CODEWITHSUNDEEP
c++multithreadingsdl-2
user8664650
user8664650

Reputation:

c++11 thread not ending in SDL

I have two thread which Displays the color changing SDL window.It compiles and runs fine, But I cant close them by clicking the close button of the window.

here is my code:-

#include <iostream>
#include <SDL2/SDL.h>
#include <thread>

using namespace std;

void th(string name,int x,int y,int w,int h,Uint32 flags)
{
    int i=0,o=0,p=0;
    SDL_Window *win;
    SDL_Event e;

    win = SDL_CreateWindow(name.c_str(),x,y,w,h,flags);
    SDL_ShowWindow(win);
    SDL_Surface *win_sur = SDL_GetWindowSurface(win);

    SDL_FillRect(win_sur,0,SDL_MapRGB(win_sur->format,i,o,p));
    SDL_UpdateWindowSurface(win);

    while(1)
    {
        while(SDL_PollEvent(&e))
        {
            if(e.type == SDL_QUIT)
                goto end;
        }
        SDL_FillRect(win_sur,0,SDL_MapRGB(win_sur->format,i,o,p));
        SDL_UpdateWindowSurface(win);
        i++;o+=2;p+=3;

        SDL_Delay(10);
    }
    end:
    SDL_DestroyWindow(win);
}

int main()
{
    int lk =0;
    SDL_Init(SDL_INIT_VIDEO);
    thread t1(th,"win1",90,100,500,500,SDL_WINDOW_OPENGL);
    thread t2(th,"win2",10,400,500,500,SDL_WINDOW_OPENGL);

    t1.join();
    t2.join();

    SDL_Quit();
}

I am using gcc 7.3 and Linux

Upvotes: 0

Views: 283

Answers (1)

Nelfeal
Nelfeal

Reputation: 13269

From the docs:

you can only call this function in the thread that set the video mode

In your case, since you call SDL_Init(SDL_INIT_VIDEO) in the main thread, you can only call SDL_PollEvent there as well. It probably never returns anything in your other threads.

Also, SDL_QUIT is generated when the user clicks on the close button of the last existing window. Check out SDL_WINDOWEVENT_CLOSE when you have multiple windows (or even by default, it's probably the better choice anyway).

Upvotes: 2

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