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SDL timer program only works when mouse is moving.

This is a discussion on SDL timer program only works when mouse is moving. within the Game Programming forums, part of the General Programming Boards category; So I'm trying to get a timer program to work using LazyFoo's Tutorial. For some reason, though, my timer only ...

  1. #1
    Registered User Kain's Avatar
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    Nov 2012
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    SDL timer program only works when mouse is moving.

    So I'm trying to get a timer program to work using LazyFoo's Tutorial.

    For some reason, though, my timer only works if the mouse is moving or a key is being pressed.

    I downloaded the sample program from the Tutorial and it works perfectly, even though the loop is nearly identical to mine.

    Could anyone tell me why does this happen?

    Thanks in advance.

    Code:
    #include "SDL/SDL.h"
    #include "SDL/SDL_image.h"
    #include "SDL/SDL_ttf.h"
    #include <string>
    #include <sstream>
    
    const int SW = 640;
    const int SH = 480;
    const int BPP = 32;
    
    SDL_Surface * screen = NULL;
    SDL_Surface * background = NULL;
    SDL_Surface * text = NULL;
    
    SDL_Event event;
    
    TTF_Font * font = NULL;
    SDL_Color tcolor = { 255 , 255 , 255 };
    
    bool init()
    {
        if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 )
        {
            return false;
        }
    
        screen = SDL_SetVideoMode( SW , SH , BPP , SDL_SWSURFACE );
    
        if( screen == NULL || TTF_Init() == -1 )
        {
            return false;
        }
    
        SDL_WM_SetCaption( "Timerz!" , NULL );
    
        return true;
    }
    
    void clean()
    {
        SDL_FreeSurface( background );
        SDL_FreeSurface( text );
    
        TTF_CloseFont( font );
        TTF_Quit();
    
        SDL_Quit();
    }
    
    SDL_Surface * load( std::string file )
    {
        SDL_Surface * loaded = NULL;
        SDL_Surface * optimized = NULL;
    
        loaded = IMG_Load( file.c_str() );
    
        if( loaded != NULL )
        {
            optimized = SDL_DisplayFormat( loaded );
            SDL_FreeSurface( loaded );
        }
    
        return optimized;
    }
    
    bool loadf()
    {
        background = load( "bg.png" );
        font = TTF_OpenFont( "Qarmic_sans_Abridged.ttf" , 24 );
    
        if( background == NULL || font == NULL )
        {
            return false;
        }
    
        return true;
    }
    
    void apply( int x , int y , SDL_Surface * get = NULL , SDL_Surface * give = NULL )
    {
        SDL_Rect off;
    
        off.x = x;
        off.y = y;
    
        SDL_BlitSurface( get , NULL , give , &off );
    }
    
    int main( int argc , char * args[] )
    {
        bool quit = false;
    
        Uint32 start = 0;
    
        bool running = true;
    
        if( init() == false )
        {
            return 1;
        }
    
        if( loadf() == false )
        {
            return 2;
        }
    
        start = SDL_GetTicks();
    
        while( quit == false )
        {
            while( SDL_PollEvent( &event ) )
            {
                if( event.type == SDL_KEYDOWN )
                {
                    if( event.key.keysym.sym == SDLK_SPACE )
                    {
                        if( running == true )
                        {
                            running = false;
                            start = 0;
                        }
                        else
                        {
                            running = true;
                            start = SDL_GetTicks();
                        }
                    }
                }
                else if( event.type == SDL_QUIT )
                {
                    quit = true;
                }
    
                apply( 0 , 0 , background , screen );
    
                if( running == true )
                {
                    std::stringstream time;
    
                    time << "Timer: " << SDL_GetTicks() - start;
    
                    text = TTF_RenderText_Solid( font , time.str().c_str() , tcolor );
    
                    apply( ( SW - text->w ) / 2 , 100 , text , screen );
    
                    SDL_FreeSurface( text );
                }
    
                if( SDL_Flip( screen ) == -1 )
                {
                 return 3;
                }
            }
        }
    
        clean();
    
        return 0;
    }

  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
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    Location
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    Posts
    32,824
    Perhaps
    Code:
    if ( SDL_PollEvent( &event ) ) {
      // do your event code
    } else {
      // nothing else to do, update timer
    }
    Or
    Code:
    if ( SDL_PollEvent( &event ) ) {
      // do your event code
    }
    // update timer
    You already have a while(quit == false) loop that will run 'forever', there is no real need to have another while loop inside it.
    Kain likes this.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  3. #3
    Registered User Kain's Avatar
    Join Date
    Nov 2012
    Posts
    17
    Hey, thanks. Implementing your suggestion I finally found the source of the problem.

    Turns out the timer update loop was outside the "SDL_PollEvent( &event )" loop, when it should be inside it.
    I put it inside it, and now it works perfectly.

    Thank you so much for the help.

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