NetNews Usenet Archive 1992 #20

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Xref: sparky comp.sys.mac.programmer:15118 news.answers:2837 Path: sparky!uunet!elroy.jpl.nasa.gov!ames!olivea!mintaka.lcs.mit.edu!bloom-picayune.mit.edu!news From: mkelly@sisters.cs.uoregon.edu ((Michael A. Kelly)) Newsgroups: comp.sys.mac.programmer,news.answers Subject: Comp.Sys.Mac.Programmer Frequently Asked Questions Part 2/2 (8/3/92) Summary: Frequently Asked Questions list for comp.sys.mac.programmer Keywords: frequently asked questions faq Message-ID: <csmp-faq/part2_715928413@athena.mit.edu> Date: 8 Sep 92 05:04:06 GMT Expires: Tue, 29 Sep 1992 05:00:13 GMT References: <csmp-faq/part1_715928413@athena.mit.edu> Sender: news@athena.mit.edu (News system) Reply-To: mkelly@cs.uoregon.edu Followup-To: poster Organization: University of Oregon Computer and Information Sciences Dept. Lines: 718 Approved: news-answers-request@MIT.Edu Supersedes: <csmp-faq/part2_715323611@athena.mit.edu> X-Last-Updated: 1992/08/11 Nntp-Posting-Host: pit-manager.mit.edu Archive-name: csmp-faq/part2 Last-modified: 1992/08/03 +---------------------------------+ | Frequently Asked Questions List | | for Comp.Sys.Mac.Programmer | | August 3, 1992 | | PART TWO | +---------------------------------+ This FAQ list is automatically posted once a week to comp.sys.mac.programmer. It is also available via anonymous ftp from ftp.cs.uoregon.edu [128.223.8.8] (user name 'anonymous', your internet address as password) in the files /pub/mac/csmp-faq-1 and /pub/mac/csmp-faq-2. This FAQ list is maintained by Michael A. Kelly. He can be reached at the following addresses: Internet: mkelly@cs.uoregon.edu SnailMail: Computer Science Dept. University of Oregon Eugene, Oregon 97403 The purpose of the FAQ list is to answer some of the most common questions asked on this group, and to refer people left with unanswered questions to available sources of additional help. You should read the FAQ list before posting to comp.sys.mac.programmer. Submissions, comments, etcetera, should be sent to Michael Kelly, as above. All such material sent will be considered to have entered the public domain (and will be subject to editing) unless specific text to the contrary accompanies the message (which may render the submission unusable). Changes since July 24, 1992 --------------------------- - Fixed some typos. - Reorganized section 3. - Added 3.2.1, 3.2.2, 3.2.3, and 3.3.3. - Updated 3.1.2. - Updated 4.1 and 4.2, moved 4.7 to 4.8 and added 4.7. - Updated 6.8.1. Table of Contents ----------------- Part One (separate file) --------------------- I. Development Software 1. Compilers 2. Debuggers 3. Other Tools II. Apple Developer Programs 1. The Associates and Partners Programs 2. Apple Developer University 3. APDA 4. Developer CDs III. Sources of Information 1. Books and Periodicals 1. Technical Books 2. Teaching Books 3. Periodicals 2. Mailing Lists 1. Comp.Sys.Mac.Programmer Digest 2. Think Class Library Discussion 3. MacPsych 3. Miscellaneous 1. Usenet Mac Programmer's Guide (UMPG) 2. Kent Sandvik's Frequently Asked MPW C++ and MacApp Questions 3. Comp.Sys.Mac.FAQ IV. Archive Sites 1. ftp.apple.com [130.43.2.3] 2. sumex-aim.stanford.edu [36.44.0.6] 3. rascal.ics.utexas.edu [128.83.138.20] 4. mac.archive.umich.edu [141.211.164.153] 5. ftp.cs.uoregon.edu [128.223.8.8] 6. ics.uci.edu [128.195.1.1] 7. ftp.brown.edu [128.148.176.55] 8. comp.binaries.mac [newsgroup] V. One-liners 1. The Main Loop and Events 2. Menus 3. Resources 4. Windows, Alerts, and Dialogs 5. Drawing 6. Files 7. Interrupts and VBL Tasks 8. Handles and Pointers 9. General Part Two (this file) ------------------------- VI. Specific Questions Answered 1. The Main Loop and Events 1. How do you tell if a specific key is being pressed? 2. How can I get millisecond timing from the keyboard (or mouse)? 2. Menus 1. When do you put an ellipsis on the end of a menu item? 2. How do I get the menubar to disappear and re-appear? 3. What's the difference between the resource ID of a 'MENU' resource and the menuID field of that resource? 3. Windows, Alerts, and Dialogs 1. How do you put a border around the default button in a dialog? 4. Drawing 1. What is the fastest way to paint one pixel on the screen? 2. How do you draw directly into a pixmap without using QuickDraw? 3. How do you draw directly onto the screen without using QuickDraw? 4. What RGB value does the system use for dimmed buttons, menus and window titles? 5. Files 1. Why is the File Manager so hard to use? 2. How do you get a full pathname? 3. How do you set the SFGet/PutFile directory? 4. How do you access the application's data fork? 6. Handles and Pointers 1. When should I call MoveHHi? 