Move DataTable cursor with page up/down, home, end (#2228)

* Add pageup and pagedown actions to DataTable, with no impls

* Pagedown moves DataTable cursor now

* Account for header height in pagedown action

* Page Up support in the DataTable

* Fix and off-by-1, ensure page up/down works on col cursor

* Add placeholder scroll home/end action handlers to datatable

* Add scroll home and scroll end

* Hide hover cursor when home or end is used

* Ensure home and end work correctly with all curosrs

* Testing home/end/pagedown/pageup cursor movement in DataTable

* Docstrings for new datatable actions

* Fix a broken unit test for the DataTable

Author: darrenburns

src/textual/widgets/_data_table.py

@@ -203,6 +203,8 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
         Binding("down", "cursor_down", "Cursor Down", show=False),
         Binding("right", "cursor_right", "Cursor Right", show=False),
         Binding("left", "cursor_left", "Cursor Left", show=False),
+        Binding("pageup", "page_up", "Page Up", show=False),
+        Binding("pagedown", "page_down", "Page Down", show=False),
     ]
     """
     | Key(s) | Description |
@@ -247,7 +249,7 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
         background: $surface ;
         color: $text;
         height: auto;
-        max-height: 100vh
+        max-height: 100vh;
     }
     DataTable > .datatable--header {
         text-style: bold;
@@ -1976,6 +1978,76 @@ def on_click(self, event: events.Click) -> None:
             self._scroll_cursor_into_view(animate=True)
             event.stop()
 
+    def action_page_down(self) -> None:
+        """Move the cursor one page down."""
+        self._set_hover_cursor(False)
+        cursor_type = self.cursor_type
+        if self.show_cursor and (cursor_type == "cell" or cursor_type == "row"):
+            height = self.size.height - self.header_height if self.show_header else 0
+
+            # Determine how many rows constitutes a "page"
+            offset = 0
+            rows_to_scroll = 0
+            row_index, column_index = self.cursor_coordinate
+            for ordered_row in self.ordered_rows[row_index:]:
+                offset += ordered_row.height
+                if offset > height:
+                    break
+                rows_to_scroll += 1
+
+            self.cursor_coordinate = Coordinate(
+                row_index + rows_to_scroll - 1, column_index
+            )
+            self._scroll_cursor_into_view()
+        else:
+            super().action_page_down()
+
+    def action_page_up(self) -> None:
+        """Move the cursor one page up."""
+        self._set_hover_cursor(False)
+        cursor_type = self.cursor_type
+        if self.show_cursor and (cursor_type == "cell" or cursor_type == "row"):
+            height = self.size.height - self.header_height if self.show_header else 0
+
+            # Determine how many rows constitutes a "page"
+            offset = 0
+            rows_to_scroll = 0
+            row_index, column_index = self.cursor_coordinate
+            for ordered_row in self.ordered_rows[: row_index + 1]:
+                offset += ordered_row.height
+                if offset > height:
+                    break
+                rows_to_scroll += 1
+
+            self.cursor_coordinate = Coordinate(
+                row_index - rows_to_scroll + 1, column_index
+            )
+            self._scroll_cursor_into_view()
+        else:
+            super().action_page_up()
+
+    def action_scroll_home(self) -> None:
+        """Scroll to the top of the data table."""
+        self._set_hover_cursor(False)
+        cursor_type = self.cursor_type
+        if self.show_cursor and (cursor_type == "cell" or cursor_type == "row"):
+            row_index, column_index = self.cursor_coordinate
+            self.cursor_coordinate = Coordinate(0, column_index)
+            self._scroll_cursor_into_view()
+        else:
+            super().action_scroll_home()
+
+    def action_scroll_end(self) -> None:
+        """Scroll to the bottom of the data table."""
+        self._set_hover_cursor(False)
+        cursor_type = self.cursor_type
+        if self.show_cursor and (cursor_type == "cell" or cursor_type == "row"):
+            row_index, column_index = self.cursor_coordinate
+            self.cursor_coordinate = Coordinate(self.row_count - 1, column_index)
+            self._scroll_cursor_into_view()
+        else:
+            super().action_scroll_end()
+
     def action_cursor_up(self) -> None:
         self._set_hover_cursor(False)
         cursor_type = self.cursor_type

tests/test_data_table.py

@@ -167,10 +167,36 @@ async def test_datatable_message_emission():
 async def test_empty_table_interactions():
     app = DataTableApp()
     async with app.run_test() as pilot:
-        await pilot.press("enter", "up", "down", "left", "right")
+        await pilot.press(
+            "enter", "up", "down", "left", "right", "home", "end", "pagedown", "pageup"
+        )
         assert app.message_names == []
 
 
+async def test_cursor_movement_with_home_pagedown_etc():
+    app = DataTableApp()
+
+    async with app.run_test() as pilot:
+        table = app.query_one(DataTable)
+        table.add_columns("A", "B")
+        table.add_rows(ROWS)
+        await pilot.press("right", "pagedown")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(2, 1)
+
+        await pilot.press("pageup")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(0, 1)
+
+        await pilot.press("end")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(2, 1)
+
+        await pilot.press("home")
+        await pilot.pause()
+        assert table.cursor_coordinate == Coordinate(0, 1)
+
+
 async def test_add_rows():
     app = DataTableApp()
     async with app.run_test():