TweetFollow Us on Twitter

May 92 - PRINT HINTS

PRINT HINTS

TOP 10 PRINTING CRIMES

PETE ("LUKE") ALEXANDER

[IMAGE Luke.GIF]


In this issue, we're going to take a slightly different tack. Instead of dealing with one printing hint, we're going to give you ten. We'll take a look at the "Top 10 Printing Crimes" that I've seen during my three and a half year adventure in Apple's Developer Technical Support Group. I'll start by listing these crimes, and then I'll discuss the solution to each one.

Here's the list:

    Loading PDEFs directly from within your application.

    9. Poor memory management at print time.

    8. Assuming the grafPort returned by PrOpenDoc is black and white.

    7. Not saving and restoring the grafPort or resource file in your application's pIdle procedure.

    6. Not using PrGeneral when you should to determine and set the resolution of the current device. <

    5. Not reading Macintosh Technical Note #91, "PicComments--The Real Deal," before you start using PicComments in your application.

    4. Opening the Printing Manager when your application starts up.

    3. Mixing high-level and low-level printing calls.

    2. Accessing private and unused fields in the print record.

    1. Adding printing to your application two weeks before going final.

All of these crimes are very easy to avoid. Let's take a look at the solution to each one.

SOLUTIONS TO THE PRINTING CRIMES

10. Loading PDEFs directly from within your application.  A PDEF is a printer driver's CODE resource definition. Each printer driver contains multiple PDEFs, which implement the various functions of the driver (such as displaying the Print dialogs, opening the connection with the printer, and supporting PrGeneral). A few applications load and call these PDEFs directly, probably because they feel this will improve printing performance. Instead, this approach will usually cause serious compatibility problems and headaches for printer driver developers. Also, it's very difficult for printing utilities (for example, utilities that count the number of pages printed) to patch into printing if an application isn't using the printing trap (PrGlue). Finally, this approach could cause some serious compatibility problems for users when a new printer and its associated driver software are released.

Solution:  The main function of the Printing Manager is to load the printer driver PDEFs in a device- and driver-independent manner. Using the Printing Manager to load the PDEFs is the simplest and most compatible method.

9. Poor memory management at print time.  Poor memory management at print time will cause some interesting problems with various printer drivers. Usually, some object in your document won't print or you'll receive a blank page. The problem is that each printer driver available on the Macintosh requires a different amount of memory; some require very little memory, while others require a lot. For example, the LaserWriter SC is one of the piggier drivers. What's an application to do?

Solution:  Since each printer driver uses a different amount of memory, there's not a magic amount of memory that will always ensure the success of a print job. The best solution to this problem is to unload all  unnecessary code and data segments at print time. The more memory available, the better. In addition to ensuring that printing will work OK, more memory can improve printing performance significantly, which your users will thank you for.

8. Assuming the grafPort returned by PrOpenDoc is black and white.  Yes, PrOpenDoc can return a color grafPort, if the printer driver you're using supports color. Unfortunately, not all printer drivers are capable of returning a color grafPort. This feature caused compatibility headaches for us when we released LaserWriter driver version 6.0, which was the first printer driver from Apple that could return a color grafPort. Many applications assumed that the grafPort it returned was black and white, and this assumption caused quite a few applications to die when printing to LaserWriter driver 6.0. This assumption can also have some very ugly results if your user is printing to a color printer and you're only sending black-and-white data.

Solution:  A good rule of thumb when printing: never assume anything. Usually there are methods available to enable your application to determine the environment it's in. Printing isn't any different; in fact, this is probably even more important for printing. You should check the grafPort returned by PrOpenDoc to see whether it's color or black and white: if the high bit in the rowBytes of the grafPort is set, you have a color grafPort.

7. Not saving and restoring the grafPort or resource file in your application's pIdle procedure.  Many applications install a pIdle procedure at print time. This procedure allows the application to present the print job status to the user. This is a very good idea--but you must be a little defensive to keep a printer driver happy.

Solution:  When your application enters its pIdle procedure, you should save the current grafPort and resource file (that is, the printer driver's). When you exit your pIdle procedure, you should restore the grafPort and resource file back to the original. This is extremely important, because the printer driver assumes that the current grafPort and resource file are always its own. If they're not, when you exit your pIdle procedure you won't be drawing into the correct grafPort, and when the printer driver makes the next Resource Manager call, it will have the wrong resource file. Technical Note #294, "Me And My pIdle Proc (or how to let users know what's going on during print time . . . )," describes the details of creating and using a pIdle procedure within your application.

