Update allowed input types for stretch and cuts

Author: mwcraig

src/astro_image_display_api/dummy_viewer.py

@@ -8,6 +8,7 @@
 from astropy.table import Table, vstack
 from astropy.units import Quantity, get_physical_type
 from astropy.wcs import WCS
+from astropy.visualization import BaseInterval, BaseStretch, ManualInterval
 from numpy.typing import ArrayLike
 
 from .interface_definition import ImageViewerInterface
@@ -50,12 +51,12 @@ class ImageViewer:
     _center: tuple[float, float] = (0.0, 0.0)
 
     @property
-    def stretch(self) -> str:
+    def stretch(self) -> BaseStretch:
         return self._stretch
 
     @stretch.setter
-    def stretch(self, value: str) -> None:
-        if value not in self.stretch_options:
+    def stretch(self, value: BaseStretch) -> None:
+        if not isinstance(value, BaseStretch):
             raise ValueError(f"Stretch option {value} is not valid. Must be one of {self.stretch_options}.")
         self._stretch = value
 
@@ -65,16 +66,13 @@ def cuts(self) -> tuple:
 
     @cuts.setter
     def cuts(self, value: tuple) -> None:
-        if isinstance(value, str):
-            if value not in self.autocut_options:
-                raise ValueError(f"Cut option {value} is not valid. Must be one of {self.autocut_options}.")
-            # A real viewer would calculate the cuts based on the data
-            self._cuts = (0, 1)
-            return
-
-        if len(value) != 2:
-            raise ValueError("Cuts must have length 2.")
-        self._cuts = value
+        if isinstance(value, tuple) and len(value) == 2:
+            self._cuts = ManualInterval(value[0], value[1])
+        elif isinstance(value, BaseInterval):
+            self._cuts = value
+        else:
+            raise ValueError("Cuts must be an Astropy.visualization Interval object or a tuple of two values.")
+
 
     @property
     def cursor(self) -> str:

src/astro_image_display_api/interface_definition.py

@@ -6,6 +6,7 @@
 from astropy.nddata import NDData
 from astropy.table import Table
 from astropy.units import Quantity
+from astropy.visualization import BaseInterval, BaseStretch
 
 from numpy.typing import ArrayLike
 
@@ -34,8 +35,8 @@ class ImageViewerInterface(Protocol):
     autocut_options: tuple
     cursor: str
     marker: Any
-    cuts: Any
-    stretch: str
+    cuts: tuple | BaseInterval
+    stretch: BaseStretch
     # viewer: Any
 
     # Allowed locations for cursor display

src/astro_image_display_api/widget_api_test.py

@@ -9,6 +9,7 @@
 from astropy.table import Table, vstack  # noqa: E402
 from astropy import units as u  # noqa: E402
 from astropy.wcs import WCS  # noqa: E402
+from astropy.visualization import AsymmetricPercentileInterval, LogStretch, ManualInterval
 
 __all__ = ['ImageWidgetAPITest']
 
@@ -279,26 +280,27 @@ def test_stretch(self):
         # A bad value should leave the stretch unchanged
         assert self.image.stretch is original_stretch
 
-        self.image.stretch = 'log'
+        self.image.stretch = LogStretch()
         # A valid value should change the stretch
         assert self.image.stretch is not original_stretch
+        assert isinstance(self.image.stretch, LogStretch)
 
     def test_cuts(self, data):
-        with pytest.raises(ValueError, match='[mM]ust be one of'):
+        assert len(self.image.autocut_options) > 0
+        with pytest.raises(ValueError, match='[mM]ust be'):
             self.image.cuts = 'not a valid value'
 
-        with pytest.raises(ValueError, match='must have length 2'):
+        with pytest.raises(ValueError, match='[mM]ust be'):
             self.image.cuts = (1, 10, 100)
 
-        assert 'histogram' in self.image.autocut_options
-
         # Setting using histogram requires data
         self.image.load_image(data)
-        self.image.cuts = 'histogram'
-        assert len(self.image.cuts) == 2
+        self.image.cuts = AsymmetricPercentileInterval(0.1, 99.9)
+        assert isinstance(self.image.cuts, AsymmetricPercentileInterval)
 
         self.image.cuts = (10, 100)
-        assert self.image.cuts == (10, 100)
+        assert isinstance(self.image.cuts, ManualInterval)
+        assert self.image.cuts.get_limits(data) == (10, 100)
 
     @pytest.mark.skip(reason="Not clear whether colormap is part of the API")
     def test_colormap(self):