Add tracking property to sliders. When False, changed only emits on release.

examples/log_slider.py

@@ -5,7 +5,7 @@
 @magicgui(
     auto_call=True,
     result_widget=True,
-    input={"widget_type": "LogSlider", "max": 10000, "min": 1},
+    input={"widget_type": "LogSlider", "max": 10000, "min": 1, "tracking": False},
 )
 def slider(input=1):
     return round(input, 4)

magicgui/backends/_qtpy/widgets.py

@@ -477,6 +477,17 @@ def _mgui_get_orientation(self) -> Any:
     def _mgui_set_readout_visibility(self, value: bool):
         raise NotImplementedError()
 
+    def _mgui_get_tracking(self) -> bool:
+        # Progressbar also uses this base, but doesn't have tracking
+        if hasattr(self._qwidget, "hasTracking"):
+            return self._qwidget.hasTracking()
+        return False
+
+    def _mgui_set_tracking(self, value: bool) -> None:
+        # Progressbar also uses this base, but doesn't have tracking
+        if hasattr(self._qwidget, "setTracking"):
+            self._qwidget.setTracking(value)
+
 
 class Slider(_Slider):
     _qwidget: QtW.QSlider

magicgui/widgets/_bases/slider_widget.py

@@ -15,10 +15,29 @@ class SliderWidget(RangedWidget, _OrientationMixin):
 
     _widget: _protocols.SliderWidgetProtocol
 
-    def __init__(self, orientation: str = "horizontal", readout=True, **kwargs):
+    def __init__(
+        self, orientation: str = "horizontal", readout=True, tracking=True, **kwargs
+    ):
         kwargs["backend_kwargs"] = {"readout": readout, "orientation": orientation}
         self._readout = readout
         super().__init__(**kwargs)
+        self.tracking = tracking
+
+    @property
+    def tracking(self) -> bool:
+        """Return whether slider tracking is enabled.
+
+        If tracking is enabled (the default), the slider emits the changed()
+        signal while the slider is being dragged. If tracking is disabled,
+        the slider emits the valueChanged() signal only when the user releases
+        the slider.
+        """
+        return self._widget._mgui_get_tracking()
+
+    @tracking.setter
+    def tracking(self, value: bool) -> None:
+        """Set whether slider tracking is enabled."""
+        self._widget._mgui_set_tracking(value)
 
     @property
     def options(self) -> dict:

magicgui/widgets/_concrete.py

@@ -18,6 +18,7 @@
 
 from magicgui.application import use_app
 from magicgui.types import FileDialogMode, PathLike
+from magicgui.widgets import _protocols
 from magicgui.widgets._bases.mixins import _OrientationMixin, _ReadOnlyMixin
 
 from ._bases import (
@@ -304,8 +305,15 @@ class LogSlider(TransformedRangedWidget):
         The base to use for the log, by default math.e.
     """
 
+    _widget: _protocols.SliderWidgetProtocol
+
     def __init__(
-        self, min: float = 1, max: float = 100, base: float = math.e, **kwargs
+        self,
+        min: float = 1,
+        max: float = 100,
+        base: float = math.e,
+        tracking=True,
+        **kwargs,
     ):
         for key in ("maximum", "minimum"):
             if key in kwargs:
@@ -329,6 +337,23 @@ def __init__(
             widget_type=app.get_obj("Slider"),
             **kwargs,
         )
+        self.tracking = tracking
+
+    @property
+    def tracking(self) -> bool:
+        """Return whether slider tracking is enabled.
+
+        If tracking is enabled (the default), the slider emits the changed()
+        signal while the slider is being dragged. If tracking is disabled,
+        the slider emits the valueChanged() signal only when the user releases
+        the slider.
+        """
+        return self._widget._mgui_get_tracking()
+
+    @tracking.setter
+    def tracking(self, value: bool) -> None:
+        """Set whether slider tracking is enabled."""
+        self._widget._mgui_set_tracking(value)
 
     @property
     def _scale(self):

magicgui/widgets/_protocols.py

@@ -416,6 +416,12 @@ class SliderWidgetProtocol(RangedWidgetProtocol, SupportsOrientation, Protocol):
     def _mgui_set_readout_visibility(self, visible: bool) -> None:
         """Set visibility of readout widget."""
 
+    def _mgui_get_tracking(self) -> bool:
+        """If tracking is False, valueChanged is only emitted when released."""
+
+    def _mgui_set_tracking(self, tracking: bool) -> None:
+        """If tracking is False, valueChanged is only emitted when released."""
+
 
 # CONTAINER ----------------------------------------------------------------------
 

tests/test_widgets.py

@@ -614,3 +614,10 @@ def test_container_removal():
     c.pop()
     assert len(c) == 0
     assert c.native.layout().count() == 0
+
+
+def test_tracking():
+    slider = widgets.Slider(tracking=False)
+    assert slider.tracking is False
+    slider.tracking = True
+    assert slider.tracking