TweetFollow Us on Twitter

File Dialog
Volume Number:3
Issue Number:2
Column Tag:ToolBox Tricks

Not So Standard File Dialogs

By Paul Snively, Contributing Editor, Icom Simulations, Inc.

Last month I discussed how INIT resources could be debugged using TMON, as I did in developing my Set/Boot Paths desk accessory, used in TML Pascal 2.0. Set Paths allows the user to specify what path to use via what I prefer to call the Not-So-Standard File dialog. It's Not-So-Standard because it doesn't display file names at all, only folder names. That's not so weird (nor is it particularly difficult to code), but the "Open" button has become "Select" and, the tricky part, double-clicking on a folder name opens it exactly the way you'd expect, whereas highlighting a folder name and clicking on "Select" returns you to your program with pertinent information about the selection.

Experienced Standard File hackers may knot their brows at this (as I did when I was asked to do it that way) because they know that the Standard File internally coerces double-clicks on names to be a single click followed by a click on the "Open" button, so that the Standard File hook can filter double-clicks. The trick, then, is being able to use a user-written Standard File hook to distinguish between a double-clicked name and a selected name followed by a "Select" click.

Note that my solution is a kludge by just about any definition of the word, and would be universally spurned (even by me) were it not for one simple, overriding fact: it does NOT rely on internal knowledge of Standard File's workings AT ALL, and it was simple and obvious enough to have gone from concept to implementation in less than twelve hours (an important consideration for me; I modemed the resultant files to TML Systems Sunday evening; TML Pascal 2.0 started shipping the next day)!

To start off on an embarrassing note, in the process of writing Set Paths I discovered a bug in my McAssembly Pascal interface macros. Those were published in MacTutor Vol. 2, No. 3, in March 1986, which says two things to me: I need to be more careful in my testing of things before I publish them, and no one has done anything significant with those macros, otherwise they would have encountered the bug and, hopefully, written a letter to the editor about it! I'm profoundly disappointed

Anyway, the bug is in the "Exit" macro. There's a line which is responsible for adjusting the stack back to normal by dropping input parameters. It says:

add.l    #.fsize-.parms,sp

This is a definite boo-boo, because it totally neglects the space that we allocated for the stacked A6 register and the return address of the function. The line SHOULD read:

add.l   #.fsize-.parms-8,sp.

Boy, do I feel appropriately chastized!

Having cleared that up, I can talk safely about using those macros to implement the Not-So-Standard File dialog.

First we need to come up with a way to display NO files at all. The first time I tackled this, ol' Paul thought he'd be tricky and just set the numTypes parameter to _SFGetFile to zero, thereby forcing _SFGetFile to ignore all files, right? Wrong! Even though I had a typeList consisting of all zeros and a numTypes of zero, _SFGetFile insisted on displaying ALL files on the volume, and it took forever to do it, too!

I decided to do something about the INCREDIBLY slow response I was getting from the above scheme. Besides, it didn't work! I changed numTypes to one and used a fileType of '????' to get as few files as possible (theoretically zero). Since every so often you will indeed see a file of type '????' it behooved me to ensure that they didn't show up in the file list. To do that I had to use that fileFilter that I had tried to avoid.

The fileFilter proc is, like most such things for the Macintosh, designed with the expectation that it will be written conforming to Pascal-style parameter passing conventions. It is (in Pascal terms, anyway) a function, not a procedure, since it returns a value. It takes one parameter, a pointer to a low-level parameter block a lá the file system, and returns a boolean. It seems a little backwards: the boolean should be TRUE if the file is NOT to be displayed, and FALSE if the file IS to be displayed. So, since we want to display NO files, we should simply set the boolean to TRUE and we are done! In Pascal this would look something like this:

FUNCTION MyFileFilter(PB : ParamBlockRec;) : BOOLEAN;

BEGIN {MyFileFilter} 
 MyFileFilter := TRUE;
END; {MyFileFilter}

In McAssembly, with my Pascal macros, it's almost as easy: (See MacTutor Vol. 2, No. 3 March 1986 for the definition of these Macros.)

 MyFileFilter  EQU *
 ;
 SFBegin
 WordResult MyFilterResult
 Long   MyParamBlock
 SFEnd
 ;
 Enter
 move.w #-1,MyFilterResult
 Exit

The combination of the file type of '????' and the above fileFilter works like a charm; by golly, no files show up!

SFHook

The remaining magic is in an underdiscussed piece of code called a SFHook. Apple describes the SFHook as something that can be used to make a non-standard get or put file (which I almost do) or to make the normal one behave in non-standard ways (which is EXACTLY what I do)!