2. Why does malloc/calloc keep crashing or returning NULL in Think C? 7. Standalone Code 1. How do I write an INIT? 8. General 1. How do I register signatures and file types with Apple? 2. How do I go about writing serial port communications? VII. Eternal Debates: 1. Why doesn't the Mac do preemptive multitasking? ============================================================================= =========================================== Section VI: Specific Questions Answered =========================================== 6.1 The Main Loop and Events ----------------------------- ---------------------------------------------------------- 6.1.1 How do you tell if a specific key is being pressed? ---------------------------------------------------------- Use GetKeys. GetKeys fills a 16-byte KeyMap structure with the state of every key. Each bit represents a single key on the keyboard; 1 means the key is down, 0 means it is up. Note that there can be a maximum of seven keys being pressed at a time - any of the modifier keys plus at most two other keys. Here's an example in C: Boolean IsKeyDown( unsigned short theKey ) // a keyboard-specific scan code for a key { unsigned char keyMap[16]; GetKeys( (void *) keyMap ); return ((keyMap[theKey>>3] >> (theKey & 7)) & 1); } ----------------------------------------------------------------------------- 6.1.2 I'm writing a psychology experiment. How can I get millisecond timing from the keyboard (or mouse)? ----------------------------------------------------------------------------- The simple answer is that you can't. Although the new time manager can call routines every couple of microseconds, input goes through the event manager, which only posts events about every 16 milliseconds. Thus, even if you poll the keyboard every 30 microseconds, you will not get better than 16 ms. resolution. If you really need millisecond accuracy, you need to use external hardware. The good news is that you probably don't need better than 16 ms. resolution anyway. Measuring with 16 ms. accuracy only increases the standard deviation of your RT means by about 4.8 msec. Read: Ulrich, R. and Giray, M. (1989). Time resolution of clocks: Effects on reaction time measurement -- Good news for bad clocks. British Journal of Mathematical and Statistical Psychology, 42, 1-12. By the way, there is a mailing list dedicated to running psychology experiments on the Mac. It frequently gets tied up in arguments about millisecond timing. The address to write to is macpsych-request@stolaf.edu. 6.2 Menus ---------- ------------------------------------------------------------- 6.2.1 When do you put an ellipsis on the end of a menu item? ------------------------------------------------------------- Put an ellipsis (...) at the end of any menu item which requires more information in order to complete or simply displays information. Usually this involves a dialog of some kind, be it modal or non modal. ----------------------------------------------------------- 6.2.2 How do I get the menubar to disappear and re-appear? ----------------------------------------------------------- A set of routines to do this in Pascal can be found in the Usenet Macintosh Programmer's Guide. You can also ftp some sample code in C from skinner.cs.uoregon.edu in /pub/mac/menu-bar.c. ----------------------------------------------------------------------------- 6.2.3 What's the difference between the resource ID of a 'MENU' resource and the menuID field of that resource? ----------------------------------------------------------------------------- The resource ID of a 'MENU' resource is just the resource ID - it has no hidden meaning. What is normally expected by beginning programmers is that the number that MenuSelect and MenuKey return is the resource ID of the menu. In fact, the number returned is the value of the menuID field of the menu, and has no relation to the resource ID of the menu. You can set the menuID to any number you want, but by convention it is expected to be the same as the resource ID of the menu. (You can change this value in ResEdit by opening the menu you wish to change, and selecting 'Edit Menu & MDEF ID...' from the MENU menu.) 6.3 Windows, Alerts, and Dialogs --------------------------------- --------------------------------------------------------------------- 6.3.1 How do you put a border around the default button in a dialog? --------------------------------------------------------------------- The most common way to do this is to create a dummy user item in the dialog, and use SetDItem to install a procedure that outlines the default button. The dialog's "Initially visible" bit should be false and you should call ShowWindow before calling ModalDialog; otherwise, if the button is very tall, part of the outline won't be