TweetFollow Us on Twitter

Multifile Dialogs in CPX

Volume Number: 13 (1997)
Issue Number: 7
Column Tag: Toolbox Essentials

Creating Multi-File Dialogs in CPX

by John Shackelford, Tangent Systems

How to build a custom file dialog with CustomGetFile and how to manage the dialog callback routines

Introduction

The ease that applications are built in CPX often masks the flexibility of writing low-level code for the Macintosh. Prograph CPX ships with a class library called Application Building Classes (ABCs) which, in the world of Macintosh application frameworks, ranks among the richest. However, one particularly useful chunk of code that you will not find in the ABCs is the fancy file dialog you create using CustomGetFile.

You use the CustomGetFile feature to add source files to projects in several popular Macintosh applications like CodeWarrior, Roaster or Symantec Project Manager. The File classes in the ABCs all use the Standard GetFile dialog to retrieve files. This is fine for single file operations, but if your application must provide the ability to manipulate several files at once, CustomGetFile must be used to add controls for collecting the list of files. Surprisingly, when I wrote the code for a CPX version of CustomGetFile, it was difficult to find a complete example in C or Pascal on which to base the design. I did find some chunks or pieces in C and some CPX that I used as a basis for MultiFile.

MultiFile is a CPX section. It provides a class for a multifile dialog of the type shown below. It allows you to navigate, add and subtract several files all in one dialog session. The section also provides a basic file dialog allowing you to specify the user prompt. However, this article focuses on MultiFile Dialog -- it shows you how to use the MultiFile Dialog class and discusses key code snippets.

MultiFile Demo Application

The demo application opens a MultiFile Dialog and allows you to add and subtract files. Its purpose is to demonstrate what a MultiFile Dialog provides (see Figure 1). The demo application is one of those minimal apps. It does not use the ABCs and has no value other than showing you how the MultiFile Dialog looks.

Figure 1. The Demo Application opens a MultiFile Dialog.

The Macintosh Toolbox provides a function called CustomGetFile for creating custom file dialogs. First, I'll show you the top level CPX code for using it. That way, if all you want is to use MultiFile and you don't care about how it works, you'll have all you need to know. I will also show the function prototype and build up the associated functions for it in CPX.

Figure 2. The MultiFile section comes with an example method for using MultiFile.

Using MultiFile is pretty straightforward -- explaining it will be much more difficult. However, as you can see in Figure 2, all you do is create an instance of MultiFile Dialog, setup the type of files you want with the message "/setTypeList" and finally send the message "/multiFileGet" to get the whole process rolling. When the method completes, the list of selected files appears on the output of "/multiFileGet."

How it All Works

I'll first decompose the main method "/multiFileGet," describe the attributes of MultiFile Dialog and then expose in detail the major chunks of code that makes MultiFile Dialog work in support of CustomGetFile -- the Toolbox call we are encapsulating.

MultiFile Dialog Constructor

The first thing to look at is the constructor for MultiFile Dialog (Figure 3). When an instance of MultiFile Dialog is created, several attributes are initialized. The "Files" attribute will end up holding a new instance of File Results. This object will eventually hold the FSSpecs for the selected files, and it provides methods to add and remove FSSpecs from its internal list of FSSpecs. The attribute "Select List" is set to NULL. Eventually, it will hold a pointer to the scroll list item created by a call to LNew. The Persistent called "The Dialog" is set to the current MultiFile Dialog instance. Two other methods are executed -- one creates a Standard File Reply record while the other ("/makeCallbacks") sets up pointers to the callback functions. So by design a "The Dialog" (global) holds the MultiFile Dialog instance. Everything else hangs off of that -- the lower scroll list, StandardReplyRec and the File Results object. The callbacks rely on "The Dialog" to access the scroll list, the File Results object and the StandardReplyRec.

Figure 3. The "Constructor" for MultiFile Dialog sets up 3 Persistants.

