TweetFollow Us on Twitter

OD Contain Yourself
Volume Number:12
Issue Number:1
Column Tag:New Apple Technology

OpenDoc: Contain Yourself ...

Updating applications to work with OpenDoc

By Eric Soldan, Apple Developer Technical Support

It’s time to be an OpenDoc™ container application. It’s not too soon, and it’s not too late. So how do you decide if your application should be an OpenDoc container application or not? Here’s an easy test:

• Will your application benefit from Internet access?

If the answer is yes, then being an OpenDoc container application is probably the right thing to do. By becoming an OpenDoc container application, you automatically get the benefits of everything that is OpenDoc, including CyberDog, which will provide component oriented Internet clients and other Internet services. Now is not the time to ignore the Internet bandwagon. It’s worth jumping on. The only question remaining is how to jump. Do you learn Open Transport and MacTCP and recode your entire application to support the Internet? Or do you look for alternatives, like OpenDoc?

A logical question therefore would be: “Is OpenDoc really the fastest way to add Internet to your application?” Adding Internet support with OpenDoc boils down to adding basic OpenDoc support; in this article we will evaluate the difficulty of adding OpenDoc to an existing application. Then you can decide.

The Container Application Library: Your Friend.

CALib, the Container Application Library, has been evolving for a while. It’s looking really good right now. Joshua Susser, of OpenDoc engineering, and I have been adding CALib support to an application I originally developed in Developer Tech Support called DTS.Draw. I wrote DTS.Draw years ago, without ever considering the possibility of adding something like OpenDoc later. DTS.Draw’s document model, while flexible, is a closed model, so adding OpenDoc support is therefore a very interesting test case for CALib.

It turns out that the amount of additional coding necessary is minimal. However, due to CALib’s flexibility, there were many development issues that had to be discussed for quite a while. If these discussions were not held, the implementation would not have been as robust. I will present what we’ve learned from these discussions.

First, let’s talk about DTS.Draw for a while. When adding OpenDoc, it’s important to understand how the existing application works. Since you are probably not familiar with DTS.Draw, I’ll give you a quick overview.

DTS.Draw is an AppsToGo framework based application. AppsToGo is an object-oriented C framework written by DTS. DTS.Draw is also all C code. DTS.Draw is a “standard” drawing application. It has a tool palette of a variety of drawing objects. It has a hierarchical document architecture which allows for grouping and ungrouping of draw objects. It supports infinite undo. It supports drag and drop.

When a document is saved, the object hierarchy is flattened and streamed to the file. When a drag-out occurs, the selected objects are streamed into a handle; this stream represents a sub-hierarchy of the document. This sub-hierarchy is then just a flavor for the clippings file. When a file is opened (or a drag-in occurs), the hierarchy is reconstructed. Very standard stuff.

Here’s a diagram of a representative DTS.Draw document:

For a save, the objects in the hierarchy are streamed in simple tree-walk order, as indicated by the numbering. The drag objects 2, 4, 5, and 6 can be any supported object. The current implementation of DTS.Draw allows for line, rect, round rect, oval, and pie objects. More can be added of course, and this exactly is how we added OpenDoc support to DTS.Draw; we just added a new OpenDoc Part object into the application. The difference with this object is that the content isn’t anything specifically manipulated by DTS.Draw. It is simply a part the user adds to the document. The DTS.Draw object just serves as a “container” for the OpenDoc part. If a user were to add two OpenDoc parts to the above DTS.Draw document, the document hierarchy might end up looking something like:

The implementation in DTS.Draw is relatively simple. The Part object inherits from DTS.Draw’s native rect object. The difference is that it has a much more complex content that the rect object in the standard DTS.Draw application. The content of the Part object can be any OpenDoc part, of course. The content of the Part object is managed using CALib. Given this information, look at this diagram and see exactly what the relationship between the Part objects and CALib :

As shown above, there’s a lot more to the DTS.Draw document now. Fortunately, most of the new stuff is managed by CALib and OpenDoc. CALib uses a “proxy part” to contain the parts that are placed into the document content. Normally, OpenDoc expects there to be a root part that is an OpenDoc container, but since other parts are “embedded” into your application’s non-OpenDoc document, a proxy container part is created and the “embedded” parts are stored in there. The proxy part, as far as OpenDoc is concerned, is what actually contains the other parts that are referenced from the DTS.Draw native content.

