TweetFollow Us on Twitter

November 91 - User Selected Folders & Indexing Through Directories

User Selected Folders & Indexing Through Directories

Dan Wendin

MacApp 2 programmers can usually ignore working directories; however, you need to use them when the user selects a folder and your program accesses the files in it without further user interaction. Selecting a folder gives you a real directory and MacApp 2 usually expects a working directory.

Working directories were introduced with the Hierarchical File System (HFS) in 1986 as a way to maintain compatibility with the original flat file system. They are returned by the standard file dialogs and passed to the MacApp 2 file methods that deal with opening files.

Most applications let MacApp 2 take care of this. And the file manager chapter in Inside Mac Volume IV covers working directories in gruesome detail, making it difficult to sort out what you need to know. Hence this article.

To set the stage, suppose your file-based application has an Export function to generate a text file for a 4D data base application. To make things easier on the 4D application, the user can export any number of files into a single export file with a fixed name. The user puts all the files to be processed into one folder before starting your application. In your application, the user selects a folder and you take care of everything from that point on.

I have implemented a set of file based objects similar to Tom Becker's approach in his April Frameworks article and which (hopefully) anticipate MacApp 3. This is reflected to some extent in the sample code on the FrameWorks Disk.

CHOOSING A FOLDER

I adapted the code in DTS's sample code SC.018.StdFile to work with MacApp 2. This puts up a slightly modified version of the selection dialog used by MPW's Set Directory command (Figure 1). This dialog is a real DLOG/DITL resource pair, not a MacApp dialog. Its definition must be copied into one of your myApp.r files and then created using Res.

Once you have it in a myApp.rsrc file, you can change it using ResEdit or AppMaker (the standard AppMaker version 1.1, not the MacApp version 1.2). ViewEdit cannot access these resources.

The Select Button completes the selection process. Double clicking on a folder (or clicking the Open button) opens the folder and displays the folders one level down. The Select Current Folder button keeps the user from having to go up one level to select the current folder.

The call to SFPGetFile that displays the dialog looks like this:

SFPGetFile(where, '', @FoldersOnly, numTypes, pTypeList^,
            @FolderHook, gFolderReply, kGetFoldersDlgId, nil);

FoldersOnly and FolderHook are filter functions. These functions, and any variables they need to access, must be global within their unit. They can't be methods, nor can they be local to the procedure containing SFPGetFile. Tech Note 265, "Pascal To C-PROCEDURE Parameters," explains why-it has to do with limitations in the toolbox with respect to nested procedures.

The FoldersOnly function simply tests the ioFlAttrib field of the parameter block passed to it and returns true if a folder. The parameter numTypes is -1 to tell StdFile to consider all types filtered by FoldersOnly. The pTypeList parameter is ignored-except that it must point to a valid memory location.

The FolderHook function does the real work. The tricky part is that there are only two states for the gFolderReply.good field-true or false-and there is no way to set it to true because the Open button doesn't exit. So FolderHook sets a global flag to true and then acts as if the Cancel button was hit. The Cancel button sets this flag to false. In either case, gFolderReply.good is false, so it is ignored.

FolderHook puts the directory and vRefnum in globals for return to the client. These are the real directory and the real vRefnum. The vRefnum is obtained from low memory location $214, which contains the negative of the current vRefnum. The directory hilighted in the list is in gFolderReply.fType. This is returned in the global if the user clicks the Select button. The current directory is in low memory location $398 and this is returned if the user clicks the Select Current Folder button.

Are there files in the folder? The function ThereAreFiles asks for the first file of the required type using the same function GetFileInFolder that is used to index through the files in the folder. (This is discussed in detail below.)

index := 1;
ThereAreFiles := Self.fFolderDoc.GetFileInFolder(fDirectory,
                                    index, anAppFile, kFileType);

GetFileInFolder returns true if a file is found, and the parameter anAppFile identifies the file. It's ignored here, since we only care whether or not there is a file.

Does the output file already exist?

Because the same file name is used for all export files, I don't want to let the user to destroy an existing file, as the normal SFPPutFile would allow him to do. So, the code needs to check for that case and prevent him from going further. My ThisFileExistsInDir method does this using the toolbox call PBHGetFInfo to get the file's Finder info. The real vRefnum and directory ID are passed in the parameter block's ioVRefnum and ioDirID fields. If successful, then the file exists, and the method returns true:
with pBlock, theAppFile do {an HParamBlockRec}
begin
    ioNamePtr := @fName;
    ioFDirIndex := 0;
    ioVRefnum := vRefnum; {real vRefNum}
    ioDirID := theDirectory
end;
err := PBHGetFInfo(@pBlock, false);
ThisFileExistsInDir := err = noErr

OPENING THE OUTPUT FILE

Now it's time to worry about the distinction between real and working directories. The MacApp methods and utility functions that open files expect working directories as their vRefnum parameters. The first thing they do is convert to a real directory and vRefnum. In allocating and opening a file based object, fOutputFile, we switch to a working directory, open the new file and then switch back.
Self.SwitchToWorkDir(theAppFile, itsDirectory);
Self.OpenNewFile(theAppFile);
Self.RestoreVRefnum(theAppFile);

