Developing for multiple screen sizes on BlackBerry

Question

Android and iOS have a concept of a "density independent pixel" so your layouts look the same on devices with different densities and screen sizes.

Up until now I've written code to manually space elements using pixels (i.e. I want this button to be 10 pixels from the left side of the screen). This is great on a Curve, but when I load it up on a Bold the resolution is much higher, so 10 pixels is a much smaller physical space.

What are the best practices for multiple screen sizes on BlackBerry? Is there any easy way to define a density independent pixel? RIM seems to not offer much in terms of documentation or APIs to make this easy.

Answer 1

Points are density independent pixels (to a good degree of accuracy).

For BlackBerry, the most relevant class is net.rim.device.api.ui.Ui which defines a UNITS_pt constant (and a UNITS_px constant), a convertSize method to convert between points and pixels (since operations on Graphics take pixels instead of points).

A useful methodology for BlackBerry apps is to take everything in relation to your font sizes, which you define in points - there's a version of net.rim.device.api.ui.Font.derive that takes a units parameter and makes it easy to get fonts with a particular point size.

Of course, you can't take anything for granted - defining things in points will make things easier, but with BlackBerry you deal with lots of different pixel densities and aspect ratios so test thoroughly, at least on the simulators.