Hi, My application present a (raster) moving map. I need to be able to show the map rotated base on any given angle. The program is currently in VC++/MFC but the problem is generic. I have a source bitmap (CBitmap or HBITMAP) and draw it to the device context (CDC) using StretchBlt. While this works fast and smooth for angle=0 (and the user can grab the map smoothly with the mouse), this is not the case if I try to rotate the bitmap and then present it (the rotation of the bitmap using SetWorldTransform() or so takes hundreds of miliseconds and this is too slow).
I think that the solution is to be able to relate only to the pixels that currently on the screen and not rotating the original source bitmap - and this is the key.
If someone has experience with similar implementation then it might save me lots of trial and error efforts. Thanks! Avi.