buttons: Add a generic Button class

This Button is like a Gtk.Button, except it provides ways to set the
icon-size. I also default to large buttons, since that'll be a good
portion of the users.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

emmental/buttons.py

@@ -4,6 +4,27 @@ from gi.repository import GObject
 from gi.repository import Gtk
 
 
+class Button(Gtk.Button):
+    """A Gtk.Button with extra properties and default large size."""
+
+    icon_name = GObject.Property(type=str)
+    icon_size = GObject.Property(type=Gtk.IconSize,
+                                 default=Gtk.IconSize.NORMAL)
+    icon_opacity = GObject.Property(type=float, default=1.0,
+                                    minimum=0.0, maximum=1.0)
+
+    def __init__(self, **kwargs):
+        """Initialize a Button."""
+        super().__init__(focusable=False, **kwargs)
+        self._image = Gtk.Image(icon_name=self.icon_name,
+                                icon_size=self.icon_size,
+                                opacity=self.icon_opacity)
+        self.bind_property("icon-name", self._image, "icon-name")
+        self.bind_property("icon-size", self._image, "icon-size")
+        self.bind_property("icon-opacity", self._image, "opacity")
+        self.set_child(self._image)
+
+
 class PopoverButton(Gtk.MenuButton):
     """A MenuButton with a Gtk.Popover attached."""
 

tests/test_buttons.py

@@ -5,6 +5,53 @@ import emmental.buttons
 from gi.repository import Gtk
 
 
+class TestButton(unittest.TestCase):
+    """Test a Button."""
+
+    def setUp(self):
+        """Set up common variables."""
+        self.button = emmental.buttons.Button()
+
+    def test_init(self):
+        """Test that the button is configured correctly."""
+        self.assertIsInstance(self.button, Gtk.Button)
+        self.assertIsInstance(self.button._image, Gtk.Image)
+        self.assertEqual(self.button.get_child(), self.button._image)
+        self.assertFalse(self.button.get_focusable())
+
+    def test_icon_name(self):
+        """Test the icon-name property."""
+        self.assertEqual(self.button.icon_name, "")
+        self.button.icon_name = "icon-name"
+        self.assertEqual(self.button._image.get_icon_name(), "icon-name")
+
+        button2 = emmental.buttons.Button(icon_name="icon-name")
+        self.assertEqual(button2.icon_name, "icon-name")
+        self.assertEqual(button2._image.get_icon_name(), "icon-name")
+
+    def test_icon_size(self):
+        """Test the icon-size property."""
+        self.assertEqual(self.button.icon_size, Gtk.IconSize.NORMAL)
+        self.button.icon_size = Gtk.IconSize.LARGE
+        self.assertEqual(self.button._image.get_icon_size(),
+                         Gtk.IconSize.LARGE)
+
+        button2 = emmental.buttons.Button(icon_size=Gtk.IconSize.LARGE)
+        self.assertEqual(button2.icon_size, Gtk.IconSize.LARGE)
+        self.assertEqual(button2._image.get_icon_size(), Gtk.IconSize.LARGE)
+
+    def test_icon_opacity(self):
+        """Test the icon-opacity property."""
+        self.assertEqual(self.button.icon_opacity, 1.0)
+        self.button.icon_opacity = 0.5
+        self.assertAlmostEqual(self.button._image.get_opacity(),
+                               0.5, delta=0.005)
+
+        button2 = emmental.buttons.Button(icon_opacity=0.25)
+        self.assertAlmostEqual(button2.icon_opacity, 0.25, delta=0.005)
+        self.assertAlmostEqual(button2._image.get_opacity(), 0.25, delta=0.005)
+
+
 class TestPopoverButton(unittest.TestCase):
     """Test a Popover Button."""