New Movieclip()

When we talk about mobile development, we have to make sure our application is optimized as good as possible to run smooth on a wide variety of devices. Like Kevin Lynch said at MAX 2010, mobile development is like desktop/web development 7 years ago. Let’s take a look on how we can make sure that our mobile applications run smooth. I can already tell you that always a lot of testing (starting early in your development process) on different devices will be necessary to achieve the results you want.

When your application slows down on a device, it means that your code execution per frame or the rendering per frame or both is the bottleneck.

What to display in the DisplayList ?

Always make sure you use the right DisplayOject for the right job. As you know, a MovieClip uses more bytes then a Sprite and Sprite uses more bytes than a Bitmap…etc. When building up your DisplayList always keep in mind that the DisplayList really affects the memory usage of your application. If you have a set of Sprites on your stage for example, you can draw them in a BitmapData object and put that in a bitmap on the DisplayList. That approach will save some memory for sure!

When we talk about Bitmaps, we have to say something about the 2 Flash player render operations also. In the Flash Player every graphical element in your application is rasterized inside a bit/pixel buffer (=rasterizing) and those tiles of pixels are then arranged to make up your scene (=scene compositing) in the main pixel buffer (what you finally see on the device). Every frame, the player calculates a dirty region (=the redraw regions) to see what must be rasterized again and merged again in the main pixel buffer. All those tasks are done by the CPU when doing web/desktop development but with Adobe AIR 2.5 targeting mobile devices, you can choose if the CPU or the GPU needs to do those important tasks.

CPU/GPU rendering

At this moment on IOS, a ‘special’ GPU mode is only supported, it is called GPU Blend. This means that the task of the the creation of the different pixel buffers is done by the CPU and then the CPU sends it to the GPU. The GPU finally does the scene compositing.

On Android, when you use GPU rendering, this is called GPU Vector, the tasks are done fully by the GPU. So, the creation of individual pixel buffers and the scene compositing, it all happens at the GPU. This can give you a huge performance boost. But can we make sure we are using GPU rendering?

That is where bitmap caching comes in.

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