The SFHook is also a Pascal-like entity; it takes two parameters; the item number (an integer), and the DialogPtr to the Standard File dialog. It returns an integer (an item number also, although it may or may not be the same as the one that was passed to it)!

The SFHook is called constantly throughout the operation of the Standard File dialog; it's called before the dialog is drawn, it's called when there are significant events, and it's even called when there are NO significant events!

The key to understanding the Standard File dialog as it applies to writing a SFHook is the item number. The item number is ordinarily simply the item number of whatever the user clicked on in the dialog box. In addition to that there have always been a few "phony" items numbers, such as item # 100 (which is what was passed when nothing interesting was going on) or keystrokes (item # 1000 plus the ASCII value of the key). Another useful value is -1, which is the value passed before the dialog is displayed. By trapping on this value we can do neat things like changing the title of the "Open" button to "Select." You'll see an example of that a bit later.

The introduction of HFS added a whole new wrinkle to the issue of the Standard File dialog. It had to be expanded in a way that retained the power and flexibility of the original design, yet also remain upwardly compatible. WDRefNum's and a few new phony item numbers fit the bill rather nicely.

As all users of the Standard File dialog are aware of at one level or another, "Opening" a folder doesn't return you to the application, it simply makes that folder the current directory and shows you the files in it, etc. You must open a FILE to get back from _SFGetFile.

Internally what happens is that opening a folder passes a phony item # 103 to the SFHook, as opposed to a file open, which passes item # 1 (the item # of the "Open" button). So we could catch the 103, coerce it to a 1, and pass it back. The problem there, of course, is the one mentioned before: double-clicks on filenames and filename select/"Open" click sequences are equivalent by the time you get to the SFHook! The result is that double-clicking on a foldername returns from _SFGetFile just as surely as selecting one and clicking "Open" does!

Argh!!!

Ok, enough beating around the bush. Obviously the solution to the problem is to find out which item we clicked on, the file list or the "Select" button. I decided that the Mac was fast enough that I could determine within the SFHook where the mouse was, check to see if it was over the file list and, if it was not, coerce the 103 to a 1. Fortunately, one of the things passed to the SFHook is the DialogPtr, making calls to _GetDItem possible. Among other things, _GetDItem returns the viewRect of the item - just what the doctor ordered! _GetMouse gives us our mouse location in local coordinates (another stroke of luck) and _PtInRect answers the burning question: are we pointing to this item or aren't we?

Pulling it all together into a nice, not-so-neat package gives us the following:

UseSF  move.w  #100,-(sp) Top = 100
 move.w #100,-(sp) Left = 100
 pea  PromptString Use promptstring
 pea  myFileFilter Use brief fileFilter
 move.w #1,-(sp) No. of filetypes
 pea  MyListPoint to my list
 pea  myDlgHook  Point to our dlgHook
 pea  myReplyRec Point to reply rec
 _SFGetFile Use std file dialog
 
myDlgHook
;
 sfbeginDeclare stack frame
 wordresult myDlgResult Function result
 word mySFItem Which item was hit?
 long theDialog  SFGetFile dialog ptr
 sfend  That's all!
;
 enter  Set up stack frame
 move.w mySFItem,d0Get the item#
 cmp.w  #-1,d0 Is this first time?
 bne  NotFirst Go if not
 sub.l  #14,sp Room for VAR params
 move.l theDialog,-(sp) Stack DialogPtr
 move.w #getOpen,-(sp)  Stack item # of "Open"
 pea  18(sp)VAR itemType
 pea  18(sp)VAR itemHandle
 pea  14(sp)VAR dispRect
 _GetDItemTell me about button
 movea.l8(sp),a0 Get handle
 add.l  #14,sp Drop data structure
 move.l a0,-(sp) Stack item handle
 pea  myTitle  Pass title address
 _SetCTitle Make title = STR
 moveq  #-1,d0 Make sure we're here
NotFirstequ *
 cmp.w  #103,d0  Was it "Select?"
 bne.s  NotSelectGo if not
;***********************************************************
;***  This is where we will do all kinds of nifty magic ***
;**********************************************************
 sub.l  #14,sp Room for VAR params
 move.l theDialog,-(sp) Stack DialogPtr
 move.w #7,-(sp) Stack File List item#
 pea  18(sp)VAR itemType
 pea  18(sp)VAR itemHandle
 pea  14(sp)VAR dispRect
 _GetDItemTell me about File List
 clr.l  -(sp)  Room for pt
 pea  (sp)Point to the point
 _GetMouseHere, mousie, mousie...
 pea  4(sp) Point to the rect
 _PtInRectAre we in File List?
 move.w #103,d0  Just to make sure
 move.b (sp)+,d1 Get answer
 add.l  #12,sp Drop remaining data
 bne.s  NotSelectIf in File List, leave
 move.w #1,d0  Treat like file open
NotSelect equ  *
 move.w d0,myDlgResult  Store function result
 exit   Exit the function
;
myFileFilterequ  *
 loc  New locals here; needed for McAssembly
;
 sfbeginStack Frame Begin
 wordresult myFilterResultA boolean
 long parmBlkPtr A pointer
 sfend  Stack Frame End
;
 enter  Set up stack frame
 move.w #-1,myFilterResultTRUE;
 exit   Clean up and leave
;
PromptStringequ  *
 text # "Highlight a folder and click /"Select/""
 align
myTitle equ *
 text # "Select" title for "Open" button
 align
myList  equ *
 text "????"Any old file type will do
 dcb.b  12,0Remaining are nulls

