added constant

Author: willmcgugan

CHANGELOG.md

@@ -45,6 +45,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - OptionList no longer supports `Separator`, a separator may be specified with `None`
+- Implemented smooth (pixel perfect) scrolling on supported terminals. Set `TEXTUAL_SMOOTH_SCROLL=0` to disable. 
 
 ### Removed
 

src/textual/_xterm_parser.py

@@ -287,7 +287,12 @@ def send_escape() -> None:
                         setting_parameter = int(mode_report_match["setting_parameter"])
                         if mode_id == "2026" and setting_parameter > 0:
                             on_token(messages.TerminalSupportsSynchronizedOutput())
-                        elif mode_id == "2048" and not IS_ITERM:
+                        elif (
+                            mode_id == "2048"
+                            and constants.SMOOTH_SCROLL
+                            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
                             )

src/textual/constants.py

@@ -157,3 +157,7 @@ def _get_textual_animations() -> AnimationLevel:
 """Textual theme to make default. More than one theme may be specified in a comma separated list.
 Textual will use the first theme that exists.
 """
+
+SMOOTH_SCROLL: Final[bool] = _get_environ_int("TEXTUAL_SMOOTH_SCROLL", 1) == 1
+"""Should smooth scrolling be enabled? set `TEXTUAL_SMOOTH_SCROLL=0` to disable smooth scrolling.
+"""

src/textual/drivers/linux_driver.py

@@ -136,6 +136,7 @@ def _enable_mouse_support(self) -> None:
         #       extensions.
 
     def _enable_mouse_pixels(self) -> None:
+        """Enable mouse reporting as pixels."""
         if not self._mouse:
             return
         self.write("\x1b[?1016h")

src/textual/events.py

@@ -399,26 +399,32 @@ def __init__(
 
     @property
     def x(self) -> int:
+        """The relative X coordinate."""
         return int(self._x)
 
     @property
     def y(self) -> int:
+        """The relative Y coordinate."""
         return int(self._y)
 
     @property
     def delta_x(self) -> int:
+        """Change in `x` since last message."""
         return int(self._delta_x)
 
     @property
     def delta_y(self) -> int:
+        """Change in `y` since the last message."""
         return int(self._delta_y)
 
     @property
     def screen_x(self) -> int:
+        """X coordinate relative to top left of screen."""
         return int(self._screen_x)
 
     @property
     def screen_y(self) -> int:
+        """Y coordinate relative to top left of screen."""
         return int(self._screen_y)
 
     @classmethod

src/textual/scrollbar.py

@@ -379,7 +379,6 @@ async def _on_mouse_move(self, event: events.MouseMove) -> None:
                     (event._screen_x - self.grabbed.x)
                     * (virtual_size / self.window_size)
                 )
-            print(event)
             self.post_message(ScrollTo(x=x, y=y))
         event.stop()