fix for selecting cells

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 
 - Fixed type hint aliasing for App under TYPE_CHECKING https://github.com/Textualize/textual/pull/6152
+- Fixed for text selection with double width characters https://github.com/Textualize/textual/pull/6186
 
 ### Changed
 

src/textual/_compositor.py

@@ -927,8 +927,10 @@ def get_widget_and_offset_at(
         offset_x = 0
         offset_x2 = 0
 
+        from rich.cells import get_character_cell_size
+
         for segment in line:
-            end += len(segment.text)
+            end += segment.cell_length
             style = segment.style
             if style is not None and style._meta is not None:
                 meta = style.meta
@@ -937,11 +939,14 @@ def get_widget_and_offset_at(
                     offset_x2 = offset_x + len(segment.text)
 
                     if x < end and x >= start:
-                        if x == end - 1:
-                            segment_offset = len(segment.text)
-                        else:
-                            first, _ = segment.split_cells(x - start)
-                            segment_offset = len(first.text)
+                        segment_cell_length = 0
+                        cell_cut = x - start
+                        segment_offset = 0
+                        for character in segment.text:
+                            if segment_cell_length >= cell_cut:
+                                break
+                            segment_cell_length += get_character_cell_size(character)
+                            segment_offset += 1
                         return widget, (
                             None
                             if offset_y is None

src/textual/screen.py

@@ -1652,14 +1652,22 @@ def _forward_event(self, event: events.Event) -> None:
                 ):
                     end_widget = self._select_end[0]
                     select_offset = end_widget.content_region.bottom_right_inclusive
-                    self._select_end = (end_widget, event.offset, select_offset)
+                    self._select_end = (
+                        end_widget,
+                        event.screen_offset,
+                        select_offset,
+                    )
 
                 elif (
                     select_widget is not None
                     and select_widget.allow_select
                     and select_offset is not None
                 ):
-                    self._select_end = (select_widget, event.offset, select_offset)
+                    self._select_end = (
+                        select_widget,
+                        event.screen_offset,
+                        select_offset,
+                    )
 
         elif isinstance(event, events.MouseEvent):
             if isinstance(event, events.MouseUp):
@@ -1730,7 +1738,6 @@ def _watch__select_end(
         Args:
             select_end: The end selection.
         """
-
         if select_end is None or self._select_start is None:
             # Nothing to select
             return

src/textual/selection.py

@@ -56,12 +56,12 @@ def extract(self, text: str) -> str:
             return lines[start_line][start_offset:end_offset]
 
         selection: list[str] = []
-        selected_lines = lines[start_line:end_line]
+        selected_lines = lines[start_line : end_line + 1]
         if len(selected_lines) >= 2:
             first_line, *mid_lines, last_line = selected_lines
             selection.append(first_line[start_offset:])
             selection.extend(mid_lines)
-            selection.append(last_line[: end_offset + 1])
+            selection.append(last_line[:end_offset])
         else:
             return lines[start_line][start_offset:end_offset]
         return "\n".join(selection)

tests/test_selection.py

@@ -1,7 +1,9 @@
 import pytest
 
+from textual.app import App, ComposeResult
 from textual.geometry import Offset
 from textual.selection import Selection
+from textual.widgets import Static
 
 
 @pytest.mark.parametrize(
@@ -20,3 +22,24 @@
 def test_extract(text: str, selection: Selection, expected: str) -> None:
     """Test Selection.extract"""
     assert selection.extract(text) == expected
+
+
+async def test_double_width():
+    """Test that selection works with double width characters."""
+
+    TEXT = """😂❤️👍Select😊🙏😍\nme🔥💯😭😂❤️👍"""
+
+    class TextSelectApp(App):
+        def compose(self) -> ComposeResult:
+            yield Static(TEXT)
+
+    app = TextSelectApp()
+    async with app.run_test() as pilot:
+        await pilot.pause()
+        assert await pilot.mouse_down(offset=(2, 0))
+        await pilot.pause()
+        assert await pilot.mouse_up(offset=(7, 1))
+        selected_text = app.screen.get_selected_text()
+        expected = "❤️👍Select😊🙏😍\nme🔥💯😭"
+
+    assert selected_text == expected