paned: Add a paned handle class

Instead of bending GtkGizmo to the breaking point,
split off a GtkPanedHandle class that just does
what is needed here. Its simpler, and lets us keep
GtkGizmo simpler too. Everybody wins.

gtk/gtkpaned.c

@@ -30,16 +30,13 @@
 #include "gtkeventcontrollermotion.h"
 #include "gtkgesturepan.h"
 #include "gtkgesturesingle.h"
-#include "gtkgizmoprivate.h"
+#include "gtkpanedhandleprivate.h"
 #include "gtkintl.h"
 #include "gtkmarshalers.h"
 #include "gtkorientable.h"
 #include "gtkprivate.h"
-#include "gtkrendericonprivate.h"
-#include "gtkcssnodeprivate.h"
 #include "gtktypebuiltins.h"
 #include "gtkwidgetprivate.h"
-#include "gtkcssboxesprivate.h"
 #include "gtkbuildable.h"
 
 #include <math.h>
@@ -300,26 +297,6 @@ get_handle_area (GtkPaned        *paned,
   graphene_rect_inset (area, - extra, - extra);
 }
 
-static gboolean
-gtk_paned_handle_contains (GtkGizmo *handle,
-                           double    x,
-                           double    y)
-{
-  GtkWidget *paned;
-  GtkCssBoxes boxes;
-  graphene_rect_t area;
-
-  gtk_css_boxes_init (&boxes, GTK_WIDGET (handle));
-
-  graphene_rect_init_from_rect (&area, gtk_css_boxes_get_border_rect (&boxes));
-
-  paned = gtk_widget_get_parent (GTK_WIDGET (handle));
-  if (!gtk_paned_get_wide_handle (GTK_PANED (paned)))
-    graphene_rect_inset (&area, - HANDLE_EXTRA_SIZE, - HANDLE_EXTRA_SIZE);
-
-  return graphene_rect_contains_point (&area, &GRAPHENE_POINT_INIT (x, y));
-}
-
 static void
 gtk_paned_compute_expand (GtkWidget *widget,
                           gboolean  *hexpand,
@@ -1407,21 +1384,6 @@ gtk_paned_unrealize (GtkWidget *widget)
   GTK_WIDGET_CLASS (gtk_paned_parent_class)->unrealize (widget);
 }
 
-static void
-gtk_paned_render_handle (GtkGizmo    *gizmo,
-                         GtkSnapshot *snapshot)
-{
-  GtkWidget *widget = GTK_WIDGET (gizmo);
-  GtkCssStyle *style = gtk_css_node_get_style (gtk_widget_get_css_node (widget));
-  int width, height;
-
-  width = gtk_widget_get_width (widget);
-  height = gtk_widget_get_height (widget);
-
-  if (width > 0 && height > 0)
-    gtk_css_style_snapshot_icon (style, snapshot, width, height);
-}
-
 static void
 connect_drag_gesture_signals (GtkPaned   *paned,
                               GtkGesture *gesture)
@@ -1479,7 +1441,7 @@ gtk_paned_init (GtkPaned *paned)
   gtk_widget_add_controller (GTK_WIDGET (paned), GTK_EVENT_CONTROLLER (gesture));
   paned->drag_gesture = gesture;
 
-  paned->handle_widget = gtk_gizmo_new ("separator", NULL, NULL, gtk_paned_render_handle, gtk_paned_handle_contains, NULL, NULL);
+  paned->handle_widget = gtk_paned_handle_new ();
   gtk_widget_set_parent (paned->handle_widget, GTK_WIDGET (paned));
   gtk_widget_set_cursor_from_name (paned->handle_widget, "col-resize");
 }