The difficulty here is that the proxy part isn’t “real.” It has no geometry information, and OpenDoc doesn’t automatically bind the proxy part to any code, as is the normal case with OpenDoc parts. Thus, OpenDoc is unable to offer the full range of services for the embedded parts. But this is okay. The proxy part isn’t all that smart, nor should it be. It is simply a part that is used by CALib to have somewhere to put the other parts.

So it’s up to DTS.Draw to control the layout and presentation for the OpenDoc parts. Only the application knows the geometry information for the embedded parts, which is stored in DTS.Draw Part objects. The DTS.Draw Part object also has a persistent reference to the corresponding object embedded in the proxy part. Fortunately, CALib offers API calls to help manage these and other OpenDoc interactions, so the above and other OpenDoc related tasks are relatively simple to implement.

For example, to perform screen updates and such, DTS.Draw simply tells CALib to tell the part to draw itself. All that is needed is the Part Ref value, which indicates to CALib which embedded part to draw. The application doesn’t have to care what it references. It references something, and that thing knows how to draw itself.

Streaming Your Objects

Given that the proxy part can’t really deal with containing parts by itself, (i.e., without your application doing the geometry), the proxy part and its embedded parts do not constitute a valid OpenDoc document. This is important when we decide what type of document you want to create when you save it to disk.

The choices are:

1. A Bento stream placed inside your document.

2. Your document stream placed inside a Bento document.

The right choice will of course depend on your application. For DTS.Draw, we chose 1. Choice 1 is closer to existing Macintosh applications. Choice 2 is closer to regular OpenDoc parts. If you were to consider the development choices, from application to OpenDoc part, with CALib applications somewhere in between, your choices look something like this:

Application:

Standard document architecture.

CALib-friendly application:

Standard document architecture with embedded Bento stream.

CALib-savvy application:

Bento document with application data streamed into an OpenDoc storage unit
value.

OpenDoc part editor:

Bento document with part editor data residing in an OpenDoc storage unit.

When considering drag and drop, the above categories are very important. When applications drag something to the desktop, a clippings file is created. When OpenDoc parts are dragged to the desktop, an OpenDoc document is created, instead of a clippings file. This is an important distinction between applications and OpenDoc. Applications create clippings files because they are a standard and flexible intermediate format. OpenDoc parts create OpenDoc documents on a drag-out because an OpenDoc document is already a universal format. There’s no reason to resort to creating a clippings file.

If you are a CALib application, the choice is no longer so clear. Our suggestion is to base your drag-out decision on whether your document format is still “native,” or if you use a Bento file with your native content embedded.

So, if you are a CALib application, what is one to do on a drag-out? The answer lies in the document type. If the document type is an OpenDoc document (CALib-savvy), then the drag-out type is OpenDoc document. If the document type is a standard document (CALib-friendly), then the drag-out type is a clippings file.

DTS.Draw’s native content is simply streamed out. After adding CALib support, this is still the case. The Bento document is streamed out, as well. Here’s the new document format:

Byte offset Description

0 to 3: length of Bento stream

4 to nativeContent - 1: Bento stream

nativeContent to EOF: native content stream, i.e.,
DTS.Draw old format

There was much discussion as to whether or not the Bento stream should be at the front of the file or the end. It turns out that you can do some interesting things if it is at the front of the file. Try out this situation:

1. Your machine has CALib. You add some OpenDoc parts to your DTS.Draw document.

2. You then send the document to some poor individual who doesn’t have CALib or OpenDoc.

Guess what? If the Bento stream is in the front of the file, the unfortunate individual can still use the file with your CALib-friendly application. The user without CALib can actually edit the native content and save it out. The native content changes size, but hey, it’s on the end of the file.

On machines that don’t have CALib but need to display Part objects in their content, the standard look for “NoPart” should be used. This is what OpenDoc displays when an editor for a particular part isn’t available. In the case of CALib applications, it works for when CALib isn’t available, as well.

Making your CALib-based documents work on machines with or without CALib takes a bit of extra coding, but from a version control standpoint, it is well worth it. Documents can go anywhere. A CALib document can be given to someone without CALib. That this person can actually edit the native content of the document, and then give the document back to you, is pretty nifty.

On machines where CALib isn’t available, users obviously won’t be able to add any new parts to the document. They will be restricted to editing the native content. However, this may include moving part objects around that someone else was nice enough to put in the document. This works. Remember that the geometry information is stored in the native objects, which all users can edit. The proxy part doesn’t handle the geometry. In addition, the user can delete the Part objects (which are displayed using the “No Part” look). This of course means that there is data orphaned in the Bento stream. (Since the user doesn’t have CALib, there is no way their machine can modify the Bento stream.) Fortunately, the stream will be compacted the next time the document is saved on a machine with CALib.

