C++ how to drag bitmap around screen -

hi i'm trying make little ufo bitmap (drawing/painting taken care of) can dragged around screen. can't seem make ufo position update , redraw repeatedly mousebuttondown() function (simplified code mouse event handler). suggestions on detecting dragging , redrawing accordingly? code below relevant functions:

void mousebuttondown(int x, int y, bool bleft) {   if (bleft)   {     while(_bmousemoving == true && _bmousedragrelease == false)  {           _isaucerx = x - (_psaucer->getwidth() / 2);         _isaucery = y - (_psaucer->getheight() / 2);         invalidaterect(_pgame->getwindow(), null, false);     }          // set saucer position mouse position         _isaucerx = x - (_psaucer->getwidth() / 2);         _isaucery = y - (_psaucer->getheight() / 2);    }   else   {     // stop saucer     _ispeedx = 0;     _ispeedy = 0;   } }  void mousebuttonup(int x, int y, bool bleft) {     _bmousedragrelease = true; }  void mousemove(int x, int y) {     _bmousemoving = true;   } 

to clarify chris said, you're going wm_xbuttondown message once, , you'll need use toggle dragging state can query when recieve wm_mousemove message.

when mouse move message during dragging state, you'll want invalidate rectangle surrounding ufo was, , rectangle surrounding is.

invalidating rectangle causes wm_paint messages, redraw whatever behind ufo, , ufo in it's new place.

or cheat , make ufo cursor when you're dragging :)