Support for pinch events

wgpu/gui/qt.py

@@ -27,13 +27,15 @@
     try:
         WA_PaintOnScreen = QtCore.Qt.WidgetAttribute.WA_PaintOnScreen
         WA_DeleteOnClose = QtCore.Qt.WidgetAttribute.WA_DeleteOnClose
+        PinchGesture = QtCore.Qt.GestureType.PinchGesture
         PreciseTimer = QtCore.Qt.TimerType.PreciseTimer
         KeyboardModifiers = QtCore.Qt.KeyboardModifier
         FocusPolicy = QtCore.Qt.FocusPolicy
         Keys = QtCore.Qt.Key
     except AttributeError:
         WA_PaintOnScreen = QtCore.Qt.WA_PaintOnScreen
         WA_DeleteOnClose = QtCore.Qt.WA_DeleteOnClose
+        PinchGesture = QtCore.Qt.PinchGesture
         PreciseTimer = QtCore.Qt.PreciseTimer
         KeyboardModifiers = QtCore.Qt
         FocusPolicy = QtCore.Qt
@@ -146,6 +148,7 @@ def __init__(self, *args, **kwargs):
         self.setAutoFillBackground(False)
         self.setMouseTracking(True)
         self.setFocusPolicy(FocusPolicy.StrongFocus)
+        self.grabGesture(PinchGesture)
 
         # A timer for limiting fps
         self._request_draw_timer = QtCore.QTimer()
@@ -244,6 +247,13 @@ def _key_event(self, event_type, event):
         }
         self._handle_event_and_flush(ev)
 
+    def event(self, event):
+        if isinstance(event, QtWidgets.QGestureEvent):
+            self._handle_gesture_event(event)
+            return True
+        else:
+            return super().event(event)
+
     def keyPressEvent(self, event):  # noqa: N802
         self._key_event("key_down", event)
 
@@ -327,6 +337,20 @@ def wheelEvent(self, event):  # noqa: N802
         accum_keys = {"dx", "dy"}
         self._handle_event_rate_limited(ev, call_later, match_keys, accum_keys)
 
+    def _handle_gesture_event(self, event):
+        for gesture in event.activeGestures():
+            if gesture.gestureType() == PinchGesture:
+                ev = {
+                    "event_type": "pinch",
+                    "scale": gesture.scaleFactor(),
+                    "angle": gesture.lastRotationAngle() - gesture.rotationAngle(),
+                    # "buttons": buttons,  -> event does not have them. Drop or track these?
+                    # "modifiers": modifiers,
+                }
+                match_keys = set()
+                accum_keys = {"scale", "angle"}
+                self._handle_event_rate_limited(ev, call_later, match_keys, accum_keys)
+
     def resizeEvent(self, event):  # noqa: N802
         ev = {
             "event_type": "resize",