[gnome-builder] layout: implement basic transient focus tracking

[Christian Hergert <chergert src gnome org>]

commit 4e21a709eb54380997972194f67ac85a96da1a95
Author: Christian Hergert <chergert redhat com>
Date:   Thu Jul 13 00:12:06 2017 -0700

    layout: implement basic transient focus tracking
    
    This tries to keep the transient panel visible while the view
    is active. When focus enters another view or outside the view
    hierarchy, the sidebar is released.

 libide/layout/ide-layout-transient-sidebar.c |  159 +++++++++++++++++++++++++-
 libide/layout/ide-layout-transient-sidebar.h |    4 +
 2 files changed, 162 insertions(+), 1 deletions(-)
---
diff --git a/libide/layout/ide-layout-transient-sidebar.c b/libide/layout/ide-layout-transient-sidebar.c
index fa248f6..bc14dcc 100644
--- a/libide/layout/ide-layout-transient-sidebar.c
+++ b/libide/layout/ide-layout-transient-sidebar.c
@@ -18,16 +18,173 @@
 
 #define G_LOG_DOMAIN "ide-layout-transient-sidebar"
 
+#include "layout/ide-layout-stack.h"
 #include "layout/ide-layout-transient-sidebar.h"
 
-G_DEFINE_TYPE (IdeLayoutTransientSidebar, ide_layout_transient_sidebar, IDE_TYPE_LAYOUT_PANE)
+typedef struct
+{
+  DzlSignalGroup *toplevel_signals;
+  GWeakRef        view_ref;
+} IdeLayoutTransientSidebarPrivate;
+
+G_DEFINE_TYPE_WITH_PRIVATE (IdeLayoutTransientSidebar,
+                            ide_layout_transient_sidebar,
+                            IDE_TYPE_LAYOUT_PANE)
+
+static gboolean
+has_view_related_focus (IdeLayoutTransientSidebar *self)
+{
+  IdeLayoutTransientSidebarPrivate *priv = ide_layout_transient_sidebar_get_instance_private (self);
+  g_autoptr(IdeLayoutView) view = NULL;
+  GtkWidget *focus_view;
+  GtkWidget *toplevel;
+  GtkWidget *focus;
+  GtkWidget *stack;
+
+  g_assert (IDE_IS_LAYOUT_TRANSIENT_SIDEBAR (self));
+
+  /* If there is no view, then nothing more to do */
+  view = g_weak_ref_get (&priv->view_ref);
+  if (view == NULL)
+    return FALSE;
+
+  /* We need the toplevel to get the current focus */
+  toplevel = gtk_widget_get_toplevel (GTK_WIDGET (self));
+  if (!GTK_IS_WINDOW (toplevel))
+    return FALSE;
+
+  /* Synthesize succes when there is no focus, this can happen inbetween
+   * various state transitions.
+   */
+  focus = gtk_window_get_focus (GTK_WINDOW (toplevel));
+  if (focus == NULL)
+    return TRUE;
+
+  /* If focus is inside this widget, then we don't want to hide */
+  if (gtk_widget_is_ancestor (focus, GTK_WIDGET (self)))
+    return TRUE;
+
+  /* If focus is in the view, then we definitely don't want to hide */
+  if (gtk_widget_is_ancestor (focus, GTK_WIDGET (view)))
+    return TRUE;
+
+  /* If the focus has entered another view, then we can release. */
+  focus_view = gtk_widget_get_ancestor (focus, IDE_TYPE_LAYOUT_VIEW);
+  if (focus_view && focus_view != GTK_WIDGET (view))
+    return FALSE;
+
+  /* If the focus has ended up in layout stack, we're okay too */
+  stack = dzl_gtk_widget_get_relative (focus, IDE_TYPE_LAYOUT_STACK);
+  if (dzl_gtk_widget_is_ancestor_or_relative (focus, stack))
+    return TRUE;
+
+  return FALSE;
+}
+
+static void
+ide_layout_transient_sidebar_after_set_focus (IdeLayoutTransientSidebar *self,
+                                              GtkWidget                 *focus,
+                                              GtkWindow                 *toplevel)
+{
+  IdeLayoutTransientSidebarPrivate *priv = ide_layout_transient_sidebar_get_instance_private (self);
+
+  g_assert (IDE_IS_LAYOUT_TRANSIENT_SIDEBAR (self));
+  g_assert (GTK_IS_WINDOW (toplevel));
+
+  /*
+   * If we are currently visible, then check to see if the focus has gone
+   * somewhere outside the panel or the view. If so, we need to dismiss
+   * the panel.
+   *
+   * We try to be tolerant of sibling focus on such things like the stack
+   * header.
+   */
+  if (gtk_widget_get_visible (GTK_WIDGET (self)))
+    {
+      if (!has_view_related_focus (self))
+        {
+          dzl_dock_revealer_set_reveal_child (DZL_DOCK_REVEALER (self), FALSE);
+          g_weak_ref_set (&priv->view_ref, NULL);
+        }
+    }
+}
+
+static void
+ide_layout_transient_sidebar_hierarchy_changed (GtkWidget *widget,
+                                                GtkWidget *old_toplevel)
+{
+  IdeLayoutTransientSidebar *self = (IdeLayoutTransientSidebar *)widget;
+  IdeLayoutTransientSidebarPrivate *priv = ide_layout_transient_sidebar_get_instance_private (self);
+  GtkWidget *toplevel;
+
+  g_assert (IDE_IS_LAYOUT_TRANSIENT_SIDEBAR (self));
+  g_assert (!old_toplevel || GTK_IS_WIDGET (old_toplevel));
+
+  toplevel = gtk_widget_get_toplevel (widget);
+  if (!GTK_IS_WINDOW (toplevel))
+    toplevel = NULL;
+
+  dzl_signal_group_set_target (priv->toplevel_signals, toplevel);
+}
+
+static void
+ide_layout_transient_sidebar_finalize (GObject *object)
+{
+  IdeLayoutTransientSidebar *self = (IdeLayoutTransientSidebar *)object;
+  IdeLayoutTransientSidebarPrivate *priv = ide_layout_transient_sidebar_get_instance_private (self);
+
+  g_clear_object (&priv->toplevel_signals);
+  g_weak_ref_clear (&priv->view_ref);
+
+  G_OBJECT_CLASS (ide_layout_transient_sidebar_parent_class)->finalize (object);
+}
 
