Following my post yesterday about the addition of Loader.unloadAndStop to the Flash Player 10 API, I chatted with Werner Sharp, who is one of the Adobe engineers that worked on the feature (and an all round good guy). Following that discussion, I thought it would be helpful to post a summary of what I know about it, and disseminate some of the information Werner provided.

The unloadAndStop method was added in response to challenges ActionScript developers were facing with halting loaded SWF content, and removing it from memory. These issues were detailed in an article I posted in early April titled “Failure to Unload: Flash Player 9’s Dirty Secret“.

This API addition is not a magic bullet for solving all of the listed problems. What it does do, is attempt to prepare the loaded content for collection, and then hint to the Garbage Collector that it should initiate a collection pass. You can prevent the latter by passing false as the first parameter. It is still easy to get a SWF stuck in memory, but it is much harder to do accidentally.

Continue reading →

Adobe has announced the addition of the new Loader.unloadAndStop() method for Flash Player 10. Here is the description from the beta 2 release notes:

unloadAndStop — This new ActionScript 3.0 API adds unload functionality similar to the unload behavior in ActionScript 2.0. After calling unloadAndStop on loaded content it will be immediately removed stopping all audio, removing eventListeners, and becoming inaccessible through ActionScript.

This new API addresses some of the issues I raised in my article “Failure to Unload: Flash Player 9’s Dirty Secret“. It doesn’t enable content sandboxing, or provide a complete mechanism for explicit unloading, but it does make it much simpler to free a loaded SWF for garbage collection. It’s still possible to prevent a SWF from being unloaded, but it’s much more difficult to do by accident.

Kudos to the player team for putting this in. If you’re concerned about this topic, please help Adobe out by testing this feature and reporting any problems.

Update: You can find more details on the Loader.unloadAndStop feature in my article “Additional Information on Loader.unloadAndStop“.

Source Code Licenses

I think there is a critical lack of understanding about the implications of different source code licenses in the Flash and Flex world. As my company has grown, and we have tackled more critical projects for larger clients, I have had to educate myself and my team on this topic.

I think this is a hugely important topic, so I’ve devoted quite a lot of time and energy to research and synthesize information on some of the most popular source code licenses being used in the Flash community today. I would also encourage you to spread this information around, either by linking to this article from your blog, or by sharing its contents with your colleagues. Hopefully it helps developers sharing their code to choose appropriate licenses (I’m getting sick of seeing LGPL source code), and also help the community to use shared source code legally and appropriately.

While I have worked hard to research everything in this article, I am not a lawyer, or an expert on this topic, so I make no claims that it is accurate or correct. It is also written from the perspective of someone who releases free code, and runs a service oriented development shop. Implications may vary for product development.

Below you will find an overview of some of the most common open source licenses. I have tried to list them in order from most restrictive to most permissive.

Continue reading →

I get asked a lot of questions about my tree experiments, such as sakura and interactive elm. I thought I would write up a simple explanation to point people in the right direction.

The easiest place to start is with recursion. Trees are beautiful examples of recursion in the natural world. Recursion is a deep and very important topic, but for our purposes can be simplified to the idea of code calling itself. In the example below, each time you click the stage, all of the “active” (outermost) branches call code to draw two more branches at their ends, the next time you click, those new branches call the same code. Move your mouse around to vary the angle of all of the branches. As an aside, this example also has an interesting “emergent” property of drawing hexagons (try moving your mouse to the bottom when all of the branches are drawn).

Continue reading →

Last year I ran an intensive, one day workshop on ActionScript 3 covering a wide range of topics including AS3 / AVM2, migrating from AS2, runtime errors, the event model, the display list, regular expressions, E4X (XML), loading data and assets, optimization, and more.

Today I released all 167 slides from the workshop on my talks page at gskinner.com/talks/. I’m not planning any workshops in the immediate future, and I thought the notes would be useful for developers learning AS3. The content ranges from basic to intermediate, and includes a few obscure tips and architectural ideas.

I haven’t looked over the notes since I ran the workshop, so please pardon any errors.

I’m bad at drawing curved lines in ActionScript. I’m always too lazy to figure out how to calculate exactly where the control point should go when using curveTo. Because of this, most of my experiments have relied on drawing a lot of short straight line segments to simulate curves, rather than figuring out how to draw the curves properly. For example, my tree experiments are drawn entirely with straight line segments.

While revisiting my grass simulations I decided to bite the bullet and figure out an easy way to work with curves. The result is a couple of “spikes” or isolated test cases that demonstrate the logic behind converting a series of straight lines into a nice looking curve.

The basic concept is to bisect each of the straight lines, then draw a curve between the bisections, using the original points as the curve’s control point. Nothing new I’m sure, but it works really well for me, because I can continue to think in straight lines, but draw in curves.

Continue reading →

I showed this experiment at FitC Toronto, then forgot to post it until today.

I’ve been experimenting on and off with grass simulations in ActionScript 3 (ex1 , ex2) for a little over a year. I recently rewrote the logic to draw the grass and wanted to build out a new experiment to use it. (I’ll be posting a bit about the drawing mechanism in the next day or two)

The result was cutByTheWind, which you can see below. I tried to do something that was more cinematic than most of the pieces I’ve built to date, and had some form of open ended narrative. This isn’t really my usual forte, but I’m fairly happy with the results. It is very CPU intensive, so don’t be surprised to hear your fans start up.

Special thanks to Keith and his lovely wife for translating the title into Japanese.

Continue reading →