iup_pthread.c

/**************************************************************************************************
 * IUP program that runs a "long" function in a second thread when the user clicks the button.    *
 * cc iup_pthread.c -o iup_pthread -W -pedantic -ansi -std=c99 -I/usr/include/iup -liup -lpthread *
 **************************************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <iup.h>

pthread_t thread1;
int  iret1;

void *worker_function( void *ptr )
{
    /**************************************************************************************
     * Do not call IUP functions from other threads as IUP 3 is currently not thread-safe *
     **************************************************************************************/
    for (int i = 0; i < 100; i++) {
        sleep(5);
        printf("%s \n", "worker function");
    }
    return NULL;
}

int btn_cb( Ihandle *self )
{
    /************************************************************************************
     * Do not use variables created on the callback function as they will lose context  *
     * as soon as the callback function reach the return point.                         *
     * Use global variables instead if you need to pass arguments to the second thread. *
     ************************************************************************************/
    iret1 = pthread_create( &thread1, NULL, worker_function, NULL);
    pthread_detach(thread1);
    return IUP_DEFAULT;
}

int main(int argc, char **argv)
{
  Ihandle *dlg, *button, *label, *vbox;

  IupOpen(&argc, &argv);

  label =  IupLabel("Start second thread:");
  button = IupButton("Start", NULL);
  vbox = IupVbox(
    label,
    button,
    NULL);
  IupSetAttribute(vbox, "ALIGNMENT", "ACENTER");
  IupSetAttribute(vbox, "GAP", "10");
  IupSetAttribute(vbox, "MARGIN", "10x10");

  dlg = IupDialog(vbox);
  IupSetAttribute(dlg, "TITLE", "pthread test");

  /* Registers callbacks */
  IupSetCallback(button, "ACTION", (Icallback) btn_cb);

  IupShowXY(dlg, IUP_CENTER, IUP_CENTER);

  IupMainLoop();

  IupClose();
  return EXIT_SUCCESS;
}