6. Not using PrGeneral when you should to determine and set the resolution of the current device.  The PrGeneral trap allows a developer to determine the supported resolutions of the current printer, and also to set the resolution, determine the page orientation selected by the user, and force draft printing. Many developers who want resolution information don't use the power of this trap, but instead use a device-dependent method, which isbad . PrGeneral allows you to determine the resolution in a device-independent manner, so that you'll be able to print toall  printers connected to the Macintosh without knowing about the printer you're talking to. There are now over 130 printer drivers available on the Macintosh. It would be a real shame if your application couldn't maximize its output to a device just because you made a bad assumption.

Solution:  This is a case where you can becompletely device independent in your print code without sacrificing anything. You can obtain outstanding results if you use the PrGeneral trap correctly. Any time you're interested in the available resolutions for the current printer, you should use the GetRsl opcode supplied by PrGeneral. For details about getting and setting the resolution, see the "Meet PrGeneral" article in Issue 3 ofdevelop.  If you don't have the article handy, it's available on theDeveloper CD Series disc. Accompanying the article on the CD is an application named PrGeneralPlay that contains complete sample code for PrGeneral. You should probably also take a look atInside Macintosh Volume V, pages 410-416.

5. Not reading Macintosh Technical Note #91, "PicComments--The Real Deal," before you start using PicComments in your application.  Many developers have tried to use PicComments in their applications before understanding their function, with very mixed results. If you don't follow the recommendations in Technical Note #91, you'll definitely receive some undesirable results--especially if you don't match all "open" calls with a "close" call.

Solution:  Read Technical Note #91before you start using any PicComments in your application. This Note has been rewritten with new pictures, sample code, and descriptions to help developers properly use PicComments in their printing code. It will help you avoid many of the pitfalls and misuses of PicComments. It's also helpful to look at pictures generated by other applications, to see what they're doing.

4. Opening the Printing Manager when your application starts up.  In the early Macintosh days, it was recommended that you always call PrOpen at application startup. This hasn't been the recommendation for a long time. Why? When you open the Printing Manager, it loads some of the printer driver's resources into memory. This means that less memory is available for your application. However, the real problem is that other applications or DAs cannot print until you close the Printing Manager, since the Printing Manager isnot  reentrant. Unfortunately, there isn't a reliable method for determining whether the Printing Manager is open, nor is there a method for closing it if it's already open. This isn't much of a problem any more because the majority of applications today no longer call PrOpen at startup.

Solution:  Do not  open the Printing Manager until you're ready to print or perform some other printing-related task (for example, initializing a print record when your application starts up). You should close the Printing Manager when the print job is complete or when you've accomplished the task at hand. You should never allow a user to switch your application out with the Printing Manager open (that is, never call WaitNextEvent between PrOpen and PrClose).

3. Mixing high-level and low-level printing calls.  This is one of the classic printing problems. You shouldnever mix the high-level and low-level printing calls. This approach will usually cause instant death at print time, because the high-level and low-level calls do very similar things. One of the common mistakes is calling PrDrvrClose after calling PrClose. Printer drivers are not designed to use both interfaces simultaneously.

Solution:  In general, all applications should be using the high-level printing calls. Please follow the advice in Technical Note #161, "A Printing Loop That Cares . . . , " which describes the use of the high-level calls. Always match each "open" printing call with its corresponding "close" call. Also, check the PrError function for a printing error before making the next printing call.

The only advantage gained by using the low-level calls would be when you're text streaming, which is easier with those calls. Technical Note #192, "Surprises in LaserWriter 5.0 and Newer," describes the use of the low-level interface.

As you might expect, there's a minor exception to this rule. If you've read the Printing Manager chapter ofInside Macintosh Volume II, you may have noticed that the PrDrvrVers function is defined in the "Low-Level Driver Access Routines" section (page 162). This function can also be used with the high-level interface (it's theonly low-level call that can be called in the high-level interface). PrDrvrVers is very useful for determining the version of a printer driver, which will enable you to work around bugs that may exist in a specific version of a printer driver.

2. Accessing private and unused fields in the print record.  Many of the print record fields should not be accessed by an application because they're used by the printer driver as storage locations, which means the information in themwill change during a print job.

Solution:  You should never  use any information from fields in the print record that have "PT" at the end of the field name. All of them have corresponding "public" fields in the print record for application use. For example, you should use the information stored in rPage, and not rPagePT. Printer drivers store some of their private information in the fields with "PT" at the end of the field name. During printing, the values in these fields will change. Furthermore, different printer drivers use these fields differently, so accessing one of them might work on one driver but not another. Use the public fields!

1. Adding printing to your application two weeks before going final.  This one might be a slight exaggeration, but it's definitely in the ballpark. Believe it or not, I've talked to quite a few developers who have left printing as the last feature they add to their application (or maybe next to last, just before Undo). This can cause some serious problems in your development schedule.

