ui/curses: add colors

pqcli/ui/curses/widgets/focusable.py

@@ -0,0 +1,42 @@
+import contextlib
+import curses
+import typing as T
+
+from pqcli.ui.curses.colors import COLOR_FOCUSED, has_colors
+from pqcli.ui.curses.event_handler import EventHandler
+
+
+@contextlib.contextmanager
+def focus_standout(focused: bool, win: T.Any) -> T.Generator:
+    if focused:
+        if has_colors():
+            win.attron(curses.color_pair(COLOR_FOCUSED))
+        else:
+            win.standout()
+    yield
+    if focused:
+        if has_colors():
+            win.attroff(curses.color_pair(COLOR_FOCUSED))
+        else:
+            win.standend()
+
+
+class Focusable:
+    def __init__(self, *args: T.Any, **kwargs: T.Any) -> None:
+        self._focused = False
+        self._on_focus_change = EventHandler()
+        super().__init__(*args, **kwargs)
+
+    @property
+    def focused(self) -> bool:
+        return self._focused
+
+    @focused.setter
+    def focused(self, focused: bool) -> None:
+        self._focused = focused
+        self._on_focus_change()
+
+    @contextlib.contextmanager
+    def focus_standout(self, win: T.Any) -> T.Generator:
+        with focus_standout(self._focused, win):
+            yield