

all planned to be supported by LaserWriter version 8.4, except for the ones that aren't

used by LaserWriter 8 (as noted in the table). Refer to the article "Meet PrGeneral

in develop Issue 3 for more information about PrGeneral.

Table 1. The PrGeneral opcodes

Opcode Operation

4 getRslDataOp

5 setRslOp

6 draftBitsOp

7 noDraftBitsOp

8 getRotnOp

9 NoGrayScl (not used by LaserWriter 8)

10 getPSInfoOp

11 PSIntentionsOp

12 enableColorMatchingOp

13 registerProfileOp (ColorSync 1 only; not used by LaserWriter 8)

14 PSAdobeOp

15 PSPrimaryPPDOp

16 kLoadCommProcsOp

17 kUnloadCommProcsOp

18 kExtendPrintRecOp (LaserWriter version 8.4 and later only)

19 kGetExtendedPrintRecOp (LaserWriter version 8.4 and later only)

20 kPrinterDirectOpCode (not used by any LaserWriter driver)

21 kSetExtendedPrintRecOp (LaserWriter version 8.4 and later only)

NEW PRINT DIALOGS

The print dialogs have been completely redesigned for LaserWriter version 8.4.

Applications that use the approved method of extending the print dialogs will continue

to function. But if your application uses a nonstandard method of extending the print

dialogs, it's in trouble. The definitive source about how to extend a print dialog is

PDlog Expand, available as sample code on this issue's CD and included with the

Macintosh Technical Note "Print Dialogs: Adding Items" (PR 09).

The new print dialogs have a pop-up menu that lets the user select between multiple

panes of the dialog. In Figure 1, the General pane has been selected from the pop-up

menu. When an application adds items to the print dialog, they're added to a pane that

has the name of the application. Because of this new multipane dialog, applications that

extend the print dialogs in a nonstandard manner will cause many problems, such as

dialog items appearing in the wrong locations, standard items being overwritten

within the dialog, and standard items being drawn incorrectly.

Figure 1. The new multipane print dialog

Applications also shouldn't assume that the print dialog's foreground color is black or

that the background color is white. Furthermore, when applications exit their CDEFs

or user items, they should be careful to leave the foreground and background colors as

they found them. Other items in the dialog rely on these colors, so if you change them

the standard controls in the print dialog could take on unusual colors.

ONE-PASS PRINTING

With LaserWriter version 8.4, when background printing is disabled, printing is

one-pass. This means that there are no longer any big spool files to fill up your hard

drive, and the first printed page comes out of the printer more quickly (because it

doesn't have to wait for the entire document to spool). The downside is that because the

LaserWriter driver isn't making two passes over the data to be printed, it might not be

able to perform the same optimizations on the PostScript(TM) code as when

background printing is enabled.

As a result, jobs printed with background printing disabled might print more slowly,

and in a few cases the final quality could suffer. With the advent of one-pass printing,

if your application has its own PostScript LaserPrep dictionary, it should use the

PREC 103 mechanism for this dictionary. With this mechanism, the driver downloads

to the printer the PostScript dictionary contained in the PREC 103 resource before

it's needed by application-generated PostScript code. If the application doesn't do this

and defines its own PostScript procedures at the page level, these procedures will be

undefined as part of the one-pass font-handling mechanism and you'll get PostScript

errors (mostly undefined operators, because the operators you defined aren't there).

PORTIONS OF THE CODE IN SHARED LIBRARIES

Some of the functionality of LaserWriter version 8.4 has been broken out into shared

libraries, including the following:

• Converter library -- generation of PostScript code

• PPD library -- parsing of the PostScript printer description file

• Preferences and Collection libraries -- storage and retrieval of

preferences file data

• Downloader library -- downloading of PostScript and EPS files to a

printer

• PostScript Utilities library -- PostScript utility functions

• Communications library -- communications

In the future, Apple may provide APIs to these shared libraries for third parties.

CHANGES TO PARSING AND HANDLING OF PPD FILES

If you're a printer developer, you should know that the way PPD files are parsed and

handled has changed in LaserWriter version 8.4. Previous versions of the driver

would supply a "Printer's Default" choice so that the user could choose not to decide

about a certain feature and accept the default setting of the printer. With version 8.4,

the driver will no longer provide this option. If PPD creators want to continue to have

a Printer's Default option for a user interface feature (called UIFeature in the PPD

specification), they'll have to add it to the PPD file in the list of options for that

feature.

Also, common features available through the PPD file will be added to the correct

pane of the print dialog. Features that aren't recognized or that are vendor-specific

will be placed in their own pane. This can cause problems: if you use a nonstandard

naming convention for a common feature, it will be placed with all other unknown

features, and if you use a standard name for a nonstandard feature, it will probably end

up in the wrong location.

One other change is that you can specify the graphic elements you'd like to use for UI

features specified within the PPD file. See "LaserWriter 8.4 PPDs" on the CD for

information about how to design your own pane for use with LaserWriter version 8.4.

The latest Apple PPD files are the best examples of how to implement the new features.

NEW ERROR CODES

LaserWriter 8 introduced a number of new error codes, but they haven't been

documented -- until now, that is. See the unofficial documentation "LaserWriter 8

Errors" on the CD. Future versions of this document will be released as Technotes.

These error codes are provided for debugging purposes. Be aware that they may change

in the future, so you probably don't want your application to depend on them.

WRAPPING IT UP

That's a quick rundown of the new features of the newest version of the LaserWriter

driver. These features should make printing a better experience for the user, should

give the developer more flexibility, and should require no changes to most

applications. And to top it all off, they're cool!

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