Merge pull request matplotlib#26500 from Tsufael/add-qt-interpolation_stage-selector-for-images

closes matplotlib#26477 ENH: Add interpolation_stage in qt figureoptions

Author: timhoffm

lib/matplotlib/backends/qt_editor/figureoptions.py

@@ -164,6 +164,12 @@ def prepare_data(d, init):
             mappabledata.append((
                 'Interpolation',
                 [mappable.get_interpolation(), *interpolations]))
+
+            interpolation_stages = ['data', 'rgba']
+            mappabledata.append((
+                'Interpolation stage',
+                [mappable.get_interpolation_stage(), *interpolation_stages]))
+
         mappables.append([mappabledata, label, ""])
     # Is there a scalarmappable displayed?
     has_sm = bool(mappables)
@@ -227,9 +233,11 @@ def apply_callback(data):
         # Set ScalarMappables.
         for index, mappable_settings in enumerate(mappables):
             mappable = labeled_mappables[index][1]
-            if len(mappable_settings) == 5:
-                label, cmap, low, high, interpolation = mappable_settings
+            if len(mappable_settings) == 6:
+                label, cmap, low, high, interpolation, interpolation_stage = \
+                  mappable_settings
                 mappable.set_interpolation(interpolation)
+                mappable.set_interpolation_stage(interpolation_stage)
             elif len(mappable_settings) == 4:
                 label, cmap, low, high = mappable_settings
             mappable.set_label(label)

lib/matplotlib/image.py

@@ -773,6 +773,14 @@ def set_interpolation(self, s):
         self._interpolation = s
         self.stale = True
 
+    def get_interpolation_stage(self):
+        """
+        Return when interpolation happens during the transform to RGBA.
+
+        One of 'data', 'rgba'.
+        """
+        return self._interpolation_stage
+
     def set_interpolation_stage(self, s):
         """
         Set when interpolation happens during the transform to RGBA.

lib/matplotlib/image.pyi

@@ -89,6 +89,7 @@ class _ImageBase(martist.Artist, cm.ScalarMappable):
     def get_shape(self) -> tuple[int, int, int]: ...
     def get_interpolation(self) -> str: ...
     def set_interpolation(self, s: str | None) -> None: ...
+    def get_interpolation_stage(self) -> Literal["data", "rgba"]: ...
     def set_interpolation_stage(self, s: Literal["data", "rgba"]) -> None: ...
     def can_composite(self) -> bool: ...
     def set_resample(self, v: bool | None) -> None: ...