[libchamplain] kinetic-scroll-view: Make it exclusive to pointer/single-touch

[Jiří Techet <jiritechet src gnome org>]

commit 30c52851a8e73baa81a4439492c8022d3a5a90b5
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Jun 6 20:16:12 2015 +0200

    kinetic-scroll-view: Make it exclusive to pointer/single-touch
    
    If we receive touch events, obey a single sequence and cancel all
    operations if more are received.
    
    The return value in the event handlers has been changed so the
    event is propagated, and kinetic scroll can work in cooperation
    with pinch/zoom gestures.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=709606

 champlain/champlain-kinetic-scroll-view.c |   45 +++++++++++++++++++++++++----
 1 files changed, 39 insertions(+), 6 deletions(-)
---
diff --git a/champlain/champlain-kinetic-scroll-view.c b/champlain/champlain-kinetic-scroll-view.c
index 20867ff..d210aea 100644
--- a/champlain/champlain-kinetic-scroll-view.c
+++ b/champlain/champlain-kinetic-scroll-view.c
@@ -57,6 +57,7 @@ struct _ChamplainKineticScrollViewPrivate
   gdouble decel_rate;
 
   ClutterActor *viewport;
+  ClutterEventSequence *sequence;
 };
 
 enum
@@ -259,7 +260,7 @@ motion_event_cb (ClutterActor *stage,
   gfloat x, y;
 
   if ((event->type != CLUTTER_MOTION || !(event->modifier_state & CLUTTER_BUTTON1_MASK)) &&
-      event->type != CLUTTER_TOUCH_UPDATE)
+      (event->type != CLUTTER_TOUCH_UPDATE || priv->sequence != clutter_event_get_event_sequence 
((ClutterEvent *) event)))
     return FALSE;
 
   if (clutter_actor_transform_stage_point (actor,
@@ -310,7 +311,7 @@ motion_event_cb (ClutterActor *stage,
       g_get_current_time (&motion->time);
     }
 
-  return TRUE;
+  return FALSE;
 }
 
 
@@ -390,10 +391,9 @@ button_release_event_cb (ClutterActor *stage,
   ClutterActor *actor = CLUTTER_ACTOR (scroll);
   gboolean decelerating = FALSE;
 
-
   if ((event->type != CLUTTER_MOTION || event->modifier_state & CLUTTER_BUTTON1_MASK) &&
       (event->type != CLUTTER_BUTTON_RELEASE || event->button != 1) && 
-      event->type != CLUTTER_TOUCH_END)
+      (event->type != CLUTTER_TOUCH_END || priv->sequence != clutter_event_get_event_sequence ((ClutterEvent 
*) event)))
     return FALSE;
 
   g_signal_handlers_disconnect_by_func (stage,
@@ -567,6 +567,8 @@ button_release_event_cb (ClutterActor *stage,
         }
     }
 
+  priv->sequence = NULL;
+
   /* Reset motion event buffer */
   priv->last_motion = 0;
 
@@ -576,7 +578,12 @@ button_release_event_cb (ClutterActor *stage,
       g_signal_emit_by_name (scroll, "panning-completed", NULL);
     }
 
-  return TRUE;
+  /* Due to the way gestures in progress connect to the stage in order to
+   * receive events, we must let these events go through, as they could be
+   * essential for the management of the ClutterZoomGesture in the
+   * ChamplainView.
+   */
+  return FALSE;
 }
 
 
@@ -589,8 +596,27 @@ button_press_event_cb (ClutterActor *actor,
   ClutterButtonEvent *bevent = (ClutterButtonEvent *) event;
   ClutterActor *stage = clutter_actor_get_stage (actor);
 
+  if (event->type == CLUTTER_TOUCH_BEGIN && priv->sequence)
+    {
+      /* On multi touch input, shy away an cancel everything */
+      priv->sequence = NULL;
+
+      g_signal_handlers_disconnect_by_func (stage,
+          motion_event_cb,
+          scroll);
+      g_signal_handlers_disconnect_by_func (stage,
+          button_release_event_cb,
+          scroll);
+
+      champlain_kinetic_scroll_view_stop (scroll);
+      clamp_adjustments (scroll);
+      g_signal_emit_by_name (scroll, "panning-completed", NULL);
+
+      return FALSE;
+    }
+
   if ((((event->type == CLUTTER_BUTTON_PRESS) && (bevent->button == 1)) ||
-      event->type == CLUTTER_TOUCH_BEGIN) &&
+      (event->type == CLUTTER_TOUCH_BEGIN && !priv->sequence)) &&
       stage)
     {
       ChamplainKineticScrollViewMotion *motion;
@@ -611,6 +637,8 @@ button_press_event_cb (ClutterActor *actor,
               priv->deceleration_timeline = NULL;
             }
 
+          priv->sequence = clutter_event_get_event_sequence (event);
+
           g_signal_connect (stage,
               "captured-event",
               G_CALLBACK (motion_event_cb),
@@ -622,6 +650,11 @@ button_press_event_cb (ClutterActor *actor,
         }
     }
 
+  /* Due to the way gestures in progress connect to the stage in order to
+   * receive events, we must let these events go through, as they could be
+   * essential for the management of the ClutterZoomGesture in the
+   * ChamplainView.
+   */
   return FALSE;
 }