TweetFollow Us on Twitter

June 93 - GRAPHICAL TRUFFLES

GRAPHICAL TRUFFLES

FOUR COMMON GRAPHICS ANSWERS

BILL GUSCHWAN

[IMAGE 054-057_Graphics_col._re1.GIF]

QuickDraw regions were almost lost when Bill Atkinson crashed his car and nearly killed himself. Considering that Steve Wozniak also crashed his airplane, crashing must be a hallmark of Apple genius. I'm no Macintosh wizard, though I did crash my car once. To aid and abet other non- wizards, I'll divulge four cool answers that apply to nearly any QuickDraw question:

  • Check the graphics state.
  • Check the QuickDraw version.
  • Do it off-screen.
  • Use the bottlenecks.

They may not answer your questions completely, but they'll probably get you partway there.

CHECK THE GRAPHICS STATE
Whenever you call a QuickDraw routine, its behavior depends heavily on the state of the machine at the time of the call: things like the pen size, transfer mode, and color environment all affect the drawing. Most of the state information QuickDraw depends on can be found in two handy locations -- the current grafPort and the current GDevice.

The grafPort maintains state information for the pen, the text, and the bitmap (or pixel map) to draw into. The GDevice defines the color environment, among other things. This information is accessed by many QuickDraw routines. For example, the LineTo routine draws a line from the current pen location to the point you pass to the routine, using the current pen size, pattern, and transfer mode; all these values are fields of the current grafPort. Because most QuickDraw routines use these "implied" parameters, you can't fully understand the behavior of a QuickDraw routine without knowing about them.

The current grafPort also defines where your drawing will occur. Even though you call a routine, it may not draw, because QuickDraw applies a rectangle -- the portRect -- and two regions -- the visRgn and clipRgn -- to your drawing. No drawing will occur outside the intersection of these areas. QuickDraw places control of the clipRgn in your hands, first initializing it to be wide open (a rectangular region that covers the entire QuickDraw coordinate space). If your grafPort is in a window, control of the visRgn is placed in the hands of the Window Manager. (A region is a truly marvelous concept, a compact description of strange shapes that can be extended and changed dynamically. It's a good thing Bill Atkinson survived his crash.)

Let's try applying this first answer to a common QuickDraw question: Why can't you nest calls to OpenPicture? Well, as you may know, when you call OpenPicture to begin saving picture data, a handle is created to store the picture information until the corresponding ClosePicture call. This handle is kept in the picSave field of the current grafPort. If you nest a second OpenPicture call, where in the grafPort will you store the newly created handle? Answer: There is no place, so you can't nest OpenPicture calls. Because so many other Managers rely on QuickDraw, this answer will help with questions about other Managers as a bonus.

CHECK THE QUICKDRAW VERSION
There are currently seven versions of QuickDraw.
You can find out which version is available using Gestalt, and that's usually the most important thing for your code to know about. But many developers also want to know which machine and system software combinations produce which versions of QuickDraw. For example, some developers code for 32-Bit QuickDraw and want to inform their users of the minimum Macintosh machine requirement. The ROM version, extensions, and system software all combine to affect which version of QuickDraw is available.

ROM versions of QuickDraw can be neatly categorized into three classes of machines: black and white, Color QuickDraw, and "ci class." The original Macintosh and the Macintosh 512K, Plus, Portable, SE, and PowerBook 100 are examples of the black-and-white class. The Macintosh II, IIx, IIcx, and SE/30 fall into the Color QuickDraw (256K ROM) class. The Macintosh IIci, IIsi, LC II, IIfx, and later models belong to the ci class (>256K ROM).

Black-and-white class. There are only two common versions of QuickDraw on black-and-white machines today: original black-and-white QuickDraw and System 7 black-and-white QuickDraw. (The uncommon ones are present only with pre-Macintosh Plus ROMs or system versions earlier than 4.2.) When System 7 is installed on a machine of this class, it installs some new routines so that a few Color QuickDraw routines can be used (you get 1-bit GWorlds, you can correctly display pictures containing direct-color information, you can create version 2 pictures, and so on).

Black-and-white QuickDraw is documented inInside MacintoshVolumes I and IV. For a comprehensive list of the routines that System 7 adds to black-and-white QuickDraw, see "QuickDraw's CopyBits Procedure: Better Than Ever in System 7.0" in develop Issue 6.

Color QuickDraw class. This class of machines has 8-bit Color QuickDraw built into ROM, so it will always be there regardless of the system version. When these machines are running system versions earlier than System 7, they can be extended to handle direct color through the use of the 32-Bit QuickDraw INIT. Finally, if they're running System 7, System 7 Color QuickDraw is available.

