Fix CursorTool issue with LogMapper (#803)

* add regression test

* update cursor_tool.py so test passes

* add a now failing test showing use with LinearMapper

* remove commented out lines

* make new test pass by having LinearMapper match behavior of LogMapper

* fix failing test

* add copyright header

chaco/linear_mapper.py

@@ -59,6 +59,8 @@ def map_screen(self, data_array):
             else:
                 return array([self.low_pos])
         else:
+            if not isinstance(data_array, ndarray):
+                data_array = array(data_array, ndmin=1)
             return (data_array - self.range.low) * self._scale + self.low_pos
 
     def map_data(self, screen_val):

chaco/tools/cursor_tool.py

@@ -200,7 +200,7 @@ def draw(self, gc, view_bounds=None):
         if plot is None:
             return
 
-        sx, sy = plot.map_screen(self.current_position)
+        sx, sy = plot.map_screen(self.current_position)[0]
         orientation = plot.orientation
 
         if orientation == "h" and sx is not None:
@@ -221,7 +221,7 @@ def is_draggable(self, x, y):
         plot = self.component
         if plot is not None:
             orientation = plot.orientation
-            sx, sy = plot.map_screen(self.current_position)
+            sx, sy = plot.map_screen(self.current_position)[0]
             if orientation == "h" and numpy.abs(sx - x) <= self.threshold:
                 return True
             elif orientation == "v" and numpy.abs(sy - y) <= self.threshold:

chaco/tools/tests/test_cursor_tool.py

@@ -0,0 +1,96 @@
+# (C) Copyright 2005-2021 Enthought, Inc., Austin, TX
+# All rights reserved.
+#
+# This software is provided without warranty under the terms of the BSD
+# license included in LICENSE.txt and may be redistributed only under
+# the conditions described in the aforementioned license. The license
+# is also available online at http://www.enthought.com/licenses/BSD.txt
+#
+# Thanks for using Enthought open source!
+import unittest
+
+import numpy as np
+
+from enable.api import ComponentEditor
+from enable.testing import EnableTestAssistant
+from traits.api import HasTraits, Instance
+from traits.etsconfig.api import ETSConfig
+from traitsui.api import Item, View
+from traitsui.testing.api import UITester
+
+from chaco.api import ArrayPlotData, Plot
+from chaco.tools.cursor_tool import CursorTool
+
+
+class TestCursorTool(unittest.TestCase, EnableTestAssistant):
+
+    # regression test for enthought/chaco#289
+    @unittest.skipIf(ETSConfig.toolkit == "null", "Skip on 'null' toolkit")
+    def test_use_with_log_mappers(self):
+        class TestCursor(HasTraits):
+            plot = Instance(Plot)
+
+            traits_view = View(
+                Item('plot', editor=ComponentEditor(), show_label=False),
+                width=500,
+                height=500,
+                resizable=True
+            )
+
+            def _plot_default(self):
+                arr = np.logspace(0, 10, num=10)
+                data = ArrayPlotData(x=arr, y=arr)
+                plot = Plot(data)
+                renderer = plot.plot(
+                    ("x", "y"),
+                    index_scale="log",
+                    value_scale="log"
+                )[0]
+
+                cursor = CursorTool(renderer)
+
+                renderer.overlays.append(cursor)
+
+                return plot
+
+        tester = UITester()
+        test_cursor = TestCursor()
+        with tester.create_ui(test_cursor):
+            # should not fail
+            self.mouse_move(
+                test_cursor.plot, 10, 10
+            )
+
+    @unittest.skipIf(ETSConfig.toolkit == "null", "Skip on 'null' toolkit")
+    def test_use_with_linear_mappers(self):
+        class TestCursor(HasTraits):
+            plot = Instance(Plot)
+
+            traits_view = View(
+                Item('plot', editor=ComponentEditor(), show_label=False),
+                width=500,
+                height=500,
+                resizable=True
+            )
+
+            def _plot_default(self):
+                arr = np.logspace(0, 10, num=10)
+                data = ArrayPlotData(x=arr, y=arr)
+                plot = Plot(data)
+                renderer = plot.plot(
+                    ("x", "y"),
+                )[0]
+
+                cursor = CursorTool(renderer)
+
+                renderer.overlays.append(cursor)
+
+                return plot
+
+        tester = UITester()
+        test_cursor = TestCursor()
+        with tester.create_ui(test_cursor):
+            # should not fail
+            self.mouse_move(
+                test_cursor.plot, 10, 10
+            )