pdf viewer by poppler library

pdfviewer.c

#include <stdio.h>
#include <stdlib.h>
#include <glib.h>
#include <gtk/gtk.h>
#include <gdk/gdk.h>
#include <cairo.h>
#include <poppler.h>

/* gcc `pkg-config --cflags --libs gtk+-2.0 poppler-glib` -o pdfviewer pdfviewer.c */

static PopplerDocument* doc;
static PopplerPage* page;

static void
on_destroy(GtkWidget* w, gpointer data) {
    gtk_main_quit();
}

static gboolean
on_expose(GtkWidget* w, GdkEventExpose* e, gpointer data) {
    cairo_t* cr;
    cr = gdk_cairo_create(w->window);
    poppler_page_render(page, cr);
    cairo_destroy(cr);
    return FALSE;
}

int main(int argc, char* argv[]) {
    GtkWidget* win;
    GError* err = NULL;

    if (argc != 2) {
        printf("Useage: pdfviewer <uri>\n");
        return 1;
    }

    gtk_init(&argc, &argv);

    doc = poppler_document_new_from_file(argv[1], NULL, &err);
    if (!doc) {
        printf("%s\n", err->message);
        g_object_unref(err);
        return 2;
    }

    page = poppler_document_get_page(doc, 0);
    if(!page) {
        printf("Could not open first page of document\n");
        g_object_unref(doc);
        return 3;
    }

    int pages = poppler_document_get_n_pages(doc);
    printf("There are %d pages in this pdf.\n", pages);
     
    win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    g_signal_connect(G_OBJECT(win), "destroy",      G_CALLBACK(on_destroy), NULL);
    g_signal_connect(G_OBJECT(win), "expose-event", G_CALLBACK(on_expose), NULL);
    gtk_widget_set_app_paintable(win, TRUE);
    gtk_widget_show_all(win);

    gtk_main();

    g_object_unref(page);
    g_object_unref(doc);

    return 0;
}