Efficient image scaling in Blackberry

How to scale image (Bitmap/EncodedImage) efficiently in Blackberry (using OpenVG/OpenGL if hardware acceleration supported). Can something like VGField/GLField be used to achieve that?

I have already tried Bitmap.scaleInto(...), EncodedImage.scaleImage32(..) and some naive algorithms (raw data manipulation). Also I can't use ZoomScreen because it is not possible (?) to change the image of an ZoomScreen instance dynamically.

Need some idea about how the de开发者_如何学JAVAfault image viewer application in BlackBerry device (e.g. Torch 9800) performs smooth pinch zooming.

The usual technique is:

• Step 1: scale the current thumbnail, so you get a rather blocky looking image, but has the advantage of working nearly instantaneously.

• Step 2: kick off the higher resolution image decoder on a separate thread. When it is done, it sends the newly decoded image back to the UI thread to replace the approximate image that was used from step 1.