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

Microsoft Remote Desktop 8.0.19 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
OmniGraffle 6.3 - Create diagrams, flow...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more
PDFKey Pro 4.3.2 - Edit and print passwo...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Ableton Live 9.2.2 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Macs Fan Control 1.3.1.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more
NetShade 6.3.1 - Browse privately using...
NetShade is an anonymous proxy and VPN app+service for Mac. Unblock your Internet through NetShade's high-speed proxy and VPN servers spanning seven countries. NetShade masks your IP address as you... Read more
Dragon Dictate 4.0.7 - Premium voice-rec...
With Dragon Dictate speech recognition software, you can use your voice to create and edit text or interact with your favorite Mac applications. Far more than just speech-to-text, Dragon Dictate lets... Read more
Persecond 1.0.2 - Timelapse video made e...
Persecond is the easy, fun way to create a beautiful timelapse video. Import an image sequence from any camera, trim the length of your video, adjust the speed and playback direction, and you’re done... Read more
GIMP 2.8.14p2 - Powerful, free image edi...
GIMP is a multi-platform photo manipulation tool. GIMP is an acronym for GNU Image Manipulation Program. The GIMP is suitable for a variety of image manipulation tasks, including photo retouching,... Read more
Sandvox 2.10.2 - Easily build eye-catchi...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more

ReBoard: Revolutionary Keyboard (Utilit...
ReBoard: Revolutionary Keyboard 1.0 Device: iOS Universal Category: Utilities Price: $1.99, Version: 1.0 (iTunes) Description: Do everything within the keyboard without switching apps! If you are in WhatsApp, how do you schedule a... | Read more »
Tiny Empire (Games)
Tiny Empire 1.1.3 Device: iOS Universal Category: Games Price: $2.99, Version: 1.1.3 (iTunes) Description: Launch cannonballs and blow tiny orcs into thousands of pieces in this intuitive fantasy-themed puzzle shooter! Embark on an... | Read more »
Astropad Mini (Productivity)
Astropad Mini 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: *** 50% off introductory price! ​*** Get the high-end experience of a Wacom tablet at a fraction of the price with Astropad... | Read more »
Emo Chorus (Music)
Emo Chorus 1.0.0 Device: iOS Universal Category: Music Price: $1.99, Version: 1.0.0 (iTunes) Description: Realistic Choir simulator ranging from simple Chorus emulation to full ensemble Choir with 128 members. ### introductory offer... | Read more »
Forest Spirit (Games)
Forest Spirit 1.0.5 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.5 (iTunes) Description: | Read more »
Ski Safari 2 (Games)
Ski Safari 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: The world's most fantastical, fun, family-friendly skiing game is back and better than ever! Play as Sven's sister Evana, share... | Read more »
Lara Croft GO (Games)
Lara Croft GO 1.0.47768 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.47768 (iTunes) Description: Lara Croft GO is a turn based puzzle-adventure set in a long-forgotten world. Explore the ruins of an ancient... | Read more »
Whispering Willows (Games)
Whispering Willows 1.23 Device: iOS Universal Category: Games Price: $4.99, Version: 1.23 (iTunes) Description: **LAUNCH SALE 50% OFF** - Whispering Willows is on sale for 50% off ($4.99) until September 9th. | Read more »
Calvino Noir (Games)
Calvino Noir 1.1 Device: iOS iPhone Category: Games Price: $3.99, Version: 1.1 (iTunes) Description: The film noir stealth game. Calvino Noir is the exploratory, sneaking adventure through the 1930s European criminal underworld.... | Read more »
Angel Sword (Games)
Angel Sword 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Prepare to adventure in the most epic full scale multiplayer 3D RPG for mobile! Experience amazing detailed graphics in full HD.... | Read more »

Price Scanner via MacPrices.net

Apple and Cisco Partner to Deliver Fast-Lane...
Apple and Cisco have announced a partnership to create a “fast lane” for iOS business users by optimizing Cisco networks for iOS devices and apps. The alliance integrates iPhone with Cisco enterprise... Read more
Apple offering refurbished 2015 13-inch Retin...
The Apple Store is offering Apple Certified Refurbished 2015 13″ Retina MacBook Pros for up to $270 (15%) off the cost of new models. An Apple one-year warranty is included with each model, and... Read more
Apple refurbished 2015 MacBook Airs available...
The Apple Store has Apple Certified Refurbished 2015 11″ and 13″ MacBook Airs (the latest models), available for up to $180 off the cost of new models. An Apple one-year warranty is included with... Read more
21-inch iMacs on sale for up to $120 off MSRP
B&H Photo has 21″ iMacs on sale for up to $120 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $999.99 $100 off - 21″ 2.7GHz iMac: $1199.99 $100 off - 21″ 2.9GHz iMac... Read more
5K iMacs on sale for up to $150 off MSRP, fre...
B&H Photo has the 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. They have the 27″ 3.5GHz 5K iMac on sale for $2149.99 $2199.99, $... Read more
1.4GHz Mac mini, refurbished, available for $...
The Apple Store has Apple Certified Refurbished 1.4GHz Mac minis available for $419. Apple’s one-year warranty is included, and shipping is free. Their price is $80 off MSRP, and it’s the lowest... Read more
iPad Air 2 on sale for up to $100 off MSRP
Best Buy has iPad Air 2s on sale for up to $100 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online... Read more
MacBook Airs on sale for $100 off MSRP
Best Buy has MacBook Airs on sale for $100 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary... Read more
Big Grips Lift Handle For iPad Air and iPad A...
KEM Ventures, Inc. which pioneered the extra-large, super-protective iPad case market with the introduction of Big Grips Frame and Stand in 2011, is launching Big Grips Lift featuring a new super-... Read more
Samsung Launches Galaxy Tab S2, Its Most Powe...
Samsung Electronics America, Inc. has announced the U.S. release of the Galaxy Tab S2, its thinnest, lightest, ultra-fast tablet. Blending form and function, elegant design and multitasking power,... Read more

Jobs Board

*Apple* Evangelist - JAMF Software (United S...
The Apple Evangelist is responsible for building and cultivating strategic relationships with Apple 's small and mid-market business development field teams. This Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Desktop Analyst - KDS Staffing (Unit...
…field and consistent professional recruiting achievement. Job Description: Title: Apple Desktop AnalystPosition Type: Full-time PermanentLocation: White Plains, NYHot Read more
*Apple* Systems Engineer (Mclean, VA and NYC...
Title: Apple Systems Engineer (Mclean, VA and NYC) Location: United States-New York-New York-200 Park Ave (22005) Other Locations: United States-Virginia-Vienna-Towers Read more
*Apple* Systems Engineer (Mclean, VA and NYC...
…Assist in providing strategic direction and technical leadership within the Apple portfolio, including desktops, laptops, and printing environment. This person will Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.