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

Paragraphs 1.0.1 - Writing tool just for...
Paragraphs is an app just for writers. It was built for one thing and one thing only: writing. It gives you everything you need to create brilliant prose and does away with the rest. Everything in... Read more
BlueStacks App Player 0.9.21 - Run Andro...
BlueStacks App Player lets you run your Android apps fast and fullscreen on your Mac. Version 0.9.21: Note: Now requires OS X 10.8 or later running on a 64-bit Intel processor. Initial stable... Read more
Apple iTunes 12.2 - Play Apple Music...
Apple iTunes lets you organize and stream Apple Music, download and watch video and listen to Podcasts. It can automatically download new music, app, and book purchases across all your devices and... Read more
Apple Security Update 2015-005 - For OS...
Apple Security Update 2015-005 is recommended for all users and improves the security of OS X. For detailed information about the security content of this update, please visit: http://support.apple.... Read more
Apple HP Printer Drivers 3.1 - For OS X...
Apple HP Printer Drivers includes the latest HP printing and scanning software for OS X Lion or later. For information about supported printer models, see this page. Version 3.1: The latest printing... Read more
Epson Printer Drivers 3.1 - For OS X 10....
Epson Printer Drivers installs the latest software for your EPSON printer or scanner for OS X Yosemite, OS X Mavericks, OS X Mountain Lion, and OS X Lion. For more information about printing and... Read more
Xcode 6.4 - Integrated development envir...
Xcode provides everything developers need to create great applications for Mac, iPhone, and iPad. Xcode brings user interface design, coding, testing, and debugging into a united workflow. The Xcode... Read more
OS X Yosemite 10.10.4 - Apple's lat...
OS X Yosemite is Apple's newest operating system for Mac. An elegant design that feels entirely fresh, yet inherently familiar. The apps you use every day, enhanced with new features. And a... Read more
Dash 3.0.2 - Instant search and offline...
Dash is an API Documentation Browser and Code Snippet Manager. Dash helps you store snippets of code, as well as instantly search and browse documentation for almost any API you might use (for a full... Read more
FontExplorer X Pro 5.0 - Font management...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more

Heroki (Games)
Heroki 1.0 Device: iOS Universal Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: CLEAR THE SKIES FOR A NEW HERO!The peaceful sky village of Levantia is in danger! The dastardly Dr. N. Forchin and his accomplice,... | Read more »
Hands-On With Raceline CC
Set for release soon, Rebellion’s motorbike racing game, Raceline CC certainly looks stylish. But how does it play? I got my hands on a preview build to answer exactly that. | Read more »
Siegefall - Tips, Tricks, and Strategies...
So, you fancy establishing a base and ruling the world again. Siegefall is a convenient place to do that, but how about some great tips and tricks on how best to go about it? Here are a few ideas on how to get ahead as a beginner to this medieval... | Read more »
The WWE Comes to Racing Rivals - Because...
Racing Rivals is a racing game that's all about, well, rivalry. And who knows rivalry better than WWE superstars (shhhh, that was rhetorical)? [Read more] | Read more »
Hey, Who Put Apple Music in My SoundHoun...
One of the App Store's popular music discovery sources - SoundHound - has already been updated to include Apple's own music discovery source - Apple Music. That was fast! [Read more] | Read more »
Arcane Legends has a New Expansion Calle...
Arcane Legends has been going strong since it debuted at the tail end of 2012. So well, in fact, that it's already up to its sixth expansion. [Read more] | Read more »
Vector 2 is Officially a Thing and it...
Vector is a pretty cool parkour-driven runner that's gotten a pretty decent following since it first came out - although personally I think more people could stand to show it some love. Anyway, Nekki has announced that a sequel isofficially on its... | Read more »
Get Ready to Trucksform and Roll Out (an...
It looks like NuOxygen is bringing the truck-transforming racer Trucksform (get it?) to iOS in a couple of weeks. Although really it's more of an auto-driver than a racer. But still, transforming trucks! [Read more] | Read more »
This Week at 148Apps:June 22-26, 2015
June's Summer Journey Continues With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice,... | Read more »
LEGO® Minifigures Online (Games)
LEGO® Minifigures Online 1.0.1 Device: iOS iPhone Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

Logo Pop Free Vector Logo Design App For OS X...
128bit Technologies has released of Logo Pop Free 1.2 for Mac OS X, a vector based, full-fledged, logo design app available exclusively on the Mac App Store for the agreeable price of absolutely free... Read more
21-inch 1.4GHz iMac on sale for $999, save $1...
B&H Photo has new 21″ 1.4GHz iMac on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Best Buy has the 21″ 1.4GHz iMac on sale for $999.99 on their... Read more
16GB iPad mini 3 on sale for $339, save $60
B&H Photo has the 16GB iPad mini 3 WiFi on sale for $339 including free shipping plus NY tax only. Their price is $60 off MSRP. Read more
Save up to $40 on iPad Air 2, NY tax only, fr...
B&H Photo has iPad Air 2s on sale for up to $40 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $489 $10 off - 64GB iPad Air 2 WiFi: $559 $40 off - 128GB iPad Air... Read more
Apple Releases OS X 10.10.4 With WIFi Fix, iO...
On Tuesday, Apple released final versions of OS X 10.10.4 and iOS 8.4, as well as updates for the Safari browser for OS X Yosemite, Mavericks, and Mountain Lion. The OS X 10.10.4 update focuses on... Read more
Dual-Band High-Gain Antennas for Home Wi-Fi N...
Linksys has announced what it claims are the first dual-band, omni-directional high-gain antennas for the consumer market. The new Linksys high-gain antennas available in a 2- and 4-pack (WRT004ANT... Read more
Apple refurbished 2014 15-inch Retina MacBook...
The Apple Store has Apple Certified Refurbished 2014 15″ 2.2GHz Retina MacBook Pros available for $1609, $390 off original MSRP. Apple’s one-year warranty is included, and shipping is free. They have... Read more
Clearance 2014 MacBook Airs available for up...
Adorama has 2014 MacBook Airs on sale for up to $301 off original MSRP including NY + NJ sales tax and free shipping: - 11″ 256GB MacBook Air: $798 $301 off original MSRP - 13″ 128GB MacBook Air: $... Read more
5K iMacs on sale for $100 off MSRP, free ship...
B&H Photo has the new 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 $2199, also $100... Read more
27-inch 3.2GHz iMac on sale for $1679, save $...
B&H Photo has the 27″ 3.2GHz iMac on sale for $1679.99 including free shipping plus NY sales tax only. Their price is $120 off MSRP. Read more

Jobs Board

Senior Payments Security Manager - *Apple*...
**Job Summary** Apple , Inc. is looking for a highly motivated, innovative and hands-on senior payments security manager to join the Apple Pay security team. You will Read more
Project Manager - *Apple* Pay Security - Ap...
**Job Summary** The Apple Pay Security team is seeking a highly organized, results-driven Project Manager to drive the development of Apple Pay Security. If you are Read more
Web Developer, *Apple* Online Store Innovat...
**Job Summary** The Apple Online Store Innovation Lab team is seeking a talented individual with strong web development and design skills to prototype future Apple Read more
*Apple* TV Live Streaming Frameworks Test En...
**Job Summary** Work and contribute towards the engineering of Apple 's state-of-the-art products involving video, audio, and graphics in Interactive Media Group (IMG) at Read more
Project Manager, WW *Apple* Fulfillment Ope...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.