The method "/makeCallbacks" (Figure 4) checks each of 4 attributes in MultiFile Dialog and creates a pointer to a callback method if a method name is specified. This provides a nice way for users of the class to specify their own callback methods -- just by specifying their own methods in the initialization list that can be fed to the Constructor. And of course if that does not provide enough flexibility, you can always subclass the whole thing and define "/makeCallbacks" anew.

Figure 4. "/makeCallbacks" checks each of 4 MultiFile Dialog attributes.

The local method "file filter proc" (Figure 5) is typical of the calls in "/makeCallbacks". An improvement on this local method would be to verify that the universal method is actually defined and if it isn't, then fail into a next case and set the "callback" attribute (in this specific case "File Filter Callback") value to NULL.

Figure 5. This local method is typical for what a "/makeCallbacks" method does.

The method "/multiFileGet" (Figure 6) is composed of three methods itself. The first performs the Toolbox call, the second retrieves the selected files and the final method cleans up.

Figure 6. "/multiFileGet" retrieves a list of file specifications.

/callCustomGet

The method "/callCustomGet" (Figure 7) makes the Toolbox call "CustomGetFile". The MultiFile Dialog instance carries the values necessary for the function to operate as the user wants.

Figure 7. "/callCustomGet" makes the low level Toolbox call.

Let's first look at the CustomGetFile arguments and what Prograph uses. The calling arguments for CustomGetFile are shown below (bold) with the MultiFile Dialog Attribute (underlined):

FileFilterYDProcPtr FileFilter Callback
A pointer to an optional file filter function, provided by your application, through which CustomGetFile passes files of the specified types.

short Num Types
The number of file types to be displayed. If you specify a "Num Types" value of -1, the first filtering passes files of all types.

SFTypeList /Type List
A list of file types to be displayed. You can define it using the call "/setTypeList" which automatically sets the value of attribute "Num Types" used above.

StandardFileReply * YourDataPointer
The reply record, which CustomGetFile fills in before returning. We create a pointer to a Reply record in the Constructor for MultiFile Dialog.

short DialogID
The resource ID of a customized dialog template. To use the standard template, set this parameter to 0. The MultiFile Dialog defines this value to be 1001. If you want to customize the look of the dialog, create a new dialog resource and set the DialogID to the new value in a subclass of MultiFile Dialog for the "new" dialog.

Point Where
The upper-left corner of the dialog box in global coordinates. This value is predefined to be {-1, -1} which will place it in the middle of the screen.

DlgHookYDProcPtr DialogHook Callback
A pointer to the dialog hook function, which handles item selections received from the Dialog Manager. This is in many ways the "meat" (I suppose I should instead say "fiber" for those vegetarians among us) of the matter; clicks within the dialog get handled by this method.

ModalFilterYDProcPtr ModalFilter Callback
A pointer to your modal-dialog filter function, which determines how the Dialog Manager filters events when called by CustomGetFile. Specify a value of NIL if you are not supplying your own function. We need a modal-dialog filter function because we must provide scroll control for our scrolling list. This method handles clicks in the user-defined lower scroll list. (Control of the upper list "comes" with CustomGetFile.)

short ActiveList

ActivateYDProcPtr Activate Proc Callback

void * YourDataPointer

These last three parameters are not used, and are set to NULL.

Figure 8. The default attributes are defined to work with a dialog resource 1001.

Figure 9 shows the default MultiFile dialog (ID = 1001) and the index numbers for its items.

Figure 9. Default MultiFile dialog (ID = 1001).

When CustomGetFile is called, three methods (all are Universals) take over until the user clicks "Cancel" or "Done" in the dialog window. They are "filterProc", "modalFilterYD" and "dialogHook". We'll describe each in turn.

Filter Proc Method

The "filterProc" method (Figure 10) does one job. It is called whenever the upper scroll list is about to be filled with files (after passing through the internal "types" filter). It gives us a chance to do further processing. The output of this method is a Boolean which determines whether or not the file should appear in the upper list. A TRUE output removes the item from the upper list while a FALSE value allows it to appear in the upper list. This method checks the list of FSSpecs in the File Results object. If the file is in the File Results object, this filter will remove it from the upper list.

