widget: tighten the conditions at which a press event is emulated

Make it really sure that the event is only emitted after every gesture
that consumed the button press is done with the sequence.
The event must only be emulated if a gesture in the capture phase happened
to consume the event, be cancelled, and

2 files changed, 71 insertions, 28 deletions

diff --git a/gtk/gtkgesture.c b/gtk/gtkgesture.c
index 420ad9ffa3..e738e61c1c 100644
--- a/gtk/gtkgesture.c
+++ b/gtk/gtkgesture.c
@@ -510,7 +510,10 @@ gtk_gesture_handle_event (GtkEventController *controller,
           PointData *data;
 
           data = g_hash_table_lookup (priv->points, sequence);
-          data->press_handled = TRUE;
+
+          /* If the sequence was claimed early, the press event will be consumed */
+          if (gtk_gesture_get_sequence_state (gesture, sequence) == GTK_EVENT_SEQUENCE_CLAIMED)
+            data->press_handled = TRUE;
         }
 
       break;
@@ -820,7 +823,7 @@ gtk_gesture_set_sequence_state (GtkGesture            *gesture,
     return FALSE;
 
   if (data->state == state)
-    return TRUE;
+    return FALSE;
 
   /* denied sequences remain denied */
   if (data->state == GTK_EVENT_SEQUENCE_DENIED)
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 87ac87396d..18eed60716 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -4181,31 +4181,65 @@ _gtk_widget_get_emulating_sequence (GtkWidget         *widget,
 }
 
 static gboolean
+gtk_widget_needs_press_emulation (GtkWidget        *widget,
+                                  GdkEventSequence *sequence)
+{
+  GtkWidgetPrivate *priv = widget->priv;
+  gboolean sequence_press_handled = FALSE;
+  GList *l;
+
+  /* Check whether there is any remaining gesture in
+   * the capture phase that handled the press event
+   */
+  for (l = priv->event_controllers; l; l = l->next)
+    {
+      EventControllerData *data;
+      GtkGesture *gesture;
+
+      data = l->data;
+
+      if (data->phase != GTK_PHASE_CAPTURE)
+        continue;
+      if (!GTK_IS_GESTURE (data->controller))
+        continue;
+
+      gesture = GTK_GESTURE (data->controller);
+      sequence_press_handled |=
+        (gtk_gesture_handles_sequence (gesture, sequence) &&
+         _gtk_gesture_handled_sequence_press (gesture, sequence));
+    }
+
+  return !sequence_press_handled;
+}
+
+static gint
 _gtk_widget_set_sequence_state_internal (GtkWidget             *widget,
                                          GdkEventSequence      *sequence,
                                          GtkEventSequenceState  state,
-                                         GList                 *group)
+                                         GtkGesture            *emitter)
 {
+  gboolean emulates_pointer, sequence_handled = FALSE;
   GtkWidgetPrivate *priv = widget->priv;
   const GdkEvent *mimic_event;
-  gboolean send_event = FALSE;
-  gboolean emulates_pointer;
+  GList *group = NULL, *l;
   GdkEventSequence *seq;
-  gboolean handled = FALSE;
-  GList *l;
+  gint n_handled = 0;
 
   if (!priv->event_controllers && state != GTK_EVENT_SEQUENCE_CLAIMED)
     return TRUE;
 
+  if (emitter)
+    group = gtk_gesture_get_group (emitter);
+
   emulates_pointer = _gtk_widget_get_emulating_sequence (widget, sequence, &seq);
   mimic_event = _gtk_widget_get_last_event (widget, seq);
 
   for (l = priv->event_controllers; l; l = l->next)
     {
       GtkEventSequenceState gesture_state;
-      gboolean sequence_handled, retval;
       EventControllerData *data;
       GtkGesture *gesture;
+      gboolean retval;
 
       seq = sequence;
       data = l->data;
@@ -4216,6 +4250,14 @@ _gtk_widget_set_sequence_state_internal (GtkWidget             *widget,
 
       gesture = GTK_GESTURE (data->controller);
 
+      if (gesture == emitter)
+        {
+          sequence_handled |=
+            _gtk_gesture_handled_sequence_press (gesture, sequence);
+          n_handled++;
+          continue;
+        }
+
       if (seq && emulates_pointer &&
           !gtk_gesture_handles_sequence (gesture, seq))
         seq = NULL;
@@ -4233,29 +4275,30 @@ _gtk_widget_set_sequence_state_internal (GtkWidget             *widget,
         }
 
       g_signal_handler_block (data->controller, data->sequence_state_changed_id);
-
-      sequence_handled =
-        _gtk_gesture_handled_sequence_press (gesture, seq);
       retval = gtk_gesture_set_sequence_state (gesture, seq, gesture_state);
-      handled |= retval;
-
       g_signal_handler_unblock (data->controller, data->sequence_state_changed_id);
 
-      /* If the sequence goes denied, check whether this is a controller attached
-       * to the capture phase, that additionally handled the button/touch press (ie.
-       * it was consumed), the corresponding press will be emulated for widgets
-       * beneath, so the widgets beneath get a coherent stream of events from now on.
-       */
-      if (retval && sequence_handled &&
-          data->phase == GTK_PHASE_CAPTURE &&
-          state == GTK_EVENT_SEQUENCE_DENIED)
-        send_event = TRUE;
+      if (retval || gesture == emitter)
+        {
+          sequence_handled |=
+            _gtk_gesture_handled_sequence_press (gesture, seq);
+          n_handled++;
+        }
     }
 
-  if (send_event && mimic_event)
+  /* If the sequence goes denied, check whether this is a controller attached
+   * to the capture phase, that additionally handled the button/touch press (ie.
+   * it was consumed), the corresponding press will be emulated for widgets
+   * beneath, so the widgets beneath get a coherent stream of events from now on.
+   */
+  if (n_handled > 0 && sequence_handled &&
+      state == GTK_EVENT_SEQUENCE_DENIED &&
+      gtk_widget_needs_press_emulation (widget, sequence))
     _gtk_widget_emulate_press (widget, mimic_event);
 
-  return handled;
+  g_list_free (group);
+
+  return n_handled;
 }
 
 static gboolean
@@ -16683,12 +16726,9 @@ event_controller_sequence_state_changed (GtkGesture            *gesture,
   GtkWidget *event_widget;
   gboolean cancel = TRUE;
   const GdkEvent *event;
-  GList *group;
 
-  group = gtk_gesture_get_group (gesture);
   handled = _gtk_widget_set_sequence_state_internal (widget, sequence,
-                                                     state, group);
-  g_list_free (group);
+                                                     state, gesture);
 
   if (!handled || state != GTK_EVENT_SEQUENCE_CLAIMED)
     return;