Parallax effect scrolling of live wallpaper background

Question

I'm trying to get a background in a live wallpaper to behave like a regular wallpaper with regard to scrolling when the user changes homescreens. I know the method required for this is onOffestsChanged, but I can't seem to get it working.

Does anyone have advice or a code snippet to get this working?

Answer 1

Have your engine implement onOffsetsChanged. The xOffset variable is a float value from 0 to 1 with 0 being the leftmost screen and 1 being the rightmost. Use the width of the screen (from onSurfaceChanged) and the width of your image to determine the left x coordinate with which to draw your image.

(screenWidth - yourImageWidth) * (1 - xOffset);

This should work with both screenWidth > yourImageWidth and screenWidth < yourImageWidth.