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

Smultron 10.0 - Easy-to-use, powerful te...
Smultron 10 is an elegant and powerful text editor that is easy to use. You can use Smultron 10 to create or edit any text document. Everything from a web page, a note or a script to any single piece... Read more
BetterTouchTool 2.304 - Customize multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Drive Genius 5.0.5 - $49.50 (50% off)
Drive Genius features a comprehensive Malware Scan. Automate your malware protection. Protect your investment from any threat. The Malware Scan is part of the automated DrivePulse utility. DrivePulse... Read more
Apple Keynote 7.3 - Apple's present...
Easily create gorgeous presentations with the all-new Keynote, featuring powerful yet easy-to-use tools and dazzling effects that will make you a very hard act to follow. The Theme Chooser lets you... Read more
Apple Numbers 4.3 - Apple's spreads...
With Apple Numbers, sophisticated spreadsheets are just the start. The whole sheet is your canvas. Just add dramatic interactive charts, tables, and images that paint a revealing picture of your data... Read more
Apple Pages 6.3 - Apple's word proc...
Apple Pages is a powerful word processor that gives you everything you need to create documents that look beautiful. And read beautifully. It lets you work seamlessly between Mac and iOS devices, and... Read more
Smultron 9.4.2 - Easy-to-use, powerful t...
Smultron 9 is an elegant and powerful text editor that is easy to use. Use it to create or edit any text document. Everything from a web page, a note or a script to any single piece of text or code.... Read more
Xcode 9.0 - Integrated development envir...
Xcode includes everything developers need to create great applications for Mac, iPhone, iPad, and Apple Watch. Xcode provides developers a unified workflow for user interface design, coding, testing... Read more
iShowU Instant 1.2.0 - Full-featured scr...
iShowU Instant gives you real-time screen recording like you've never seen before! It is the fastest, most feature-filled real-time screen capture tool from shinywhitebox yet. All of the features you... Read more
Apple Safari 11.0 - Apple's Web bro...
Note: The direct download link is currently unavailable. It is available in the OS X 10.12.6 release, as well as in the Apple Security Updates. Apple Safari is Apple's web browser that comes with... Read more

The best games to play while you wait fo...
SteamWorld Dig 2 is out this week on PC and Switch, and people are understandably excited. This clever series by Image and Form combines our favorite metroidvania mechanics with an esquisite universe, excellent storytelling, and true wit. While... | Read more »
Drag'n'Boom beginner's gu...
Have you ever wanted to burn and pillage a village as a bloodthirsty dragon? If you answered yes to that question, Drag'n'Boom offers you the perfect chance to do so, casting you as an adorable little dragon that wants to set humankind aflame. It... | Read more »
Thimbleweed Park (Games)
Thimbleweed Park 1.0.0 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.0 (iTunes) Description: A brand new adventure game from Ron Gilbert and Gary Winnick, creators of the classics Monkey Island and Maniac Mansion!... | Read more »
The best simulation games on mobile
There's nothing like a good sim -- from the seemingly ridiculous to the incredibly mundane, you can be there's a simulation game out there for your every whim. [Read more] | Read more »
INKS guide - how to create works of pinb...
INKS puts a clever new spin on everyone's favorite classic arcade game, pinball. The core mechanics are the same -- keep a little ball pinging around the board for as long as possible without letting it fall into the precarious holes in the board.... | Read more »
Warbands: Bushido (Games)
Warbands: Bushido 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: Warbands:Bushido is a miniatures board game with cards, miniatures, dice and beautiful terrains to fight on, with both... | Read more »
The best mobile games like Divinity: Ori...
Divinity: Original Sin 2 launched this week to the excitement of RPG fans everywhere. The game, which derives a lot of of its story and mechanics from old-school isometric RPGs and Dungeons & Dragons, has unseated PlayerUnknown's... | Read more »
Iron Marines guide - beginner tips and t...
Iron Marines is a brilliant RTS title that feels a bit like Starcraft. It's got a sci-fi setting and some of the most spectacular strategy mechanics we've seen in mobile games to date. With that said, the RTS genre can be a bit tricky to break... | Read more »
The best new games we played this week -...
The work week can be tough, but on the bright side, it's almost overandthere are bunches of brand new games to try out this weekend. This week definitely makes up for last week's sleepiness ten-fold. We've got one of the finest RTS game on mobile... | Read more »
Through the Ages (Games)
Through the Ages 1.0.60 Device: iOS Universal Category: Games Price: $9.99, Version: 1.0.60 (iTunes) Description: The offical adaptation of Vlaada Chvátil’s strategy classic, the second best board game ever by Board Game Geek website... | Read more »

