PocketMatrix

Resizing is simple. Just change the size of the source rectangle.

Try:
CRect srcrect(0, 0, srcsurface->GetWidth(), srcsurface->GetHeight());
destsurface->AlphaBlt(NULL, srcsurface, srcrect, ...);

If you make the source rectangle smaller, the result will be an "upsizing" during the blit.

To downsize, simply adjust the _destination_ rectangle.

Rotation of CGapiRGBASurfaces is not implemented, but since you can get access to the raw surface buffer (GetBuffer) you can add it yourself if you want it...