TweetFollow Us on Twitter

June 1994 - Graphical Truffles

Graphical Truffles

The Debugging Version of QuickDraw GX

Pete ("Luke") Alexander

By now, many of you have installed one of the beta versions of QuickDraw GX onto your Macintosh -- and possibly by the time you read this, QuickDraw GX Software Developer's Kit version 1.0 will be available from APDA. Maybe you've played with the various sample applications and are now ready to work on your first QuickDraw GX application. Perhaps you've even read my article in develop; Issue 15, "Getting Started With QuickDraw GX." In this column, I'll talk about something I referred to briefly in that article: the two versions of QuickDraw GX's combined graphics and layout portions, and how to take advantage of the debugging version during the development of your QuickDraw GX-based application. Along the way I'll update you on a few changes since I wrote the article.

THE EXTENSIONS OF QUICKDRAW GX
The QuickDraw GX system extension comes in two flavors: a nondebugging and a debugging version. When you run the QuickDraw GX installer script, the nondebugging version is installed, including the complete QuickDraw GX system. The nondebugging version is lean and mean, so it's significantly faster than the debugging version; it performs quite a bit less error checking than the debugging version.

The debugging version of the extension provides extensive error checking and other debugging amenities. When developing a QuickDraw GX application, you should use this version to shake out the bugs. The debugging extension is in the DEBUG Init folder and is named "GXGraphics (debug)" in version 1.0 (it used to be named aSecretGraphics.debug); just drag it into your System Folder and reboot. As your system starts up you'll see the debugging extension's icon displayed before the QuickDraw GX icon.

An explanation of what's really going on here may help clarify things (and it has changed): There are actually three extensions within the QuickDraw GX extension -- one for graphics and layout, one for printing, and one for the Finder printing extension. The QuickDraw GX extension knows, if "GXGraphics (debug)" has already loaded, to use that extension instead of the nondebugging version of the graphics and layout extension. (Note that since the debugging extension must load before the nondebugging version, you should not change the debugging extension's name.)

THE ADVANTAGES OF THE DEBUGGING VERSION DURING DEVELOPMENT
Let's look at some differences between the two extensions, and specifically how to take advantage of the debugging version during the development of your QuickDraw GX application.

Notices, warnings, and errors. With the debugging version of the extension, you can get three types of information about drawing problems: notices, warnings, and errors. For a complete list of these, look at the graphics errors.h interface file. The many notices, warnings, and errors defined between #ifdef debugging and #endif in that file are available only with the debugging version. You'll need to #define debugging in your application to take advantage of them. (Make sure debugging is not defined when you build your final version.)

With the nondebugging version, notices aren't available at all, and the list of errors and warnings you need to respond to in your application consists only of those relatively few that lie outside #ifdef debugging and #endif in the graphics errors.h file. Your application must be set up to handle these errors and warnings, which in general indicate that the QuickDraw GX system could not honor your application's request. For example:

shape_is_nil
size_of_path_exceeds_implementation_limit
picture_index_out_of_range

The debugging version checks for errors that you're likely to run into while developing your application, such as passing a negative pen size to GXSetShapePen or a curve to GXGetGlyphMetrics. The nondebugging version doesn't check for these types of errors; it assumes you've already shaken them out of the code.

Validation routines. The GXSetValidation and GXValidateShape routines are available only in the debugging version. These routines allow your application to tell whether it's passing valid parameters into a QuickDraw GX function, to validate the contents of all QuickDraw GX objects (such as a shape, style, and ink) before their use, and to validate the QuickDraw GX memory your application is using.

Speed optimizations. The nondebugging version has optimizations for speed built in -- not only fewer error checks but also inline functions. The debugging version doesn't optimize for speed. This shouldn't have any impact on your application development except that there's not a one-to-one correspondence between stack crawls using the debugging and nondebugging versions. A performance analysis of your QuickDraw GX application should only be donewithout the "GXGraphics (debug)" file in your Extensions folder.

GraphicsBug. The GraphicsBug debugging tool allows you to explore the contents of any QuickDraw GX object to make sure it contains the correct information. Another change from before is that GraphicsBug is available in both the debugging and nondebugging versions. This ability to spy on an object's contents is important to your application development because otherwise you could only access information in objects by making API calls, which would be very tedious during debugging.

There's a slight advantage when using GraphicsBug with the debugging version: heaps are listed by name rather than by hex address in the Heaps menu.

Memory. The debugging version's memory blocks in the QuickDraw GX heap are a bit bigger to help detect errors when your application writes over the end of a block: all the blocks end with the same signature, 'grfx'.

