CODEWITHSUNDEEP
clinuxubuntugccgtk3
ganeshredcobra
ganeshredcobra

Reputation: 2081

call external functions in GTK+ gui

Am having a main.c which is linked with some headers and other c files.After completing the program its a terminal based program which works with user input using switch.Its associated with a hardware board when i gives "o" it opens and "c" it closes.

I got a sample GTK+ gui code written in c with open cloase and quit buttons.How would i link my open and close functions with the open and cloase buttons in gui.

This is the GTK Code am Having

#include <gtk/gtk.h>

static void
print_hello (GtkWidget *widget,
             gpointer   data)
{
    g_print ("Hello World\n");
}

int
main (int   argc,
      char *argv[])
{
    GtkWidget *window;
    GtkWidget *grid;
    GtkWidget *button;

    /* This is called in all GTK applications. Arguments are parsed
     * from the command line and are returned to the application.
     */
    gtk_init (&argc, &argv);

    /* create a new window, and set its title */
    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_title (GTK_WINDOW (window), "CANMate");
    g_signal_connect (window, "destroy", G_CALLBACK (gtk_main_quit), NULL);
    gtk_container_set_border_width (GTK_CONTAINER (window), 50);

    /* Here we construct the container that is going pack our buttons */
    grid = gtk_grid_new ();

    /* Pack the container in the window */
    gtk_container_add (GTK_CONTAINER (window), grid);

    button = gtk_button_new_with_label ("Open");
    g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

    /* Place the first button in the grid cell (0, 0), and make it fill
     * just 1 cell horizontally and vertically (ie no spanning)
     */
    gtk_grid_attach (GTK_GRID (grid), button, 0, 0, 1, 1);

    button = gtk_button_new_with_label ("Close");
    g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

    /* Place the second button in the grid cell (1, 0), and make it fill
     * just 1 cell horizontally and vertically (ie no spanning)
     */
    gtk_grid_attach (GTK_GRID (grid), button, 1, 0, 1, 1);

    button = gtk_button_new_with_label ("Quit");
    g_signal_connect (button, "clicked", G_CALLBACK (gtk_main_quit), NULL);

    /* Place the Quit button in the grid cell (0, 1), and make it
     * span 2 columns.
     */
    gtk_grid_attach (GTK_GRID (grid), button, 0, 1, 2, 1);

    /* Now that we are done packing our widgets, we show them all
     * in one go, by calling gtk_widget_show_all() on the window.
     * This call recursively calls gtk_widget_show() on all widgets
     * that are contained in the window, directly or indirectly.
     */
    gtk_widget_show_all (window);

    /* All GTK applications must have a gtk_main(). Control ends here
     * and waits for an event to occur (like a key press or a mouse event),
     * until gtk_main_quit() is called.
     */
    gtk_main ();

    return 0;
}

Upvotes: 0

Views: 1598

Answers (1)

ptomato
ptomato

Reputation: 57854

In the line

g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);

you are "connecting" a "signal handler": specifying that when button is clicked (that is, it emits the "clicked" signal), the function print_hello() should be called.

Just replace print_hello() with your open or close function, in the appropriate call for the open or close button.

EDIT: Passing parameters to the function

The signal handler is expected to have a prototype of the form:

void signal_handler (GtkButton *button, void *user_data)

The button parameter gets the button that was clicked, and user_data gets whatever you specified as the last parameter of g_signal_connect() -- in this case, NULL.

If you want to pass parameters to your open or close function, you will have to write an adapter function, such as the following:

void
on_open_click (GtkButton *open_button, void *user_data)
{
    if (my_open_function (my_parameter_1, my_parameter_2) == UH_OH_ERROR) {
        fprintf(stderr, "Something went wrong.\n");
}

And then connect it with g_signal_connect() instead of print_hello:

g_signal_connect (button, "clicked", G_CALLBACK (on_open_click), NULL);

In this case, my_parameter_1 and my_parameter_2 can be literal values, or global variables. You can also connect the signal in such a way that you can get values for these parameters through the user_data parameter in your signal handler. It's hard to say whether you need to do that, without knowing more about your open and close functions.

Upvotes: 1

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