Now that I've given the code that does the trick, I should probably say a few words about how the replyRec looks when you've opened a folder instead of a file.

First of all, you can forget about the fName field. It won't be valid. Instead, vRefNum will contain the vRefNum of the folder, just like it does for a file, and - get this - fType will return the DirID of the folder ("Sorry about the type conflict," says Apple in the software supplement...obviously talking to Pascal programmers). Of course, the vRefNum and DirID are sufficient for all HFS OSTraps that deal with folders or files within a specific folder. Another thing that you can do if you want or need to is convert the vRefNum and DirID to a pathname extending from the root to the folder (or more precisely, from the folder to the root). One implementation of that algorithm appeared in MacTutor's special HFS issue (January '86). It was written in C by Mike Schuster. Translating it to the language of the reader's choice is an exercise left to the reader (the assembler version is actually rather simple).

That just about covers it. Feel free to use the Not-So-Standard File dialog anytime you have a reason to want to select a folder instead of a file!

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

PhotoDesk 4.1.5 - Instagram client for p...
PhotoDesk lets you view, like, comment, and download Instagram pictures/videos. (NO Uploads! / Image Posting! Instagram forbids that! AND you need an existing Instagram account). But you can do so... Read more
Capo 3.5.1 - Slow down and learn to play...
Capo lets you slow down your favorite songs so you can hear the notes and learn how they are played. With Capo, you can quickly tab out your songs atop a highly-detailed OpenCL-powered spectrogram... Read more
HandBrake 1.0.2 - Versatile video encode...
HandBrake is a tool for converting video from nearly any format to a selection of modern, widely supported codecs. Features Supported Sources VIDEO_TS folder, DVD image or real DVD (unencrypted... Read more
Sound Studio 4.8.6 - Robust audio record...
Sound Studio lets you easily record and professionally edit audio on your Mac. Easily rip vinyls and digitize cassette tapes, or record lectures and voice memos. Prepare for live shows with live... Read more
HandBrake 1.0.2 - Versatile video encode...
HandBrake is a tool for converting video from nearly any format to a selection of modern, widely supported codecs. Features Supported Sources VIDEO_TS folder, DVD image or real DVD (unencrypted... Read more
PhotoDesk 4.1.5 - Instagram client for p...
PhotoDesk lets you view, like, comment, and download Instagram pictures/videos. (NO Uploads! / Image Posting! Instagram forbids that! AND you need an existing Instagram account). But you can do so... Read more
Sound Studio 4.8.6 - Robust audio record...
Sound Studio lets you easily record and professionally edit audio on your Mac. Easily rip vinyls and digitize cassette tapes, or record lectures and voice memos. Prepare for live shows with live... Read more
Capo 3.5.1 - Slow down and learn to play...
Capo lets you slow down your favorite songs so you can hear the notes and learn how they are played. With Capo, you can quickly tab out your songs atop a highly-detailed OpenCL-powered spectrogram... Read more
Google Earth 7.1.8.3036 - View and contr...
Google Earth gives you a wealth of imagery and geographic information. Explore destinations like Maui and Paris, or browse content from Wikipedia, National Geographic, and more. Google Earth combines... Read more
QuickBooks 16.1.11.1556 R12 - Financial...
QuickBooks helps you manage your business easily and efficiently. Organize your finances all in one place, track money going in and out of your business, and spot areas where you can save. Built for... Read more