With some extra work, you can even allow the user to resize the Part objects without CALib. When this occurs, the information in the Bento stream for that part is no longer up to date. The native content object will need to be flagged as having been resized. When the document is opened on a machine with CALib, these objects will need to have their frame information renegotiated and resolved to reflect their new size.

We’ve been discussing types of editing that can still occur to a CALib document Part object when CALib isn’t available. There are, of course, edits that can’t be performed. Here are two:

1. Dragging that includes a Part object. Streaming the drag data must include streaming the Bento information into the flavor. This can’t be done without CALib. All that’s in the native object is a persistent reference to somewhere inside the Bento stream. You can’t resolve the reference without CALib.

2. Copying the object. At first, it would seem that you would just copy the native content object. It has a persistent reference. Both copies of the object would then point to the same Bento information, i.e., the part. This is a bad thing. When opened again on a CALib machine, each copy of the part should be independent of the other. (You could flag the copy as an unresolved copy, and then clone the object when the document is next opened on a CALib machine.)

As you can see from this discussion, CALib can be used to add OpenDoc capability to your existing applications without radically changing the way they work. The actual amount of code added to an application isn’t all that bad, either. Of course, this will vary, depending on architecture and document content, but most likely, it’s not a complete recode with major modifications throughout your application. Look for the latest CALib and CASample sample code on the OpenDoc DR4 release.

Have fun out there!

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

BetterTouchTool 2.25 - Customize Multi-T...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
WhiteCap 6.7.1 - Visual plug-in for iTun...
WhiteCap is a sleek and sophisticated music visualizer and screensaver that features futuristic, wireframe mesh visuals with dynamic backgrounds and colors. WhiteCap contains thousands of visual... Read more
DiskMaker X 6.0 rc5 - Make a bootable OS...
DiskMaker X (was Lion DiskMaker) helps you to build a bootable drive from the official OS X installer app (the one you download from the Mac App Store). It detects the OS X Install program with... Read more
Lyn 1.9 - Lightweight image browser and...
Lyn is a fast, lightweight image browser and viewer designed for photographers, graphic artists, and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it delivers... Read more
WhiteCap 6.7.1 - Visual plug-in for iTun...
WhiteCap is a sleek and sophisticated music visualizer and screensaver that features futuristic, wireframe mesh visuals with dynamic backgrounds and colors. WhiteCap contains thousands of visual... Read more
DiskMaker X 6.0 rc5 - Make a bootable OS...
DiskMaker X (was Lion DiskMaker) helps you to build a bootable drive from the official OS X installer app (the one you download from the Mac App Store). It detects the OS X Install program with... Read more
Lyn 1.9 - Lightweight image browser and...
Lyn is a fast, lightweight image browser and viewer designed for photographers, graphic artists, and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it delivers... Read more
MacFamilyTree 8.2.1 - Create and explore...
MacFamilyTree gives genealogy a facelift: modern, interactive, convenient and fast. Explore your family tree and your family history in a way generations of chroniclers before you would have loved.... Read more
LaunchBar 6.9 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more
LaunchBar 6.9 - Powerful file/URL/email...
LaunchBar is an award-winning productivity utility that offers an amazingly intuitive and efficient way to search and access any kind of information stored on your computer or on the Web. It provides... Read more

