From 3fdfe7b7efdcaf5cef83755e535b7b9f9d704797 Mon Sep 17 00:00:00 2001
From: Jonathan Thomas <jonathan@openshot.org>
Date: Tue, 12 May 2026 16:46:55 -0500
Subject: [PATCH] Allow mouse wheel tilt (left/right) to scroll timeline

- Restored horizontal timeline scrolling via mouse-wheel tilt by handling angleDelta().x() / pixelDelta().x() in wheelEvent() and routing that input through the existing deferred horizontal scroll accumulator/timer path. This allows left/right wheel tilt to scroll without requiring Shift.
- Kept existing Shift + wheel behavior intact (still mapped to horizontal scrolling using Y delta).
- Extended timeline helper wheel-event stubs to support X-axis deltas, enabling regression tests for tilt input in unit tests.
- Added a regression test that verifies horizontal scroll occurs from tilt-wheel input with no modifier keys.
---
 src/tests/test_timeline_helpers.py            | 36 ++++++++++++++++---
 .../views/timeline_backend/qwidget/base.py    | 19 +++++++++-
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/src/tests/test_timeline_helpers.py b/src/tests/test_timeline_helpers.py
index 1af847f9e..cf0b7aad3 100644
--- a/src/tests/test_timeline_helpers.py
+++ b/src/tests/test_timeline_helpers.py
@@ -546,10 +546,14 @@ class TimelineHelperTests(unittest.TestCase):
                 return self.active
 
         class DeltaStub:
-            def __init__(self, y=0.0, is_null=False):
+            def __init__(self, x=0.0, y=0.0, is_null=False):
+                self._x = float(x)
                 self._y = float(y)
                 self._is_null = bool(is_null)
 
+            def x(self):
+                return self._x
+
             def y(self):
                 return self._y
 
@@ -576,13 +580,13 @@ class TimelineHelperTests(unittest.TestCase):
                 self.accepted = True
 
         class WheelEventStub:
-            def __init__(self, delta, modifiers=Qt.ControlModifier, pixel_delta=None):
+            def __init__(self, delta, modifiers=Qt.ControlModifier, pixel_delta=None, x_delta=0.0):
                 self._modifiers = modifiers
-                self._angle_delta = DeltaStub(delta, is_null=False)
+                self._angle_delta = DeltaStub(x=x_delta, y=delta, is_null=False)
                 if pixel_delta is None:
-                    self._pixel_delta = DeltaStub(0.0, is_null=True)
+                    self._pixel_delta = DeltaStub(is_null=True)
                 else:
-                    self._pixel_delta = DeltaStub(pixel_delta, is_null=False)
+                    self._pixel_delta = DeltaStub(y=pixel_delta, is_null=False)
                 self.accepted = False
                 self.ignored = False
 
@@ -2869,6 +2873,28 @@ class TimelineHelperTests(unittest.TestCase):
         self.assertAlmostEqual(helper.timeline_scrolled[0][1], 0.64)
         self.assertEqual(helper.timeline_scrolled[0][2:], [400.0, 100.0])
 
+    def test_qwidget_tilt_wheel_scrolls_horizontally_without_shift(self):
+        helper, _event_cls, wheel_event_cls = self.make_qwidget_ctrl_zoom_helper()
+        event = wheel_event_cls(0.0, modifiers=Qt.NoModifier, x_delta=-120.0)
+        app = types.SimpleNamespace(
+            window=types.SimpleNamespace(
+                TimelineScrolled=types.SimpleNamespace(
+                    emit=lambda positions: helper.timeline_scrolled.append(list(positions))
+                )
+            )
+        )
+
+        with patch.object(self.qwidget_base_module, "get_app", return_value=app):
+            self.qwidget_base_module.TimelineWidgetBase.wheelEvent(helper, event)
+            helper._hscroll_timer.active = False
+            self.qwidget_base_module.TimelineWidgetBase._flush_pending_horizontal_scroll(helper)
+
+        self.assertTrue(event.accepted)
+        self.assertFalse(event.ignored)
+        self.assertEqual(helper._hscroll_timer.started, 1)
+        self.assertAlmostEqual(helper.scrollbar_position[0], 0.24)
+        self.assertAlmostEqual(helper.scrollbar_position[1], 0.64)
+
     def test_qwidget_set_zoom_factor_keeps_playhead_at_existing_viewport_ratio(self):
         helper = types.SimpleNamespace()
         helper.zoom_factor = 10.0
diff --git a/src/windows/views/timeline_backend/qwidget/base.py b/src/windows/views/timeline_backend/qwidget/base.py
index 960a809b8..a49de8dc3 100644
--- a/src/windows/views/timeline_backend/qwidget/base.py
+++ b/src/windows/views/timeline_backend/qwidget/base.py
@@ -2032,9 +2032,26 @@ class TimelineWidgetBase(QWidget):
             event.accept()
             return
 
+        horizontal_delta = 0.0
+        pixel_delta = event.pixelDelta()
+        angle_delta = event.angleDelta()
+        if not pixel_delta.isNull():
+            horizontal_delta = pixel_delta.x()
+        if not horizontal_delta:
+            horizontal_delta = angle_delta.x()
+
+        if horizontal_delta and self.scrollbar_position[3] > 0 and self.scrollbar_position[2] > self.scrollbar_position[3]:
+            delta = -horizontal_delta / 120.0
+            self._pending_hscroll_delta += delta
+            if not self._hscroll_timer.isActive():
+                # Process accumulated wheel events once the event queue is flushed
+                self._hscroll_timer.start(0)
+            event.accept()
+            return
+
         if event.modifiers() & Qt.ShiftModifier:
             if self.scrollbar_position[3] > 0 and self.scrollbar_position[2] > self.scrollbar_position[3]:
-                delta = -event.angleDelta().y() / 120.0
+                delta = -angle_delta.y() / 120.0
                 if delta:
                     self._pending_hscroll_delta += delta
                     if not self._hscroll_timer.isActive():