Find correct default image for AboutDialog (#1142)

* Add a test that fails because image is not loaded correctly.

* Move AboutDialog trait definitions to mixin class.

This ensures that the Image trait can find the about.png file in pyface/images

* Fix flake8 issues.

pyface/i_about_dialog.py

@@ -13,7 +13,6 @@
 
 from traits.api import HasTraits, List, Str
 
-
 from pyface.i_dialog import IDialog
 from pyface.ui_traits import Image
 
@@ -37,3 +36,16 @@ class MAboutDialog(HasTraits):
     """ The mixin class that contains common code for toolkit specific
     implementations of the IAboutDialog interface.
     """
+
+    #: Additional strings to be added to the dialog.
+    additions = List(Str)
+
+    #: Additional copyright strings to be added above the standard ones.
+    copyrights = List(Str)
+
+    #: The image displayed in the dialog.
+    image = Image()
+
+    def _image_default(self):
+        from .image_resource import ImageResource
+        return ImageResource('about')

pyface/tests/test_about_dialog.py

@@ -8,7 +8,7 @@
 #
 # Thanks for using Enthought open source!
 
-
+import os
 import unittest
 
 from ..about_dialog import AboutDialog
@@ -104,3 +104,16 @@ def test__create_html(self):
         self.assertIn(
             "Copyright &copy; copyright<br />Copyright &copy; copyleft", html
         )
+
+    def test_image_default(self):
+        # test that the default image is found
+        import pyface
+        expected_path = os.path.join(
+            os.path.dirname(pyface.__file__),
+            "images",
+            "about.png",
+        )
+        self.assertEqual(
+            self.dialog.image.absolute_path,
+            expected_path,
+        )

pyface/ui/qt4/about_dialog.py

@@ -12,13 +12,11 @@
 
 import platform
 
-from traits.api import Any, Callable, List, provides, Str, Tuple
+from traits.api import Any, Callable, List, provides, Tuple
 
 from pyface.qt import QtCore, QtGui
 from pyface.i_about_dialog import IAboutDialog, MAboutDialog
-from pyface.ui_traits import Image
 from .dialog import Dialog
-from .image_resource import ImageResource
 
 
 # The HTML displayed in the QLabel.
@@ -60,14 +58,6 @@ class AboutDialog(MAboutDialog, Dialog):
     IAboutDialog interface for the API documentation.
     """
 
-    # 'IAboutDialog' interface ---------------------------------------------
-
-    additions = List(Str)
-
-    copyrights = List(Str)
-
-    image = Image(ImageResource("about"))
-
     # Private interface ---------------------------------------------------#
 
     #: A list of connected Qt signals to be removed before destruction.

pyface/ui/wx/about_dialog.py

@@ -18,12 +18,10 @@
 import wx.html
 import wx.lib.wxpTag
 
-from traits.api import List, provides, Str
+from traits.api import provides
 
 from pyface.i_about_dialog import IAboutDialog, MAboutDialog
-from pyface.ui_traits import Image
 from .dialog import Dialog
-from .image_resource import ImageResource
 
 
 _DIALOG_TEXT = """
@@ -70,14 +68,6 @@ class AboutDialog(MAboutDialog, Dialog):
     IAboutDialog interface for the API documentation.
     """
 
-    # 'IAboutDialog' interface ---------------------------------------------
-
-    additions = List(Str)
-
-    copyrights = List(Str)
-
-    image = Image(ImageResource("about"))
-
     # ------------------------------------------------------------------------
     # Protected 'IDialog' interface.
     # ------------------------------------------------------------------------