fix: Update text after settings decimals in SliderLabel

src/superqt/sliders/_labeled.py

@@ -677,8 +677,7 @@ def __init__(
         self._decimals = -1
         self.setFocusPolicy(Qt.FocusPolicy.ClickFocus)
         self.setMode(EdgeLabelMode.LabelIsValue)
-        self.setDecimals(0)
-        self.setText(str(self._value))
+        self.setDecimals(0)  # calls updateText
         validator = QDoubleValidator(self)
         validator.setNotation(QDoubleValidator.Notation.ScientificNotation)
         self.setValidator(validator)
@@ -713,6 +712,7 @@ def setRange(self, min_: float, max_: float) -> None:
     def setDecimals(self, prec: int) -> None:
         # super().setDecimals(prec)
         self._decimals = prec
+        self.updateText()
         self._update_size()
 
     def decimals(self) -> int:

tests/zz_test_sliders/test_labeled_slider.py

@@ -84,3 +84,19 @@ def test_editing_float(qtbot):
     slider._label.setValue(0.5)
     slider._label.editingFinished.emit()
     assert slider.value() == 0.5
+
+
+def test_slider_label_decimals_update_text(qtbot):
+    slider = QLabeledDoubleSlider()
+    qtbot.addWidget(slider)
+
+    # Set a value with default 2 decimals
+    slider.setValue(3.14159)
+    assert slider.value() == 3.14159
+    assert slider._label.text() == "3.14"
+
+    slider.setDecimals(0)
+    assert slider._label.text() == "3"
+
+    slider.setDecimals(4)
+    assert slider._label.text() == "3.1416"