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 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.)

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:


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.

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!


  • "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

Path Finder 7.2 - Powerful, award-winnin...
Become a master of file management with Path Finder. Take full control over your file system. Save your time: compare and synchronize folders, view hidden files, use Dual Pane and full keyboard... Read more
Sid Meier's Civilization: Beyond Ea...
Sid Meier's Civilization: Beyond Earth is a new science-fiction-themed entry into the award-winning Civilization series. Set in the future, global events have destabilized the world leading to a... Read more
ForkLift 2.6.6 - Powerful file manager:...
ForkLift is a powerful file manager and ferociously fast FTP client clothed in a clean and versatile UI that offers the combination of absolute simplicity and raw power expected from a well-executed... Read more
Microsoft Remote Desktop 8.0.21 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
OnyX 3.1.0 - Maintenance and optimizatio...
OnyX is a multifunctional utility for OS X. It allows you to verify the startup disk and the structure of its System files, to run miscellaneous tasks of system maintenance, to configure the hidden... Read more
Spotify - Stream music, crea...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more
ExpanDrive - Access cloud storag...
ExpanDrive builds cloud storage in every application, acts just like a USB drive plugged into your Mac. With ExpanDrive, you can securely access any remote file server directly from the Finder or... Read more
Markly 1.5.3 - Create measurement and de...
Markly is a measurement and design-spec plugin/extension for Photoshop and Sketch. It is made for modern Web designers and app front-end developers. You can add specification marks simply by clicking... Read more
Suitcase Fusion 6 17.3.0 - Font manageme...
Suitcase Fusion 6 is the creative professional's font manager. Every professional font manager should deliver the basics: spectacular previews, powerful search tools, and efficient font organization... Read more
Nisus Writer Pro 2.1.2 - Multilingual wo...
Nisus Writer Pro is a powerful multilingual word processor, similar to its entry level products, but brings new features such as table of contents, indexing, bookmarks, widow and orphan control,... Read more

Balls & Holes - Tips and tricks to h...
Balls & Holes is a gorgeous new endless runner that challenges you to make it as far up a mountain as possible before inevitably being sliced into a load of gooey bits. Making this task more difficult are both the wide variety of balls that... | Read more »
Balloony Land offers a fresh twist on th...
Balloony Land by Palringo offers a fresh twist on the match three genre and is out now on iOS and Android. First-off, you'll be popping balloons instead of crushing candy and the balloons will float up and fill the empty spaces instead of dropping... | Read more »
Graphic - vector illustration and design...
Graphic - vector illustration and design 1.0 Device: iOS iPhone Category: Productivity Price: $2.99, Version: 1.0 (iTunes) Description: Autodesk Graphic is a powerful full-featured vector drawing and illustration application right in... | Read more »
Sago Mini Babies (Education)
Sago Mini Babies 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: Introducing the Sago Mini babies. Boys and girls love caring for these adorable characters. Feed Robin her favorite mush... | Read more »
PAUSE - Relaxation at your fingertip (H...
PAUSE - Relaxation at your fingertip 1.1 Device: iOS iPhone Category: Healthcare & Fitness Price: $1.99, Version: 1.1 (iTunes) Description: | Read more »
Super Sharp (Games)
Super Sharp 1.1 Device: iOS Universal Category: Games Price: $1.99, Version: 1.1 (iTunes) Description: Your finger has never been so sharp! Cut with skill to complete the 120 ingenious physics levels of Super Sharp and become a cut... | Read more »
Assembly - Graphic design for everyone...
Assembly - Graphic design for everyone 1.0 Device: iOS Universal Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Assembly is the easiest most powerful design tool on the App Store. Create anything you can... | Read more »
Dub Dash (Games)
Dub Dash 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: ARE YOU READY FOR THE ULTIMATE CHALLENGE? UNIQUE SYMBIOSIS OF MUSIC AND GRAPHICS | Read more »
Leave Me Alone (Games)
Leave Me Alone 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: 33% off launch sale!!! Somewhere between the 1980s and 1990s there exists a world that never was. A world of skatepunks,... | Read more »
YAMGUN (Games)
YAMGUN 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: The invasion has begun! Protect the walls of the citadel against waves of enemies! But watch out, you will soon run out of ammo...... | Read more »

Price Scanner via

Apple Products Four Of 2015′s Top Ten Most Wa..., Future’s global technology brand and the UK’s biggest technology website, has unveiled results from extensive research that show • The Smart Home is what excites the public most about... Read more
13-inch 2.7GHz/128GB Retina MacBook Pro on sa...
Best Buy has the 13″ 2.7GHz/128GB Retina MacBook Pro on sale for $1174.99 for a limited time. Choose free shipping or free local store pickup (if available). Sale price for online orders only, in-... Read more
App Tamer 2.1 Makes El Capitan Cooler, Quiete...
St. Clair Software has announced the availability of a free update to its App Tamer utility for Mac OS X. App Tamer 2.1 delivers compatibility with Yosemite and improves its support for a number of... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has 2015 15″ Retina MacBook Pros on sale for up to $160 off MSRP including free shipping plus NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1849.99 $150 off - 15″ 2.5GHz Retina... Read more
12-inch Retina MacBooks on sale for $100 off...
Best Buy has 12″ Retina MacBooks available for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Discounted prices available for online orders only... Read more
MacBook Airs on sale for up to $100 off MSRP
Save up to $100 on the purchase of a new 2015 13″ or 11″ 1.6GHz MacBook Air at the following resellers. Shipping is free with each model: 11" 128GB MSRP $899 11" 256GB... Read more
Save 15% with Apple refurbished Mac Pros
The Apple Store has Apple Certified Refurbished Mac Pros available for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more
Apple restocks refurbished Mac minis for up t...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more
TP-LINK Next-Gen Routers Support a Large Numb...
TP-LINK, specialists in consumer and business networking products, have announced the availability of Archer C2600, the company’s next-generation router featuring wireless AC, multi-user MIMO, and 4-... Read more
Apple refurbished 2014 MacBook Airs available...
Apple has Certified Refurbished 2014 MacBook Airs available starting at $679. An Apple one-year warranty is included with each MacBook, and shipping is free: - 11″ 1.4GHz/128GB MacBook Air: $679... Read more

Jobs Board

Project Manager: *Apple* Pay - Apple (Unite...
…The iOS Systems team is looking for a project manager who will manage Apple Pay server side integration project resources in a matrix organization, track tasks, prepare Read more
*Apple* Retail - Multiple Positions (US) - A...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, you're Read more
Validation Engineering Manager - *Apple* Wa...
…hardware and software development to lead the validation of the next generation Apple Watch and related products. The Validation Team works closely with many Read more
Senior Payments Architect - *Apple* Pay - A...
**Job Summary** Apple , Inc. is looking for a highly motivated, innovative and hands-on senior payments architect to join the Apple Pay Engineering team. You will Read more
*Apple* Retail for Business Support Supervis...
…is looking for a motivated, outgoing, and creative individual who wants to offer Apple Business Customers an unparalleled customer experience. The Apple Retail for Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.