Inside MacintoshVolume V describes 8-bit Color QuickDraw. For documentation on the various 32- Bit QuickDraw versions, including System 7 Color QuickDraw, the best place to look is Inside Macintosh Volume VI. If you really need to know the differences in capabilities among the versions, 32-Bit QuickDraw v. 1.0 is covered in "Realistic Color for Real-World Applications" in develop Issue 1, and the features added in 32-Bit QuickDraw v. 1.2 are documented in the Tech Note "32-Bit QuickDraw: Version 1.2 Features."

ci class. This class of machines has only three possible QuickDraw versions. The least common version, 32-Bit QuickDraw v. 1.01, is found on a IIci running system software version 6.0.4. The other machines in this class that can run System 6 need at least version 6.0.5, which will patch in 32- Bit QuickDraw v. 1.2. Finally, System 7 provides its own version of Color QuickDraw.

Again, for documentation on the various 32-Bit QuickDraw versions, including System 7 Color QuickDraw, seeInside MacintoshVolume VI.

In the GestaltEqu.h header file, you'll find Gestalt values for six QuickDraw versions:

gestaltOriginalQD =0x000,// 1-bit QD
gestalt8BitQD =  0x100,// 8-bit color QD
gestalt32BitQD = 0x200,// 32-bit v1.0
gestalt32BitQD11 =0x210,// 32-bit v1.1
gestalt32BitQD12 =0x220,// 32-bit v1.2
gestalt32BitQD13 =0x230,// 32-bit v1.3

One of these -- gestalt32BitQD11 -- will never be returned, so this list accounts for only five of the total of seven versions. The sixth is 32-Bit QuickDraw v. 1.01, mentioned above, which returns the Gestalt value 0x201 but doesn't have a gestalt constant defined for it. The seventh is System 7 with a black-and-white machine: You'll need to check for both black-and-white QuickDraw (gestaltOriginalQD) and System 7 (gestaltSystemVersion greater than or equal to $0700). If both are true, you're running System 7 black-and-white QuickDraw. That's the only way to tell.

Table 1 shows all the possible combinations, in one handy location.

Table 1Possible Combinations of ROM Versions and System Software Versions

ROM ClassSystem VersionGestalt Value
Black-and-white classPre-7.0gestaltOriginalQD
7.0 and latergestaltOriginalQD and gestaltSystemVersion = $0700 or greater
Color QuickDraw classPre-7.0, no INITsgestalt8BitQD
6.0.3 or 6.0.4, andgestalt32BitQD
32-Bit QuickDraw INIT v. 1.0
System 6 from 6.0.5 on, andgestalt32BitQD12
32-Bit QuickDraw INIT v. 1.2
7.0 and latergestalt32BitQD13
ci class6.0.4gestalt32BitQD + 1
System 6 from 6.0.5 ongestalt32BitQD12
7.0 and latergestalt32BitQD13

Exactly which permutations you need to code for depends entirely on what you're doing, but typically the major divisions are color versus black-and-white, direct color versus indexed color, and GWorlds versus no GWorlds. Whenever possible, of course, you should make decisions in your code based on the QuickDraw version rather than on the specific machine configuration.

DO IT OFF-SCREEN
Off-screen environments give you explicit and total control over an image. Since the image and its associated data structures are no longer tied to a physical device, many of the complexities and limitations of QuickDraw are reduced, and your hands -- previously tied tightly behind your back -- are now freed. You'll typically manipulate your image off-screen and then use CopyBits to move the image to the screen. The FX snippet on this issue's CD provides a robust demonstration of some snazzy CopyBits effects, and there's a nice overview of how to perform animation using off-screen graphics environments in the Graphical Truffles column ("Animation at a Glance") in develop Issue 12.

Using CopyBits and off-screen environments for speed is covered eloquently in Konstantin Othmer and Mike Reed's article "Drawing in GWorlds for Speed and Versatility" in develop Issue 10, so I won't dwell on it here. Also, the Tech Note "Principia Offscreen Graphics Environments" gives details for creating off-screen environments on machines without 32-Bit QuickDraw (see the discussion above).

The point is this: when faced with a question in the "How do I . . ." category, try this answer on for size first. That may be as far as you need to go.

USE THE BOTTLENECKS
QuickDraw routines are easily customizable, which can be incredibly useful; however, this feature is typically underused. (In fact, most of the Macintosh is customizable. There ought to be a whole chapter in Inside Macintosh on customization; there are so many places in the OS that you can intercept, you could probably patch out the whole OS if you were so inclined.) You can replace QuickDraw's "guts" with viscera of your own design, completely (and reversibly) transforming QuickDraw's functionality.