Latest Forum Discussions

See All

This War of Mine gets a new ending and m...
This War of Mine just got a big new update, featuring free DLC that adds a new ending to the game, among other exciting changes. The update is celebrating the game's two-year release anniversary. Apart from the new ending, which will be quite... | Read more »
Summon eight new heroes in Fire Emblem H...
Nintendo keeps coming at us with Fire Emblem Heroes updates, and it doesn't look like that trend is stopping anytime soon. The folks behind the game have just announced the new War of the Clerics Voting Gauntlet, expected to start next Tuesday. [... | Read more »
The best deals on the App Store this wee...
iOS publishers are pulling out all the stops this week -- there's a huge number of seriously great games at discounted prices this week. Let's not waste any time and get right down to business. [Read more] | Read more »
The House of da Vinci (Games)
The House of da Vinci 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: Enter The House of Da Vinci, a new must-try 3D puzzle adventure game. Solve mechanical puzzles, discover hidden... | Read more »
Solve the disappearance of history’s gre...
Blue Brain Games invites you to indulge in an immersive hands-on 3D puzzle adventure in similar vein to The Room series, with its debut release The House of Da Vinci. Set during the historic period of the Italian Renaissance (when Leonardo himself... | Read more »
Age of Rivals (Games)
Age of Rivals 3.3 Device: iOS Universal Category: Games Price: $.99, Version: 3.3 (iTunes) Description: Deep civilization-building strategy in a fast-paced card game! | Read more »
Panthera Frontier (Games)
Panthera Frontier 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Angry Birds Evolution beginner's gu...
Angry Birds changes things up a fair bit in its latest iteration, Angry Birds Evolution. The familiar sling-shot physics mechanics are still there, but the game now features team-based gameplay, RPG elements, and a new top-down view. With all of... | Read more »
Sega Forever is for the retro game fans
Sega is launching a new retro games service titled Sega Forever, in a move that's sure to delight games enthusiasts with a bit of nostalgia. Sega's releasing five classic games for free. The titles include Sonic the Hedgehog, Phantasy Star II,... | Read more »
The Little Acre (Games)
The Little Acre 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

ABBYY TextGrabber 6 for iOS Implements Instan...
ABBYY has announced the release of TextGrabber 6.0.0, an important feature update to the company’s productivity app developed for iOS and Android devices. TextGrabber 6.0 now offers Real-Time... Read more
vPhone, First Smartphone That Can’t Be Lost,...
Austin, Texas based Hypori has introduced the vPhone, a virtual smartphone that affords every business user the benefits of separate work and personal phones, conveniently delivered on a single... Read more
Save this weekend with 2016 refurbished MacBo...
Apple has dropped prices on Certified Refurbished 2016 15″ and 13″ MacBook Pros by as much as $590 off original MSRP. An Apple one-year warranty is included with each model, and shipping is free: -... Read more
New 27-inch 3.4GHz iMac on sale for $1699, sa...
MacMall has the new 2017 27″ 3.4GHz iMac (MNE92LL/A) in stock and on sale for $1699 including free shipping. Their price is $100 off MSRP. Read more
Clearance 2016 MacBook Pros available for up...
B&H Photo has clearance 2016 13″ and 15″ MacBook Pros in stock today and on sale for up to $400 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: - 15″ 2.7GHz... Read more
Apple Ranks 9th In comScore Top 50 U.S. Digit...
comScore, Inc. has released its monthly ranking of U.S. online activity at the top digital media properties for May 2017 based on data from comScore Media Metrix Multi-Platform. * Entity has... Read more
10.5-inch iPad Pros available for up to $20 o...
B&H Photo has the new 2017 10.5″ iPad Pros available for up to $20 off MSRP including free shipping plus NY & NJ sales tax only: - 64GB iPad Pro WiFi: $649 - 256GB iPad Pro WiFi: $749 - 512GB... Read more
Three Off-The-Beaten-Track iOS Apps That Dese...
One of the great things about using iPads and iPhones is the vast selection of apps available for most anything you want or need to do. The three outlined in this article have been in my core app... Read more
Apple No. 1 Spot In Gartner Top 100 Vendors i...
Gartner, Inc. has unveiled the top global 100 vendors in IT in 2016 based on their revenue across IT (excluding communication services) and component market segments. In the Gartner Global Top 100:... Read more
Clearance iMacs available for up to $300 off...
B&H Photo has clearance 21″ and 27″ Apple iMacs available starting at $949, each including free shipping plus NY & NJ sales tax only: - 27″ 3.3GHz iMac 5K: $1999 $300 off original MSRP - 27″... Read more

Jobs Board

*Apple* News Product Marketing Mgr., Publish...
…organizational consensus on strategy and vision for publisher tools, authoring, and Apple News Format.Carries this strategy and vision across the organization to 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
Security Data Analyst - *Apple* Information...
…data sources need to be collected to allow Information Security to better protect Apple employees and customers from a wide range of threats.Act as the subject matter Read more
Lead *Apple* Solutions Consultant - Apple I...
…integrity, and trust.Success Metrics/Key Performance Indicators:Quantitative* Year over Year growth in Apple Product and Beyond the Box sales in the assigned Point of Read more
*Apple* Solutions Consultant till v%u00E5r...
…ethics, integrity, and trust.Success Metrics/Key Performance Indicators:QuantitativeYear over Year growth in Apple Product and Beyond the Box sales in the assigned Point Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.