drawn. Here is an example in C: /* This function draws a border around dialog item #1 */ pascal void OutlineDefault( DialogPtr theDialog, short theItem ) { Rect itemRect; Handle itemHandle; short itemType; short diameter; GetDItem( theDialog, 1, &itemType, &itemHandle, &itemRect ); diameter = (itemRect.bottom - itemRect.top) / 2 + 6; if ( diameter < 16 ) diameter = 16; PenSize( 3, 3 ); InsetRect( &itemRect, -4, -4 ); FrameRoundRect( &itemRect, diameter, diameter ); } /* Assume myDialog has been initialized, and item #4 is the dummy user item for outlining the default button. The following lines install the outlining procedure OutlineDefault into the user item, so that OutlineDefault will be called by the Dialog Manager each time the dialog needs to be redrawn. Depending on your compiler, you may have to cast OutlineDefault to a Handle. */ GetDItem( myDialog, 4, &itemType, &itemHandle, &itemRect ); SetDItem( myDialog, 4, itemType, OutlineDefault, &itemRect ); 6.4 Drawing ------------ ---------------------------------------------------------------- 6.4.1 What is the fastest way to paint one pixel on the screen? ---------------------------------------------------------------- Using QuickDraw, the fastest way to draw one pixel is MoveTo( x, y ); Line( 0, 0 ); making sure that the pen size is 1 by 1. This is about twice as fast as setting the pen size to 0 by 1 or 1 by 0 and calling Line( 1, 0 ) or Line( 0, 1 ), respectively. I'm not sure why.... See below for how to draw a pixel without using QuickDraw. ---------------------------------------------------------------------- 6.4.2 How do you draw directly into a pixmap without using QuickDraw? ---------------------------------------------------------------------- As an example, here is a routine that paints a single pixel in a pixmap. To use this procedure, you just have to know what 'value' to pass in. This depends on the current bit-depth of 'thePixMap.' The rightmost n bits of 'value' are used for the pixel value for depth = n. For depths of eight or less, the value of each pixel is an index into a color table. For depth = 16, each 16-bit pixel is interpreted as an RGB value, as follows: Bit: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Value: R R R R R G G G G G B B B B B U where R = Red, G = Green, B = Blue, and U = Unused. For depth = 32, each 32-bit pixel is interpreted as an RGB value as follows: Bit: 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 Value: A A A A A A A A R R R R R R R R Bit: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Value: G G G G G G G G B B B B B B B B where R = Red, G = Green, B = Blue, and A = Alpha. void SetPixel( short x, short y, long value, PixMapHandle thePixMap ) { unsigned long rowBytes; unsigned char mask; unsigned char shiftBits; unsigned char *thePixel; unsigned char pixelDepth; char mode = true32b; Boolean swapMode; swapMode = PixMap32Bit( thePixMap ); LockPixels( thePixMap ); rowBytes = (unsigned long) ((*thePixMap)->rowBytes & 0x1fff); thePixel = (unsigned char *) GetPixBaseAddr( thePixMap ); pixelDepth = (*thePixMap)->pixelSize; switch ( pixelDepth ) { case 1: case 2: case 4: case 8: thePixel += (rowBytes * y) + (((unsigned long) pixelDepth * x) / 8L); shiftBits = ((8 - pixelDepth) - ((x * pixelDepth) % 8)); mask = (unsigned char) ((1 << pixelDepth) - 1) << shiftBits; if ( swapMode ) { SwapMMUMode( &mode ); } *thePixel &= ~mask; *thePixel |= (unsigned char) value << shiftBits; break; case 16: thePixel += (rowBytes * y) + (2L * x); if ( swapMode ) { SwapMMUMode( &mode ); } *((unsigned short *)thePixel) = (unsigned short) value; break; case 32: thePixel += (rowBytes * y) + (4L * x); if ( swapMode ) { SwapMMUMode( &mode ); } *((unsigned long *)thePixel) = value; break; default: break; } if ( swapMode ) { SwapMMUMode( &mode ); } UnlockPixels( thePixMap ); } ------------------------------------------------------------------------ 6.4.3 How do you draw directly onto the screen without using QuickDraw? ------------------------------------------------------------------------ Get the pixmap for the monitor that you want to draw on, and send it to the above procedure. For example, to draw a red dot at position 10,10 on the main screen (if the main screen is in 32-bit mode): GDHandle theDevice; theDevice = GetMainDevice(); SetPixel( x, y, 0x00FF0000, (*theDevice)->gdPMap ); If you are drawing directly to the screen, you should always wrap your drawing with calls to ShieldCursor and ShowCursor. Some monitors such as the Radius Pivot series keep a virtual screen, and they don't update the real screen unless they have to. When you write directly to the screen, you're actually writing to the virtual screen, and your drawing won't show up on the real screen until the system has some other