Autofocus when scanning QR code

I'm working on a BlackBerry app which will be used in cafes and restaurants, and one of the features is QR code scanning

Is there any way to make the camera autofocus the QR 开发者_高级运维code?

Searching, I found FocusControl, which looks like the one I'm looking for. Unfortunately, it's only available since OS 5.0.

I wonder how to achieve the same thing on OS 4.5, 4.6, and 4.7.

Any suggestions?

You can't. In OSs prior to 4.5, you can launch the native camera app and listen for recently created image files (FileSystemJournalListener). This way, if the BB has autofocus, the image has more definition.

However, there's no way to do this for every BB. Unless you apply some image algorithm of your own after taking the image.