SDL_MOUSEMOTION is detecting movement when there is none

SDL Development
1

Hi…have searched google and the forums but have not found anyone with the same problem.

I suspect I am misunderstanding how SDL_PollEvent works.

In the following code when I replace SDL_MOUSEMOTION with SDL_QUIT, SDL_MOUSEBUTTONDOWN, or even SDL_MOUSEBUTTONUP
the code behaves as I would expect for each case.

However when I use SDL_MOUSEMOTION my program window only stays up for the 2 seconds delay I have put in and then the window closes and the program exits,

even if I didn’t move my mouse at all, or even touch it.

I start the program using the keyboard in a Windows console window, so don’t touch the mouse at all before the program starts.

I was thinking that perhaps the program was taking existing events from a window buffer or something like that when it starts and that maybe I should clear before using SDL_PollEvent.

But from reading different articles on SDL_PollEvent it’s my understanding that this isn’t necessary, so I guess I am just missing something.

Any help or comments is appreciated, thank you.

Code:

SDL_Surface *screen = NULL;
SDL_Event event;

int main( int argc, char* args[] )
{

SDL_Init( SDL_INIT_EVERYTHING );

screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE );

SDL_Delay( 2000 );

bool quit = false;

while( quit == false )
{
while( SDL_PollEvent( &event ) )
    {
    if( event.type == SDL_MOUSEMOTION )
        {
        quit = true;
        }
    }
}

SDL_FreeSurface( screen );

SDL_Quit();
return 0;

}

2

Probably due to implementation decisions in the underlying operating
system: http://blogs.msdn.com/b/oldnewthing/archive/2003/10/01/55108.aspx

You can probably capture the initial position using SDL_GetMouseState(),
and only process “mouse moves” when the position reported by
SDL_MOUSEMOTION is different from the last known co-ordinates - essentially
the same workaround suggested in the link.On 7 April 2012 16:16, TonyBalony wrote:

**

Any help or comments is appreciated, thank you.

3

Thanks Brian…thought it might be something like that…your link clarifies this…and thanks for suggestion to work around.