Add a logarithmic scale slider class

magicgui/_qt/widgets/__init__.py

@@ -1,6 +1,7 @@
 """Custom widgets for magicgui."""
 from .data_combobox import QDataComboBox
 from .double_slider import QDoubleSlider
+from .log_slider import QLogSlider
 from .eval_lineedit import LiteralEvalEdit
 from .file_dialog import MagicFileDialog, MagicFilesDialog
 from .widget import WidgetType
@@ -10,6 +11,7 @@
     "MagicFileDialog",
     "MagicFilesDialog",
     "QDoubleSlider",
+    "QLogSlider",
     "QDataComboBox",
     "WidgetType",
 ]

magicgui/_qt/widgets/double_slider.py

@@ -16,10 +16,10 @@ def value(self):
         """Get the slider value and convert to float."""
         return super().value() / self.PRECISION
 
-    def setValue(self, value):
+    def setValue(self, value: float):
         """Set integer slider position from float ``value``."""
         super().setValue(value * self.PRECISION)
 
-    def setMaximum(self, value):
+    def setMaximum(self, value: float):
         """Set maximum position of slider in float units."""
         super().setMaximum(value * self.PRECISION)

magicgui/_qt/widgets/log_slider.py

@@ -0,0 +1,33 @@
+"""A Slider with a natural logarithmic scale."""
+import math
+
+from qtpy.QtCore import Qt
+from qtpy.QtWidgets import QSlider
+
+
+class QLogSlider(QSlider):
+    """A Slider Widget with a natural logarithmic scale."""
+
+    PRECISION = 1000
+
+    def __init__(self, parent=None, *, base=math.e):
+        super().__init__(Qt.Horizontal, parent=parent)
+        self.base = base
+        self.setMinimum(0)
+        self.setMaximum(10)
+
+    def value(self):
+        """Get the natural log slider value as a float."""
+        return math.log(super().value() / self.PRECISION, self.base)
+
+    def setValue(self, value: float):
+        """Set integer slier position from float ``value``."""
+        super().setValue(int(math.pow(self.base, value) * self.PRECISION))
+
+    def setMinimum(self, value: float):
+        """Set minimum position of slider in float units."""
+        super().setMinimum(int(math.pow(self.base, value) * self.PRECISION))
+
+    def setMaximum(self, value: float):
+        """Set maximum position of slider in float units."""
+        super().setMaximum(int(math.pow(self.base, value) * self.PRECISION))

magicgui/_tests/test_ qt.py → magicgui/_tests/test_qt.py

@@ -5,17 +5,22 @@
 import datetime
 from enum import Enum
 from pathlib import Path, PosixPath, WindowsPath
+from typing import List, Sequence, Tuple
 
 import pytest
-from qtpy import QtCore
+from qtpy import QtCore, API_NAME
 from qtpy import QtWidgets as QtW
 
 from magicgui import _qt, event_loop
-from typing import Sequence, List, Tuple
 
 
+@pytest.mark.skipif(API_NAME == "PyQt5", reason="Couldn't delete app on PyQt")
 def test_event():
     """Test that the event loop makes a Qt app."""
+    if QtW.QApplication.instance():
+        import shiboken2
+
+        shiboken2.delete(QtW.QApplication.instance())
     assert not QtW.QApplication.instance()
     with event_loop():
         app = QtW.QApplication.instance()

magicgui/_tests/test_widgets.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+"""Tests for `magicgui` widgets."""
+import math
+import pytest
+
+from magicgui._qt.widgets import QDoubleSlider, QLogSlider
+
+
+@pytest.mark.parametrize("SliderClass", [QDoubleSlider, QLogSlider])
+def test_slider(qtbot, SliderClass):
+    """Test magicgui sliders."""
+    slider = SliderClass()
+    qtbot.addWidget(slider)
+    assert slider.value() == 0  # default slider value is zero
+    slider.setValue(math.pi)
+    assert math.isclose(slider.value(), math.pi, abs_tol=0.01)
+    slider.setMaximum(10)
+    slider.setValue(11)  # above maximum allowed value, value will be clipped
+    assert math.isclose(slider.value(), 10, abs_tol=1e-07)