Super Mario Run dashes onto Android in M...
Super Mario Run was one of the biggest mobile launches in 2016 before it was met with a lukewarm response by many. While the game itself plays a treat, it's pretty hard to swallow the steep price for the full game. With that said, Android users... | Read more »
WarFriends Beginner's Guide: How to...
Chillingo's new game, WarFriends, is finally available world wide, and so far it's a refreshing change from common mobile game trends. The game's a mix of tower defense, third person shooter, and collectible card game. There's a lot to unpack here... | Read more »
Super Gridland (Entertainment)
Super Gridland 1.0 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 1.0 (iTunes) Description: Match. Build. Survive. "exquisitely tuned" - Rock Paper Shotgun No in-app purches, and no ads! | Read more »
Red's Kingdom (Games)
Red's Kingdom 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Mad King Mac has kidnapped your father and stolen your golden nut! Solve puzzles and battle goons as you explore and battle your... | Read more »
Turbo League Guide: How to tame the cont...
| Read more »
Fire Emblem: Heroes coming to Google Pla...
Nintendo gave us our first look at Fire Emblem: Heroes, the upcoming mobile Fire Emblem game the company hinted at last year. Revealed at the Fire Emblem Direct event held today, the game will condense the series' tactical RPG combat into bite-... | Read more »
ReSlice (Music)
ReSlice 1.0 Device: iOS Universal Category: Music Price: $9.99, Version: 1.0 (iTunes) Description: Audio Slice Machine Slice your audio samples with ReSlice and create flexible musical atoms which can be triggered by MIDI notes or... | Read more »
Stickman Surfer rides in with the tide t...
Stickson is back and this time he's taken up yet another extreme sport - surfing. Stickman Surfer is out this Thursday on both iOS and Android, so if you've been following the other Stickman adventures, you might be interested in picking this one... | Read more »
Z-Exemplar (Games)
Z-Exemplar 1.4 Device: iOS Universal Category: Games Price: $3.99, Version: 1.4 (iTunes) Description: | Read more »
5 dastardly difficult roguelikes like th...
Edmund McMillen's popular roguelike creation The Binding of Isaac: Rebirth has finally crawled onto mobile devices. It's a grotesque dual-stick shooter that tosses you into an endless, procedurally generated basement as you, the pitiable Isaac,... | Read more »

Price Scanner via MacPrices.net

12-inch 1.2GHz Space Gray Retina MacBook on s...
Amazon has the 2016 12″ 1.2GHz/512GB Space Gray Retina MacBook (Apple model #MLH82LL/A) on sale for $1299.99 including free shipping. Their price is $300 off MSRP. Read more
Twelve South Releases RelaxedLeather Cases fo...
Inspired by the laid-back luxury of burnished leather boots and crafted in rich tones of taupe, herb and marsala, RelaxedLeather cases deliver smart, easy protection for the iPhone 7. Each genuine... Read more
Week’s Best Deal: New 2016 13-inch 2.0GHz Mac...
Amazon has the new 2016 13″ 2.0GHz non-Touch Bar MacBook Pros on sale for a limited time for $225 off MSRP including free shipping: - 13″ 2.0GHz MacBook Pro, Space Gray (MLL42LL/A): $1274.99 $225 off... Read more
Back in stock: Apple refurbished Mac minis fr...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
Apple Ranked ‘Most Intimate Brand’
The top ranked ‘”intimate” brands continued to outperform the S&P and Fortune 500 indices in revenue and profit over the past 10 years, according to MBLM’s Brand Intimacy 2017 Report, the largest... Read more
B-Eng introduces SSD Health Check for Mac OS
Fehraltorf, Switzerland based independant Swiss company- B-Eng has announced the release and immediate availability of SSD Health Check 1.0, the company’s new hard drive utility for Mac OS X. As the... Read more
Apple’s Education discount saves up to $300 o...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free: -... Read more
4-core 3.7GHz Mac Pro on sale for $2290, save...
Guitar Center has the 3.7GHz 4-core Mac Pro (MD253LL/A) on sale for $2289.97 including free shipping or free local store pickup (if available). Their price is a $710 savings over standard MSRP for... Read more
128GB Apple iPad Air 2, refurbished, availabl...
Apple has Certified Refurbished 128GB iPad Air 2s WiFis available for $419 including free shipping. That’s an $80 savings over standard MSRP for this model. A standard Apple one-year warranty is... Read more
13-inch 2.7GHz Retina MacBook Pro on sale for...
B&H Photo has the 2015 13″ 2.7GHz/128GB Retina Apple MacBook Pro on sale for $100 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro (MF839LL/A): $... Read more

Jobs Board

*Apple* macOS Systems Integration Administra...
…most exceptional support available in the industry. SCI is seeking an Junior Apple macOS systems integration administrator that will be responsible for providing Read more
*Apple* Retail - Multiple Positions- Deer Pa...
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: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Technician - nfrastructure (United S...
Let’s Work Together Apple Technician This position is based in Portland, ME Life at nfrastructure At nfrastructure, we understand that our success results from our Read more
*Apple* Mobile Master - Best Buy (United Sta...
**467692BR** **Job Title:** Apple Mobile Master **Location Number:** 000602-Columbia MO-Store **Job Description:** **What does a Best Buy Apple Mobile Master Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.