Merge pull request #5558 from Textualize/smooth-scroll-detect

Smooth scrolling detection

Author: willmcgugan

CHANGELOG.md

@@ -13,11 +13,17 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed height of auto container which contains auto height children https://github.com/Textualize/textual/pull/5552
 - Fixed `Content.from_markup` not stripping control codes https://github.com/Textualize/textual/pull/5557
 - Fixed `delta_x` and `delta_y` in mouse events when smooth scrolling is enabled https://github.com/Textualize/textual/pull/5556
+- Fixed detection of smooth scrolling https://github.com/Textualize/textual/pull/5558
 
 ### Added
 
 - Added `pointer_x`, `pointer_y`, `pointer_screen_x`, and `pointer_screen_y` attributes to mouse events https://github.com/Textualize/textual/pull/5556
 
+### Changed
+
+- Animating the scrollbar while dragging is disabled if smooth scrolling is available https://github.com/Textualize/textual/pull/5558
+- Renamed `TerminalSupportsInBandWindowResize` to `InBandWindowResize` https://github.com/Textualize/textual/pull/5558
+
 ## [2.0.4] - 2025-02-17
 
 ### Fixed

src/textual/_xterm_parser.py

@@ -298,8 +298,10 @@ def send_escape() -> None:
                             and not IS_ITERM
                         ):
                             # TODO: iTerm is buggy in one or more of the protocols required here
-                            in_band_event = messages.TerminalSupportInBandWindowResize.from_setting_parameter(
-                                setting_parameter
+                            in_band_event = (
+                                messages.InBandWindowResize.from_setting_parameter(
+                                    setting_parameter
+                                )
                             )
                             on_token(in_band_event)
                         break

src/textual/app.py

@@ -795,7 +795,7 @@ def __init__(
         self._clipboard: str = ""
         """Contents of local clipboard."""
 
-        self.supports_smooth_scrolling: bool = True
+        self.supports_smooth_scrolling: bool = False
         """Does the terminal support smooth scrolling?"""
 
         if self.ENABLE_COMMAND_PALETTE:
@@ -4647,14 +4647,10 @@ def _on_delivery_failed(self, event: events.DeliveryComplete) -> None:
                 "Failed to save screenshot", title="Screenshot", severity="error"
             )
 
-    @on(messages.TerminalSupportInBandWindowResize)
-    def _on_terminal_supports_in_band_window_resize(
-        self, message: messages.TerminalSupportInBandWindowResize
-    ) -> None:
-        """There isn't much we can do with this information currently, so
-        we will just log it.
-        """
-        self.supports_smooth_scrolling = True
+    @on(messages.InBandWindowResize)
+    def _on_in_band_window_resize(self, message: messages.InBandWindowResize) -> None:
+        """In band window resize enables smooth scrolling."""
+        self.supports_smooth_scrolling = message.enabled
         self.log.debug(message)
 
     def _on_idle(self) -> None:

src/textual/drivers/linux_driver.py

@@ -21,7 +21,7 @@
 from textual.drivers._writer_thread import WriterThread
 from textual.geometry import Size
 from textual.message import Message
-from textual.messages import TerminalSupportInBandWindowResize
+from textual.messages import InBandWindowResize
 
 if TYPE_CHECKING:
     from textual.app import App
@@ -453,7 +453,7 @@ def process_selector_events(
 
     def process_message(self, message: Message) -> None:
         # intercept in-band window resize
-        if isinstance(message, TerminalSupportInBandWindowResize):
+        if isinstance(message, InBandWindowResize):
             if message.supported:
                 self._in_band_window_resize = True
                 if message.enabled:
@@ -462,9 +462,7 @@ def process_message(self, message: Message) -> None:
                 else:
                     # Supported, but not enabled
                     self._enable_in_band_window_resize()
-                    super().process_message(
-                        TerminalSupportInBandWindowResize(True, True)
-                    )
+                    super().process_message(InBandWindowResize(True, True))
                 self._enable_mouse_pixels()
                 return
 

src/textual/messages.py

@@ -100,7 +100,7 @@ class TerminalSupportsSynchronizedOutput(Message):
 
 
 @rich.repr.auto
-class TerminalSupportInBandWindowResize(Message):
+class InBandWindowResize(Message):
     """Reports if the in-band window resize protocol is supported.
 
     https://gist.github.com/rockorager/e695fb2924d36b2bcf1fff4a3704bd83"""
@@ -121,18 +121,16 @@ def __rich_repr__(self) -> rich.repr.Result:
         yield "enabled", self.enabled
 
     @classmethod
-    def from_setting_parameter(
-        cls, setting_parameter: int
-    ) -> TerminalSupportInBandWindowResize:
+    def from_setting_parameter(cls, setting_parameter: int) -> InBandWindowResize:
         """Construct the message from the setting parameter.
 
         Args:
             setting_parameter: Setting parameter from stdin.
 
         Returns:
-            New TerminalSupportInBandWindowResize instance.
+            New InBandWindowResize instance.
         """
 
         supported = setting_parameter not in (0, 4)
         enabled = setting_parameter in (1, 3)
-        return TerminalSupportInBandWindowResize(supported, enabled)
+        return InBandWindowResize(supported, enabled)

src/textual/scrollbar.py

@@ -379,7 +379,9 @@ async def _on_mouse_move(self, event: events.MouseMove) -> None:
                     (event._screen_x - self.grabbed.x)
                     * (virtual_size / self.window_size)
                 )
-            self.post_message(ScrollTo(x=x, y=y))
+            self.post_message(
+                ScrollTo(x=x, y=y, animate=not self.app.supports_smooth_scrolling)
+            )
         event.stop()
 
     async def _on_click(self, event: events.Click) -> None: