fix is_transparent

Author: willmcgugan

src/textual/color.py

@@ -209,7 +209,7 @@ def inverse(self) -> Color:
     @property
     def is_transparent(self) -> bool:
         """Is the color transparent (i.e. has 0 alpha)?"""
-        return self.a == 0 and self.ansi is not None
+        return self.a == 0 and self.ansi is None
 
     @property
     def clamped(self) -> Color:

tests/test_color.py

@@ -256,3 +256,12 @@ def test_gradient():
     assert gradient.get_color(1.2) == Color(0, 255, 0)
     assert gradient.get_color(0.5) == Color(0, 0, 255)
     assert gradient.get_color(0.7) == Color(0, 101, 153)
+
+
+def test_is_transparent():
+    """Check is_transparent is reporting correctly."""
+    assert Color(0, 0, 0, 0).is_transparent
+    assert Color(20, 20, 30, 0).is_transparent
+    assert not Color(20, 20, 30, a=0.01).is_transparent
+    assert not Color(20, 20, 30, a=1).is_transparent
+    assert not Color(20, 20, 30, 0, ansi=1).is_transparent