Avoid flicker when starting kittens such as the hints kitten

Fixes #4674

kittens/hints/main.py

@@ -159,6 +159,7 @@ class Hints(Handler):
     def initialize(self) -> None:
         self.init_terminal_state()
         self.draw_screen()
+        self.cmd.overlay_ready()
 
     def on_text(self, text: str, in_bracketed_paste: bool = False) -> None:
         changed = False
@@ -752,7 +753,7 @@ def linenum_handle_result(args: List[str], data: Dict[str, Any], target_window_i
             }[action])(*cmd)
 
 
-@result_handler(type_of_input='screen-ansi')
+@result_handler(type_of_input='screen-ansi', has_ready_notification=True)
 def handle_result(args: List[str], data: Dict[str, Any], target_window_id: int, boss: BossType) -> None:
     if data['customize_processing']:
         m = load_custom_processor(data['customize_processing'])

kittens/runner.py

@@ -69,6 +69,7 @@ def create_kitten_handler(kitten: str, orig_args: List[str]) -> Any:
     ans = partial(m['end'], [kitten] + orig_args)
     setattr(ans, 'type_of_input', getattr(m['end'], 'type_of_input', None))
     setattr(ans, 'no_ui', getattr(m['end'], 'no_ui', False))
+    setattr(ans, 'has_ready_notification', getattr(m['end'], 'has_ready_notification', False))
     return ans
 
 

kittens/tui/handler.py

@@ -206,18 +206,23 @@ class HandleResult:
     type_of_input: Optional[str] = None
     no_ui: bool = False
 
-    def __init__(self, impl: Callable[..., Any], type_of_input: Optional[str], no_ui: bool):
+    def __init__(self, impl: Callable[..., Any], type_of_input: Optional[str], no_ui: bool, has_ready_notification: bool):
         self.impl = impl
         self.no_ui = no_ui
         self.type_of_input = type_of_input
+        self.has_ready_notification = has_ready_notification
 
     def __call__(self, args: Sequence[str], data: Any, target_window_id: int, boss: BossType) -> Any:
         return self.impl(args, data, target_window_id, boss)
 
 
-def result_handler(type_of_input: Optional[str] = None, no_ui: bool = False) -> Callable[[Callable[..., Any]], HandleResult]:
+def result_handler(
+    type_of_input: Optional[str] = None,
+    no_ui: bool = False,
+    has_ready_notification: bool = False
+) -> Callable[[Callable[..., Any]], HandleResult]:
 
     def wrapper(impl: Callable[..., Any]) -> HandleResult:
-        return HandleResult(impl, type_of_input, no_ui)
+        return HandleResult(impl, type_of_input, no_ui, has_ready_notification)
 
     return wrapper

kittens/tui/operations.py

@@ -413,6 +413,11 @@ def restore_colors() -> str:
     return '\x1b[#Q'
 
 
+@cmd
+def overlay_ready() -> str:
+    return '\x1bP@kitty-overlay-ready|\x1b\\'
+
+
 @cmd
 def write_to_clipboard(data: Union[str, bytes], use_primary: bool = False) -> str:
     from base64 import standard_b64encode

kittens/unicode_input/main.py

@@ -377,6 +377,7 @@ class UnicodeInput(Handler):
     def initialize(self) -> None:
         self.init_terminal_state()
         self.draw_screen()
+        self.cmd.overlay_ready()
 
     def draw_title_bar(self) -> None:
         entries = []
@@ -585,7 +586,7 @@ def main(args: List[str]) -> Optional[str]:
     return None
 
 
-@result_handler()
+@result_handler(has_ready_notification=True)
 def handle_result(args: List[str], current_char: str, target_window_id: int, boss: BossType) -> None:
     w = boss.window_id_map.get(target_window_id)
     if w is not None: