optimize from_union add docstrings

sandbox/will/basic.css

@@ -15,9 +15,9 @@
   scrollbar-size-vertical: 2;
 }
 
-*:hover {
+/* *:hover {
   tint: red 30%;
-}
+} */
 
 App > Screen {
   layout: dock;

src/textual/_border.py

@@ -186,6 +186,8 @@ class Border:
         if has_bottom and lines:
             lines.pop(-1)
 
+        # TODO: Divide is probably quite inefficient here,
+        # It could be much faster for the specific case of one off the start end end
         divide = Segment.divide
         if has_left and has_right:
             for line in lines:

src/textual/geometry.py

@@ -8,6 +8,7 @@ from __future__ import annotations
 
 import sys
 from functools import lru_cache
+from operator import itemgetter, attrgetter
 from typing import Any, Collection, NamedTuple, Tuple, TypeVar, Union, cast
 
 if sys.version_info >= (3, 10):
@@ -93,7 +94,10 @@ class Offset(NamedTuple):
         """
         x1, y1 = self
         x2, y2 = destination
-        return Offset(int(x1 + (x2 - x1) * factor), int((y1 + (y2 - y1) * factor)))
+        return Offset(
+            int(x1 + (x2 - x1) * factor),
+            int(y1 + (y2 - y1) * factor),
+        )
 
     def get_distance_to(self, other: Offset) -> float:
         """Get the distance to another offset.
@@ -195,7 +199,14 @@ class Region(NamedTuple):
     height: int = 0
 
     @classmethod
-    def from_union(cls, regions: Collection[Region]) -> Region:
+    def from_union(
+        cls,
+        regions: Collection[Region],
+        _get_x=itemgetter(0),
+        _get_y=itemgetter(1),
+        _get_right=attrgetter("right"),
+        _get_bottom=attrgetter("bottom"),
+    ) -> Region:
         """Create a Region from the union of other regions.
 
         Args:
@@ -206,10 +217,10 @@ class Region(NamedTuple):
         """
         if not regions:
             raise ValueError("At least one region expected")
-        min_x = min([region.x for region in regions])
-        max_x = max([x + width for x, _y, width, _height in regions])
-        min_y = min([region.y for region in regions])
-        max_y = max([y + height for _x, y, _width, height in regions])
+        min_x = min(regions, key=_get_x).x
+        max_x = max(regions, key=_get_right).right
+        min_y = min(regions, key=_get_y).y
+        max_y = max(regions, key=_get_bottom).bottom
         return cls(min_x, min_y, max_x - min_x, max_y - min_y)
 
     @classmethod

src/textual/widget.py

@@ -428,14 +428,17 @@ class Widget(DOMNode):
         )
 
     def _set_dirty(self, *regions: Region) -> None:
-        """Set the Widget as 'dirty' (requiring re-render)."""
+        """Set the Widget as 'dirty' (requiring re-paint).
 
-        # self._dirty_regions.clear()
-        # # TODO: Does this need to be content region?
-        # self._dirty_regions.append(self.size.region)
+        Regions should be specified as positional args. If no regions are added, then
+        the entire widget will be considered dirty.
+
+        Args:
+            *regions (Region): Regions which require a repaint.
+
+        """
 
         if regions:
-            content_offset = self.content_offset
             self._dirty_regions.update(regions)
         else:
             self._dirty_regions.clear()
@@ -444,6 +447,11 @@ class Widget(DOMNode):
             self._dirty_regions.add(self.size.region)
 
     def get_dirty_regions(self) -> Collection[Region]:
+        """Get regions which require a repaint.
+
+        Returns:
+            Collection[Region]: Regions to repaint.
+        """
         regions = self._dirty_regions.copy()
         return regions