
	while(isRunning == true)
	{
		SDL_PollEvent(&event);
		if (event.type == SDL_KEYDOWN)
		{
			printf("Oh! Key Press.\n");
			if(event.key.keysym.sym == SDLK_ESCAPE)
			{
				printf("Quiting SDL.\n");
				isRunning = false;
			}		

			if(event.key.keysym.sym == SDLK_m)
			{
				printf("Toggling Mouse.\n");
                int isMouse = SDL_ShowCursor(SDL_QUERY);
                printf("%d",isMouse);
                if (isMouse == SDL_ENABLE)
                {
       				printf("Disable Mouse.\n");
                    SDL_ShowCursor(SDL_DISABLE);
                } else {
       				printf("Enable Mouse.\n");
                    SDL_ShowCursor(SDL_ENABLE);
                }
			}

		}

When I press the escape key the program exits. As should. And my log file looks like:


Initializing SDL.
SDL initialized.
Oh! Key Press.
Quiting SDL.
Quiting....

When I press m and then escape my log file looks like:


Initializing SDL.
SDL initialized.
Oh! Key Press.
Toggling Mouse.
isMouse = 1.
...
...
...
Oh! Key Press.
Toggling Mouse.
isMouse = 1.
Quiting SDL.
Quiting....

Only it's actually a 4mb file! Plus the cursor doesn't toggle. I can't see what I'm doing wrong, it looks perfectly logical to me the code. [Edited by - Narusegawa on October 28, 2004 8:56:43 AM]

Roboguy

794

October 26, 2004 06:05 AM

you might need to put a pause before the SDL_PollEvent, it may be registering multiple key presses because it polled more than one time before the key is released.

http://www.roboguy.net(WIP) - lisperati - SICP - Haskell - Python - OCaml - Lambda the Ultimate - Good Math, Bad Math - Wiki (not Wikipedia) - Pure - Term-Rewriting Functional Language

Anonymous

October 26, 2004 06:23 AM

no thats not the case, an event is only created when a state is changed, eg. m is pressed, m is released, that is 2 events, not m is still down.

but you may wish to use SDL_WaitEvent(&event); which will only progress onto the rest of your code when an new event is in the event queue

actually that is where your problem lies, you poll for a new event but there is none, so it uses the info from the last event (as the variable event wasn't cleared), and therefore, registers m being pressed until a new event is created.

Narusegawa

Author

122

October 26, 2004 06:32 AM

Thanks Anon! That works.

"SDL_PollEvent -- Polls for currently pending events."

I thought that once you'd done something with an event it'd be taken from the queue.

Anonymous

October 26, 2004 02:01 PM

You should always check the return value of SDL_PollEvent. If it returns 0, the SDL_Event structure you passed to it doesn't get filled in but still contains the last event (which in your case is the key down event of the 'm' key).

Anonymous

October 27, 2004 06:07 PM

the event is removed from the queue when poll event gives it to you, however, it doesn't remove it from your event variable

Narusegawa

Author

122

October 28, 2004 08:55 AM

Thanks, I've now got the following in my main loop.

	while(isRunning == true)	{        SDL_Event event;        while(SDL_PollEvent(&event))        {            if (event.type == SDL_KEYDOWN)            {                printf("Oh! Key Press.\n");    			if(event.key.keysym.sym == SDLK_ESCAPE)    			{    				printf("Quiting SDL.\n");    				isRunning = false;    			}		        			if(event.key.keysym.sym == SDLK_m)    			{    				printf("Toggling Mouse.\n");                    int isMouse = SDL_ShowCursor(SDL_QUERY);                    if (isMouse == SDL_ENABLE)                    {           				printf("Disable Mouse.\n");                        SDL_ShowCursor(SDL_DISABLE);                    } else {           				printf("Enable Mouse.\n");                        SDL_ShowCursor(SDL_ENABLE);                    }    			}    			if(event.key.keysym.sym == SDLK_d)    			{                    DrawTile(0,0);                    DrawTile(0,1);                    DrawTile(1,0);                    DrawTile(1,1);                    SDL_Flip(screen);    			}		     }	    		if (event.type == SDL_QUIT)    		{    			printf("Quiting SDL.\n");    			isRunning = false;    	   	}                        printf("Active for %.2f seconds at %.2f fps.\n", ((float) SDL_GetTicks()/1000), (100/((float) SDL_GetTicks()/1000)));				          }	}

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