Special MacsBug messages. The debugging version generates MacsBug messages that are intended solely for the consumption of the Apple engineers in unusual circumstances. (One of my favorites is "Curious if this ever happens.") If we did our jobs right, you should never see one of these messages. In case you do, however, we're really interested in hearing what caused you to receive it; please let us know at AppleLink APPLE.BUGS.

CLEANING UP
You should design your application to take advantage of the extensive capabilities of the debugging extension, but turn those capabilities off when you create your final shipping application, to improve its performance. For example, calling GXValidateShape with the nondebugging extension installed will only result in a jump and return (that is, it will be a no-op). This is a wonderful method for testing the QuickDraw GX dispatcher, but it doesn't help the performance of your application.

In the final compile of your shipping application, you'll most likely want to remove all calls to validation routines, posting of notices, and extra warnings and errors available only in the debugging version. One approach would be to have various compilation flags associated with pairs of #ifdef and #endif to turn these features on and off.

For more information, see my article in Issue 15 if you haven't already -- or just dig into the QuickDraw GX documentation. Enjoy your journey into the QuickDraw GX world!

RELATED READING

  • "Getting Started With QuickDraw GX" by Pete ("Luke") Alexander, develop  Issue 15.
  • "Print Hints: Looking Ahead to QuickDraw GX" by Pete ("Luke") Alexander, develop  Issue 13.

PETE ("LUKE") ALEXANDER has been providing developer support for QuickDraw GX ever since it was way up in the air. He's happy it's making its final approach, and he's hoping it lands smack dab in the middle of your software. As a glider pilot, Luke knows how important control is -- and with QuickDraw GX, you'll be able to maneuver your software into spaces you never thought possible. Since QuickDraw GX can help you do lots of great graphics stunts that you used to have to ask him about, Luke is about to soar off into the wild blue yonder and do some stunts of his own. Soon he'll be ready for the preflight check that will launch his sabbatical faster than QuickDraw GX handles two-byte text. For many weeks he'll be thinking about nothing but white sand beaches, white puffy clouds, and white-capped mountains. He'll lie on his back and watch the sway of the trees until they stop reminding him of the swashes of L's. So if you see him somewhere in Montana, Utah, Nevada, California, or Idaho, be sure to say hello -- but try not to use any words that have a G and an X in them. *

Thanks to Hugo Ayala, Cary Clark, and Herb Derby for reviewing this column. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Together 3.7 - Store and organize all of...
Together helps you organize your Mac, giving you the ability to store, edit and preview your files in a single clean, uncluttered interface. Features Smart storage. With simple drag-and-drop... Read more
EtreCheck 3.1.4 - 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
Postbox 5.0.9 - Powerful and flexible em...
Postbox is a new email application that helps you organize your work life and get stuff done. It has all the elegance and simplicity of Apple Mail, but with more power and flexibility to manage even... Read more
DiskCatalogMaker 6.5.16 - Catalog your d...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast. Finder-like intuitive look and feel. Super-fast search algorithm. Can compress catalog data... Read more
TrailRunner 3.8.827 - Route planning for...
TrailRunner is the perfect companion for runners, bikers, hikers, and all people wandering under the sky. Plan routes on a geographical map. Import GPS or workout recordings and journalize your... Read more
VueScan 9.5.61 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
Postbox 5.0.9 - Powerful and flexible em...
Postbox is a new email application that helps you organize your work life and get stuff done. It has all the elegance and simplicity of Apple Mail, but with more power and flexibility to manage even... Read more
VueScan 9.5.61 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
DiskCatalogMaker 6.5.16 - Catalog your d...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast. Finder-like intuitive look and feel. Super-fast search algorithm. Can compress catalog data... Read more
TrailRunner 3.8.827 - Route planning for...
TrailRunner is the perfect companion for runners, bikers, hikers, and all people wandering under the sky. Plan routes on a geographical map. Import GPS or workout recordings and journalize your... Read more