Figure 10. "filterProc" is called whenever the upper scroll list is about to be filled with files.

The field "ioNamePtr" holds a pointer to a Pascal string. The first byte in a Pascal string must be the length of the string. we execute "get-integer" to determine the length of the string, and then we execute "get-text" using that value and start at byte 1 of the buffer. We then check the list of file names held by the File Results object (retrieved with "getFiles"). If a matching file name is found, the primitive "(in)" will return an integer greater than 0 indicating the files position in the list. In that case the method outputs TRUE. Otherwise it will output FALSE.

Modal Filter yd Method

The "modalFilterYD" method (Figure 11) is called as part of the event processing in the window. It is needed to control scrolling of the lower scroll list (the "Select List"). It is written such that it will only handle clicks within the scroll lists vertical control.

Figure 11. "modalFilterYD" controls scrolling of the lower scroll list.

Dialog Hook Method

The "dialogHook" is the biggest of these three methods. It installs the lower scroll list the first time the method is called. It also handles all clicks in the dialog. So for example when the "Add" button is clicked, the dialog hook method defines what happens in the window.

Instead of going through every case of this method (there are 15 cases), I'll just provide an overview of what the method is supposed to do:

First Time Through -- Creates the lower scroll list and installs it in the dialog window.

Add -- Adds the filename of the selected file to lower list. The file is removed from the upper the list through the file filter function. The FSSpec for the file is added to the File Results object.

Add All -- The names of all available files in the upper scroll list are added to the lower list. The FSSpecs are added to the File Results object. All files that get successfully added to the File Results are filtered from the upper list display by the file filter method.

Remove -- Enabled if an item is selected in the lower list. The selected item is removed from the File Results object, removed from the lower list and added to the upper list by the file filter method.

Remove All -- Enabled if there are any files in lower list. All files in the File Results object are removed, all items in the lower list are removed. The file filter method then allows available files to appear in the upper list.

Cancel -- Deletes all FSSpecs from the File Results object, then closes the dialog.

Done -- Closes the dialog.

Here is the code of two interesting cases to drive home how things work: what happens the first time though -- that's when we create and install the lower scroll list -- and how Add works. I leave the other cases as a review exercise for you and your CPX Debugger.

First Time Through

The first time "dialogHook" is executed, we must detect that this is the first time and display the lower list box.

Figure 12. The First Time Through case creates the lower scroll list item.

Figure 13. "initList" creates a new scroll list and places it in the position of window item 18 in the dialog resource.

The Toolbox call "LNew" creates a new scroll list. We define the rectangle for the list by getting the rectangle for window item 18 (see Figure 9). We "send" the new scroll list to the MultiFile Dialog in the message "/setSelectList".

Add file

The Add file case duplicates the FSSpec representing the selected file and sends that FSSpec as an argument in the call to "addFile".

Figure 14. The "Add" case calls "addFile" universal.

Figure 15. "addFile" universal also enables item 19 in the dialog window.

The "addFile" universal method performs several tasks. It first checks if the file can really be added. If so, it continues on by getting the value of the name field in the FSSpec and asking the File Results object for the number of items in its files list to form an index. It send those two values (name and index) as arguments to "addCell" which adds a new cell to the "Select List". It then sends the FSSpec to the File Results object in a message "/addItem" which adds the FSSpec to the File Result object. After all that, the lower scroll list is redrawn in method "updateScrollList" and window item 19 (Remove All) is enabled.

At this point "dialogHook" case 12:15 (Figure 14) outputs "sfHookRebuildList" and the method ends. The new item now appears in the lower scroll list and disappears from the upper list. The multifile dialog window waits for the next event.

Conclusion

This article describes the CPX code in the MultiFile section. MultiFile contains classes for creating special file dialogs that don't come out of the box with CPX. These classes are useful if you need a file dialog that can deal with several files at once or if you want to specify a unique prompt in a standard file dialog.

