[libchamplain] Implement events handling of kinetic scroll view the same way as in Mx

[Jiří Techet <jiritechet src gnome org>]

commit e0cf7a204227698741a97806efe37d4397c38167
Author: JiÅ?í Techet <techet gmail com>
Date:   Sat Feb 26 01:17:11 2011 +0100

    Implement events handling of kinetic scroll view the same way as in Mx
    
    The implementation in Mx is superior to the tidy implementation
    (which tends to do strange things with the mouse events) so let's use it.

 champlain/champlain-kinetic-scroll-view.c |  142 ++++++++++++++---------------
 1 files changed, 70 insertions(+), 72 deletions(-)
---
diff --git a/champlain/champlain-kinetic-scroll-view.c b/champlain/champlain-kinetic-scroll-view.c
index 7d58de5..d476373 100644
--- a/champlain/champlain-kinetic-scroll-view.c
+++ b/champlain/champlain-kinetic-scroll-view.c
@@ -61,6 +61,7 @@ struct _ChamplainKineticScrollViewPrivate
   gdouble                decel_rate;
 
   ClutterActor *child;
+  gboolean in_drag;
 };
 
 enum {
@@ -408,13 +409,16 @@ clutter_container_iface_init (ClutterContainerIface *iface)
 
 
 static gboolean
-motion_event_cb (ClutterActor *actor,
+motion_event_cb (ClutterActor *stage,
                  ClutterMotionEvent *event,
                  ChamplainKineticScrollView *scroll)
 {
+  ChamplainKineticScrollViewPrivate *priv = scroll->priv;
+  ClutterActor *actor = CLUTTER_ACTOR (scroll);
   gfloat x, y;
 
-  ChamplainKineticScrollViewPrivate *priv = scroll->priv;
+  if (event->type != CLUTTER_MOTION)
+    return FALSE;
 
   if (clutter_actor_transform_stage_point (actor,
                                            event->x,
@@ -423,6 +427,23 @@ motion_event_cb (ClutterActor *actor,
     {
       ChamplainKineticScrollViewMotion *motion;
 
+      if (!priv->in_drag)
+        {
+          guint threshold = 8; // default value
+
+          motion = &g_array_index (priv->motion_buffer,
+                                   ChamplainKineticScrollViewMotion, 0);
+
+          if ((ABS (motion->x - x) >= threshold) ||
+              (ABS (motion->y - y) >= threshold))
+            {
+              clutter_set_motion_events_enabled (TRUE);
+              priv->in_drag = TRUE;
+            }
+          else
+            return FALSE;
+        }
+
       if (priv->child)
         {
           gdouble dx, dy;
@@ -434,13 +455,19 @@ motion_event_cb (ClutterActor *actor,
 
           motion = &g_array_index (priv->motion_buffer,
                                    ChamplainKineticScrollViewMotion, priv->last_motion);
-          dx = (motion->x - x) +
-               champlain_adjustment_get_value (hadjust);
-          dy = (motion->y - y) +
-               champlain_adjustment_get_value (vadjust);
-
-          champlain_adjustment_set_value (hadjust, dx);
-          champlain_adjustment_set_value (vadjust, dy);
+          if (hadjust)
+            {
+              dx = (motion->x - x) +
+                   champlain_adjustment_get_value (hadjust);
+              champlain_adjustment_set_value (hadjust, dx);
+            }
+          
+          if (vadjust)
+            {
+              dy = (motion->y - y) +
+                   champlain_adjustment_get_value (vadjust);
+              champlain_adjustment_set_value (vadjust, dy);
+            }
         }
 
       priv->last_motion ++;
@@ -579,25 +606,29 @@ deceleration_new_frame_cb (ClutterTimeline *timeline,
 }
 
 static gboolean
-button_release_event_cb (ClutterActor *actor,
+button_release_event_cb (ClutterActor *stage,
                          ClutterButtonEvent *event,
                          ChamplainKineticScrollView *scroll)
 {
   ChamplainKineticScrollViewPrivate *priv = scroll->priv;
+  ClutterActor *actor = CLUTTER_ACTOR (scroll);
   gboolean decelerating = FALSE;
-  gboolean moved = TRUE;
 
-  if (event->button != 1)
+  if ((event->type != CLUTTER_BUTTON_RELEASE) ||
+      (event->button != 1))
     return FALSE;
 
-  g_signal_handlers_disconnect_by_func (actor,
+  g_signal_handlers_disconnect_by_func (stage,
                                         motion_event_cb,
                                         scroll);
-  g_signal_handlers_disconnect_by_func (actor,
+  g_signal_handlers_disconnect_by_func (stage,
                                         button_release_event_cb,
                                         scroll);
 
