SwipeGestureHandler: better support of embedded SwipeGestureHandler's

 - When checking the threshold, make sure that the change in the
   interrested dirrection is much more significant that the delta in the
   orthogonal direction (hence the `/ 2`)

 - Accept all mouse move event as we otherwise don't get them further if
   the event was delayed by another SwipeGestureHandler or flickable

Author: ogoffart

internal/core/items/input_items.rs

@@ -521,20 +521,10 @@ impl Item for SwipeGestureHandler {
                     InputEventFilterResult::Intercept
                 } else if !self.pressed.get() {
                     InputEventFilterResult::ForwardEvent
+                } else if self.is_over_threshold(position) {
+                    InputEventFilterResult::Intercept
                 } else {
-                    let pressed_pos = self.pressed_position();
-                    let dx = position.x - pressed_pos.x as Coord;
-                    let dy = position.y - pressed_pos.y as Coord;
-                    let threshold = super::flickable::DISTANCE_THRESHOLD.get();
-                    if (self.handle_swipe_down() && dy > threshold)
-                        || (self.handle_swipe_up() && dy < -threshold)
-                        || (self.handle_swipe_left() && dx < -threshold)
-                        || (self.handle_swipe_right() && dx > threshold)
-                    {
-                        InputEventFilterResult::Intercept
-                    } else {
-                        InputEventFilterResult::ForwardAndInterceptGrab
-                    }
+                    InputEventFilterResult::ForwardAndInterceptGrab
                 }
             }
             MouseEvent::Wheel { .. } => InputEventFilterResult::ForwardAndIgnore,
@@ -576,25 +566,20 @@ impl Item for SwipeGestureHandler {
             }
             MouseEvent::Moved { position } => {
                 if !self.pressed.get() {
-                    return InputEventResult::EventIgnored;
+                    return InputEventResult::EventAccepted;
                 }
                 self.current_position.set(crate::lengths::logical_position_to_api(*position));
-                if !self.swiping() {
-                    let pressed_pos = self.pressed_position();
-                    let dx = position.x - pressed_pos.x as Coord;
-                    let dy = position.y - pressed_pos.y as Coord;
-                    let threshold = super::flickable::DISTANCE_THRESHOLD.get();
-                    let start_swipe = (self.handle_swipe_down() && dy > threshold)
-                        || (self.handle_swipe_up() && dy < -threshold)
-                        || (self.handle_swipe_left() && dx < -threshold)
-                        || (self.handle_swipe_right() && dx > threshold);
-
-                    if start_swipe {
-                        Self::FIELD_OFFSETS.swiping.apply_pin(self).set(true);
-                    }
+                let mut swiping = self.swiping();
+                if !swiping && self.is_over_threshold(position) {
+                    Self::FIELD_OFFSETS.swiping.apply_pin(self).set(true);
+                    swiping = true;
                 }
                 Self::FIELD_OFFSETS.moved.apply_pin(self).call(&());
-                InputEventResult::GrabMouse
+                if swiping {
+                    InputEventResult::GrabMouse
+                } else {
+                    InputEventResult::EventAccepted
+                }
             }
             MouseEvent::Wheel { .. } => InputEventResult::EventIgnored,
             MouseEvent::DragMove(..) | MouseEvent::Drop(..) => InputEventResult::EventIgnored,
@@ -672,6 +657,17 @@ impl SwipeGestureHandler {
             Self::FIELD_OFFSETS.cancelled.apply_pin(self).call(&());
         }
     }
+
+    fn is_over_threshold(self: Pin<&Self>, position: &LogicalPoint) -> bool {
+        let pressed_pos = self.pressed_position();
+        let dx = position.x - pressed_pos.x as Coord;
+        let dy = position.y - pressed_pos.y as Coord;
+        let threshold = super::flickable::DISTANCE_THRESHOLD.get();
+        (self.handle_swipe_down() && dy > threshold && dy > dx.abs() / 2 as Coord)
+            || (self.handle_swipe_up() && dy < -threshold && dy < -dx.abs() / 2 as Coord)
+            || (self.handle_swipe_left() && dx < -threshold && dx < -dy.abs() / 2 as Coord)
+            || (self.handle_swipe_right() && dx > threshold && dx > dy.abs() / 2 as Coord)
+    }
 }
 
 #[cfg(feature = "ffi")]

tests/cases/elements/swipegesturehandler.slint

@@ -139,7 +139,7 @@ assert_eq!(instance.get_left_swiping(), false);
 assert_eq!(instance.get_right_swiping(), false);
 instance.set_r("".into());
 
-// FIXME: this shouldn'g be necessary, but otherwise we don't send exit event to the toucharea
+// FIXME: this shouldn't be necessary, but otherwise we don't send exit event to the toucharea
 instance.window().dispatch_event(WindowEvent::PointerMoved { position: LogicalPosition::new(316.0, 463.0) });
 
 // Left
@@ -150,20 +150,23 @@ assert_eq!(instance.get_left_swiping(), false);
 assert_eq!(instance.get_right_swiping(), false);
 slint_testing::mock_elapsed_time(20);
 instance.window().dispatch_event(WindowEvent::PointerPressed { position: LogicalPosition::new(100.0, 100.0), button: PointerEventButton::Left });
-slint_testing::mock_elapsed_time(120); // FIXME: it should also work with smaller delay, but now the top swipe catches it
+slint_testing::mock_elapsed_time(20);
 assert_eq!(instance.get_ta_hover(), false);
 assert_eq!(instance.get_down_swiping(), false);
 assert_eq!(instance.get_left_swiping(), false);
 assert_eq!(instance.get_right_swiping(), false);
 assert_eq!(instance.get_r(), "");
+slint_testing::mock_elapsed_time(20);
 instance.window().dispatch_event(WindowEvent::PointerMoved { position: LogicalPosition::new(80.0, 100.0) });
+slint_testing::mock_elapsed_time(80);
+instance.window().dispatch_event(WindowEvent::PointerMoved { position: LogicalPosition::new(65.0, 112.0) });
 assert_eq!(instance.get_ta_hover(), false);
 assert_eq!(instance.get_down_swiping(), false);
 assert_eq!(instance.get_right_swiping(), false);
 assert_eq!(instance.get_left_swiping(), true);
-assert_eq!(instance.get_r(), "M2(20)");
+assert_eq!(instance.get_r(), "M2(37)");
 instance.window().dispatch_event(WindowEvent::PointerExited);
-assert_eq!(instance.get_r(), "M2(20)C2(20)");
+assert_eq!(instance.get_r(), "M2(37)C2(37)");
 assert_eq!(instance.get_down_swiping(), false);
 assert_eq!(instance.get_left_swiping(), false);
 assert_eq!(instance.get_right_swiping(), false);