TweetFollow Us on Twitter

New PrGeneral

Volume Number: 13 (1997)
Issue Number: 6
Column Tag: develop

The New PrGeneral Version Opcode

by Ingrid Kelly

For the past 12 years, printer driver developers have used the print record's wDev field in the TPrStl data structure to store their device information. Specifically, they've consistently used the high-order byte of this field - commonly known as the wDev ID - to store the device code. Unfortunately, due to the design limitations of the print record and the wDev field, the Printing Manager allowed for a maximum of only 256 IDs. Surprisingly enough (ha ha), with the expansion of the printer market, we're running out of numbers! As a result, with LaserWriter driver version 8.4, we've added a PrGeneral opcode and new structures to the Printing Manager so that developers can work around this limitation.

Both printer driver and application developers need to add code to support this new information, but the changes are minimal. Accompanying this column on the MacTech Web site is a sample application, called PrGeneral Version, that shows you how to properly retrieve the new version information when your application is looking for the features of a particular printer driver.

The New PrGeneral Opcode:

kprversionop

LaserWriter driver version 8.4 introduced several new PrGeneral opcodes, including a new opcode for driver version information: kPrVersionOp. Using kPrVersionOp is now the recommended way for applications to find out the printer driver currently in use. Remember that for printer drivers that haven't updated to use this new PrGeneral opcode, your application needs to keep its wDev-checking code as well.

For more information on the extended print record opcodes introduced with LaserWriter version 8.4, read the Print Hints column "The All-New LaserWriter Driver Version 8.4" in develop Issue 27. There you'll find a table that lists all the other PrGeneral opcodes supported in Apple printer drivers. See the article "Meet PrGeneral, the Trap That Makes the Most of the Printing Manager" in develop Issue 3 for more information on PrGeneral.

What Printer Driver Developers Need to Know

From now on, Apple's Developer Support Center will assign all printer drivers a wDev ID of 255. If you have an old wDev ID number (which is less than 255), you should still use the number you were assigned so that you don't break any applications that vary their behavior based on your driver's wDev. In addition, you should implement the new kPrVersionOp opcode as described here so that new applications can take advantage of it with your driver.

Listing 1 shows the new opcode and structures that you'll need to implement in your PDEF 7 resource. You need to place your creator type in the driver.creator field of the TPrVersion structure. You should also place your version number in driver.release so that application developers know what version of the driver is available.

Listing 1. The new version opcode and structures

enum {
   ...
   kPrVersionOp = 22             // LaserWriter version 8.4 and later only
};

typedef struct {
   OSType     architecture;      // Architecture (for example, 'pwpc', 'm68k')
   OSType     creator;           // Driver's creator type (for example, 'AAPL')
   unsigned longrelease;         // Release number (for example, 0x8480)
   unsigned longinterfaces;      // Interfaces version (for example, 0x8480)
} TVersion;

typedef struct {
   short       iOpCode;          // Must be kPrVersionOp
   short       iError;           // For returning errors
   long        lReserved;        // Reserved, set to 0
   TVersion    driver;           // Driver information
   TVersion    reserved;         // Reserved, set to 0
} TPrVersion;

The release and interfaces fields have the same format as the first long in a 'vers' resource - that is, the following four 1-byte values: a major version number, a minor version number, a revision stage (development = 0x20, alpha = 0x40, beta = 0x60, and release = 0x80), and a prerelease version number.

That's all you'll need to do to support the new PrGeneral opcode in your driver - hard to believe, but true!

What Application Developers Need to Know

Although Apple doesn't recommend that application developers check the wDev field of the print record, many do. They assume that the wDev value means they can count on certain features being present in the printer. For instance, many developers assume that a wDev of 3 means the printer driver supports PostScript. In fact, it indicates only that the current printer uses the Apple LaserWriter driver. This leaves out the possibility that a user has a non-Apple PostScript printer driver with an ID of, say, 243.

Even though Apple doesn't recommend that application developers rely on the wDev field (or the new PrGeneral opcode, for that matter), if you're going to change application behavior based on the number or creator returned, at least do so properly so that your applications don't break with future releases of printer drivers. We recommend that you use the PrGeneral kPrVersionOp opcode, if available, to get the structure and then check the driver.creator and driver.release fields to determine the current printer driver and version (see Listing 1). You should also continue to support the old wDev method for printer drivers that have not yet updated to the new PrGeneral opcode. For your reference, the PrGeneral Version sample that accompanies this column shows how to properly retrieve the version and wDev information.

Go Forth and Print!

As you can see, the changes that printer driver and application developers need to make to support the new PrGeneral opcode are minimal. We've already adopted this new method with the LaserWriter version 8.4.x drivers. We hope you will, too!


WDEV Registration

Although from now on all printer drivers will be assigned a wDev ID of 255, we still request that you register your printer driver with Apple's Developer Support Center, to avoid creator type conflicts. To do so, register at http://www.devworld.apple.com/dev/wdev/. Here is the information you need to provide:

  • Company name and address
  • Contact name, phone number, and e-mail address
  • Make and model of device supported (for example, Apple LaserWriter 16/600)
  • Type of connection (for example, serial)
  • Creator type (for example, 'AAPL')

You'll receive confirmation of your registration within five to ten working days. If you have questions about wDev registration, write to devsupport@apple.com.


Related Reading

  • "Print Hints: The All-New LaserWriter Driver Version 8.4" by Dave Polaschek, develop Issue 27.
  • "Meet PrGeneral, the Trap that Makes the Most of the Printing Manager" by Pete "Luke" Alexander, develop Issue 3.

