Add "Invert colormap" feature to Colormap Manager with real-time updates

Closes #53

Author: PierreRaybaut

doc/release_notes/release_2.09.md

@@ -14,3 +14,10 @@
   * New `quiver()` function in the interactive plotting interface (`plotpy.pyplot`)
   * Integrated with plot autoscale (initial zoom and middle-click reset)
   * Item icon displayed in the item list widget
+* Added "Invert colormap" checkbox directly in the Colormap Manager dialog. This
+  closes [Issue #53](https://github.com/PlotPyStack/PlotPy/issues/53):
+  * Reflects the current inversion state when the dialog is opened
+  * Allows toggling inversion from the colormap selection widget
+  * Updates the colormap preview in real-time when toggled
+  * Inversion is treated as a display parameter, independent of the colormap
+    definition (toggling does not mark the colormap as having unsaved changes)

plotpy/tools/image.py

@@ -605,10 +605,13 @@ def activate_command(self, plot: BasePlot, checked: bool) -> None:
         ):
             return
         manager = ColorMapManager(
-            plot.parentWidget(), active_colormap=self._active_colormap.name
+            plot.parentWidget(),
+            active_colormap=self._active_colormap.name,
+            invert=self._active_colormap.invert,
         )
         manager.SIG_APPLY_COLORMAP.connect(self.update_plot)
         if exec_dialog(manager) and (cmap := manager.get_colormap()) is not None:
+            cmap.invert = manager.get_invert()
             self.activate_cmap(cmap)
 
     def activate_cmap(self, cmap: str | EditableColormap) -> None:
@@ -627,17 +630,20 @@ def activate_cmap(self, cmap: str | EditableColormap) -> None:
             self.update_plot(self._active_colormap.name)
             self.update_status(plot)
 
-    def update_plot(self, cmap_name: str) -> None:
+    def update_plot(self, cmap_name: str, invert: bool | None = None) -> None:
         """Update the plot with the given colormap.
 
         Args:
             cmap_name: Colormap name
+            invert: Invert colormap state. If None, uses the active colormap's
+             invert state. Defaults to None.
         """
+        if invert is not None:
+            self._active_colormap.invert = invert
         plot: BasePlot = self.get_active_plot()
         items = get_selected_images(plot, IColormapImageItemType)
         for item in items:
-            cmap = item.get_color_map()
-            item.set_color_map(cmap_name, cmap.invert)
+            item.set_color_map(cmap_name, self._active_colormap.invert)
             plot.SIG_ITEM_PARAMETERS_CHANGED.emit(item)
         plot.invalidate()
 
@@ -659,6 +665,7 @@ def update_status(self, plot: BasePlot) -> None:
                 if cmap is not None:
                     icon = build_icon_from_cmap_name(cmap.name)
                     self._active_colormap = get_cmap(cmap.name)
+                    self._active_colormap.invert = cmap.invert
                     cmap_name = cmap.name
             else:
                 self.action.setEnabled(False)

plotpy/widgets/colormap/manager.py

@@ -122,6 +122,8 @@ class ColorMapManager(QW.QDialog):
     Args:
         parent: parent QWidget. Defaults to None.
         active_colormap: name of the active colormap.
+        invert: initial state of the 'Invert colormap' checkbox.
+         Defaults to False.
 
     .. note::
 
@@ -134,12 +136,13 @@ class ColorMapManager(QW.QDialog):
         that the colormap cannot be removed.
     """
 
-    SIG_APPLY_COLORMAP = QC.Signal(str)
+    SIG_APPLY_COLORMAP = QC.Signal(str, bool)
 
     def __init__(
         self,
         parent: QW.QWidget | None = None,
         active_colormap: str | None = None,
+        invert: bool = False,
     ) -> None:
         super().__init__(parent)
         self.setWindowIcon(get_icon("cmap_edit.png"))
@@ -148,6 +151,7 @@ def __init__(
         self.active_cmap_name = default_colormap = active_colormap
 
         self.__returned_colormap: EditableColormap | None = None
+        self.__returned_invert: bool = invert
 
         if default_colormap is None or not cmap_exists(default_colormap, ALL_COLORMAPS):
             default_colormap = next(iter(ALL_COLORMAPS))
@@ -171,6 +175,10 @@ def __init__(
         self._remove_btn.setEnabled(is_custom_cmap)
         self._remove_btn.clicked.connect(self.remove_colormap)
 
