New, more modern KivaFont trait (#929)

* Add a new font-editor that uses Enable to draw fonts

This font editor is laregly toolkit independent - it embeds a Window with a
Label component to display the font and the simple editor uses the Pyface
font dialog to get new font values.

Some functionality is broken out into experimental base classes for building
editors with components.

* New more modern KivaFont trait

This creates a KivaFont TraitType, which is:
- in enable, rather than Kiva, meaning Kiva can potentially not need traits
- has a better font parser that supports more weight types
- the font parser can be swapped out for something better easily
- uses the new KivaFontEditor, which is available for Qt
- converts Pyface Fonts to Kiva Fonts

* Fix long line.

* Save all files before finishing merge!

* Fix tests.

* Apply suggestions from code review

Co-authored-by: Mark Dickinson <mdickinson@enthought.com>

* Handle color editor tests for null backend.

* Fixes from PR review.

* Some more small fixes coming from PR discussion.

Co-authored-by: Mark Dickinson <mdickinson@enthought.com>

docs/source/enable/traits.rst

@@ -18,8 +18,9 @@ the form of an HTML color name ("blue" or "#0000FF").
 
 font_trait
 ----------
-:class:`~.font_trait` is a synonym for :class:`kiva.trait_defs.api.KivaFont`.
-The trait maps a font-description string to a valid :class:`kiva.fonttools.Font`
+:class:`~.font_trait` is a synonym for
+:class:`enable.trait_defs.kiva_font_trait.KivaFont`. The trait maps a
+font-description string to a valid :class:`kiva.fonttools.Font`
 instance which can be passed to :py:meth:`AbstractGraphicsContext.set_font`
 
 LineStyle

docs/source/kiva/drawing_details.rst

@@ -280,17 +280,17 @@ The ``KivaFont`` trait and ``set_font``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 If you're already doing your drawing within an application using traits, you can
-use the :class:`~kiva.trait_defs.kiva_font_trait.KivaFont` trait.
+use the :class:`~enable.trait_defs.kiva_font_trait.KivaFont` trait.
 
-:class:`~kiva.trait_defs.kiva_font_trait.KivaFont` traits are initialized with
+:class:`~enable.trait_defs.kiva_font_trait.KivaFont` traits are initialized with
 a string which describes the font: "Times Italic 18", "Courier Bold 10", etc.
 The *value* of the trait is a :class:`~kiva.fonttools.font.Font` instance which
 can be passed to the :py:meth:`~.AbstractGraphicsContext.set_font` method.
 
 *Supported backends*: all backends
 
 .. note::
-    The :class:`~kiva.trait_defs.kiva_font_trait.KivaFont` parser is very
+    The :class:`~enable.trait_defs.kiva_font_trait.KivaFont` parser is very
     simplistic and special-cases some words.  For example "roman" means a
     generic serif-style font family, so for example a face name of "Times New
     Roman" will not resolve as expected.  In these cases, use a

enable/drawing/drawing_canvas.py

@@ -9,7 +9,7 @@
 # Thanks for using Enthought open source!
 from enable.api import Container, Component, ColorTrait
 from kiva.api import FILL, FILL_STROKE
-from kiva.trait_defs.api import KivaFont
+from enable.trait_defs.kiva_font_trait import KivaFont
 from traits.api import Any, Bool, Delegate, Enum, Instance, Int, List, Str
 
 

enable/enable_traits.py

@@ -15,7 +15,7 @@
 from numpy import array, ndarray
 
 # Enthought library imports
-from kiva.trait_defs.api import KivaFont
+from enable.trait_defs.kiva_font_trait import KivaFont
 from traits.api import (
     BaseFloat, List, Map, PrefixList, PrefixMap, Range, TraitType, Union,
 )

enable/examples/demo/enable/container_demo.py

@@ -13,7 +13,7 @@
 from enable.api import ColorTrait
 from enable.examples._example_support import DemoFrame, demo_main
 from enable.tools.api import DragTool
-from kiva.trait_defs.api import KivaFont
+from enable.trait_defs.api import KivaFont
 
 
 class Region(PlotComponent, DragTool):

enable/examples/demo/enable/editors/font_editor.py

@@ -10,7 +10,7 @@
 from traits.api import HasStrictTraits
 from traitsui.api import View, Item
 
-from enable.api import Container, TextField, font_trait
+from enable.trait_defs.api import KivaFont
 from enable.trait_defs.ui.api import KivaFontEditor
 from enable.examples._example_support import demo_main
 
@@ -26,14 +26,19 @@
 class Demo(HasStrictTraits):
     """ An example which shows the KivaFontEditor's variations. """
 
-    font = font_trait(Font("Times", 24, SWISS, WEIGHT_BOLD, ITALIC))
+    font = KivaFont(Font("Times", 24, SWISS, WEIGHT_BOLD, ITALIC))
 
     view = View(
-        Item('font', editor=KivaFontEditor(), style='simple', label="Simple"),
-        Item('font', editor=KivaFontEditor(), style='custom', label="Custom"),
-        Item('font', editor=KivaFontEditor(), style='text', label="Text"),
-        Item('font', editor=KivaFontEditor(), style='readonly', label="Readonly"),
-        Item('font', editor=KivaFontEditor(sample_text=sample_text), style='readonly', label="sample text"),
+        Item('font', style='simple', label="Simple"),
+        Item('font', style='custom', label="Custom"),
+        Item('font', style='text', label="Text"),
+        Item('font', style='readonly', label="Readonly"),
+        Item(
+            'font',
+            editor=KivaFontEditor(sample_text=sample_text),
+            style='readonly',
+            label="sample text",
+        ),
         resizable=True,
         width=size[0],
         height=size[1],

enable/gadgets/vu_meter.py

@@ -11,7 +11,7 @@
 
 from traits.api import Float, Property, List, Str, Range
 from enable.api import Component
-from kiva.trait_defs.api import KivaFont
+from enable.trait_defs.kiva_font_trait import KivaFont
 from kiva import affine
 