reason to update the monitor. Calling ShieldCursor each time you draw will force these systems to update the real screen when you expect them to. ----------------------------------------------------------------------- 6.4.4 What RGB value does the system use for dimmed buttons, menus and window titles? ----------------------------------------------------------------------- The gray color does not have a fixed RGB value. It is a weighted average of the foreground and background colors. To obtain the appropriate 'gray' color for a given foreground and background color, use the Palette Manager routine GetGray (documented in Inside Macintosh Volume VI). pascal Boolean GetGray( GDHandle device, const RGBColor *backGround, RGBColor *foreGround ) = {0x303C,0x1219,0xAAA2}; If at least one gray or intermediate color is available, GetGray stores the color in foreGround and returns true. If no gray is available, or, if you supplied two colors, no third distinguishable color is available, the foreGround parameter is unchanged and the function returns false. GetGray is not available in older versions of the system. Use Gestalt to determine whether it is available. 6.5 Files ---------- ---------------------------------------------- 6.5.1 Why is the File Manager so hard to use? ---------------------------------------------- Its always those pesky wdrn's that are the problem. Here is a summary of some of the things to know: vrn = volume reference number (small negative number; e.g. -2) wdrn = working directory reference number (large negative number; e.g. -32123) dirID = directory ID (small (but long integer!) positive number; e.g. 4123) - vrn's and wdrn's can be used interchangably for the most part. - A vrn represents either a volume, or the root directory of a volume. - A wdrn represents a directory on a volume. - A dirID represents nothing without a vrn or a wdrn. - A dirID overrides the directory otherwise specified by the vrn or wdrn unless it's zero, in which case it's ignored. If it is 2 it specifies the root directory of the volume. - You should always use vrn,dirID pairs. To convert a wdrn into a vrn,dirID pair use GetWDInfo, which returns the vRefNum, the dirID and the procID of the wdRefNum. The procID is almost always 'ERIK'. - You can also use GetVol/SetVol to convert volume names to/from vrns. - To store a vrn,dirID pair (between invocations of a program) convert the vrn to a volume name & creation date (for verification) and store them and the dirID (and a filename perhaps). -------------------------------------- 6.5.2 How do you get a full pathname? -------------------------------------- Take a look at Tech Note #238, available from APDA (and other places). It tells you everything you need to know to get a full pathname, and why you should, in general, use a volume name, dirID, filename (and perhaps volume creation date) triple instead. Also check out the code snippets available from ftp.apple.com et al. There are a couple of snippets that give code to get a full pathname, as well as many other cool file manager tricks. -------------------------------------------------- 6.5.3 How do you set the SFGet/PutFile directory? -------------------------------------------------- To set the directory that is displayed by SFGet/PutFile, stuff the volume reference number into SFSaveDisk, and the dirID into CurDirStore. CurDirStore = $398; Current dirID from Standard File (long) SFSaveDisk = $214; Negative of current vRefNum ----------------------------------------------------- 6.5.3 How do you access the application's data fork? ----------------------------------------------------- Call CurResFile when the application starts up. Call PBGetFCBInfo to convert that refNum into a vRefNum, dirID and name. Call HOpen with the vRefNum, dirID, and name to open up your data fork. 6.6 Handles and Pointers ------------------------- ---------------------------------- 6.6.1 When should I call MoveHHi? ---------------------------------- MoveHHi is an expensive operation; calling it when you don't need to can significantly slow down your program. Additionally, over-calling of MoveHHi can fragment the top of your heap. Call MoveHHi before locking a handle that is followed by some memory allocation. To efficiently move a handle high in the heap and then lock it, you might want to call HLockHi, a call new with MPW 3.2 and THINK C 5.0 (probably THINK Pascal 4.0 as well). ------------------------------------------------------------------------- 6.6.2 Why does malloc/calloc keep crashing or returning NULL in Think C? ------------------------------------------------------------------------- #include <stdlib.h> Explanation: In THINK C, parameters and return values are 2-byte ints by default, which causes the value passed to malloc to be $10000 times as large as you think it is, and causes the upper bytes of the return value to be zeroed. Including stdlib includes a prototype which overrides the defaults. Another common cause of problems with malloc is overwriting the end of a string, such as only mallocing the size of the string and then writing the string plus a null into the malloc'd space. Think's malloc algorithm stores block size information in space adjacent to the storage it allocates, so overwriting the storage tends to cause havoc. The problem may not show immediately since it will probably be the next malloc that encounters problems. 