c - How to add a GtkWidget in a custom one?

Question

I made a custom GTK widget and I need to add a GTK Button to it so to inherit its signals in the custom one. The custom widget is a timeline so I thought to use GTK Buttons to avoid messing with mouse coordinates. When the user wants to move the picture represented by the button or just extend its delay on the timeline itself, signals will be emitted from the button widget and my life will be much easier.

The button of course is not shown on the timeline. that's my problem. I know I have to put the button inside a container but how to do it in the draw function? Does anyone have a clue on how to do it? I googled and looked here but with no luck.

This is the custom widget draw function:

static gboolean img_timeline_draw(GtkWidget *da, cairo_t *cr)
{
  GtkWidget *button; 
  ImgTimelinePrivate *priv = img_timeline_get_instance_private((ImgTimeline*)da);
  gint width = gtk_widget_get_allocated_width(da);
  
  cairo_translate (cr, 0 , 12);

  img_timeline_draw_time_ticks(da, cr, width);
  
  //Video timeline
  cairo_translate (cr, 0 , 20);
  cairo_set_source_rgba(cr, priv->video_background[0], priv->video_background[1], priv->video_background[2], priv->video_background[3]);
  cairo_set_line_width(cr, 1);
  cairo_rectangle(cr, 0,10, width - 2, 59);
  cairo_fill(cr);
  //separator
  cairo_set_source_rgb(cr, 1, 1, 1);
  cairo_rectangle(cr, 0,69, width - 2, 3);
  cairo_fill(cr);
  //Audio timeline
  cairo_set_source_rgba(cr, priv->audio_background[0], priv->audio_background[1], priv->audio_background[2], priv->audio_background[3]);
  cairo_rectangle(cr, 0,72, width - 2, 59);
  cairo_fill(cr);

  button = gtk_button_new_with_label("I'm invisible...");
  gtk_widget_set_realized(button, TRUE);
  gtk_widget_show(button);
  return FALSE;
}

And this is the main:

int main(int argc, char *argv[])
{
  gtk_init(&argc, &argv);

  GtkWidget *window=gtk_window_new(GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title(GTK_WINDOW(window), "Imagination timeline widget");
  gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
  gtk_window_set_default_size(GTK_WINDOW(window), 800, 200);
  g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);

  GtkWidget *timeline = img_timeline_new();
  g_object_set(timeline, "total_time",        300, NULL);
  g_object_set(timeline, "video_background", "#0084ff", NULL);
  g_object_set(timeline, "audio_background", "#0084ff", NULL);

  gtk_widget_add_events( timeline, GDK_BUTTON1_MOTION_MASK
                         | GDK_POINTER_MOTION_HINT_MASK
                         | GDK_BUTTON_PRESS_MASK
                         | GDK_BUTTON_RELEASE_MASK
                         | GDK_SCROLL_MASK
                         | GDK_KEY_PRESS_MASK );

  GtkWidget *scrolledwindow1 = gtk_scrolled_window_new(NULL, NULL);
  GtkWidget *viewport = gtk_viewport_new(NULL,NULL);
  g_signal_connect( G_OBJECT(timeline), "scroll-event", G_CALLBACK(img_timeline_scroll), scrolledwindow1);

  gtk_widget_set_hexpand(viewport, TRUE);
  gtk_widget_set_vexpand(viewport, TRUE);
  gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolledwindow1), GTK_POLICY_AUTOMATIC, GTK_POLICY_NEVER);
  
  gtk_container_add (GTK_CONTAINER(viewport), timeline);
  gtk_container_add (GTK_CONTAINER(scrolledwindow1), viewport);
  gtk_container_add (GTK_CONTAINER (window), scrolledwindow1);
  gtk_widget_show_all(window);

  gtk_main();
  return 0;
}

question from:https://stackoverflow.com/questions/65644081/how-to-add-a-gtkwidget-in-a-custom-one

Answer 1

Ok, the solution was to subclass GtkLayout rather than GtkDrawingArea and use gtk_container_propagate_draw() in the custom widget draw function!