Merge pull request #6 from Ledger-Donjon/fix-zoom

Don't zoom at cursor when following stage

laserstudio/widgets/viewer.py

@@ -298,27 +298,27 @@ def wheelEvent(self, event: Optional[QWheelEvent]):
         """
         if event is None:
             return
-        # We want to zoom relative to the current cursor position, not relative
-        # to the center of the widget. This involves some math...
-        # p is the pointed position in the scene, and we want to keep p at the
-        # same screen position after changing the zoom. If c1 and c2 are the
-        # camera positions before and after the zoom changes,
-        # z1 and z2 the zoom levels, then we want:
-        # z1 * (p - c1) = z2 * (p - c2)
-        # which gives:
-        # c2 = c1 * (z1/z2) + p * (1 - z1/z2)
-        # we can use zr = z2/z1, the zoom factor to apply.
-
-        # The pointed position
-        p = self.mapToScene(event.position().toPoint())
-
+        # Get current position and zoom factor of camera
+        pos, zoom = self.cam_pos_zoom
         # The zoom factor to apply
         zr = 2 ** (event.angleDelta().y() / (8 * 120))
 
-        # Get current position and zoom factor of camera
-        pos, zoom = self.cam_pos_zoom
+        if not self._follow_stage_sight:
+            # We want to zoom relative to the current cursor position, not relative
+            # to the center of the widget. This involves some math...
+            # p is the pointed position in the scene, and we want to keep p at the
+            # same screen position after changing the zoom. If c1 and c2 are the
+            # camera positions before and after the zoom changes,
+            # z1 and z2 the zoom levels, then we want:
+            # z1 * (p - c1) = z2 * (p - c2)
+            # which gives:
+            # c2 = c1 * (z1/z2) + p * (1 - z1/z2)
+            # we can use zr = z2/z1, the zoom factor to apply.
+
+            # The pointed position
+            p = self.mapToScene(event.position().toPoint())
+            pos = (pos / zr) + (p * (1 - (1 / zr)))
 
-        pos = (pos / zr) + (p * (1 - (1 / zr)))
         zoom *= zr
 
         # Update the position and zoom factors
@@ -347,18 +347,19 @@ def mousePressEvent(self, event: Optional[QMouseEvent]):
 
         # The event is a press of the right button
         if event.button() == Qt.MouseButton.RightButton:
-            # Scroll gesture mode
-            self.setDragMode(Viewer.DragMode.ScrollHandDrag)
-            # Transform as left press button event,
-            # to make the scroll by dragging actually effective.
-            event = QMouseEvent(
-                event.type(),
-                event.position(),
-                Qt.MouseButton.LeftButton,
-                event.buttons(),
-                event.modifiers(),
-                event.pointingDevice(),
-            )
+            if not self._follow_stage_sight:
+                # Scroll gesture mode
+                self.setDragMode(Viewer.DragMode.ScrollHandDrag)
+                # Transform as left press button event,
+                # to make the scroll by dragging actually effective.
+                event = QMouseEvent(
+                    event.type(),
+                    event.position(),
+                    Qt.MouseButton.LeftButton,
+                    event.buttons(),
+                    event.modifiers(),
+                    event.pointingDevice(),
+                )
 
         super().mousePressEvent(event)