creacog

The documentation is correct, so i have no excuse, but I didn’t initially read much beyond the signature of the constructor…

public function BitmapData(width:int, height:int, transparent:Boolean = true, fillColor:uint = 0xFFFFFFFF)

I needed a transparent bitmap. Reading the default “transparent:Boolean = true”, I assumed by simply supplying width and height, a transparent bitmap is what I would get. Not so! I got a white rectangle. The reason being, that the default fill colour is 100% white. (The first pair of FFs representing the alpha in ARGB).

At first it would seem slightly unintuitive for the second default to conflict with the first, until one realises that the ‘transparent’ flag is there to indicate whether the object will support transparency or not. Not to state that it should be initially created transparent. Supporting transparency increases data size from 24 bits per pixel to 32 bits per pixel.

So what i should have done :

bmd = new BitmapData( width, height, true, 0 );

Finally got around to adding a case-study to my corporate site including a screen-cast of some of the features of my longest running project, a Flex/AIR application for communicating football moves and plays. Essentially a digital, animated version of a football tactic board.

More details and the screen-cast are on the creative-cognition case-study page.

Blowing my own trumpet for a moment… last week I sat and passed as Adobe® Certified Expert in Flex with AIR. Which I hope will help make my case with prospective clients.

More information on Adobe certification programs.

Really handy! … ActionScript 3, Air and Flex documentaion distributed as an application on iPhone and iPodTouch - by Mike Chambers.

Downloaded it, had a play, simple and effective. A ‘back’ button would be nice though in future versions

An emerging pet hate of mine: AIR applications that do-away with the system chrome, only to then re-implement parts of it, but ignoring host-system conventions. Note this isn’t anything to do with AIR itself, more to do with designers and/or developers not entirely considering user-experience across all platforms.

The example above taken from Tour de Flex.

Personally for this app I see no reason not to have used the host system’s chrome. Doing so would have entirely avoided this issue. But to re-implement fundamental controls such as those pictured using positioning and icons based on only one operating system in an app which is cross-platform undermines the user-experience for users of other systems. In the example, a Windows arrangement and appearance is used which feels wrong on a Macintosh system, where the arrangement should be reversed and in the left rather than the right corner of the window. That it is Adobe setting this presedent in a number of their AIR applications is disapointing. I hope it is a convention other AIR developers will not follow. I certainly wont.

Will probably yield scary looking error:

Process terminated without establishing connection to debugger.
Command:
“/Applications/Adobe Flex Builder 3/sdks/3.2.0/bin/adl” -runtime “/Applications/Adobe Flex Builder 3/sdks/3.2.0/runtimes/air/mac” /PathToProject/bin-debug/Project-app.xml /PathToProject/bin-debug
Output from command:
error while loading initial content

So, basically by setting the project to compile against the SDK 3.2 you are implicitly changing the version of AIR you are building against from earlier versions to 1.5. To fix you need to open file :

/PathToProject/Project-app.xml

and change the namespace to “http://ns.adobe.com/air/application/1.5″

This has already been logged as a bug (FB-15687) in the bugbase against Gumbo, by the release of which, hopefully it will be intercepted to present a more meaningful message.

When using the Adobe AIR Update Framework for the first time, you will be stepping through the associated documentation. You will probably initially decide to use a configuration XML file to govern the update process. The documentation presents the following line to inform the framework of the location of your config file:

Point the configurationFile property to the location of that file: as in the following ActionScript:
appUpdater.configurationFile = new File("cfg/updateConfig.xml");

If you are familiar with the File class, you will see that this is likely to generate a run-time-error, especially when testing in adl…

ArgumentError: Error #2004: One of the parameters is invalid.
at Error$/throwError()
at flash.filesystem::File/set nativePath()
at flash.filesystem::File()

If you are like me, you’ll probably want to place the updateConfig.xml file within the application directory next to the *-app.xml file. If so, the line of code you need can be written:

appUpdater.configurationFile = new File( File.applicationDirectory.resolvePath( "updateConfig.xml" ).nativePath );

or more compactly, using the “app:/” url scheme:

appUpdater.configurationFile = new File( "app:/updateConfig.xml" );

Over the past few months I’ve been getting my head around the likes of Cairngorm, PureMVC and better use of design patterns in general. So looking forward to tonight’s LFPUG to see what the Slide Framework For Flex adds to the mix. The other stuff on large datasets looks pretty good too!

A little while ago I got around to building my version of an alert tool sampler, using it as an exercise to learn Cairngorm. (The documentation for which I have found particularly poor with the exception of a few gems such as David Tucker’s excellent Cairngorm ‘Getting started’ tutorials.)

Typically AIR developers will all want to take advantage of the Update capability, but in it’s original form requires some work. Rich Tretola’s UpdateManager did the job, but I wanted more programmatic control, interception of events and a slightly different UI work-flow, and set about creating my own.  Just as that phase of the work is completed, I find Adobe’s Update Framework on labs which although beta, does a much better job. I wish it was there a week ago.

Also, I just took the opportunity to update to AIR 1.1. Unfortunately updating Flex to use the new AIR is a little messy (in that it requires manually copying some files rather than running an installer) and means moving to the 3.0.2 stable build of the Flex SDK. However it is not difficult and the instructions to follow are here.

If you are using DataGrid in a Flex/AIR application, the chances are you will at some stage hit the following RunTime error…

TypeError: Error #1010: A term is undefined and has no properties.

.. with a traceback indicating the error occurred within DataGrid.as. At which point you will stare at your own code for a while and wonder why.

In my circumstance I pinned this down to clearing the contents of the data provider and repopulating when there is an item renderer active on the DataGrid. A use-case that probably doesn’t come up that often in web-based Flex apps, since if the user clicks another control to trigger an update, the item renderer is exited at that point and the edit committed prior to the dataprovider changing.

In an AIR app, we have native menus available to us. When the user employs native menu selection, the item editor remains active. If that menu option triggers a repolpulation of the data provider (use-case example File>Open), we then get the error.

The workaround is pretty simple. A call needs to be made to destroyItemEditor() on the DataGrid instance before repopulating it’s data. In a simple application this is no great problem. But if you’ve gone to the effort of using something like the PureMVC framework to separate Data Object from View Components, the data object isn’t supposed to have any knowledge of the view. So in my case thefix is quite crude - when issuing the open command, a notification to destory item editors will be issued so any view component that uses them may destroy their editor prior to the repopulation.

My contention is that it should be the responsibilty of the DataGrid to destroy the item editor if the dataprovider updates.

I have this logged as a bug with Adobe (SDK-15280), along with sample code demonstrating the issue. Feel free to review and vote for the bug if you are in agreement with my point and comment further therein if you disagree or have better suggestions to offer.