/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/ 
/* This is a multi threaded application that uses a progress bar to show
 * status.  It uses Gtk+ to make a smooth pulse.
 *
 * Written by Jud Bishop after studying the other examples provided with
 * libcurl.
 *
 * To compile (on a single line):
 * gcc -ggdb `pkg-config --cflags  --libs gtk+-2.0` -lcurl -lssl -lcrypto
 *   -lgthread-2.0 -dl  smooth-gtk-thread.c -o smooth-gtk-thread
 */ 
 
#include <stdio.h>
#include <gtk/gtk.h>
#include <glib.h>
#include <unistd.h>
#include <pthread.h>
 
#include <curl/curl.h>
 
#define NUMT 4
 
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
int j = 0;
gint num_urls = 9; /* Just make sure this is less than urls[]*/ 
const char * const urls[]= {
  "90022",
  "90023",
  "90024",
  "90025",
  "90026",
  "90027",
  "90028",
  "90029",
  "90030"
};
 
size_t write_file(void *ptr, size_t size, size_t nmemb, FILE *stream)
{
  /* printf("write_file\n"); */ 
  return fwrite(ptr, size, nmemb, stream);
}
 
/* http://xoap.weather.com/weather/local/46214?cc=*&dayf=5&unit=i */ 
void *pull_one_url(void *NaN)
{
  CURL *curl;
  CURLcode res;
  gchar *http;
  FILE *outfile;
 
  /* Stop threads from entering unless j is incremented */ 
  pthread_mutex_lock(&lock);
  while ( j < num_urls )
  {
    printf("j = %d\n", j);
 
    http =
      g_strdup_printf("xoap.weather.com/weather/local/%s?cc=*&dayf=5&unit=i\n",
                      urls[j]);
 
    printf( "http %s", http );
 
    curl = curl_easy_init();
    if(curl)
    {
 
      outfile = fopen(urls[j], "w");
      /* printf("fopen\n"); */ 
 
      /* Set the URL and transfer type */ 
      curl_easy_setopt(curl, CURLOPT_URL, http);
 
      /* Write to the file */ 
      curl_easy_setopt(curl, CURLOPT_WRITEDATA, outfile);
      curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_file);
 
      j++;  /* critical line */ 
      pthread_mutex_unlock(&lock);
 
      res = curl_easy_perform(curl);
 
      fclose(outfile);
      printf("fclose\n");
 
      curl_easy_cleanup(curl);
    }
    g_free (http);
 
    /* Adds more latency, testing the mutex.*/ 
    sleep(1);
 
  } /* end while */ 
  return NULL;
}
 
 
gboolean pulse_bar(gpointer data)
{
  gdk_threads_enter();
  gtk_progress_bar_pulse (GTK_PROGRESS_BAR (data));
  gdk_threads_leave();
 
  /* Return true so the function will be called again;
   * returning false removes this timeout function.
   */ 
  return TRUE;
}
 
void *create_thread(void *progress_bar)
{
  pthread_t tid[NUMT];
  int i;
  int error;
 
  /* Make sure I don't create more threads than urls. */ 
  for(i=0; i < NUMT && i < num_urls ; i++) {
    error = pthread_create(&tid[i],
                           NULL, /* default attributes please */ 
                           pull_one_url,
                           NULL);
    if(0 != error)
      fprintf(stderr, "Couldn't run thread number %d, errno %d\n", i, error);
    else
      fprintf(stderr, "Thread %d, gets %s\n", i, urls[i]);
  }
 
  /* Wait for all threads to terminate. */ 
  for(i=0; i < NUMT && i < num_urls; i++) {
    error = pthread_join(tid[i], NULL);
    fprintf(stderr, "Thread %d terminated\n", i);
  }
 
  /* This stops the pulsing if you have it turned on in the progress bar
     section */ 
  g_source_remove(GPOINTER_TO_INT(g_object_get_data(G_OBJECT(progress_bar),
                                                    "pulse_id")));
 
  /* This destroys the progress bar */ 
  gtk_widget_destroy(progress_bar);
 
  /* [Un]Comment this out to kill the program rather than pushing close. */ 
  /* gtk_main_quit(); */ 
 
 
  return NULL;
 
}
 
static gboolean cb_delete(GtkWidget *window, gpointer data)
{
  gtk_main_quit();
  return FALSE;
}
 
int main(int argc, char **argv)
{
  GtkWidget *top_window, *outside_frame, *inside_frame, *progress_bar;
 
  /* Must initialize libcurl before any threads are started */ 
  curl_global_init(CURL_GLOBAL_ALL);
 
  /* Init thread */ 
  g_thread_init(NULL);
  gdk_threads_init ();
  gdk_threads_enter ();
 
  gtk_init(&argc, &argv);
 
  /* Base window */ 
  top_window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 
  /* Frame */ 
  outside_frame = gtk_frame_new(NULL);
  gtk_frame_set_shadow_type(GTK_FRAME(outside_frame), GTK_SHADOW_OUT);
  gtk_container_add(GTK_CONTAINER(top_window), outside_frame);
 
  /* Frame */ 
  inside_frame = gtk_frame_new(NULL);
  gtk_frame_set_shadow_type(GTK_FRAME(inside_frame), GTK_SHADOW_IN);
  gtk_container_set_border_width(GTK_CONTAINER(inside_frame), 5);
  gtk_container_add(GTK_CONTAINER(outside_frame), inside_frame);
 
  /* Progress bar */ 
  progress_bar = gtk_progress_bar_new();
  gtk_progress_bar_pulse (GTK_PROGRESS_BAR (progress_bar));
  /* Make uniform pulsing */ 
  gint pulse_ref = g_timeout_add (300, pulse_bar, progress_bar);
  g_object_set_data(G_OBJECT(progress_bar), "pulse_id",
                    GINT_TO_POINTER(pulse_ref));
  gtk_container_add(GTK_CONTAINER(inside_frame), progress_bar);
 
  gtk_widget_show_all(top_window);
  printf("gtk_widget_show_all\n");
 
  g_signal_connect(G_OBJECT (top_window), "delete-event",
                   G_CALLBACK(cb_delete), NULL);
 
  if (!g_thread_create(&create_thread, progress_bar, FALSE, NULL) != 0)
    g_warning("can't create the thread");
 
  gtk_main();
  gdk_threads_leave();
  printf("gdk_threads_leave\n");
 
  return 0;
}

You'll also find all examples in the distribution archive, in the docs/examples directory.

Page updated January 16, 2012.
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