Latest Forum Discussions

See All

Great zombie games in the spirit of Dead...
Dead Rising 4 arrives tomorrow, giving enthusiasts a fresh chance to take selfies with zombies and get up to other ridiculous end-of-the-world shenanigans. To really get into the spirit of things, we've gone and gathered the best zombie games that... | Read more »
Amateur Surgeon 4 Guide: Advanced tips a...
Amateur Surgeon 4 is still tackling the competition at the top of the App Store charts, so if you haven't tried it out yet, you should probably do that right away. If you've been at it for a while, though, perhaps you're ready to start expanding... | Read more »
Amateur Surgeon 4 Guide: Become the worl...
It's time to wield your trusty pizza cutter again, as Amateur Surgeon has returned with a whole fresh set of challenges (and some old, familiar ones, too). Starting anew isn't easy, especially when all you have at your disposal is a lighter, the... | Read more »
Le Parker: Sous Chef Extraordinaire (Ga...
Le Parker: Sous Chef Extraordinaire 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Telltale Games really is working on a Gu...
Telltale Games' next episodic adventure is indeed Guardians of the Galaxy. A document tied to the voice actors strike suggested that the project was in the work, but now we have direct confirmation following an announcement at the Game Awards that... | Read more »
Amateur Surgeon returns to iOS and Andro...
Amateur Surgeon and its two sequels disappeared from the App Store some time and it was sad days for all. But now, just in time for the holidays, the Adult Swim favorite makes its joyous return in the shape of Amateur Surgeon 4, a remake with... | Read more »
The best board games on mobile
Sometimes you need to ditch all of the high speed, high action games in favor of something a little more traditional. If you don't feel like parting ways from your mobile device, though, there are still plenty of ways to get that old-school fix.... | Read more »
The best Facebook Messenger Instant Game...
Facebook's new Instant Games is now here, meaning you can play games with your friends directly via Facebook. It's a fun new way to connect with friends, of course, but it's also proving to be a solid gaming experience in its own right, with a... | Read more »
You can now play game's on Facebook...
Facebook launched its new Instant Games platform in an exciting new attempt to engage its user base. As a result, you can now play a number of different games directly through Facebook Messenger. All of these games run with HTML5, meaning you play... | Read more »
Apollo Justice Ace Attorney (Games)
Apollo Justice Ace Attorney 1.00.00 Device: iOS Universal Category: Games Price: $.99, Version: 1.00.00 (iTunes) Description: Court Is Back In Session Star as rookie defense attorney, Apollo Justice, as he visits crime scenes,... | Read more »

Price Scanner via MacPrices.net

Monday roundup of Holiday Mac sales: Up to $3...
Take up to $300 off MSRP on the price of a new Apple Mac at B&H Photo today as part of their Holiday sale. Shipping is free, and B&H charges NY sales tax only. Touch Bar MacBook Pros are in... Read more
12-inch WiFi Apple iPad Pros on sale for up t...
B&H Photo has 12″ WiFi Apple iPad Pros on sale for up to $50 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off MSRP... Read more
9-inch Apple WiFi iPad Pros on sale for $20-$...
B&H Photo has 9.7″ Apple WiFi iPad Pros on sale for $20-$50 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 9″ Space Gray 256GB WiFi iPad Pro: $779.95 $20 off MSRP... Read more
Holiday sale: Apple MacBook Airs available fo...
B&H Photo has 13″ MacBook Airs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 1.6GHz/128GB MacBook Air (MMGF2LL/A): $899 $100 off MSRP - 13″ 1.6GHz/... Read more
13-inch Silver Touch Bar MacBook Pro in stock...
Amazon has the new 2016 13″ 2.9GHz/256GB Silver Touch Bar MacBook Pro (MLVP2LL/A) in stock today and on sale for $1749 including free shipping. That’s $50 off MSRP, and it’s the lowest price... Read more
Parallels Toolbox 1.3 for Mac Offers 25 Singl...
Parallels has launched Parallels Toolbox 1.3 for Mac, an upgrade that adds five new utilities to the stand-alone application which was released in August and is available exclusively online at http... Read more
OWC Mercury Elite Pro Dual mini Ultra-Portabl...
OWC has introduced the new OWC Mercury Elite Pro Dual mini, a powerful yet ultra-portable dual-drive RAID solution. The new Mercury Elite Pro Dual mini packs phenomenal performance into a small... Read more
Clearance 13-inch Retina MacBook Pros availab...
B&H Photo has clearance 2015 13″ Retina Apple MacBook Pros available for up to $200 off original MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $... Read more
Roundup of 2016 13-inch 2.0GHz MacBook Pro sa...
B&H has the non-Touch Bar 13″ MacBook Pros in stock today for $50-$100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (MLL42LL/A): $1449 $... Read more
New 13-inch 2.0GHz Space Gray MacBook Pro in...
Adorama has the new 13″ 2.0GHz Space Gray MacBook Pro (non-Touch Bar, MLL42LL/A) in stock for $1499 including a free 3-year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax... Read more

Jobs Board

Lead *Apple* Solutions Consultant - Apple (...
# Lead Apple Solutions Consultant Job Number: 53586123 Pittsburgh, Pennsylvania, United States Posted: Nov. 28, 2016 Weekly Hours: 40.00 **Job Summary** The Lead ASC Read more
*Apple* Retail - Multiple Positions- Plano,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions- Kansas...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions- Chicago...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Hardware Design Validation Engineer - *Apple...
The Apple Watch team is looking for a Hardware Design Validation Engineer. This person will be part of the Apple Watch hardware team with responsibilities for Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.