+        self._invert_checkbox = QW.QCheckBox(_("Invert colormap"))
+        self._invert_checkbox.setChecked(invert)
+        self._invert_checkbox.toggled.connect(self._on_invert_toggled)
+
         select_gbox = QW.QGroupBox(_("Select or create a colormap"))
         select_label = QW.QLabel(_("Colormap presets:"))
         select_gbox_layout = QW.QHBoxLayout()
@@ -179,6 +187,8 @@ def __init__(
         select_gbox_layout.addSpacing(10)
         select_gbox_layout.addWidget(add_btn)
         select_gbox_layout.addWidget(self._remove_btn)
+        select_gbox_layout.addSpacing(10)
+        select_gbox_layout.addWidget(self._invert_checkbox)
         select_gbox.setLayout(select_gbox_layout)
 
         # Edit the selected colormap
@@ -192,6 +202,13 @@ def __init__(
             current_cmap = None
         self.colormap_editor = ColorMapEditor(self, colormap=current_cmap)
 
+        # Apply initial invert state to the colormap preview
+        if invert:
+            cmap = self.colormap_editor.get_colormap()
+            if cmap is not None:
+                cmap.invert = True
+                self.colormap_editor.colormap_widget.COLORMAP_CHANGED.emit()
+
         self._edit_gbox = QW.QGroupBox(_("Edit the selected colormap"))
         edit_gbox_layout = QW.QVBoxLayout()
         edit_gbox_layout.setContentsMargins(0, 0, 0, 0)
@@ -237,14 +254,33 @@ def button_clicked(self, button: QW.QAbstractButton) -> None:
             if not self.current_changes_saved and not self.save_colormap():
                 return
             self._apply_btn.setEnabled(False)
-            self.SIG_APPLY_COLORMAP.emit(self.colormap_editor.get_colormap().name)
+            self.SIG_APPLY_COLORMAP.emit(
+                self.colormap_editor.get_colormap().name,
+                self._invert_checkbox.isChecked(),
+            )
         elif button is self._save_btn:
             self.save_colormap()
         elif self.bbox.buttonRole(button) == QW.QDialogButtonBox.AcceptRole:
             self.accept()
         else:
             self.reject()
 
+    def _on_invert_toggled(self, checked: bool) -> None:
+        """Callback for the 'Invert colormap' checkbox toggle.
+
+        Inversion is a display parameter independent of the colormap definition,
+        so toggling it only updates the preview without marking the colormap as
+        having unsaved changes.
+
+        Args:
+            checked: True if the checkbox is checked, False otherwise.
+        """
+        self.__returned_invert = checked
+        cmap = self.colormap_editor.get_colormap()
+        if cmap is not None:
+            cmap.invert = checked
+            self.colormap_editor.colormap_widget.draw_colormap_image()
+
     def _changes_not_saved(self) -> None:
         """Callback function to be called when the colormap is modified. Enables the
         save button and sets the current_changes_saved attribute to False."""
@@ -270,6 +306,7 @@ def set_colormap(self, index: int) -> None:
             index: index of the colormap in the QComboBox.
         """
         cmap_copy: EditableColormap = deepcopy(self._cmap_choice.itemData(index))
+        cmap_copy.invert = self._invert_checkbox.isChecked()
         self.colormap_editor.set_colormap(cmap_copy)
 
         is_custom_cmap = cmap_exists(cmap_copy.name, CUSTOM_COLORMAPS)
@@ -287,6 +324,14 @@ def get_colormap(self) -> EditableColormap | None:
         """
         return self.__returned_colormap
 
+    def get_invert(self) -> bool:
+        """Return the current state of the 'Invert colormap' checkbox.
+
+        Returns:
+            True if the colormap should be inverted, False otherwise.
+        """
+        return self.__returned_invert
+
     def __get_new_colormap_name(self, title: str, name: str) -> str | None:
         """Return a new colormap name that does not already exists in the list of
         colormaps.