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

ExpanDrive 6.1.8 - Access cloud storage...
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
DiskCatalogMaker 7.2.7 - Catalog your di...
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 for... Read more
DiskCatalogMaker 7.2.7 - Catalog your di...
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 for... Read more
Iridient Developer 3.2.1 - Powerful imag...
Iridient Developer (was RAW Developer) is a powerful image-conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more
BusyContacts 1.2.7 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
MegaSeg 6.0.5 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
BusyContacts 1.2.7 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
MegaSeg 6.0.5 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
Iridient Developer 3.2.1 - Powerful imag...
Iridient Developer (was RAW Developer) is a powerful image-conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more
iFFmpeg 6.6.1 - Convert multimedia files...
iFFmpeg is a comprehensive media tool to convert movie, audio and media files between formats. The FFmpeg command line instructions can be very hard to master/understand, so iFFmpeg does all the hard... Read more

Latest Forum Discussions

See All

The best deals on the App Store this wee...
A new week means new discounts on the App Store. This week's deals run the gamut of action-adventure titles, puzzle games, and one of the best narrative adventure series out there. If you're looking to fill out your mobile gaming library on a... | Read more »
What you need to know about Animal Cross...
We hope you've been hard at work on collecting all of those holiday items in Animal Crossing: Pocket Camp, because you're about to get a whole new list of fun things to do as the game receives its first big update sometime soon. There are a lot of... | Read more »
Reigns: Her Majesty guide - how to use e...
Ruling a kingdom isn't easy--doubly so for a queen whose every decision is questioned by the other factions seeking a slice of power. Reigns: Her Majesty builds on the original game's swipey tactics, adding items that you can use to move the story... | Read more »
The best new games we played this week -...
Friday has crept up on us once again, so it's time to honor the best new games we've played over the past few days. This past week was a pretty exciting one, with the debut of lots of beautiful new indies and some familiar faces returning to the... | Read more »
Portal Knights guide- beginner tips and...
Portal Knights is finally making the jump to iOS and Android, and it's already climbing the ranks to become the next big MMO experience on mobile. This sprawling sandbox game will let you pursue any adventure you wish, whether you want to sling... | Read more »
Reigns: Her Majesty guide - how to swipe...
Reigns: Her Majesty is storming the App Store this week, bringing more tinder-esque kingdom building to eager players everywhere. If you've played the original Reigns, you'll know that leading a kingdom is never easy. It's a careful balancing act... | Read more »
Getting Over It (Games)
Getting Over It 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: A game I madeFor a certain kind of person To hurt them. • Climb up an enormous mountain with nothing but a hammer and a pot.•... | Read more »
Reigns: Her Majesty (Games)
Reigns: Her Majesty 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Pocket Legends Adventures guide - how to...
Pocket Legends Adventures is a fun action adventure RPG that takes control when you want it to, but also opens itself for player input, too, if you're looking to tkae a more active role in combat. Regardless of play style, the game can be quite... | Read more »
Portal Knights (Games)
Portal Knights 1.2.4 Device: iOS Universal Category: Games Price: $4.99, Version: 1.2.4 (iTunes) Description: Craft your adventure. Forge your hero. Become the ultimate Portal Knight! | Read more »

Price Scanner via MacPrices.net

Green Monday deal: 15″ 2.8GHz MacBook Pro on...
B&H Photo has the 15″ 2.8GHz Space Gray MacBook Pro on sale for $250 off MSRP for today only as part of their Green Monday/Holiday sale. Shipping is free, and B&H charges sales tax for NY... Read more
Green Monday sale: B&H offers 12″ Apple i...
B&H Photo has 12″ iPad Pros on sale for up to $150 off MSRP as part of their Green Monday/Holiday sale. Shipping is free, and B&H charges sales tax in NY & NJ only: – 12″ 64GB WiFi iPad... Read more
Holiday deal: 21″ and 27″ Apple iMacs on sale...
MacMall has 2017 21″ and 27″ Apple iMacs on sale for up to $200 off MSRP. Shipping is free: – 21″ 2.3GHz iMac: $999 $100 off MSRP – 21″ 3.0GHz iMac: $1199 $100 off MSRP – 21″ 3.4GHz iMac: $1379 $120... Read more
Holiday deal: Apple Mac minis for up to $150...
MacMall has Mac minis on sale for up to $100 off MSRP, each including free shipping: – 1.4GHz Mac mini: $399 $100 off MSRP – 2.6GHz Mac mini: $599 $100 off MSRP – 2.8GHz Mac mini: $949 $50 off MSRP... Read more
Beats by Dr. Dre – BeatsX Earphones on sale f...
Best Buy has BeatsX Earphones on sale for $109, $40 off, on their online store. Sale price for online orders only. Choose free store pickup, if available, or choose free shipping. Read more
10″ 64GB WiFi Apple iPad Pros on sale for $59...
MacMall has 10.5″ 64GB Apple iPad Pros on sale for $599 including free shipping. That’s $50 off MSRP and among the lowest prices available for these iPads from any Apple reseller. Read more
15″ 2.2GHz MacBook Pros on sale for $200-$300...
B&H Photo has the 15″ 2.2GHz MacBook Pro available for $200 off MSRP including free shipping plus NY & NJ sales tax only: – 15″ 2.2GHz MacBook Pro (MJLQ2LL/A): $1799 $200 off MSRP Apple has... Read more
Holiday sale: 15″ MacBook Pros for $200-$420...
MacMall has 15″ MacBook Pros on sale for $220-$300 off MSRP, each including free shipping: – 15″ 2.8GHz MacBook Pro Space Gray (MPTR2LL/A): $2179, $220 off MSRP – 15″ 2.8GHz MacBook Pro Silver (... Read more
Holiday sale: 13″ MacBook Airs for up to $150...
B&H Photo has 13″ MacBook Airs on sale for $100 off MSRP as part of their Holiday sale. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 1.8GHz/128GB MacBook... Read more
The best Holiday sale prices on 13″ MacBook P...
B&H Photo has 13″ MacBook Pros on sale this weekend, with models available for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
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 - Apple,...
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 - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Information Security - Security Data...
# Apple Information Security - Security Data Analyst Job Number: 113119545 Austin, Texas, United States Posted: 10-Nov-2017 Weekly Hours: 40.00 **Job Summary** This Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.