With the information in this article, CPX developers can now start using CustomGetFile based file dialogs in their applications. Simply add the MultiFile section to your project, create an instance of MultiFile Dialog, and send it the message "/multiFileGet". All of your problems will be solved.

Bibliography and References

Apple Computer's Inside Macintosh: Files, page 3-51.


John Shackelford is the founder of Tangent Systems - a software development company based in San Diego. When he's not playing with his 3 children, he's busy writing CPX code or playing the piano. He can be reached at shackx@aol.com. You can find Tangent Systems on the world wide web at http://www.tangentsys.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Tinderbox 7.0.0 - Store and organize you...
Tinderbox is a personal content management assistant. It stores your notes, ideas, and plans. It can help you organize and understand them. And Tinderbox helps you share ideas through Web journals... Read more
1Password 6.5.5 - Powerful password mana...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
Apple Remote Desktop Client 3.9 - Client...
Apple Remote Desktop Client is the best way to manage the Mac computers on your network. Distribute software, provide real-time online help to end users, create detailed software and hardware reports... Read more
Art Text 3.2.2 - $49.99
Art Text is graphic design software specifically tuned for lettering, typography, text mockups and various artistic text effects. Supplied with a great variety of ready to use styles and materials,... Read more
WhatRoute 2.0.15 - Geographically trace...
WhatRoute is designed to find the names of all the routers an IP packet passes through on its way from your Mac to a destination host. It also measures the round-trip time from your Mac to the router... Read more
Sparkle 2.1.1 - $79.99
Sparkle will change your mind if you thought building websites wasn't for you. Sparkle is the intuitive site builder that lets you create sites for your online portfolio, team or band pages, or... Read more
Dash 4.0.1 - 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
TextSoap 8.3.2 - Automate tedious text d...
TextSoap can automatically remove unwanted characters, fix up messed up carriage returns, and do pretty much anything else that we can think of to text. Save time and effort. Be more productive. Stop... Read more
Apple Remote Desktop 3.9 - Remotely cont...
Apple Remote Desktop is the best way to manage the Mac computers on your network. Distribute software, provide real-time online help to end users, create detailed software and hardware reports, and... Read more
Paragraphs 1.1.4 - 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. Features... Read more

Blasty Bubs is a colorful Pinball and Br...
QuickByte Games has another arcade treat in the works -- this time it's a mishmash of brick breaking and Pinball mechanics. It's called Blasty Bubs, and it's a top down brickbreaker that has you slinging balls around a board. [Read more] | Read more »
Corsola and Heracross are the new region...
Generation 2 finally launched in Pokémon GO, unleashing a brand new batch of Pokémon into the wild. Even before the update went live people were speculating on how to catch elusive Pokémon like the legendary "dogs", Unknown, and whether or not... | Read more »
The Warlock of Firetop Mountain (Games)
The Warlock of Firetop Mountain 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: An epic adventure through a mysterious mountain filled with monsters, magic and mayhem! “...it looks downright... | Read more »
Fantasy MMORPG MU Origin’s receives a hu...
Developer Webzen are looking to take their highly popular fantasy battler MU Origin to the next level this month, with its most ambitious overhaul yet. The latest update introduces the long sought after Server Arena, new treasure dungeons, and much... | Read more »
RPG Djinn Caster (Games)
RPG Djinn Caster 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: SPECIAL PRICE 38% OFF(USD 7.99 -> USD 4.99)!!!A Fantasy Action RPG of far foreign lands! Summon the Djinns and rise to... | Read more »
Alto's Odyssey gets its first trail...
There's finally video evidence of Alto's Odyssey, the follow up to the 2015 App Store hit, Alto's Adventure. It looks just as soothing and atmospheric as Alto's last outing, but this time players will be journeying to the desert. Whereas Alto's... | Read more »
Last week on Pocket Gamer
What’s going on in the wider world of portable gaming? Each week we ask that question of our sister website Pocket Gamer. The PG team covers iOS gaming, just like 148Apps, but it also strays into the world of Android games and handheld consoles... | Read more »
Pokémon GO Generation 2 evolution guide
At long last, Niantic Labs finally unleashed the Generation 2 Pokémon into the wild. Pokémon GO trainers are scrambling to grab up this new set of 80 Pokémon. There are some special new tricks required to catch all of these new beasties, though.... | Read more »
The best new games we played this week
It feels as though the New Year got off to a creaking start as far as mobile games go, but that's changed over the past few weeks. The last few days alone have seen the debut of a number of wonderful games, so we thought we'd take the time to... | Read more »
Recruit more scallywags and discover new...
Get ready to show off your sea legs all over again in Oceans & Empires’ new grand update, which aims to make the act of rising to the role of seven seas ruler even more fresh and appealing, thanks to a richness of new content on both iOS and... | Read more »