-  clutter_ungrab_pointer ();
+  if (!priv->in_drag)
+    return FALSE;
+
+  clutter_set_motion_events_enabled (TRUE);
 
   if (priv->kinetic && priv->child)
     {
@@ -613,6 +644,8 @@ button_release_event_cb (ClutterActor *actor,
           ChamplainAdjustment *hadjust, *vadjust;
           glong time_diff;
           gint i;
+          
+          priv->in_drag = TRUE;
 
           /* Get time delta */
           g_get_current_time (&release_time);
@@ -764,9 +797,8 @@ button_release_event_cb (ClutterActor *actor,
     }
 
   /* Reset motion event buffer */
-  if (priv->last_motion <= 1)
-      moved = FALSE;
   priv->last_motion = 0;
+  priv->in_drag = FALSE;
 
   if (!decelerating)
     {
@@ -774,58 +806,32 @@ button_release_event_cb (ClutterActor *actor,
       g_signal_emit_by_name (scroll, "panning-completed", NULL);
     }
 
-  /* Pass through events to children.
-   * FIXME: this probably breaks click-count.
-   */
-  if (!moved)
-    clutter_event_put ((ClutterEvent *)event);
-
-  return moved;
+  return TRUE;
 }
 
-static gboolean
-after_event_cb (ChamplainKineticScrollView *scroll)
-{
-  /* Check the pointer grab - if something else has grabbed it - for example,
-   * a scroll-bar or some such, don't do our funky stuff.
-   */
-  if (clutter_get_pointer_grab () != CLUTTER_ACTOR (scroll))
-    {
-      g_signal_handlers_disconnect_by_func (scroll,
-                                            motion_event_cb,
-                                            scroll);
-      g_signal_handlers_disconnect_by_func (scroll,
-                                            button_release_event_cb,
-                                            scroll);
-    }
 
-  return FALSE;
-}
 
 static gboolean
-captured_event_cb (ClutterActor     *actor,
-                   ClutterEvent     *event,
-                   ChamplainKineticScrollView *scroll)
+button_press_event_cb (ClutterActor        *actor,
+                       ClutterEvent        *event,
+                       ChamplainKineticScrollView *scroll)
 {
   ChamplainKineticScrollViewPrivate *priv = scroll->priv;
+  ClutterButtonEvent *bevent = (ClutterButtonEvent *)event;
+  ClutterActor *stage = clutter_actor_get_stage (actor);
 
-  if (event->type == CLUTTER_BUTTON_PRESS)
+  if ((event->type == CLUTTER_BUTTON_PRESS) &&
+      (bevent->button == 1) &&
+      stage)
     {
       ChamplainKineticScrollViewMotion *motion;
-      ClutterButtonEvent *bevent = (ClutterButtonEvent *)event;
-
-      if (bevent->source != actor)
-        return FALSE;
 
       /* Reset motion buffer */
       priv->last_motion = 0;
       motion = &g_array_index (priv->motion_buffer, ChamplainKineticScrollViewMotion, 0);
 
-      if ((bevent->button == 1) &&
-          (clutter_actor_transform_stage_point (actor,
-                                           bevent->x,
-                                           bevent->y,
-                                           &motion->x, &motion->y)))
+      if (clutter_actor_transform_stage_point (actor, bevent->x, bevent->y,
+                                               &motion->x, &motion->y))
         {
           g_get_current_time (&motion->time);
 
@@ -836,30 +842,23 @@ captured_event_cb (ClutterActor     *actor,
               priv->deceleration_timeline = NULL;
             }
 
-          clutter_grab_pointer (actor);
-
-          /* Add a high priority idle to check the grab after the event
-           * emission is finished.
-           */
-          g_idle_add_full (G_PRIORITY_HIGH_IDLE,
-                           (GSourceFunc)after_event_cb,
-                           scroll,
-                           NULL);
-
-          g_signal_connect (actor,
-                            "motion-event",
+          g_signal_connect (stage,
+                            "captured-event",
                             G_CALLBACK (motion_event_cb),
                             scroll);
-          g_signal_connect (actor,
-                            "button-release-event",
+          g_signal_connect (stage,
+                            "captured-event",
                             G_CALLBACK (button_release_event_cb),
                             scroll);
+
+          priv->in_drag = FALSE;
         }
     }
 
   return FALSE;
 }
 
+
 static void
 champlain_kinetic_scroll_view_init (ChamplainKineticScrollView *self)
 {
@@ -870,12 +869,11 @@ champlain_kinetic_scroll_view_init (ChamplainKineticScrollView *self)
   g_array_set_size (priv->motion_buffer, 3);
   priv->decel_rate = 1.1f;
   priv->child = NULL;
+  priv->in_drag = FALSE;
 
   clutter_actor_set_reactive (CLUTTER_ACTOR (self), TRUE);
-  g_signal_connect (CLUTTER_ACTOR (self),
-                    "captured-event",
-                    G_CALLBACK (captured_event_cb),
-                    self);
+  g_signal_connect (self, "button-press-event",
+                    G_CALLBACK (button_press_event_cb), self);
 
 
 }