 static void
 ide_layout_transient_sidebar_class_init (IdeLayoutTransientSidebarClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+
+  object_class->finalize = ide_layout_transient_sidebar_finalize;
+
+  widget_class->hierarchy_changed = ide_layout_transient_sidebar_hierarchy_changed;
 }
 
 static void
 ide_layout_transient_sidebar_init (IdeLayoutTransientSidebar *self)
 {
+  IdeLayoutTransientSidebarPrivate *priv = ide_layout_transient_sidebar_get_instance_private (self);
+
+  g_weak_ref_init (&priv->view_ref, NULL);
+
+  priv->toplevel_signals = dzl_signal_group_new (GTK_TYPE_WINDOW);
+
+  dzl_signal_group_connect_data (priv->toplevel_signals,
+                                 "set-focus",
+                                 G_CALLBACK (ide_layout_transient_sidebar_after_set_focus),
+                                 self, NULL,
+                                 G_CONNECT_AFTER | G_CONNECT_SWAPPED);
+
+}
+
+/**
+ * ide_layout_transient_sidebar_set_view:
+ * @self: a #IdeLayoutTransientSidebar
+ * @view: (nullable): An #IdeLayoutView or %NULL
+ *
+ * Sets the view for which the panel is transient for. When focus leaves the
+ * sidebar or the view, the panel will be dismissed.
+ *
+ * Since: 3.26
+ */
+void
+ide_layout_transient_sidebar_set_view (IdeLayoutTransientSidebar *self,
+                                       IdeLayoutView             *view)
+{
+  IdeLayoutTransientSidebarPrivate *priv = ide_layout_transient_sidebar_get_instance_private (self);
+
+  g_return_if_fail (IDE_IS_LAYOUT_TRANSIENT_SIDEBAR (self));
+  g_return_if_fail (!view || IDE_IS_LAYOUT_VIEW (view));
+
+  g_weak_ref_set (&priv->view_ref, view);
 }
diff --git a/libide/layout/ide-layout-transient-sidebar.h b/libide/layout/ide-layout-transient-sidebar.h
index 4604d24..ce01333 100644
--- a/libide/layout/ide-layout-transient-sidebar.h
+++ b/libide/layout/ide-layout-transient-sidebar.h
@@ -21,6 +21,7 @@
 #include <dazzle.h>
 
 #include "layout/ide-layout-pane.h"
+#include "layout/ide-layout-view.h"
 
 G_BEGIN_DECLS
 
@@ -42,4 +43,7 @@ struct _IdeLayoutTransientSidebarClass
   gpointer _reserved8;
 };
 
+void ide_layout_transient_sidebar_set_view (IdeLayoutTransientSidebar *self,
+                                            IdeLayoutView             *view);
+
 G_END_DECLS