feat(interactive.colors): implement BetterColorBarItem limit editor

A new context menu in `BetterColorBarItem`'s viewbox enables manually editing color limits.

src/erlab/interactive/colors.py

@@ -316,6 +316,65 @@ def mouseDragEvent(self, ev) -> None:
             self.sigRegionChanged.emit(self)
 
 
+class _ColorBarLimitWidget(QtWidgets.QWidget):
+    def __init__(self, colorbar: BetterColorBarItem) -> None:
+        super().__init__()
+        self.setGeometry(QtCore.QRect(0, 640, 242, 182))
+        self.cb = colorbar
+
+        layout = QtWidgets.QFormLayout(self)
+        layout.setContentsMargins(0, 0, 0, 0)
+        layout.setVerticalSpacing(0)
+        self.setLayout(layout)
+
+        self.max_spin = pg.SpinBox(dec=True, compactHeight=False, finite=False)
+        self.min_spin = pg.SpinBox(dec=True, compactHeight=False, finite=False)
+        self.rst_btn = QtWidgets.QPushButton("Reset")
+
+        self.max_spin.setObjectName("_vmax_spin")
+        self.min_spin.setObjectName("_vmin_spin")
+        self.rst_btn.setObjectName("_vlim_reset_btn")
+
+        layout.addRow("Max", self.max_spin)
+        layout.addRow("Min", self.min_spin)
+        layout.addRow(self.rst_btn)
+
+        self.cb._span.sigRegionChanged.connect(self.region_changed)
+        self.min_spin.sigValueChanged.connect(self.update_region)
+        self.max_spin.sigValueChanged.connect(self.update_region)
+        self.rst_btn.clicked.connect(self.reset)
+
+    def _set_spin_values(self, mn: float, mx: float) -> None:
+        self.max_spin.blockSignals(True)
+        self.min_spin.blockSignals(True)
+        self.max_spin.setValue(mx)
+        self.min_spin.setValue(mn)
+        self.max_spin.blockSignals(False)
+        self.min_spin.blockSignals(False)
+
+    @QtCore.Slot()
+    def region_changed(self):
+        mn, mx = self.cb._span.getRegion()
+        self._set_spin_values(mn, mx)
+
+    @QtCore.Slot()
+    def reset(self):
+        self._set_spin_values(-np.inf, np.inf)
+        self.update_region()
+
+    @QtCore.Slot()
+    def update_region(self):
+        # Trigger region change start and finish signals to simulate drag
+        self.cb._span.sigRegionChangeStarted.emit(self.cb._span)
+        self.cb.setSpanRegion((self.min_spin.value(), self.max_spin.value()))
+        self.cb._span.sigRegionChangeFinished.emit(self.cb._span)
+
+    def setVisible(self, visible: bool) -> None:
+        super().setVisible(visible)
+        if visible:
+            self.region_changed()
+
+
 class BetterColorBarItem(pg.PlotItem):
     def __init__(
         self,
@@ -361,6 +420,15 @@ def __init__(
         self.setAutoLevels(autoLevels)
         self._images: set[weakref.ref[BetterImageItem]] = set()
         self._primary_image: weakref.ref[BetterImageItem] | None = None
+
+        # Add colorbar limit editor to context menu
+        self.vb.menu.addSeparator()
+        self._clim_menu: QtWidgets.QMenu = self.vb.menu.addMenu("Edit color limits")
+        clw = _ColorBarLimitWidget(self)
+        act = QtWidgets.QWidgetAction(self._clim_menu)
+        act.setDefaultWidget(clw)
+        self._clim_menu.addAction(act)
+
         if image is not None:
             self.setImageItem(image)
         if limits is not None:

tests/interactive/test_imagetool.py

@@ -119,6 +119,18 @@ def test_itool(qtbot):
     win.slicer_area.lock_levels(True)
     win.slicer_area.levels = (1.0, 23.0)
     assert win.slicer_area._colorbar.cb._copy_limits() == str((1.0, 23.0))
+
+    # Test color limits editor
+    clw = win.slicer_area._colorbar.cb._clim_menu.actions()[0].defaultWidget()
+    assert clw.min_spin.value() == win.slicer_area.levels[0]
+    assert clw.max_spin.value() == win.slicer_area.levels[1]
+    clw.min_spin.setValue(1.0)
+    assert clw.min_spin.value() == 1.0
+    clw.max_spin.setValue(2.0)
+    assert clw.max_spin.value() == 2.0
+    clw.rst_btn.click()
+    assert win.slicer_area.levels == (0.0, 24.0)
+    win.slicer_area.levels = (1.0, 23.0)
     win.slicer_area.lock_levels(False)
 
     # Undo and redo