 

enable/label.py

@@ -16,7 +16,7 @@
 
 # Enthought library imports
 from kiva.api import FILL, STROKE
-from kiva.trait_defs.api import KivaFont
+from enable.trait_defs.kiva_font_trait import KivaFont
 from traits.api import Bool, Enum, Float, HasTraits, Int, List, Str, observe
 
 # Local, relative imports

enable/tests/trait_defs/test_kiva_font_editor.py

@@ -69,7 +69,8 @@ def test_readonly_default_view(self):
 
             self.assertIs(editor.value, new_font)
             self.assertIs(component.font, new_font)
-            self.assertEqual(editor.str_value, "24 point Helvetica Bold Italic")
+            self.assertEqual(
+                editor.str_value, "24 point Helvetica Bold Italic")
             self.assertEqual(component.text, "24 point Helvetica Bold Italic")
         finally:
             ui.dispose()
@@ -120,7 +121,8 @@ def test_simple_default_object_change(self):
             self.assertIs(editor.value, new_font)
             self.assertIs(editor.font, new_font)
             self.assertIs(component.font, new_font)
-            self.assertEqual(editor.str_value, "24 point Helvetica Bold Italic")
+            self.assertEqual(
+                editor.str_value, "24 point Helvetica Bold Italic")
             self.assertEqual(component.text, "24 point Helvetica Bold Italic")
         finally:
             ui.dispose()
@@ -151,7 +153,8 @@ def test_simple_default_editor_change(self):
             self.assertIs(editor.value, new_font)
             self.assertIs(editor.font, new_font)
             self.assertIs(component.font, new_font)
-            self.assertEqual(editor.str_value, "24 point Helvetica Bold Italic")
+            self.assertEqual(
+                editor.str_value, "24 point Helvetica Bold Italic")
             self.assertEqual(component.text, "24 point Helvetica Bold Italic")
         finally:
             ui.dispose()

enable/tests/trait_defs/test_kiva_font_trait.py

@@ -0,0 +1,97 @@
+# (C) Copyright 2008-2022 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
+
+from kiva import constants
+from kiva.fonttools.font import Font, FAMILIES, WEIGHTS, STYLES
+from pyface.font import Font as PyfaceFont
+from traits.api import HasTraits, TraitError
+
+from enable.trait_defs.kiva_font_trait import KivaFont
+
+
+class FontExample(HasTraits):
+
+    font = KivaFont()
+
+
+class TestKivaFont(unittest.TestCase):
+
+    def test_validate_str(self):
+        expected_outcomes = {}
+        expected_outcomes[""] = Font(size=10, family=constants.DEFAULT)
+
+        for weight, kiva_weight in WEIGHTS.items():
+            expected_outcomes[weight] = Font(
+                weight=kiva_weight, size=10, family=constants.DEFAULT)
+
+        for style, kiva_style in STYLES.items():
+            expected_outcomes[style] = Font(
+                style=kiva_style, size=10, family=constants.DEFAULT)
+
+        expected_outcomes["underline"] = Font(
+            underline=True, size=10, family=constants.DEFAULT)
+
+        expected_outcomes["18"] = Font(size=18, family=constants.DEFAULT)
+        expected_outcomes["18 pt"] = Font(size=18, family=constants.DEFAULT)
+        expected_outcomes["18 point"] = Font(size=18, family=constants.DEFAULT)
+
+        for family, kiva_family in FAMILIES.items():
+            expected_outcomes[family] = Font(family=kiva_family, size=10)
+
+        expected_outcomes["Courier"] = Font(
+            "Courier", size=10, family=constants.DEFAULT)
+        expected_outcomes["Comic Sans"] = Font(
+            "Comic Sans", size=10, family=constants.DEFAULT)
+        expected_outcomes["18 pt Bold Italic Underline Comic Sans script"] = Font(  # noqa: E501
+            "Comic Sans", 18, constants.SCRIPT, weight=constants.WEIGHT_BOLD,
+            style=constants.ITALIC, underline=True,
+        )
+
+        for name, expected in expected_outcomes.items():
+            with self.subTest(name=name):
+                example = FontExample(font=name)
+                result = example.font
+
+                # test we get expected font
+                self.assertIsInstance(result, Font)
+                self.assertEqual(result, expected)
+
+    def test_validate_font(self):
+        font = Font("Comic Sans", 18)
+        example = FontExample(font=font)
+
+        result = example.font
+
+        # test we get expected font
+        self.assertIsInstance(result, Font)
+        self.assertIs(result, font)
+
+    def test_validate_pyface_font(self):
+        font = Font("Comic Sans", 18, constants.DEFAULT)
+        pyface_font = PyfaceFont(family=["Comic Sans"], size=18)
+        example = FontExample(font=pyface_font)
+
+        result = example.font
+
+        # test we get expected font
+        self.assertIsInstance(result, Font)
+        self.assertEqual(result, font)
+
+    def test_font_trait_default(self):
+        example = FontExample()
+
+        self.assertIsInstance(example.font, Font)
+        self.assertEqual(example.font, Font(size=12, family=constants.SWISS))
+
+    def test_font_trait_none(self):
+        with self.assertRaises(TraitError):
+            FontExample(font=None)