Fix contrast panel: clean up histogram when the image is removed from plot

Author: PierreRaybaut

CHANGELOG.md

@@ -1,5 +1,17 @@
 # Changelog #
 
+## Version 2.4.1 ##
+
+In this release, test coverage is 79%.
+
+🛠️ Bug fixes:
+
+* Contrast adjustment panel:
+  * A regression was introduced in V2.0.0: levels histogram was no longer removed from
+    contrast adjustment panel when the associated image was removed from the plot
+  * This is now fixed: when an image is removed, the histogram is removed as well and
+    the contrast panel is refreshed (which was not the case even before the regression)
+
 ## Version 2.4.0 ##
 
 In this release, test coverage is 79%.

plotpy/panels/contrastadjustment.py

@@ -210,14 +210,18 @@ def item_removed(self, item: BaseImageItem) -> None:
         Args:
             item: item which was removed
         """
-        for _plot, items in list(self._tracked_items.items()):
-            if item in items:
+        replot = False
+        for _plot, items_dict in list(self._tracked_items.items()):
+            if item in items_dict:
                 try:
-                    self.del_item(item)
+                    self.del_item(items_dict[item])
+                    replot = True
                 except ValueError:
                     pass  # Histogram has not yet been created
-                items.pop(item)
+                items_dict.pop(item)
                 break
+        if replot:
+            self.replot()
 
     def active_item_changed(self, plot: BasePlot) -> None:
         """Active item changed callback

plotpy/tests/features/test_contrast.py

@@ -15,28 +15,39 @@
 
 from plotpy.builder import make
 from plotpy.tests import get_path
+from plotpy.tests.data import gen_image1
 
 
-def test_contrast():
-    """Test"""
-    # -- Create QApplication
+def __create_dialog_with_contrast(item):
+    """Create plot dialog with contrast panel
+
+    Args:
+        Item: item to be added to the plot
+    """
+    win = make.dialog(
+        edit=False,
+        toolbar=True,
+        wintitle="Contrast test",
+        show_contrast=True,
+        type="image",
+    )
+    plot = win.get_plot()
+    plot.add_item(item)
+    plot.set_active_item(item)
+    item.unselect()
+    win.resize(600, 600)
+    win.show()
+    return win
+
+
+def test_contrast1():
+    """Contrast test 1"""
     with qt_app_context(exec_loop=True):
-        filename = get_path("brain.png")
-        image = make.image(filename=filename, title="Original", colormap="gray")
-        win = make.dialog(
-            edit=False,
-            toolbar=True,
-            wintitle="Contrast test",
-            show_contrast=True,
-            type="image",
-        )
-        plot = win.manager.get_plot()
-        plot.add_item(image)
-        win.resize(600, 600)
-        win.show()
+        item = make.image(filename=get_path("brain.png"), colormap="gray")
+        win = __create_dialog_with_contrast(item)
         fname = "contrast.png"
         try:
-            plot.save_widget(fname)
+            win.get_plot().save_widget(fname)
         except IOError:
             # Skipping this part of the test
             # because user has no write permission on current directory
@@ -45,5 +56,22 @@ def test_contrast():
             os.unlink(fname)
 
 
+def test_contrast2():
+    """Contrast test 2
+
+    Test if level histogram is really removed when the associated image is removed from
+    the plot (the validation is not automatic)
+    """
+    with qt_app_context(exec_loop=True):
+        item1 = make.image(filename=get_path("brain.png"), colormap="gray")
+        win = __create_dialog_with_contrast(item1)
+        plot = win.get_plot()
+        plot.del_item(item1)
+        item2 = make.image(gen_image1())
+        plot.add_item(item2)
+        plot.set_active_item(item2)
+
+
 if __name__ == "__main__":
-    test_contrast()
+    # test_contrast1()
+    test_contrast2()