[libhandy] swipe-tracker: Skip swipes outside swipe area

[Adrien Plazas <aplazas src gnome org>]

commit 1bdd37314e7d4511786aad6ed13270bedd90bd96
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Fri Jun 26 19:39:50 2020 +0500

    swipe-tracker: Skip swipes outside swipe area
    
    This will help with https://gitlab.gnome.org/GNOME/libhandy/-/issues/167
    
    Signed-off-by: Alexander Mikhaylenko <alexm gnome org>

 src/hdy-swipe-tracker.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)
---
diff --git a/src/hdy-swipe-tracker.c b/src/hdy-swipe-tracker.c
index b46599bf..32e2ebae 100644
--- a/src/hdy-swipe-tracker.c
+++ b/src/hdy-swipe-tracker.c
@@ -58,6 +58,9 @@ struct _HdySwipeTracker
   gboolean allow_mouse_drag;
   GtkOrientation orientation;
 
+  gint start_x;
+  gint start_y;
+
   guint32 prev_time;
   gdouble velocity;
 
@@ -109,6 +112,9 @@ reset (HdySwipeTracker *self)
   self->initial_progress = 0;
   self->progress = 0;
 
+  self->start_x = 0;
+  self->start_y = 0;
+
   self->prev_time = 0;
   self->velocity = 0;
 
@@ -278,6 +284,9 @@ drag_begin_cb (HdySwipeTracker *self,
 {
   if (self->state != HDY_SWIPE_TRACKER_STATE_NONE)
     gtk_gesture_set_state (self->touch_gesture, GTK_EVENT_SEQUENCE_DENIED);
+
+  self->start_x = start_x;
+  self->start_y = start_y;
 }
 
 static void
@@ -412,8 +421,17 @@ handle_scroll_event (HdySwipeTracker *self,
       return GDK_EVENT_PROPAGATE;
 
     if (is_vertical == is_delta_vertical) {
-      if (!capture)
+      if (!capture) {
+        GtkWidget *widget = gtk_get_event_widget (event);
+        gdouble event_x, event_y;
+
+        gdk_event_get_coords (event, &event_x, &event_y);
+        gtk_widget_translate_coordinates (widget, GTK_WIDGET (self->swipeable),
+                                          event_x, event_y,
+                                          &self->start_x, &self->start_y);
+
         gesture_prepare (self, delta > 0 ? HDY_NAVIGATION_DIRECTION_FORWARD : HDY_NAVIGATION_DIRECTION_BACK);
+      }
     } else {
       self->is_scrolling = TRUE;
       return GDK_EVENT_PROPAGATE;
@@ -1034,6 +1052,18 @@ hdy_swipe_tracker_emit_begin_swipe (HdySwipeTracker        *self,
 {
   g_return_if_fail (HDY_IS_SWIPE_TRACKER (self));
 
+  if (direct) {
+    GdkRectangle rect;
+
+    hdy_swipeable_get_swipe_area (self->swipeable, &rect);
+
+    if (self->start_x < rect.x ||
+        self->start_x >= rect.x + rect.width ||
+        self->start_y < rect.y ||
+        self->start_y >= rect.y + rect.height)
+      return;
+  }
+
   g_signal_emit (self, signals[SIGNAL_BEGIN_SWIPE], 0, direction, direct);
 }