Solution:  There are  a few pitfalls in printing, but they can be avoided if you start early in the design phase of your application. My advice to avoid this problem is to start printing from your application as soon as possible. When you have an early prototype running, send some output to the printer. Usually you can tell very early if you'll have any problems.

One more thing: I created this list in order from the least printing crime to the worst. Actually, if you commit any of the printing crimes mentioned, you'll probably receive some undesirable results with various printers. I would suggest testing your application on at least one PostScript® printer and a QuickDraw printer.

Finally, if we take a look out onto the documentation horizon, we can see something new peeking through. What is it, you ask? It's the new and improvedInside Macintosh chapter on printing. Yes, after years of waiting, it's finally coming. I believe you'll find the new printing chapter useful and informative. It will unlock additional information about printing on the Macintosh.

REFERENCES

  • Inside Macintosh  Volume V, Chapter 22, "The Printing Manager," pages 410-416 (Addison-Wesley, 1988).
  • Inside Macintosh  Volume II, Chapter 5, "The Printing Manager," page 162 (Addison-Wesley, 1985).
  • "Meet PrGeneral, the Trap That Makes the Most of the Printing Manager," Pete "Luke" Alexander,develop  Issue 3, July 1990.
  • "Me And My pIdle Proc (or how to let users know what's going on during print time . . . )," Macintosh Technical Note #294.
  • "Surprises in LaserWriter 5.0 and Newer," Macintosh Technical Note #192.
  • "A Printing Loop That Cares . . . ," Macintosh Technical Note #161.
  • "PicComments--The Real Deal," Macintosh Technical Note #91.

PETE ("LUKE") ALEXANDER Inquiring minds want to know: Does Luke have a life beyond these weird Print Hints he dishes out occasionally? The answer is a resounding YES! This happy hacker likes to keep his head in the clouds--literally. Theproud owner of an ASW-20 sailplane, Luke's other passion (besides working at Apple) is soaring 10,000 feet above ground, while observing eagles, mountain goats, and wild horses in exotic outposts of California and Nevada. Luke has the "funnest time" when he's gliding like a bird, suspended in time with the air rushing past him. For him, it's pure, unparalleled excitement and enjoyment. *

Thanks to Dave Hersey and Scott "Zz" Zimmerman for reviewing this column. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Yasu 4.0.0 β - System maintenance app; p...
Yasu was created with System Administrators who service large groups of workstations in mind, Yasu (Yet Another System Utility) was made to do a specific group of maintenance tasks quickly within a... Read more
Skype 7.37.0.178 - Voice-over-internet p...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
EtreCheck 3.0.5 - For troubleshooting yo...
EtreCheck is an app that displays the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to... Read more
Amadeus Pro 2.3.1 - Multitrack sound rec...
Amadeus Pro lets you use your Mac computer for any audio-related task, such as live audio recording, digitizing tapes and records, converting between a variety of sound formats, etc. Thanks to its... Read more
NeoFinder 6.9.3 - Catalog your external...
NeoFinder (formerly CDFinder) rapidly organizes your data, either on external or internal disks, or any other volumes. It catalogs all your data, so you stay in control of your data archive or disk... Read more
WhatsApp 0.2.1880 - Desktop client for W...
WhatsApp is the desktop client for WhatsApp Messenger, a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for... Read more
Hazel 4.0.6 - Create rules for organizin...
Hazel is your personal housekeeper, organizing and cleaning folders based on rules you define. Hazel can also manage your trash and uninstall your applications. Organize your files using a familiar... Read more
Apple iBooks Author 2.5 - Create and pub...
Apple iBooks Author helps you create and publish amazing Multi-Touch books for iPad. Now anyone can create stunning iBooks textbooks, cookbooks, history books, picture books, and more for iPad. All... Read more
MYStuff Pro 2.0.26 - $39.99
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
MarsEdit 3.7.8 - Quick and convenient bl...
MarsEdit is a blog editor for OS X that makes editing your blog like writing email, with spell-checking, drafts, multiple windows, and even AppleScript support. It works with with most blog services... Read more

