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

calibre 3.1.1 - Complete e-book library...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
Sparkle Pro 2.2 - $79.99
Sparkle Pro will change your mind if you thought building websites wasn't for you. Sparkle is the intuitive site builder that lets you create sites for your online portfolio, team or band pages, or... Read more
Spotify 1.0.57.474. - 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
beaTunes 5.0.1 - Organize your music col...
beaTunes is a full-featured music player and organizational tool for music collections. How well organized is your music library? Are your artists always spelled the same way? Any R.E.M. vs REM?... Read more
LibreOffice 5.3.4.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more
VOX 2.8.26 - Music player that supports...
VOX just sounds better! The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features and support for all audio formats you should ever need.... Read more
iFFmpeg 6.4.0 - 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
Beamer 3.3 - Stream any movie file from...
Beamer streams to your Apple TV.... Plays any movie file - Just like the popular desktop movie players, Beamer accepts all common formats, codecs and resolutions. AVI, MKV, MOV, MP4, WMV, FLV. To... Read more
jAlbum Pro 14.0 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. You can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly... Read more
Apple Remote Desktop Client 3.9.3 - Clie...
Apple Remote Desktop Client is the best way to manage the Mac computers on your network. Distribute software, provide real-time online help to end users, create detailed software and hardware reports... Read more

Latest Forum Discussions

See All

This War of Mine gets a new ending and m...
This War of Mine just got a big new update, featuring free DLC that adds a new ending to the game, among other exciting changes. The update is celebrating the game's two-year release anniversary. Apart from the new ending, which will be quite... | Read more »
Summon eight new heroes in Fire Emblem H...
Nintendo keeps coming at us with Fire Emblem Heroes updates, and it doesn't look like that trend is stopping anytime soon. The folks behind the game have just announced the new War of the Clerics Voting Gauntlet, expected to start next Tuesday. [... | Read more »
The best deals on the App Store this wee...
iOS publishers are pulling out all the stops this week -- there's a huge number of seriously great games at discounted prices this week. Let's not waste any time and get right down to business. [Read more] | Read more »
The House of da Vinci (Games)
The House of da Vinci 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Enter The House of Da Vinci, a new must-try 3D puzzle adventure game. Solve mechanical puzzles, discover hidden... | Read more »
Solve the disappearance of history’s gre...
Blue Brain Games invites you to indulge in an immersive hands-on 3D puzzle adventure in similar vein to The Room series, with its debut release The House of Da Vinci. Set during the historic period of the Italian Renaissance (when Leonardo himself... | Read more »
Age of Rivals (Games)
Age of Rivals 3.3 Device: iOS Universal Category: Games Price: $.99, Version: 3.3 (iTunes) Description: Deep civilization-building strategy in a fast-paced card game! | Read more »
Panthera Frontier (Games)
Panthera Frontier 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Angry Birds Evolution beginner's gu...
Angry Birds changes things up a fair bit in its latest iteration, Angry Birds Evolution. The familiar sling-shot physics mechanics are still there, but the game now features team-based gameplay, RPG elements, and a new top-down view. With all of... | Read more »
Sega Forever is for the retro game fans
Sega is launching a new retro games service titled Sega Forever, in a move that's sure to delight games enthusiasts with a bit of nostalgia. Sega's releasing five classic games for free. The titles include Sonic the Hedgehog, Phantasy Star II,... | Read more »
The Little Acre (Games)
The Little Acre 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

ABBYY TextGrabber 6 for iOS Implements Instan...
ABBYY has announced the release of TextGrabber 6.0.0, an important feature update to the company’s productivity app developed for iOS and Android devices. TextGrabber 6.0 now offers Real-Time... Read more
vPhone, First Smartphone That Can’t Be Lost,...
Austin, Texas based Hypori has introduced the vPhone, a virtual smartphone that affords every business user the benefits of separate work and personal phones, conveniently delivered on a single... Read more
Save this weekend with 2016 refurbished MacBo...
Apple has dropped prices on Certified Refurbished 2016 15″ and 13″ MacBook Pros by as much as $590 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: -... Read more
New 27-inch 3.4GHz iMac on sale for $1699, sa...
MacMall has the new 2017 27″ 3.4GHz iMac (MNE92LL/A) in stock and on sale for $1699 including free shipping. Their price is $100 off MSRP. Read more
Clearance 2016 MacBook Pros available for up...
B&H Photo has clearance 2016 13″ and 15″ MacBook Pros in stock today and on sale for up to $400 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: - 15″ 2.7GHz... Read more
Apple Ranks 9th In comScore Top 50 U.S. Digit...
comScore, Inc. has released its monthly ranking of U.S. online activity at the top digital media properties for May 2017 based on data from comScore Media Metrix Multi-Platform. * Entity has... Read more
10.5-inch iPad Pros available for up to $20 o...
B&H Photo has the new 2017 10.5″ iPad Pros available for up to $20 off MSRP including free shipping plus NY & NJ sales tax only: - 64GB iPad Pro WiFi: $649 - 256GB iPad Pro WiFi: $749 - 512GB... Read more
Three Off-The-Beaten-Track iOS Apps That Dese...
One of the great things about using iPads and iPhones is the vast selection of apps available for most anything you want or need to do. The three outlined in this article have been in my core app... Read more
Apple No. 1 Spot In Gartner Top 100 Vendors i...
Gartner, Inc. has unveiled the top global 100 vendors in IT in 2016 based on their revenue across IT (excluding communication services) and component market segments. In the Gartner Global Top 100:... Read more
Clearance iMacs available for up to $300 off...
B&H Photo has clearance 21″ and 27″ Apple iMacs available starting at $949, each including free shipping plus NY & NJ sales tax only: - 27″ 3.3GHz iMac 5K: $1999 $300 off original MSRP - 27″... Read more

Jobs Board

*Apple* News Product Marketing Mgr., Publish...
…organizational consensus on strategy and vision for publisher tools, authoring, and Apple News Format.Carries this strategy and vision across the organization to 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
Security Data Analyst - *Apple* Information...
…data sources need to be collected to allow Information Security to better protect Apple employees and customers from a wide range of threats.Act as the subject matter Read more
Lead *Apple* Solutions Consultant - Apple I...
…integrity, and trust.Success Metrics/Key Performance Indicators:Quantitative* Year over Year growth in Apple Product and Beyond the Box sales in the assigned Point of Read more
*Apple* Solutions Consultant till v%u00E5r...
…ethics, integrity, and trust.Success Metrics/Key Performance Indicators:QuantitativeYear over Year growth in Apple Product and Beyond the Box sales in the assigned Point Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.