Price Scanner via MacPrices.net

Snag a 15-inch 2.2GHz Retina MacBook Pro, App...
Apple has Certified Refurbished 2015 15″ 2.2GHz Retina MacBook Pros available for $1699. That’s $300 off original MSRP, and it’s the lowest price available for a 15″ MacBook Pro currently offered by... Read more
Apple Refurbished 3TB Time Capsule for $279,...
Apple has Certified Refurbished 3TB Time Capsules available for $279 including free shipping plus Apple’s standard one-year warranty. Their price is $120 off MSRP. Read more
19% off Smart Battery Cases for iPhone 7
Amazon has both Black and White Smart Battery Cases for iPhone 7s available for $80.41 including free shipping. Their price is $18.59, or 19%, off MSRP. Read more
Back on sale: 10.5-inch 64GB iPad Pros for $5...
MacMall has 10.5″ 64GB Apple iPad Pros on sale again for $599 including free shipping. That’s $50 off MSRP and the lowest price available for this model from any reseller. Read more
Verizon offers Certified Preowned 16GB iPhone...
Verizon has the 16GB iPhone 6, Certified Preowned, available for $259.99 or $10.83 per month for 24 months. Service plan required. According to Verizon, “All CPO devices have been reconditioned to... Read more
Preorder new iPhone 8 at US Cellular, and tak...
Preorder the new iPhone 8 or iPhone 8 Plus at US Cellular, and take $50 off the prepaid price: – 64GB iPhone 8: $649.99 – 128GB iPhone 8: $799.99 – 64GB iPhone 8 Plus: $749.99 – 128GB iPhone 8 Plus... Read more
12-inch and 9-inch Apple iPad Pros, Certified...
Apple has Certified Refurbished 2016 12″ WiFi iPad Pros available starting at $589. An Apple one-year warranty is included with each model, and shipping is free: – 32GB 12″ iPad Pro WiFi: $589... Read more
QuickerTek Announces Solar PV Chargers for US...
Wichita, Kansas based QuickerTek has announced its new 30 Watt and 60 Watt USB Type-C Solar Juicz Chargers. These solar panels are the only products of their kind, featuring the USB 3.1 adapter cable... Read more
Apple refurbished 128GB iPhone 6s and 6s Plus...
Apple has Certified Refurbished 128GB iPhone 6s and 6s Plus’ available for up to $100 off the price of new models. Space Gray, Silver, Gold, and Rose Gold models are available. Each phone comes... Read more
13-inch 2.3GHz Silver MacBook Pros on sale fo...
B&H Photo has 2017 13″ 2.3GHz Silver MacBook Pros in stock today and on sale for $100 off MSRP, each including free shipping plus NY & NJ sales tax only: – 13-inch 2.3GHz/128GB Silver... Read more

Jobs Board

*Apple* News Product Marketing Mgr., Publish...
Job Summary The Apple News Product Marketing Manager will work closely with a cross-functional group to assist in defining and marketing new features and services. Read more
Development Operations and Site Reliability E...
Development Operations and Site Reliability Engineer, Apple Payment Gateway Job Number: 57572631 Santa Clara Valley, California, United States Posted: Jul. 27, 2017 Read more
*Apple* Solutions Consultant - Apple Inc. (U...
…about helping others on a team while also delighting customers? As an Apple Solutions Consultant (ASC), you will discover customers needs and help connect them Read more
Software/Data Engineer, *Apple* Media Produ...
Job Summary Apple Media Products is the team behind the App Store, Apple Music, iTunes, and many other high profile products on iPhone, Mac and AppleTV. Our Data Read more
SW Engineer , *Apple* Media - Apple Inc. (U...
Job Summary Our team is responsible for exposing Apple Media content and services to the world, and building the infrastructure for next generation internal and Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.