iconGrid: Subclass a C actor for BaseIcon

We create a lot of BaseIcons for the appGrid, one for every app, and for
all of those we have to hop through JS to get the preferred width. That
makes it another obvious target for moving to C, so let's do that.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1755>

js/ui/iconGrid.js

@@ -1,7 +1,7 @@
 // -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
 /* exported BaseIcon, IconGrid, IconGridLayout */
 
-const { Clutter, GLib, GObject, Meta, St } = imports.gi;
+const { Clutter, GLib, GObject, Meta, Shell, St } = imports.gi;
 
 const Params = imports.misc.params;
 const Main = imports.ui.main;
@@ -64,7 +64,7 @@ var DragLocation = {
 };
 
 var BaseIcon = GObject.registerClass(
-class BaseIcon extends St.Bin {
+class BaseIcon extends Shell.SquareBin {
     _init(label, params) {
         params = Params.parse(params, {
             createIcon: null,
@@ -113,11 +113,6 @@ class BaseIcon extends St.Bin {
         this._iconThemeChangedId = cache.connect('icon-theme-changed', this._onIconThemeChanged.bind(this));
     }
 
-    vfunc_get_preferred_width(_forHeight) {
-        // Return the actual height to keep the squared aspect
-        return this.get_preferred_height(-1);
-    }
-
     // This can be overridden by a subclass, or by the createIcon
     // parameter to _init()
     createIcon(_size) {

src/meson.build

@@ -105,6 +105,7 @@ libshell_public_headers = [
   'shell-mount-operation.h',
   'shell-perf-log.h',
   'shell-screenshot.h',
+  'shell-square-bin.h',
   'shell-stack.h',
   'shell-tray-icon.h',
   'shell-tray-manager.h',
@@ -149,6 +150,7 @@ libshell_sources = [
   'shell-screenshot.c',
   'shell-secure-text-buffer.c',
   'shell-secure-text-buffer.h',
+  'shell-square-bin.c',
   'shell-stack.c',
   'shell-tray-icon.c',
   'shell-tray-manager.c',

src/shell-square-bin.c

@@ -0,0 +1,43 @@
+#include "config.h"
+
+#include "shell-square-bin.h"
+
+struct _ShellSquareBin
+{
+  /*< private >*/
+  StBin parent_instance;
+};
+
+G_DEFINE_TYPE (ShellSquareBin, shell_square_bin, ST_TYPE_BIN);
+
+static void
+shell_square_bin_get_preferred_width (ClutterActor *actor,
+                                      float         for_height,
+                                      float        *min_width_p,
+                                      float        *natural_width_p)
+{
+  float min_width, nat_width;
+
+  /* Return the actual height to keep the squared aspect */
+  clutter_actor_get_preferred_height (actor, -1,
+                                      &min_width, &nat_width);
+
+  if (min_width_p)
+    *min_width_p = min_width;
+
+  if (natural_width_p)
+    *natural_width_p = nat_width;
+}
+
+static void
+shell_square_bin_init (ShellSquareBin *self)
+{
+}
+
+static void
+shell_square_bin_class_init (ShellSquareBinClass *klass)
+{
+  ClutterActorClass *actor_class = CLUTTER_ACTOR_CLASS (klass);
+
+  actor_class->get_preferred_width = shell_square_bin_get_preferred_width;
+}

src/shell-square-bin.h

@@ -0,0 +1,13 @@
+#ifndef __SHELL_SQUARE_BIN_H__
+#define __SHELL_SQUARE_BIN_H__
+
+#include <st/st.h>
+
+G_BEGIN_DECLS
+
+#define SHELL_TYPE_SQUARE_BIN (shell_square_bin_get_type ())
+G_DECLARE_FINAL_TYPE (ShellSquareBin, shell_square_bin, SHELL, SquareBin, StBin)
+
+G_END_DECLS
+
+#endif /* __SHELL_SQUARE_BIN_H__ */