Hi taazz and User 137. There is a for loop scanning through a mass of data which is put through various formulae and the results are 1500 points per image linked by LineTo. At this stage FormPaint is called, then the next group of points are evaluated. I tried using TTimer and a separate thread calling invalidate, paint, refresh etc, but that didn't display the graphics, except the last one, again. The graphics can be converted from (effectively) a vector image to a bitmap, but there is also a grid on the form displaying key values from the data. That cannot be rasterized otherwise I would lose the scrolling facility to monitor the results.
It works well in Windows. That's why I think it may be to do with android rather than Lazarus, and finding a way to modify the activity.java file may be a solution. I do not have sufficient knowledge of android and Java to answer this, but I am investigating it.
Regards