My SwitchToWorkDir method uses the toolbox call PBOpenWD to open a working directory. It passes the real vRefnum and directory ID, and the application's signature in the parameter block's ioVRefnum, ioWDDirID and ioWDProcID fields, respectively, and gets back the working directory ID in the ioVRefnum field.

with pBlock do {a WDPBRec}
begin
    ioNamePtr := nil;
    ioVRefNum := anAppFile.vRefnum; {the real vRefNum}
    ioWDDirID := theDirectory; {the real directory}
    {program signature}
    ioWDProcID := longint(kSignature); 
    {assign a working ID}
    err := PBOpenWD(@pBlock, false); 
    {switch vRefnum to Working Directory}
    anAppFile.vRefnum := ioVRefNum 
end {with}

This working directory is passed as the vRefnum to OpenNewFile. Because of this doubling up of the ioVRefnum field, the real vRefnum must be available for restoring after the file is opened. OpenNewFile is an adaptation of the MacApp 2 open new file method moved from TApplication.

There are perhaps 40 working directories available to all applications open under MultiFinder under System 6; there are fewer in System 7. There is only one working directory for each file regardless of which application is accessing the file.

Working directories that aren't in use (that is, have no active file buffers associated with them) are closed when the application that opened them quits or if an application explicitly closes them with no active file buffers associated. Therefore, there is the potential of stepping on another application if we explicitly close a working directory. However, I chose to do this rather than risk causing my application and others to run out of working directories. In reality, I have a number of extract files open and, as shown below, we have to do the same thing for the existing files we process.

My RestoreVRefnum method uses the toolbox call PBCloseWD to close the working directory, passing the working directory. It then restores the original vRefnum.

with pBlock do {a WDPBRec}
begin
    ioVRefNum := anAppFile.vRefnum; {the working directory}
    err := PBCloseWD(@pBlock, false); {release working ID}
end;

INDEXING THROUGH THE FILES

I use the GetFileInFolder method, mentioned above, to index through the file. The index is set to 1 before calling. The method returns the next file of the requested type and its index. Subsequent calls move the index on to the next file, returning false when the list is exhausted.
index := 1;
repeat
fileReturned := aFolderDoc.GetFileInFolder(fDirectory,
                                index, theAppFile, kFileType);
if fileReturned then
    begin
      {allocate an object for the file, which opens the file}
        New(anExtractDoc);
        FailNil(anExtractDoc);
        anExtractDoc.ICFExtractDoc(kFileType, kSignature,
                    theAppFile, itsDir, kFileExists, cancelled);

            {process this file if no problem opening}
        if not cancelled then
            anExtractDoc.ProcessFile(Self.fOutputFile);

        FreeIfObject(anExtractDoc)
    end
until not fileReturned;

My GetFileInFolder method first uses the toolbox call PBGetCatInfo to determine if there is an item for the current index and, if so, whether it is a directory or a file. It passes the real vRefnum (from $214), directory and index in the parameter block's ioVRefnum, ioDrDirID and ioFDirIndex fields, respectively. If there is an item, it gets back a pointer to the name and file attributes in the ioNamePtr and ioFlAttrib fields. It returns to the caller with false if there are no more items in the list. It moves on to the next item if ioFlAttrib indicates a directory, not a file.

with block do {a CInfoPBRec}
begin
    ioNamePtr := @theName; {returns file or directory name}
    ioVRefNum := -(SFSaveDisk^); {current volume refnum}
    ioFDirIndex := index;
    ioDrDirID := theDirectory;
    err := PBGetCatInfo(@Block, false)
end;

The toolbox call PBHGetFInfo gets the file type, passing the same fields (the directory is passed in the ioDirID field). The file type in the finder info is returned in ioFlFndrInfo.fdType. If it matches, the real vRefnum and file name are returned to the caller. Otherwise, it moves on to the next item.

with fblock do {HParamBlockRec}
begin
ioNamePtr := @theName; {file name}
ioVRefNum := block.ioVRefNum; {real}
ioFDirIndex := index;
ioDirID := theDirectory;
ferr := PBHGetFInfo(@fBlock, false);

    {continue if not the type requested or an error}
stillLooking := (ferr <> NoErr) or
(ioFlFndrInfo.fdType <> theFileType)
end;

Because TDocument's ReadFromFile method wants a working directory, it is surrounded by calls to SwitchToWorkDir and RestoreVRefnum.

Don't forget to free the file object at the end of the repeat loop. Happy file indexing!

 
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

Android Leads in Operating System Share Andro...
Consumer Intelligence Research Partners, LLC (CIRP) has released its latest results of its research on mobile phone operating systems for the calendar quarter that ended March 31, 2014. This analysis... Read more
Pelican Products, Inc. Introduces New Lineup...
Pelican Products, Inc., the global leader in the design and manufacture of high-performance protective cases, today announced the launch of a new line of rugged phone cases for both the Apple iPhone... Read more
SaveDrives – Car Dashboard Video Camera &...
Drivers who want to help reduce potential damage to their health and finances in the event of an accident can download the innovative new no-cost app SaveDrives – Car Dashboard Video Camera &... Read more
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

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.