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!

 
AAPL
$524.94
Apple Inc.
+5.93
MSFT
$40.01
Microsoft Corpora
-0.39
GOOG
$536.10
Google Inc.
-20.44

MacTech Search:
Community Search:

Software Updates via MacUpdate

VMware Fusion 6.0.3 - Run Windows apps a...
VMware Fusion allows you to create a Virtual Machine on your Mac and run Windows (including Windows 8.1) and Windows software on your Mac. Run your favorite Windows applications alongside Mac... Read more
Tweetbot 1.5.1 - Popular iOS twitter cli...
Tweetbot is a full-featured OS X Twitter client with a lot of personality. Whether it's the meticulously-crafted interface, sounds and animation, or features like multiple timelines and column views... Read more
Mac DVDRipper Pro 4.1.7 - Copy, backup,...
Mac DVDRipper Pro is the DVD backup solution that lets you protect your DVDs from scratches, save your batteries by reading your movies from your hard disk, manage your collection with just a few... Read more
PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more

Latest Forum Discussions

See All

This Week at 148Apps: April 14-18, 2014
Spring Into Our App Reviews   | Read more »
Have a Special Dead Trigger 2 Easter Bas...
Have a Special Dead Trigger 2 Easter Basket Full of Goodies, Courtesy of Madfinger Games Posted by Rob Rich on April 18th, 2014 [ permalink ] Dead Trigger 2 | Read more »
Almost All of Playdek’s Library is on Sa...
Almost All of Playdek’s Library is on Sale Right Now, and You Should Check it Out Posted by Rob Rich on April 18th, 2014 [ permalink ] Playdek has released quite a few great iOS ports of board and card games over the years, and now most of them... | Read more »
Zynga Launches Brand New Farmville Exper...
Zynga Launches Brand New Farmville Experience with Farmville 2: Country Escape Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
David. Review
David. Review By Cata Modorcea on April 18th, 2014 Our Rating: :: MINIMALISTIC IN A DIFFERENT WAYUniversal App - Designed for iPhone and iPad David is a minimalistic game wrapped inside of a soothing atmosphere in which the hero... | Read more »
Eyefi Unveils New Eyefi Cloud Service Th...
Eyefi Unveils New Eyefi Cloud Service That Allows Users to Share Media Across Personal Devices Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
Tales from the Dragon Mountain: The Lair...
Tales from the Dragon Mountain: The Lair Review By Jennifer Allen on April 18th, 2014 Our Rating: :: STEADY ADVENTURINGiPad Only App - Designed for the iPad Treading a safe path, Tales from the Dragon Mountain: The Lair is a... | Read more »
Yahoo Updates Flickr App with Advanced E...
Yahoo Updates Flickr App with Advanced Editing Features and More Posted by Tre Lawrence on April 18th, 2014 [ permalink ] | Read more »
My Incredible Body - A Kid's App to...
My Incredible Body - A Kid's App to Learn about the Human Body 1.1.00 Device: iOS Universal Category: Education Price: $2.99, Version: 1.1.00 (iTunes) Description: Wouldn’t it be cool to look inside yourself and see what was going on... | Read more »
Trials Frontier Review
Trials Frontier Review By Carter Dotson on April 18th, 2014 Our Rating: :: A ROUGH LANDINGUniversal App - Designed for iPhone and iPad Trials Frontier finally brings the famed stunt racing franchise to mobile, but how much does its... | Read more »

Price Scanner via MacPrices.net

Deal Alert! 13-inch MacBook Pro on sale for $...
Best Buy has the 13″ 2.5GHz MacBook Pro on sale for $999.99 on their online store. Choose free shipping or free instant local store pickup (if available). Their price is $200 off MSRP. Price is valid... Read more
Free HopTo 2.2 Helps Enhance Your Productivit...
The HopTo app helps you do more on your iPad by providing more and easier adaccess to files and documents. Version 2.2 adds Egnyte and HopTo’s Mac OSX File Connector. If you already have the hopTo... Read more
National Distracted Driving Awareness Month:...
As the country recognizes National Distracted Driving Awareness Month, Sprint is reminding wireless consumers to focus on driving while behind the wheel, to not text or email while driving, and to... Read more
13-inch 2.4GHz Retina MacBook Pro available f...
Abt has the 13″ 2.4GHz 128GB Retina MacBook Pro available for $1229 including free shipping. Their price is $70 off MSRP. Read more
iMacs on sale for up to $160 off MSRP this we...
Best Buy has iMacs on sale for up to $160 off MSRP for a limited time. Choose free home shipping or free instant local store pickup (if available). Prices are valid for online orders only, in-store... Read more
iPad Airs on sale this weekend for up to $100...
Best Buy has WiFi iPad Airs on sale for $50 off MSRP and WiFi + Cellular iPad Airs on sale for $100 off MSRP on their online store for a limited time, with prices now starting at $449. Choose free... Read more
Apple restocks refurbished Mac minis starting...
The Apple Store has restocked Apple Certified Refurbished Mac minis for up to $150 off the cost of new models. Apple’s one-year warranty is included with each mini, and shipping is free: - 2.5GHz Mac... Read more
Hyundai Brings Apple CarPlay To The 2015 Sona...
Hyundai Motor America has announced it will bring Apple CarPlay functionality to the 2015 Sonata. CarPlay is pitched as a smarter, safer and easier way to use iPhone in the car and gives iPhone users... Read more
Updated iPads Coming Sooner Than We Had Thoug...
MacRumors, cites KGI securities analyst Ming Chi Kuo, well-respected as an Apple product prognisticator, saying that Apple will introduce an upgraded iPad Air and iPad mini in 2014/Q3, meaning the... Read more
Toshiba Unveils New High And Low End Laptop M...
Toshiba has announced new laptop models covering both the high-end and low-end of the notebook computer spectrum. Toshiba 4K Ultra HD Laptop Toshiba’s new Satellite P55t features one of the world’s... Read more

Jobs Board

Position Opening at *Apple* - Apple (United...
…customers purchase our products, you're the one who helps them get more out of their new Apple technology. Your day in the Apple Store is filled with a range of Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Inc. Research Data Specialist - Appl...
…of Worldwide Market Research & Intelligence. The team is responsible for conducting Apple branded consumer market research. It is also responsible for analyzing data Read more
*Apple* Automotive Parts Department position...
Apple Automotive is one of the fastest growing dealer…and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive, we Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.