C GTK3 Remove existing buttons and Create new buttons on same grid-CodePudding

I just learned GTK3 yesterday because of a project I'm currently doing for school, I have a bit of knowledge in C but none in GTK.

I wanted to know if there was a way for me to remove all children on existing grid, and subsequently repopulate by creating new buttons to the same grid.

I currently am only able to delete the button that was clicked on, but not all the buttons with the code:

g_signal_connect(button, "clicked", G_CALLBACK(gtk_widget_destroy), button)

I have also tried deleting the grid itself using:

g_signal_connect(button, "clicked", G_CALLBACK(gtk_widget_destroy), grid)

and

g_signal_connect_swapped(button, "clicked", G_CALLBACK(NewCallback), grid)

and trying to create a new grid using my self defined function NewCallback() to no avail.

From what I understand from the documentation, the order is roughly 1 Container > 1 Window > 1 Grid > Multiple Widgets. Please correct me if I'm wrong.

#include <gtk/gtk.h>

static void NewCallback(GtkWidget *grid, gpointer user_data)
{
  gtk_widget_destroy(grid);

  GtkWidget *gridNew;
  GtkWidget *window;

  gridNew = gtk_grid_new();
  window = gtk_widget_get_toplevel(grid);
  gtk_window_set_title(GTK_WINDOW(window), "NewWindow");

}

static void activate(GtkApplication *app, gpointer user_data)
{
  GtkWidget *window;
  GtkWidget *grid;
  GtkWidget *button;

  /* create a new window, and set its title */
  window = gtk_application_window_new(app);
  gtk_window_set_title(GTK_WINDOW(window), "Test Program");
  gtk_container_set_border_width(GTK_CONTAINER(window), 100);

  /* 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("Test 1");
  g_signal_connect(button, "clicked", G_CALLBACK(printFunc), "1");
  g_signal_connect_swapped(grid, "clicked", G_CALLBACK(gtk_widget_destroy), button);

  /* Place the first button in the grid cell (0, 0), and make it fill Span 2 columns */
  gtk_grid_attach(GTK_GRID(grid), button, 0, 0, 2, 1);

  button = gtk_button_new_with_label("Test 2");
  g_signal_connect(button, "clicked", G_CALLBACK(printFunc), "2");

  /* Place the button in the grid cell (0, 1), and make it fill Span 2 columns */
  gtk_grid_attach(GTK_GRID(grid), button, 0, 1, 2, 1);
  g_signal_connect_swapped(grid, "clicked", G_CALLBACK(gtk_widget_destroy), button);

}

CodePudding user response：

The "clicked" signal callback has a GtkButton as the first argument (which is the button that got clicked) and a user_data pointer (which is given as the last argument in g_signal_connect(button, "clicked", G_CALLBACK(gtk_widget_destroy), grid) (which is grid)), and the function gtk_widget_destroy() takes in one argument-the widget to destroy. Here, it's always the button.

What you can do is to use g_signal_connect_swapped(). which will reverse the first and last arguments of the callback (ie, user_data will be passed as the first argument, and thus gtk_widget_destroy() will be fed with the user_data as the argument.

So you could simply write g_signal_connect_swapped(button, "clicked", G_CALLBACK(gtk_widget_destroy), grid) which will destroy the grid when the button is clicked, though you likely want an additional function as GCallback which will destroy the grid and repopulate it:

static void
ai_button_clicked_cb (GtkButton *button,
                      gpointer   user_data)
{
  GtkGrid *grid = user_data;

  g_assert (GTK_IS_GRID (grid));

  /* Remove all widgets in column 0 */
  gtk_grid_remove_column (grid, 0);

   /* Now add more buttons to the grid */
}

static void
activate (GtkApplication *app,
          gpointer        user_data)
{
  // ...
    g_signal_connect (button, "clicked", G_CALLBACK (ai_button_clicked_cb), grid);

  // ...
}

You may find that this is against the C standard (passing 1 arguments to a function that accepts only 1), but this has been heavily used in GObject.