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!

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

FileZilla 3.21.0 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.21.0: Fixed Vulnerabilities Fixed a string format... Read more
EtreCheck 3.0.2 - For troubleshooting yo...
EtreCheck is an app that displays the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to... Read more
Microsoft Office 2016 15.25 - Popular pr...
Microsoft Office 2016 - Unmistakably Office, designed for Mac. The new versions of Word, Excel, PowerPoint, Outlook and OneNote provide the best of both worlds for Mac users - the familiar Office... Read more
Typinator 6.10 - Speedy and reliable tex...
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
The Hit List 1.1.26 - Advanced reminder...
The Hit List manages the daily chaos of your modern life. It's easy to learn - it's as easy as making lists. And it's powerful enough to let you plan, then forget, then act when the time is right.... Read more
Fantastical 2.2.5 - Create calendar even...
Fantastical 2 is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event... Read more
Firefox 48.0.1 - Fast, safe Web browser.
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more
Adobe InDesign CC 2015 11.4.1.102 - Prof...
InDesign CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous InDesign customer). Adobe InDesign CC 2015 is part of Creative Cloud.... Read more
Corel Painter 16.0.0.400 - $499.00
Corel Painter lets you advance your digital art style with painted textures, subtle glazing brushwork, interactive gradients, and realistic Natural-Media. Easily transition from traditional to... Read more
Thunderbird 45.2.0 - Email client from M...
As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements... Read more

What is Flip Diving, and why has it take...
Move over Pokemon GO. There's a new king in town, and it's "the world's #1 cliff diving game." [Read more] | Read more »
5 places where Pokemon GO is still numbe...
In the U.S., the bloom is off the Pokemon Go rose ever so slightly. It's still doing great, sitting atop the top grossing chart as it has for some time, but it's no longer among the top 10 free apps in downloads, possibly because darn near... | Read more »
Madden NFL Mobile: How defense has chang...
Saying that defense is not a priority in Madden NFL Mobile is a bit of an understatement. In asynchronous head-to-head play, you don't take control of your defenders at all, as the AI manages them while your opponent plays offense. When it's your... | Read more »
Feed Hawk (News)
Feed Hawk 1.0.1 Device: iOS Universal Category: News Price: $2.99, Version: 1.0.1 (iTunes) Description: Feed Hawk makes it easy to subscribe to the RSS feed of the website you are visiting. From within Safari, simply open a share... | Read more »
Reigns character guide: Who's who i...
Know your foes. Keep your friends close, but your enemies closer. And there are probably some other cliches that would apply to your perilous spot on the throne in Reigns as well. [Read more] | Read more »
Match 3 puzzler Small Lime is now availa...
Set to hit Android and IOS on the 17th August, Small Lime is the newest match 3 mobile game, and hopes to throw something a little different into the mix. If you love match 3 puzzles, but are tired of the same old ideas being re-hashed again and... | Read more »
Deus Ex GO tips, tricks, and hints
When Square Enix Montreal first hit us with Hitman GO,it was seen as a clever board game twist on a property that you wouldn't normally think would fit that kind of format. Lara Croft GOexpanded things even further while keeping some of the same... | Read more »
Leap of Fate (Games)
Leap of Fate 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: *** Minimum hardware: iPad 4, iPad mini 2, iPhone 5s. *** | Read more »
Hero Generations (Games)
Hero Generations 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Hero Generations is an innovative Roguelike/4X Strategy game where every turn is one year of your life. Praised as "the... | Read more »
Legend of the Skyfish (Games)
Legend of the Skyfish 1.02 Device: iOS Universal Category: Games Price: $3.99, Version: 1.02 (iTunes) Description: Legend of the Skyfish is a beautiful action adventure puzzle game with a unique weapon and tool - a fishing pole!... | Read more »

Price Scanner via MacPrices.net

Typinator 6.10 comes with 50 improvements – G...
Ergonis Software today announced release of Typinator 6.10, a new version of their text expander utility for macOS. Typinator 6.10 comes with 50 improvements, including new features, compatibility... Read more
Taxi Sim 2016 Puts Users Behind the Wheel in...
Ovilex Soft today announces Taxi Sim 2016, an update to their ultra-realistic 3D driving simulator app for iOS and Android devices — literally a global event what with the company’s nearly 450,000... Read more
11-inch 1.6GHz/128GB MacBook Air on sale for...
Amazon has the current-generation 11″ 1.6GHz/128GB MacBook Air (sku MJVM2LL/A) on sale for $788 for a limited time. Their price is $111 off MSRP, and it’s the lowest price available for this model. Read more
Apple refurbished Mac minis available for up...
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 refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
12-inch 32GB and 128GB WiFi iPad Pros on sale...
B&H Photo has 12″ 32GB & 128GB WiFi Apple iPad Pros on sale for up to $70 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $... Read more
Apple refurbished 11-inch MacBook Airs availa...
Apple has Certified Refurbished 11″ MacBook Airs (the latest models), available for up to $170 off the cost of new models. An Apple one-year warranty is included with each MacBook, and shipping is... Read more
WaterField Launches Kickstarter for Intrepid...
San Francisco based WaterField Design have announced their first Kickstarter campaign for the one-of-a-kind Intrepid iPhone Travel Wallet. The all-new design includes iPhone play-through capability... Read more
Five of Top 10 Worldwide Mobile Phone Vendors...
Global sales of smartphones to end users totaled 344 million units in the second quarter of 2016, a 4.3 percent increase over the same period in 2015, according to Gartner, Inc. Overall sales of... Read more
DriveSavers Offers $300 Off Data Recovery Ser...
DriveSavers, with more than 30 years of experience recovering photos, videos, contact lists, financial records and other important data that may have been kept on devices damaged or even destroyed by... Read more

Jobs Board

*Apple* Retail - Multiple Positions Germanto...
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* Professional Learning Specialist - A...
# Apple Professional Learning Specialist Job Number: 51234379 Portland, Maine, Maine, United States Posted: Aug. 18, 2016 Weekly Hours: 40.00 **Job Summary** The Read more
Lead *Apple* Solutions Consultant - Apple (...
# Lead Apple Solutions Consultant Job Number: 51218465 Richmond, VA, Virginia, United States Posted: Aug. 18, 2016 Weekly Hours: 40.00 **Job Summary** The Lead ASC Read more
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 51218534 Pleasant Hill, California, United States Posted: Aug. 18, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Read more
*Apple* Retail - Multiple Positions Chestnut...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.