In order for scaling ratios to apply equally across objects that
start at different positions on the screen, the pixels that are
read from the source bitmap must all use the same pattern of
division. In other words, cels must follow the same scaling pattern
as if they were drawn starting at an even multiple of the scaling
ratio, even if they were not.
Previously sourcePos was always originating from plain 0, 0
which made some pixels not always getting drawn at the right
spot when uneven scaling was used (for example 5:12).
Seems to fix gabriel knight 1 hires graphic issues
1. Reorder member initialisations to match class member order
2. Use #pragma mark instead of comments for annotating sections
3. Remove useless >=0 checks on unsigned types
Filippos Karapetis
Colin Snover
Martin Kiewitz
Johannes Schickel