Price Scanner via MacPrices.net

Apple’s New iPad Ads Don’t Address Pro Users’...
Apple launched a new tranche of iPad Pro TV ads last week addressing actual queries and challenges from the Twitterverse, albeit using actors for the visuals. That’s great. As an iPad fan and heavy... Read more
Free Verbum Catholic Bible Study App For iOS
The Verbum mobile app runs on Logos’ powerful Bible software and is an advanced resource for mobile Catholic study. The Verbum app surrounds the Bible with the Tradition. Verbum comes with 15 free... Read more
27-inch Apple iMacs on sale for up to $200 of...
B&H Photo has 27″ Apple iMacs on sale for up to $200 off MSRP, each including free shipping plus NY sales tax only: - 27″ 3.3GHz iMac 5K: $2099.99 $200 off MSRP - 27″ 3.2GHz/1TB Fusion iMac 5K: $... Read more
15-inch 2.2GHz Retina MacBook Pro on sale for...
Amazon has 2015 15″ 2.2GHz Retina MacBook Pros (MJLQ2LL/A) available for $1849.99 including free shipping. Apple charges $1999 for this model, so Amazon’s price is represents a $150 savings. Read more
Apple refurbished iPad Air 2s available start...
Apple has Certified Refurbished iPad Air 2 WiFis available for starting at $319 including free shipping. A standard Apple one-year warranty is included: - 16GB iPad Air 2 WiFi: $319 $60 off original... Read more
Apple refurbished iPad Pros available for up...
Apple has Certified Refurbished 9″ and 12″ Apple iPad Pros available for up to $160 off the cost of new iPads. An Apple one-year warranty is included with each model, and shipping is free: - 32GB 9″... Read more
Apple restocks refurbished 2015 and 2016 13-i...
Apple has Certified Refurbished 2015 and 2016 13″ MacBook Airs available starting at $759. An Apple one-year warranty is included with each MacBook, and shipping is free: - 2016 13″ 1.6GHz/8GB/128GB... Read more
13-inch 2.5GHz MacBook Pro (Apple refurbished...
Apple has Certified Refurbished 13″ 2.5GHz MacBook Pros (MD101LL/A) available for $829, or $270 off original MSRP. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.5GHz MacBook... Read more
QuickerTek Announces 5TB Apple AC AirPort Tim...
QuickerTek Inc. has announced their new 5TB hard drive upgrade for Apple’s AC AirPort Time Capsule. By customer request, this upgrade also features six external antennas and offers the highest... Read more
Apple Certified Refurbished iMacs available f...
Apple has Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available: - 21″ 3.... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Manager *Apple* Systems Administration - Pu...
Req ID 3315BR Position Title Manager, Apple Systems Administration Job Description The Manager of Apple Systems Administration oversees the administration and Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Manager *Apple* Systems Administration - Pu...
Req ID 3315BR Position Title Manager, Apple Systems Administration Job Description The Manager of Apple Systems Administration oversees the administration and Read more
*Apple* Technician - nfrastructure (United S...
Let’s Work Together Apple Technician This position is based in Portland, ME Life at nfrastructure At nfrastructure, we understand that our success results from our Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.