Here's one example of how this can be useful: Let's say we want to find out the exact colors used in a picture that contains innumerable colors. We'll be drawing the picture to an 8-bit color monitor, and we want to manually select the best 256 colors, replacing the default color table that DrawPicture uses. There are two methods of getting the colors used in a PICT: use the System 7 Picture Utilities Package, or do it yourself. The Picture Utilities Package is available only in System 7, so if we want to run on earlier systems, our only choice is to do it ourselves. We do that by using the bottlenecks.

You can replace all the bottlenecks with no-ops except for a few carefully selected ones, then draw the picture. Your replacement bottlenecks will be able to watch all the picture data go by and can keep track, say, of the colors used in the picture. (Two sample programs on the CD, CollectPictColors and GMundo, demonstrate this technique.) So, for instance, to draw our many- colored picture with a custom-picked set of 256 colors, we actually have to draw the picture twice: the first time, we replace the bottlenecks, allowing us to use -- collect, extract, or read -- the colors in the picture. We can then set up the destination cGrafPort with the colors we want to show, restore the bottlenecks, and draw the picture again, this time to actually image it into the destination cGrafPort.

THAT'S IT FOR NOW When you're faced with a question about QuickDraw, try running through the answers in this column first, to see if any of them fit. Is the state of the machine at the time of the call different than you assumed? Did you check the QuickDraw features and version? Can you do it off-screen? Can you intercept processing at the bottleneck level to customize QuickDraw's routines? It's likely that one of these answers will help.

RELATED READING

  • "Graphical Truffles: Animation at a Glance" by Edgar Lee, develop Issue 12.
  • "Drawing in GWorlds for Speed and Versatility" by Konstantin Othmer and Mike Reed, develop Issue 10.
  • "QuickDraw's CopyBits Procedure: Better Than Ever in System 7.0" by Konstantin Othmer, develop Issue
  • "Realistic Color for Real-World Applications" by Bruce Leak, develop Issue 1.
  • Inside Macintosh Volume VI (Addison-Wesley, 1991), Chapter 17, "Color QuickDraw."
  • Inside Macintosh Volume V (Addison-Wesley, 1988), Chapter 4, "Color QuickDraw."
  • Inside Macintosh Volume IV (Addison-Wesley, 1986), Chapter 4, "QuickDraw."
  • Inside Macintosh Volume I (Addison-Wesley, 1985), Chapter 6, "QuickDraw."
  • Macintosh (Imaging) Technical Notes "Principia Offscreen Graphics Environments" (formerly #120) and "32-Bit QuickDraw: Version 1.2 Features" (formerly #275).

BILL GUSCHWAN (AppleLink ANGUS) asked Howard Roark to dialog with him: "So, Angus, you ditched med school to become a protector of the dogcow? I love you, man." Angus: "Well, Howard, as Tori Amos would say, 'Sometimes I hear my voice and it's been here silent all these years.'" Howard: "You know, I ditched architecture school, not unlike David Byrne. Speaking of Talking Heads, you got kicked out of one of his concerts because you wanted to dance." Angus: "Words are very unnecessary, they can only do harm, so I dance." Howard: "Even your idol Wittgenstein went back to school. What about you?" Angus: "As you know, Howard, even Atlas shrugged." *

Thanks to Edgar Lee, Konstantin Othmer, Brigham Stevens, Forrest Tanaka, and John Wang for reviewing this column. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