6.7 Standalone Code -------------------- ------------------------------ 6.7.1 How do I write an INIT? ------------------------------ There is a simple INIT (SetWindow INIT) with source code and explanations in the Usenet Macintosh Programmer's Guide. There is also a chapter on writing system extensions in Macintosh Programming Secrets (2nd Ed.). Be sure to check out the ftp sites (especially ftp.apple.com) for sample inits. 6.8 General ------------ -------------------------------------------------------------- 6.8.1 How do I register signatures and file types with Apple? -------------------------------------------------------------- Registering a signature and file type is free, and you don't have to be an Apple Partner or Associate. You can ftp the registration form from ftp.apple.com; it's available as /dts/mac/registration/creator-file-type-form.txt. ------------------------------------------------------------------------- 6.8.2 How do I go about writing serial port communications? These days, it is best to use the new Comunications Toolbox (CTB). By utiizing the CTB, you will be able to write your code to a single specification, and the code will work with all current CTB "tools" and all future CTB tools. The CTB tools allow programmers to extend the CTB's functionality. There is a tool for each facet of the communications puzzle: Connection Tools, Terminal Tools, and File Transfer Tools. For example, once I have written a piece of code that uses the Serial tool to connect me to a terminal server, combined with the VT102 Tool to emulate a vt102 terminal, and the XMODEM Macbinary Tool to transfer files, the same code will work with Apple Modem Tool, TCP/IP, AppleTalk ADSP, ISDN, X.25, and all future Connection Tools. Further, the terminal can emulate a VT320, ASCII, or other terminals. Files may be transfered with XMODEM, TEXT, and soon ZMODEM and Kermit protocols. The disadvantage of the CTB is that you must limit yourself to the specification of the Connection, Terminal, and File Transfer interfaces. These limitations are *rarely* a problem, but clearly something like a FAX interface program or real time data analyzer, would have to seriously consider the interfaces before committing. For most standard communications applications, such as terminal emulators, Bulletin Board Systems, etc., the CTB is the correct choice. You can only get the CTB development kit from APDA. It is affordable, somewhere just under $100. This includes working sample code. ================================ Section VII: Eternal Debates ================================ These questions have no final answers. They pop up every few months and waste a tremendous amount of valuable network resources on discussions that will never be resolved. Most people would be happy if they were never discussed again in this newsgroup. 7.1 Why doesn't the Mac do preemptive multitasking? ---------------------------------------------------- Pro-preemptives claim the current scheme is too vulnerable to ill-behaved applications and too much trouble for application writers. Anti- preemptives claim that preemptive multitasking would reduce interactive response, and that the current cooperative system works well. ============================== Credits / Acknowledgements ============================== Many thanks to Ben Haller, who started this whole thing, and did quite a lot of work on this posting before handing it off to me. Thanks to these people for proofreading this list during its development: Ben Haller Wally Wedel John B. Matthews Patrick Beard Steve Zellers Thanks to Chris Webster for the one-liners. Thanks to Peter Lewis for the answers to the following specific questions: 6.2.1 When do you put an ellipsis on the end of a menu item? 6.5.1 Why is the File Manager so hard to use? 6.5.2 How do you get a full pathname? 6.5.3 How do you set the SFGet/PutFile directory? Thanks to Greg Ferrar for the review on TMON Pro. Thanks to John Rinaldo for the review on Jasik's Debugger. And thanks to everyone who has offered suggestions or constructive criticism.... Keep those comments coming!