Fix setting contrast limits when the histogram widget is open (#309)

* Pass a list to line.set_xdata rather than a float

* Add test for changing contrast limits with histogram open

* Update changelog

Author: p-j-smith

docs/changelog.rst

@@ -1,7 +1,13 @@
 Changelog
 =========
 
-2.1.0
+3.0.1
+-----
+Bug fixes
+~~~~~~~~~
+- Fix an error that happened when changing the contrast limit when the histogram widget was open
+
+3.0.0
 -----
 New features
 ~~~~~~~~~~~~

src/napari_matplotlib/histogram.py

@@ -115,7 +115,7 @@ def _update_contrast_lims(self) -> None:
         for lim, line in zip(
             self.layers[0].contrast_limits, self._contrast_lines, strict=False
         ):
-            line.set_xdata(lim)
+            line.set_xdata([lim])
 
         self.figure.canvas.draw()
 

src/napari_matplotlib/tests/test_histogram.py

@@ -152,3 +152,15 @@ def test_change_layer(make_napari_viewer, brain_data, astronaut_data):
     viewer.layers.selection.clear()
     viewer.layers.selection.add(viewer.layers[1])
     assert_figures_not_equal(widget.figure, fig1)
+
+
+def test_change_contrast(make_napari_viewer, astronaut_data):
+    viewer = make_napari_viewer()
+    viewer.add_image(astronaut_data[0], **astronaut_data[1])
+
+    widget = HistogramWidget(viewer)
+    viewer.window.add_dock_widget(widget)
+
+    # update contrast limits of image layer, and check no errors are thrown
+    image_layer = viewer.layers[0]
+    image_layer.contrast_limits = [2, 50]