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
Herald 5.0.2 - Notification plugin for M...
Note: Versions 2.1.3 (for OS X 10.7), 3.0.6 (for OS X 10.8), and 4.0.8 (for OS X 10.9) are no longer supported by the developer. Herald is a notification plugin for Mail.app, Apple's Mac OS X email... Read more
DEVONthink Pro 2.8.3 - Knowledge base, i...
Save 10% with our exclusive coupon code: MACUPDATE10 DEVONthink Pro is your essential assistant for today's world, where almost everything is digital. From shopping receipts to important research... Read more
Boom 2 1.0.1 - System-wide pro audio app...
Boom 2 is a system-wide volume booster and equalizer app that is designed especially for OS X 10.10 Yosemite. It comes with a smart interface, self-calibrates itself according to your Mac, offers... Read more
Apple Security Update 2015-001 - For OS...
Apple Security Update 2015-001 is recommended for all users and improves the security of OS X. For detailed information about the security content of this update, please visit: http://support.apple.... Read more
Drive Genius 4.0.1 - Powerful system uti...
Drive Genius 4 gives you faster performance from your Mac while also protecting it. The award-winning and improved DrivePulse feature alerts you to hard drive issues before they become major problems... Read more
Yosemite Cache Cleaner 9.0.3 - Clear cac...
Yosemite Cache Cleaner is an award-winning general purpose tool for OS X. YCC makes system maintenance simple with an easy point-and-click interface to many OS X functions. Novice and expert users... Read more
xScope 4.1.1 - Onscreen graphic measurem...
xScope is powerful set of tools that are ideal for measuring, inspecting, and testing on-screen graphics and layouts. Its tools float above your desktop windows and can be accessed via a toolbar,... Read more
OS X Yosemite 10.10.2 - Apple's lat...
OS X Yosemite is Apple's newest operating system for Mac. An elegant design that feels entirely fresh, yet inherently familiar. The apps you use every day, enhanced with new features. And a... 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 »
Fahrenheit: Indigo Prophecy Remastered R...
Fahrenheit: Indigo Prophecy Remastered Review By Jennifer Allen on January 29th, 2015 Our Rating: Universal App - Designed for iPhone and iPad 10 years after its initial release and Fahrenheit: Indigo Prophecy still feels like a... | Read more »
Evolve: Hunters Quest is a Match-3 That...
Evolve: Hunters Quest is a Match-3 That Has You Hunting Up Some Big Game. Posted by Jessica Fisher on January 29th, 2015 [ permalink ] | Read more »
Destructamundo Review
Destructamundo Review By Jordan Minor on January 29th, 2015 Our Rating: :: WRECKING CREWUniversal App - Designed for iPhone and iPad Destructamundo blows up real good.   | Read more »
The Sandbox Gets Exclusive Update, Adds...
The Sandbox Gets Exclusive Update, Adds Invincible Characters Campagin Posted by Tre Lawrence on January 29th, 2015 [ permalink ] | Read more »
Mean Girls: The Game Review
Mean Girls: The Game Review By Jordan Minor on January 29th, 2015 Our Rating: :: FETCHUniversal App - Designed for iPhone and iPad A Mean Girls tower defense game makes way more sense than you’d think.   | Read more »

Price Scanner via MacPrices.net

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
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
15-inch 2.0GHz Retina MacBook Pro (refurbishe...
The Apple Store has Apple Certified Refurbished previous-generation 15″ 2.0GHz Retina MacBook Pros available for $1489 including free shipping plus Apple’s standard one-year warranty. Their price is... Read more
15-inch 2.5GHz Retina MacBook Pro on sale for...
Amazon has the 15″ 2.5GHz Retina MacBook Pro on sale for $2319.99 including free shipping. Their price is $180 off MSRP, and it’s the lowest price available for this model from any reseller. Read more
iPad Turns Five – The ”Book Mystique
Five years ago this week, the late Steve Jobs took the stage at an Apple special press event to unveil the first Apple iPad — a slab-shaped, hand-holdable device that was to shake the personal... Read more
Sale! 15-inch Retina MacBook Pros for up to $...
B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for $150 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1889.99... Read more
Apple refurbished Mac minis for up to $150 of...
The Apple Store has restocked Apple 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... Read more
Apple Releases New Tranche Of OS Updates For...
Apple has released incremental bugfix and security updates for its most recent Mac and iOS versions. OS X Yosemite 10.10.2 Update Apple says this update includes the following improvements: Resolves... Read more
Samsung To Be Main Supplier Of A9 Chips For i...
Korea’s Maeil Business Newspaper reports that Samsung has beat out its chipmaking rivals, Taiwan’s Qualcomm and TSMC, as supplier of chipsets for the next generations of both its own Galaxy S6 and... Read more
Save up to $340 on iMacs with Apple Certified...
The Apple Store has Apple Certified Refurbished iMacs available for up to $340 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more

Jobs Board

*Apple* Systems Engineer - Pre Sales, Educat...
…is responsible for proactively providing technical expertise to drive sales of Apple solutions into assigned accounts. The SE architects, validates, and assists in Read more
*Apple* Solutions Consultant - Retail Sales...
As an ambassador of the Apple brand, the ASC is accountable for driving sales performance by: Connecting with customers. Discovering customers' needs and values. Showing Read more
*Apple* Solutions Consultant - Retail Sales...
As an ambassador of the Apple brand, the ASC is accountable for driving sales performance by: Connecting with customers. Discovering customers' needs and values. Showing Read more
*Apple* Tree Children's Center is hirin...
Apple Tree Learning Center is Hiring Preschool Teachers! Phoenix Childrens Academy is a national leader in the early childhood education industry and we are currently Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.