Ingrid Kelly (inge@apple.com) provides technical support for developers as a member of the Multimedia, Printing, Imaging, and Graphics group in Apple's Developer Technical Support. When she's not answering developer e-mails or trying to hold the record for most Technotes written in DTS, Ingrid can be found refilling her office candy bin, trying to come up with the ultimate chocolate chip cookie recipe, or attending Navy Blue Angels flight team demonstrations with her husband, Lance.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

Combo Quest (Games)
Combo Quest 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: Combo Quest is an epic, time tap role-playing adventure. In this unique masterpiece, you are a knight on a heroic quest to retrieve... | Read more »
Hero Emblems (Games)
Hero Emblems 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: ** 25% OFF for a limited time to celebrate the release ** ** Note for iPhone 6 user: If it doesn't run fullscreen on your device... | Read more »
Puzzle Blitz (Games)
Puzzle Blitz 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Puzzle Blitz is a frantic puzzle solving race against the clock! Solve as many puzzles as you can, before time runs out! You have... | Read more »
Sky Patrol (Games)
Sky Patrol 1.0.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.1 (iTunes) Description: 'Strategic Twist On The Classic Shooter Genre' - Indie Game Mag... | Read more »
The Princess Bride - The Official Game...
The Princess Bride - The Official Game 1.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: An epic game based on the beloved classic movie? Inconceivable! Play the world of The Princess Bride... | Read more »
Frozen Synapse (Games)
Frozen Synapse 1.0 Device: iOS iPhone Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Frozen Synapse is a multi-award-winning tactical game. (Full cross-play with desktop and tablet versions) 9/10 Edge 9/10 Eurogamer... | Read more »
Space Marshals (Games)
Space Marshals 1.0.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: ### IMPORTANT ### Please note that iPhone 4 is not supported. Space Marshals is a Sci-fi Wild West adventure taking place... | Read more »
Battle Slimes (Games)
Battle Slimes 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: BATTLE SLIMES is a fun local multiplayer game. Control speedy & bouncy slime blobs as you compete with friends and family.... | Read more »
Spectrum - 3D Avenue (Games)
Spectrum - 3D Avenue 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: "Spectrum is a pretty cool take on twitchy/reaction-based gameplay with enough complexity and style to stand out from the... | Read more »
Drop Wizard (Games)
Drop Wizard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Bring back the joy of arcade games! Drop Wizard is an action arcade game where you play as Teo, a wizard on a quest to save his... | Read more »

Price Scanner via MacPrices.net

13-inch M4 MacBook Airs on sale for $150 off...
Amazon has new 13″ M4 MacBook Airs on sale for $150 off MSRP right now, starting at $849. Sale prices apply to most colors and configurations. Be sure to select Amazon as the seller, rather than a... Read more
15-inch M4 MacBook Airs on sale for $150 off...
Amazon has new 15″ M4 MacBook Airs on sale for $150 off Apple’s MSRP, starting at $1049. Be sure to select Amazon as the seller, rather than a third-party: – 15″ M4 MacBook Air (16GB/256GB): $1049, $... Read more
Amazon is offering a $50 discount on Apple’s...
Amazon has Apple’s 11th-generation A16 iPads in stock on sale for $50 (or a little more) off MSRP this week. Shipping is free: – 11″ 11th-generation 128GB WiFi iPads: $299 $50 off MSRP – 11″ 11th-... Read more
Clearance 13-inch M1 MacBook Airs available f...
Walmart has clearance, but new, Apple 13″ M1 MacBook Airs (8GB RAM, 256GB SSD) available online for $649, $360 off original MSRP, in Space Gray, Silver, and Gold colors. These are new MacBooks for... Read more
iPad minis on sale for $100 off Apple’s MSRP...
Amazon is offering $100 discounts (up to 20% off) on Apple’s newest 2024 WiFi iPad minis, each with free shipping. These are the lowest prices available for new minis among the Apple retailers we... Read more
AirPods Max headphones on sale for $479, $70...
Amazon has AirPods Max with USB-C on sale for $479.99 in all colors. Shipping is free. Their price is $70 off Apple’s MSRP, and it’s the lowest price available today for AirPods Max. Keep an eye on... Read more
14-inch M4 Pro/M4 Max MacBook Pros on sale th...
Don’t pay full price! Get a new 14″ MacBook Pro with an M4 Pro or M4 Max CPU for up to $320 off Apple’s MSRP this weekend at these retailers…they are the lowest prices available for these MacBook... Read more
Get a 15-inch M4 MacBook Air for $150 off App...
A couple of Apple retailers are offering $150 discounts on new 15″ M4 MacBook Airs this weekend. Prices at these retailers start at $1049: (1): Amazon has new 15″ M4 MacBook Airs on sale for $150 off... Read more
Unreal Mobile is offering a $100 discount on...
Unreal Mobile, an MVNO using AT&T and T-Mobile’s networks, is offering a $100 discount on any new iPhone with service. This includes new iPhone 16 models as well as iPhone 15, 13, and SE phones... Read more
16-inch M4 Pro MacBook Pros on sale for $250-...
Don’t pay full price! Amazon has 16-inch M4 Pro MacBook Pros (Silver or Black colors) on sale right now for up to $300 off Apple’s MSRP. Shipping is free. These are the lowest prices currently... Read more

Jobs Board

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.