gtk/gtkpanedhandle.c

@@ -0,0 +1,114 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * Authors:
+ * - Matthias Clasen <mclasen@redhat.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include "gtkpanedhandleprivate.h"
+#include "gtkwidgetprivate.h"
+#include "gtkcssnodeprivate.h"
+#include "gtkcssstyleprivate.h"
+#include "gtkrendericonprivate.h"
+#include "gtkcssboxesprivate.h"
+#include "gtkintl.h"
+
+#include "gtkpaned.h"
+
+
+G_DEFINE_TYPE (GtkPanedHandle, gtk_paned_handle, GTK_TYPE_WIDGET);
+
+static void
+gtk_paned_handle_snapshot (GtkWidget   *widget,
+                           GtkSnapshot *snapshot)
+{
+  GtkCssStyle *style = gtk_css_node_get_style (gtk_widget_get_css_node (widget));
+  int width, height;
+
+  width = gtk_widget_get_width (widget);
+  height = gtk_widget_get_height (widget);
+
+  if (width > 0 && height > 0)
+    gtk_css_style_snapshot_icon (style, snapshot, width, height);
+}
+
+#define HANDLE_EXTRA_SIZE 6
+
+static gboolean
+gtk_paned_handle_contains (GtkWidget *widget,
+                           double     x,
+                           double     y)
+{
+  GtkWidget *paned;
+  GtkCssBoxes boxes;
+  graphene_rect_t area;
+
+  gtk_css_boxes_init (&boxes, widget);
+
+  graphene_rect_init_from_rect (&area, gtk_css_boxes_get_border_rect (&boxes));
+
+  paned = gtk_widget_get_parent (widget);
+  if (!gtk_paned_get_wide_handle (GTK_PANED (paned)))
+    graphene_rect_inset (&area, - HANDLE_EXTRA_SIZE, - HANDLE_EXTRA_SIZE);
+
+  return graphene_rect_contains_point (&area, &GRAPHENE_POINT_INIT (x, y));
+}
+
+static void
+gtk_paned_handle_finalize (GObject *object)
+{
+  GtkPanedHandle *self = GTK_PANED_HANDLE (object);
+  GtkWidget *widget;
+
+  widget = _gtk_widget_get_first_child (GTK_WIDGET (self));
+  while (widget != NULL)
+    {
+      GtkWidget *next = _gtk_widget_get_next_sibling (widget);
+
+      gtk_widget_unparent (widget);
+
+      widget = next;
+    }
+
+  G_OBJECT_CLASS (gtk_paned_handle_parent_class)->finalize (object);
+}
+
+static void
+gtk_paned_handle_class_init (GtkPanedHandleClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->finalize = gtk_paned_handle_finalize;
+
+  widget_class->snapshot = gtk_paned_handle_snapshot;
+  widget_class->contains = gtk_paned_handle_contains;
+
+  gtk_widget_class_set_css_name (widget_class, I_("separator"));
+}
+
+static void
+gtk_paned_handle_init (GtkPanedHandle *self)
+{
+}
+
+GtkWidget *
+gtk_paned_handle_new (void)
+{
+  return g_object_new (GTK_TYPE_PANED_HANDLE, NULL);
+}

gtk/gtkpanedhandleprivate.h

@@ -0,0 +1,32 @@
+
+#ifndef __GTK_PANED_HANDLE_H__
+#define __GTK_PANED_HANDLE_H__
+
+#include "gtkwidget.h"
+#include "gtkenums.h"
+
+#define GTK_TYPE_PANED_HANDLE                 (gtk_paned_handle_get_type ())
+#define GTK_PANED_HANDLE(obj)                 (G_TYPE_CHECK_INSTANCE_CAST ((obj), GTK_TYPE_PANED_HANDLE, GtkPanedHandle))
+#define GTK_PANED_HANDLE_CLASS(klass)         (G_TYPE_CHECK_CLASS_CAST ((klass), GTK_TYPE_PANED_HANDLE, GtkPanedHandleClass))
+#define GTK_IS_PANED_HANDLE(obj)              (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GTK_TYPE_PANED_HANDLE))
+#define GTK_IS_PANED_HANDLE_CLASS(klass)      (G_TYPE_CHECK_CLASS_TYPE ((klass), GTK_TYPE_PANED_HANDLE))
+#define GTK_PANED_HANDLE_GET_CLASS(obj)       (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_PANED_HANDLE, GtkPanedHandleClass))
+
+typedef struct _GtkPanedHandle             GtkPanedHandle;
+typedef struct _GtkPanedHandleClass        GtkPanedHandleClass;
+
+struct _GtkPanedHandle
+{
+  GtkWidget parent_instance;
+};
+
+struct _GtkPanedHandleClass
+{
+  GtkWidgetClass parent_class;
+};
+
+GType      gtk_paned_handle_get_type (void) G_GNUC_CONST;
+
+GtkWidget *gtk_paned_handle_new (void);
+
+#endif

gtk/meson.build

@@ -119,6 +119,7 @@ gtk_private_sources = files([
   'gtkmenusectionbox.c',
   'gtkmenutracker.c',
   'gtkmenutrackeritem.c',
+  'gtkpanedhandle.c',
   'gtkpango.c',
   'gskpango.c',
   'gtkpasswordentrybuffer.c',