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

Apple Remote Desktop 3.8 - Remotely cont...
Apple Remote Desktop is the best way to manage the Mac computers on your network. Distribute software, provide real-time online help to end users, create detailed software and hardware reports, and... Read more
NeoOffice 2014.7 - Mac-tailored, OpenOff...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
DesktopLyrics 2.6.6 - Displays current i...
DesktopLyrics is an application that displays the lyrics of the song currently playing in "iTunes" right on your desktop. The lyrics for the song have to be set in iTunes; DesktopLyrics does nothing... Read more
Ember 1.8.3 - Versatile digital scrapboo...
Ember (formerly LittleSnapper) is your digital scrapbook of things that inspire you: websites, photos, apps or other things. Just drag in images that you want to keep, organize them into relevant... Read more
Apple iTunes 12.1 - Manage your music, m...
Apple iTunes lets you organize and play digital music and video on your computer. It can automatically download new music, app, and book purchases across all your devices and computers. And it's a... Read more
LibreOffice 4.4.3 - Free, open-source of...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
FoldersSynchronizer 4.2.1 - Synchronize...
FoldersSynchronizer is a popular and useful utility that synchronizes and backs-up files, folders, disks and boot disks. On each session you can apply special options like Timers, Multiple Folders,... Read more
Simon 4.0.2 - Monitor changes and crashe...
Simon monitors websites and alerts you of crashes and changes. Select pages to monitor, choose your alert options, and customize your settings. Simon does the rest. Keep a watchful eye on your... Read more
Cocktail 8.1.2 - General maintenance and...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Cyberduck 4.6.4 - FTP and SFTP browser....
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more

Playworld Superheroes Review
Playworld Superheroes Review By Tre Lawrence on January 30th, 2015 Our Rating: :: HERO CRAFTINGUniversal App - Designed for iPhone and iPad It’s all about the imagination, fighting bad creatures — and looking good while doing so.   | Read more »
Join the SpongeBob Bubble Party in this...
Join the SpongeBob Bubble Party in this New Match 3 Bubble Poppin’ Frenzy Posted by Jessica Fisher on January 30th, 2015 [ permalink ] | Read more »
Handpick Review
Handpick Review By Jennifer Allen on January 30th, 2015 Our Rating: :: TANTALIZING SUGGESTIONSiPhone App - Designed for the iPhone, compatible with the iPad Handpick will make you hungry, as well as inspire you to cook something... | Read more »
Storm the Halls of Echo Base in First St...
Storm the Halls of Echo Base in First Star Wars: Galactic Defense Event Posted by Jessica Fisher on January 30th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Contradiction Review
Contradiction Review By Tre Lawrence on January 30th, 2015 Our Rating: :: SPOT THE LIEiPad Only App - Designed for the iPad Contradiction is a live action point and click adventure that’s pretty engaging.   Developer: Tim Follin... | Read more »
Unlock Sunshine Girl in Ironkill with th...
Unlock Sunshine Girl in Ironkill with this special 148Apps code Posted by Rob Rich on January 29th, 2015 [ permalink ] Robo-fighter Ironkill has been out on iOS a | Read more »
Crossroad Zombies Review
Crossroad Zombies Review By Jordan Minor on January 29th, 2015 Our Rating: :: CROSSWALKING DEADiPad Only App - Designed for the iPad Crossroad Zombies is a rough draft of a cool genre mash-up.   | Read more »
Blood Brothers 2 – Tips, Cheats, and Str...
War is hell: Is it the kind of hell you want to check out? Read our Blood Brothers 2 review to find out! Blood Brothers 2, DeNA’s follow-up to the original Blood Brothers, is an intriguing card collecting / role-playing / strategy hybrid. There’s... | Read more »
Blood Brothers 2 Review
Blood Brothers 2 Review By Nadia Oxford on January 29th, 2015 Our Rating: :: AN AGGRAVATING RELATIVEUniversal App - Designed for iPhone and iPad Blood Brothers 2 is built on a simple, solid foundation, but its free-to-play system... | Read more »
I AM BREAD, the Toast of the Town, is Ro...
Have you ever dreamt of being deliciously gluten-y? Do you feel passionate about Rye and Wheat? The guys at Bossa Studios do and that is why they are bringing I AM BREAD to iOS soon. The loafy app will feature all the new content that is being... | Read more »

Price Scanner via MacPrices.net

Amazon offers 15-inch 2.2GHz Retina MacBook P...
 Amazon.com has the 15″ 2.2GHz Retina MacBook Pro on sale for $1879 including free shipping. Their price is $120 off MSRP, and it’s the lowest price available for this model from any reseller (except... Read more
Intel Aims to Transform Workplace With 5th-Ge...
Intel Corporation today announced the availability of its 5th generation Intel Core vPro processor family that provides cutting-edge features to enable a new and rapidly shifting workplace. To meet... Read more
iOS App Sharalike Introduces New Instant Smar...
Sharalike slideshow and photo management software for iOS, is making it easier than ever to create shareable meaningful moments with its new instant SmartShow technology. Staying organized is a goal... Read more
Apple Becomes World’s Largest Smartphone Vend...
According to the latest research data from Strategy Analytics, as global smartphone shipments grew 31 percent annually to reach a record 380 million units in the fourth quarter of 2014. Apple became... Read more
Cut the Cord: OtterBox Resurgence Power Case...
Dead batteries and broken phones are two of the biggest issues for smartphone users today. Otterbox addresses both with the new Resurgence Power Case for Apple iPhone 6, promising to make those panic... Read more
13-inch Retina MacBook Pros on sale for up to...
B&H Photo has 13″ Retina MacBook Pros on sale for $200 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.6GHz/128GB Retina MacBook Pro: $1199.99 save $100 - 13″ 2.6GHz/... Read more
15-inch 2.5GHz Retina MacBook Pro on sale for...
 B&H Photo has the 15″ 2.5GHz Retina MacBook Pro on sale for $2319.99 including free shipping plus NY sales tax only. Their price is $180 off MSRP, and it’s the lowest price available for this... Read more
Back in stock: Refurbished iPod nanos for $99...
The Apple Store has Apple Certified Refurbished 16GB iPod nanos available for $99 including free shipping and Apple’s standard one-year warranty. That’s $50 off the cost of new nanos. Most colors are... Read more
Apple lowers price on refurbished 256GB MacBo...
The Apple Store has lowered prices on Apple Certified Refurbished 2014 MacBook Airs with 256GB SSDs, now available for up to $200 off the cost of new models. An Apple one-year warranty is included... Read more
New Good Management Suite Simplifies Enterpri...
Good Technology has announced the availability of the Good Management Suite, a comprehensive cross-platform solution for organizations getting started with mobile business initiatives. Built on the... Read more

Jobs Board

At-Home Chat Specialist- *Apple* Online Stor...
**Job Summary** At Apple , we believe in hard work, a fun environment, and the kind of creativity and innovation that only comes about when talented people from diverse Read more
Sr. Mac Expert- *Apple* Online Store - Apple...
**Job Summary** The World Wide Apple Online Store (AOS) Sales and Service team is looking for motivated, outgoing, and tech savvy individuals who want to offer Apple Read more
*Apple* Solutions Consultant- Retail Sales (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Event Director, *Apple* Retail Marketing -...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global engagement strategy and team. Delivering an overarching brand Read more
At-Home Chat Specialist- *Apple* Online Stor...
**Job Summary** At Apple , we believe in hard work, a fun environment, and the kind of creativity and innovation that only comes about when talented people from diverse Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.