src/ui/containerize.h

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 #ifndef INKSCAPE_UI_CONTAINERIZE_H
   3 #define INKSCAPE_UI_CONTAINERIZE_H
   4
   5 #include <gtkmm/widget.h>
   6
   7 namespace Inkscape::UI {
   8
   9 /**
  10  * Make a custom widget implement sensible memory management for its children.
  11  *
  12  * This frees the implementer of a custom widget from having to manually unparent()
  13  * children added with set_parent() both in the destructor and on signal_destroy(),
  14  * a memory management detail from C that has no business leaking into C++.
  15  *
  16  * Upon destruction, or for managed widgets just before, all children are unparented.
  17  * Managed children are also deleted if they have no other references.
  18  *
  19  * This function is typically called in the constructor of a custom widget that derives
  20  * from an intrinsically childless Gtk widget, e.g. Gtk::Widget, Gtk::DrawingArea.
  21
  22  * It must not be used with any intrinsically child-containing Gtk widget, e.g.
  23  * Gtk::Box, Gtk::SpinButton.
  24  */
  25 inline void containerize(Gtk::Widget &widget)
  26 {
  27     g_signal_connect(widget.gobj(), "destroy", G_CALLBACK(+[] (GtkWidget *gobj, void *) {
  28         for (auto c = gtk_widget_get_first_child(gobj); c; ) {
  29             auto cnext = gtk_widget_get_next_sibling(c);
  30             gtk_widget_unparent(c);
  31             c = cnext;
  32         }
  33     }), nullptr);
  34 }
  35
  36 } // namespace Inkscape::UI
  37
  38 #endif // INKSCAPE_UI_CONTAINERIZE_H