[gnome-builder/wip/gtk4-port] libide/gui: implement IdePopoverPositioner on IdePane

[Christian Hergert <chergert src gnome org>]

commit dc42a22ecf2625d55ec9260a8bea24cfe077a4db
Author: Christian Hergert <chergert redhat com>
Date:   Thu Apr 28 20:28:14 2022 -0700

    libide/gui: implement IdePopoverPositioner on IdePane
    
    This will allow us to attach popovers to the pane when we can't in some
    situations (such as in GtkTreeView). It's an unfortunate hack, but at
    least it's one we can manage ourselves.

 src/libide/gui/ide-pane.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 93 insertions(+), 1 deletion(-)
---
diff --git a/src/libide/gui/ide-pane.c b/src/libide/gui/ide-pane.c
index 9d2df3544..7216b15cb 100644
--- a/src/libide/gui/ide-pane.c
+++ b/src/libide/gui/ide-pane.c
@@ -22,13 +22,105 @@
 
 #include "config.h"
 
+#include <libide-tree.h>
+
 #include "ide-pane.h"
 
-G_DEFINE_TYPE (IdePane, ide_pane, PANEL_TYPE_WIDGET)
+typedef struct
+{
+  GList *popovers;
+} IdePanePrivate;
+
+static void popover_positioner_iface_init (IdePopoverPositionerInterface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (IdePane, ide_pane, PANEL_TYPE_WIDGET,
+                         G_ADD_PRIVATE (IdePane)
+                         G_IMPLEMENT_INTERFACE (IDE_TYPE_POPOVER_POSITIONER, popover_positioner_iface_init))
+
+static void
+ide_pane_popover_closed_cb (IdePane    *self,
+                            GtkPopover *popover)
+{
+  IdePanePrivate *priv = ide_pane_get_instance_private (self);
+
+  g_assert (IDE_IS_PANE (self));
+  g_assert (GTK_IS_POPOVER (popover));
+
+  g_signal_handlers_disconnect_by_func (popover,
+                                        G_CALLBACK (ide_pane_popover_closed_cb),
+                                        self);
+  priv->popovers = g_list_remove (priv->popovers, popover);
+  gtk_widget_unparent (GTK_WIDGET (popover));
+}
+
+static void
+ide_pane_popover_positioner_present (IdePopoverPositioner *positioner,
+                                     GtkPopover           *popover,
+                                     GtkWidget            *relative_to,
+                                     const GdkRectangle   *pointing_to)
+{
+  IdePane *self = (IdePane *)positioner;
+  IdePanePrivate *priv = ide_pane_get_instance_private (self);
+  GdkRectangle translated;
+  double x, y;
+
+  g_assert (IDE_IS_PANE (self));
+  g_assert (GTK_IS_POPOVER (popover));
+  g_assert (GTK_IS_WIDGET (relative_to));
+  g_assert (pointing_to != NULL);
+
+  gtk_widget_translate_coordinates (GTK_WIDGET (relative_to),
+                                    GTK_WIDGET (self),
+                                    pointing_to->x, pointing_to->y,
+                                    &x, &y);
+  translated = (GdkRectangle) { x, y, pointing_to->width, pointing_to->height };
+  gtk_popover_set_pointing_to (popover, &translated);
+
+  priv->popovers = g_list_append (priv->popovers, popover);
+  gtk_widget_set_parent (GTK_WIDGET (popover), GTK_WIDGET (self));
+  g_signal_connect_object (popover,
+                           "closed",
+                           G_CALLBACK (ide_pane_popover_closed_cb),
+                           self,
+                           G_CONNECT_SWAPPED);
+  gtk_popover_popup (popover);
+}
+
+static void
+popover_positioner_iface_init (IdePopoverPositionerInterface *iface)
+{
+  iface->present = ide_pane_popover_positioner_present;
+}
+
+static void
+ide_pane_size_allocate (GtkWidget *widget,
+                        int        width,
+                        int        height,
+                        int        baseline)
+{
+  IdePane *self = (IdePane *)widget;
+  IdePanePrivate *priv = ide_pane_get_instance_private (self);
+
+  g_assert (IDE_IS_PANE (self));
+
+  GTK_WIDGET_CLASS (ide_pane_parent_class)->size_allocate (widget, width, height, baseline);
+
+  for (const GList *iter = priv->popovers; iter != NULL; iter = iter->next)
+    {
+      GtkPopover *popover = iter->data;
+
+      g_assert (GTK_IS_POPOVER (popover));
+
+      gtk_popover_present (popover);
+    }
+}
 
 static void
 ide_pane_class_init (IdePaneClass *klass)
 {
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  widget_class->size_allocate = ide_pane_size_allocate;
 }
 
 static void