[gtk/crossing-details] motion controller: Add getters for crossing event targets

[Matthias Clasen <matthiasc src gnome org>]

commit 17f4211e4f52b746027fecd196289437ea18e29a
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Mar 16 23:44:55 2019 -0400

    motion controller: Add getters for crossing event targets
    
    This information can be needed in signal handlers,
    so make it available.

 docs/reference/gtk/gtk4-sections.txt |  2 ++
 gtk/gtkeventcontrollermotion.c       | 67 +++++++++++++++++++++++++++++++++++-
 gtk/gtkeventcontrollermotion.h       |  5 +++
 3 files changed, 73 insertions(+), 1 deletion(-)
---
diff --git a/docs/reference/gtk/gtk4-sections.txt b/docs/reference/gtk/gtk4-sections.txt
index e0b068bcdc..5eb547bf61 100644
--- a/docs/reference/gtk/gtk4-sections.txt
+++ b/docs/reference/gtk/gtk4-sections.txt
@@ -6684,6 +6684,8 @@ gtk_event_controller_scroll_get_type
 <TITLE>GtkEventControllerMotion</TITLE>
 GtkEventControllerMotion
 gtk_event_controller_motion_new
+gtk_event_controller_motion_get_pointer_origin
+gtk_event_controller_motion_get_pointer_target
 
 <SUBSECTION Standard>
 GTK_TYPE_EVENT_CONTROLLER_MOTION
diff --git a/gtk/gtkeventcontrollermotion.c b/gtk/gtkeventcontrollermotion.c
index 377287742c..328ce4f557 100644
--- a/gtk/gtkeventcontrollermotion.c
+++ b/gtk/gtkeventcontrollermotion.c
@@ -29,7 +29,8 @@
 #include "config.h"
 
 #include "gtkintl.h"
-#include "gtkwidget.h"
+#include "gtkprivate.h"
+#include "gtkwidgetprivate.h"
 #include "gtkeventcontrollerprivate.h"
 #include "gtkeventcontrollermotion.h"
 #include "gtktypebuiltins.h"
@@ -39,6 +40,8 @@ struct _GtkEventControllerMotion
 {
   GtkEventController parent_instance;
 
+  const GdkEvent *current_event;
+
   guint is_pointer_focus       : 1;
   guint contains_pointer_focus : 1;
 };
@@ -132,7 +135,11 @@ gtk_event_controller_motion_handle_event (GtkEventController *controller,
 
       update_pointer_focus (motion, TRUE, detail);
 
+      motion->current_event = event;
+
       g_signal_emit (controller, signals[ENTER], 0, x, y, mode, detail);
+
+      motion->current_event = NULL;
     }
   else if (type == GDK_LEAVE_NOTIFY)
     {
@@ -144,13 +151,18 @@ gtk_event_controller_motion_handle_event (GtkEventController *controller,
 
       update_pointer_focus (motion, FALSE, detail);
 
+      motion->current_event = event;
+
       g_signal_emit (controller, signals[LEAVE], 0, mode, detail);
+
+      motion->current_event = NULL;
     }
   else if (type == GDK_MOTION_NOTIFY)
     {
       double x, y;
 
       gdk_event_get_coords (event, &x, &y);
+
       g_signal_emit (controller, signals[MOTION], 0, x, y);
     }
 
@@ -300,3 +312,56 @@ gtk_event_controller_motion_new (void)
   return g_object_new (GTK_TYPE_EVENT_CONTROLLER_MOTION,
                        NULL);
 }
+
+/**
+ * gtk_event_controller_motion_get_pointer_origin:
+ * @controller: a #GtkEventControllerMotion
+ *
+ * Returns the widget that contained the pointer before.
+ *
+ * This function can only be used in handlers for the
+ * #GtkEventControllerMotion::enter and
+ * #GtkEventControllerMotion::leave signals.
+ *
+ * Returns: (transfer none): the previous pointer focus
+ */
+GtkWidget *
+gtk_event_controller_motion_get_pointer_origin (GtkEventControllerMotion *controller)
+{
+  GtkWidget *origin;
+
+  g_return_val_if_fail (GTK_IS_EVENT_CONTROLLER_MOTION (controller), NULL);
+  g_return_val_if_fail (controller->current_event != NULL, NULL);
+
+  if (gdk_event_get_event_type (controller->current_event) == GDK_ENTER_NOTIFY)
+    origin = (GtkWidget *)gdk_event_get_related_target (controller->current_event);
+  else
+    origin = (GtkWidget *)gdk_event_get_target (controller->current_event);
+
+  return origin;
+}
+
+/**
+ * gtk_event_controller_motion_get_pointer_target:
+ * @controller: a #GtkEventControllerMotion
+ *
+ * Returns the widget that will contain the pointer afterwards.
+ *
+ * This function can only be used in handlers for the
+ * #GtkEventControllerMotion::enter and
+ * #GtkEventControllerMotion::leave signals.
+ *
+ * Returns: (transfer none): the next pointer focus
+ */
+GtkWidget *
+gtk_event_controller_motion_get_pointer_target (GtkEventControllerMotion *controller)
+{
+  g_return_val_if_fail (GTK_IS_EVENT_CONTROLLER_MOTION (controller), NULL);
+  g_return_val_if_fail (controller->current_event != NULL, NULL);
+
+  if (gdk_event_get_event_type (controller->current_event) == GDK_ENTER_NOTIFY)
+    return (GtkWidget *)gdk_event_get_target (controller->current_event);
+  else
+    return (GtkWidget *)gdk_event_get_related_target (controller->current_event);
+}
+
diff --git a/gtk/gtkeventcontrollermotion.h b/gtk/gtkeventcontrollermotion.h
index 9377a7ba12..05d1852986 100644
--- a/gtk/gtkeventcontrollermotion.h
+++ b/gtk/gtkeventcontrollermotion.h
@@ -45,6 +45,11 @@ GType               gtk_event_controller_motion_get_type (void) G_GNUC_CONST;
 GDK_AVAILABLE_IN_ALL
 GtkEventController *gtk_event_controller_motion_new      (void);
 
+GDK_AVAILABLE_IN_ALL
+GtkWidget *         gtk_event_controller_motion_get_pointer_origin (GtkEventControllerMotion *controller);
+GDK_AVAILABLE_IN_ALL
+GtkWidget *         gtk_event_controller_motion_get_pointer_target (GtkEventControllerMotion *controller);
+
 G_END_DECLS
 
 #endif /* __GTK_EVENT_CONTROLLER_MOTION_H__ */