How to get past Vulture Island's tr...
Vulture Island is a colorful and quirky mish-mash of platforming and puzzles. It’s creative and fresh, but sometimes the game can throw a curveball at you, leaving you stuck as to how you should progress. These tips will help you explore smoothly... | Read more »
The new Clash of Kings is just for Weste...
If you’ve played the original Clash of Kings, you’ll probably recognise the city building, alliance forging and strategic battles in Clash of Kings: The West. What sets this version apart is that it’s tailor made for a Western audience and the... | Read more »
Frost - Survival card game (Games)
Frost - Survival card game 1.12.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.12.1 (iTunes) Description: *Warning: the game will work on iPhone 5C and above and iPad Pro / 4. Other devices are not supported* | Read more »
How to build and care for your team in D...
Before you hit the trail and become a dog sledding legend, there’s actually a fair bit of prep work to be done. In Dog Sled Saga, you’re not only racing, you’re also building and caring for a team of furry friends. There’s a lot to consider—... | Read more »
How to win every race in Dog Sled Saga
If I had to guess, I’d say Dog Sled Saga is the most adorable racing game on the App Store right now. It’s a dog sled racing sim full of adorable, loyal puppies. Just look at those fluffy little tails wagging. Behind that cute, pixelated facade is... | Read more »
Let the war games commence in Gunship Ba...
Buzz Lightyear famously said, “This isn’t flying, this is falling – with style!” In the case of Gunship Battle: Second War, though, this really is flying - with style! The flight simulator app from Joycity puts you in control of 20 faithfully... | Read more »
How to get a high score in Fired Up
Fired Up is Noodlecake Games’ high score chasing, firefighting adventure. You take control of a wayward firefighter who propels himself up the side of a highrise with blasts of water. Sound silly? It is. It’s also pretty difficult. You can’t... | Read more »
NBA 2K17 (Games)
NBA 2K17 1.0 Device: iOS iPhone Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: Following the record-breaking launch of NBA 2K16, the NBA 2K franchise continues to stake its claim as the most authentic sports video... | Read more »
Dog Sled Saga (Games)
Dog Sled Saga 1.0.1 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0.1 (iTunes) Description: A game by Dan + Lisa As a rookie musher, foster a dogsledding team whose skills will grow if they're treated right. Week by... | Read more »
60 Seconds! Atomic Adventure (Games)
60 Seconds! Atomic Adventure 1.2 Device: iOS Universal Category: Games Price: $2.99, Version: 1.2 (iTunes) Description: 60 Seconds! is a dark comedy atomic adventure of scavenge and survival. Collect supplies and rescue your family... | Read more »

Price Scanner via MacPrices.net

21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 3.1GHz iMac 4K: $1379 $120 off MSRP - 21″ 2.8GHz iMac: $1199.99 $100 off MSRP - 21″ 1... Read more
13-inch 2.7GHz/256GB Retina MacBook Pro on sa...
Amazon.com has the 13″ 2.7GHz/256GB Retina Apple MacBook Pro on sale for $151 off MSRP including free shipping: - 13″ 2.7GHz/256GB Retina MacBook Pro (sku MF840LL/A): $1348 $151 off MSRP Read more
Apple TVs on sale for up to $50 off MSRP
Best Buy has 32GB and 64GB Apple TVs on sale for $40-$50 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
Duplicate Sweeper Free On Mac App Store For O...
To celebrate the launch of Apple’s latest macOS Sierra, Stafford, United Kingdom based Wide Angle Software has announced that its duplicate file finder software, Duplicate Sweeper, is now available... Read more
13-inch Retina MacBook Pros on sale for up to...
B&H Photo has 13″ Retina Apple MacBook Pros on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1174.99 $125 off MSRP - 13... Read more
Evidence Surfaces Pointing To New A10X Chip F...
Citing a job description for a Project Lead position at Apple’s Austin, Texas engineering labs, Motley Fool’s Ashraf Eassa deduces that development is progressing well on Apple’s next-generation in-... Read more
Check Print’R for macOS Allows Anyone to Easi...
Delaware-based Match Software has announced the release and immediate availability of Check Print’R 3.21, an important update to their easy-to-use check printing application for macOS. Check Print’R... Read more
Apple refurbished 11-inch MacBook Airs availa...
Apple has Certified Refurbished 11″ MacBook Airs (the latest models), available for up to $170 off the cost of new models. An Apple one-year warranty is included with each MacBook, and shipping is... Read more
Apple refurbished 15-inch Retina MacBook Pros...
Apple has Certified Refurbished 2015 15″ Retina MacBook Pros available for up to $380 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2... Read more

Jobs Board

Sr. *Apple* Mac Engineer - Net2Source Inc....
…staffing, training and technology. We have following position open with our client. Sr. Apple Mac Engineer6+ Months CTH Start date : 19th Sept Travelling Job If Read more
*Apple* Retail - Multiple Positions-Norfolk,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Lead *Apple* Solutions Consultant - Apple (...
# Lead Apple Solutions Consultant Job Number: 51829230 Detroit, Michigan, United States Posted: Sep. 19, 2016 Weekly Hours: 40.00 **Job Summary** The Lead ASC is an Read more
US- *Apple* Store Leader Program - Apple (Un...
…Summary Learn and grow as you explore the art of leadership at the Apple Store. You'll master our retail business inside and out through training, hands-on Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.