m2-GTK4/examples/styling.mod

MODULE styling ;

(*
   m2-GTK4 example - CSS styling.

   Loads a stylesheet from a string and installs it for the display,
   then toggles a CSS class on a label.

   Build:  make examples
   Run:    ./build/examples/styling
*)

FROM Gio IMPORT g_application_run;
FROM GtkApplication IMPORT gtk_application_new;
FROM GtkWindow IMPORT gtk_application_window_new, gtk_window_set_title,
   gtk_window_set_default_size, gtk_window_set_child, gtk_window_present;
FROM GtkBox IMPORT gtk_box_new, gtk_box_append, gtk_box_set_spacing;
FROM GtkEnums IMPORT GtkVertical;
FROM GtkLabel IMPORT gtk_label_new;
FROM GtkButton IMPORT gtk_button_new_with_label;
FROM GtkWidget IMPORT gtk_widget_add_css_class, gtk_widget_remove_css_class,
   gtk_widget_set_margin_top, gtk_widget_set_margin_bottom,
   gtk_widget_set_margin_start, gtk_widget_set_margin_end;
FROM GtkCssProvider IMPORT gtk_css_provider_new,
   gtk_css_provider_load_from_string;
FROM GtkStyleContext IMPORT gtk_style_context_add_provider_for_display,
   GtkStyleProviderPriorityApplication;
FROM Gdk IMPORT gdk_display_get_default;
FROM GtkClosures IMPORT Connect2;
FROM SYSTEM IMPORT ADDRESS;
FROM libc IMPORT printf;

CONST
   AppId = "org.example.m2gtk4.Styling";
   Css = ".m2accent { color: #e01b24; font-weight: bold; }";

VAR
   label: ADDRESS;
   accented: BOOLEAN;

PROCEDURE OnToggle (button: ADDRESS; user: ADDRESS);
BEGIN
   IF accented THEN
      gtk_widget_remove_css_class(label, "m2accent");
      accented := FALSE
   ELSE
      gtk_widget_add_css_class(label, "m2accent");
      accented := TRUE
   END
END OnToggle;

PROCEDURE OnActivate (application: ADDRESS; data: ADDRESS);
VAR
   window, box, provider, toggle: ADDRESS;
BEGIN
   provider := gtk_css_provider_new();
   gtk_css_provider_load_from_string(provider, Css);
   gtk_style_context_add_provider_for_display(gdk_display_get_default(),
      provider, GtkStyleProviderPriorityApplication);

   label := gtk_label_new("Styled label");
   accented := FALSE;
   toggle := gtk_button_new_with_label("Toggle accent");
   Connect2(toggle, "clicked", OnToggle, NIL);

   box := gtk_box_new(GtkVertical, 12);
   gtk_box_set_spacing(box, 12);
   gtk_widget_set_margin_top(box, 14);
   gtk_widget_set_margin_bottom(box, 14);
   gtk_widget_set_margin_start(box, 14);
   gtk_widget_set_margin_end(box, 14);
   gtk_box_append(box, label);
   gtk_box_append(box, toggle);

   window := gtk_application_window_new(application);
   gtk_window_set_title(window, "m2-GTK4 Styling");
   gtk_window_set_default_size(window, 360, 160);
   gtk_window_set_child(window, box);
   gtk_window_present(window)
END OnActivate;

VAR
   app: ADDRESS;
BEGIN
   app := gtk_application_new(AppId, 0);
   IF app = NIL THEN
      printf("gtk_application_new failed\n");
      HALT(1)
   END;
   Connect2(app, "activate", OnActivate, NIL);
   g_application_run(app, 0, NIL)
END styling.