added node expanding

src/textual/widgets/_tree.py

@@ -15,7 +15,7 @@ from ..geometry import clamp, Region, Size
 from .._loop import loop_last
 from .._cache import LRUCache
 from ..message import Message
-from ..reactive import reactive
+from ..reactive import reactive, var
 from .._segment_tools import line_crop, line_pad
 from .._types import MessageTarget
 from .._typing import TypeAlias
@@ -47,7 +47,7 @@ class _TreeLine:
 class TreeNode(Generic[TreeDataType]):
     def __init__(
         self,
-        tree: Tree,
+        tree: Tree[TreeDataType],
         parent: TreeNode[TreeDataType] | None,
         id: NodeID,
         label: Text,
@@ -60,7 +60,7 @@ class TreeNode(Generic[TreeDataType]):
         self.id = id
         self.label = label
         self.data: TreeDataType = data
-        self.expanded = expanded
+        self._expanded = expanded
         self.children: list[TreeNode] = []
 
         self._hover = False
@@ -70,6 +70,15 @@ class TreeNode(Generic[TreeDataType]):
         yield self.label.plain
         yield self.data
 
+    @property
+    def expanded(self) -> bool:
+        return self._expanded
+
+    @expanded.setter
+    def expanded(self, expanded: bool) -> None:
+        self._expanded = expanded
+        self._tree.invalidate()
+
     @property
     def last(self) -> bool:
         """Check if this is the last child.
@@ -101,7 +110,7 @@ class TreeNode(Generic[TreeDataType]):
         else:
             text_label = label
         node = self._tree._add_node(self, text_label, data)
-        node.expanded = expanded
+        node._expanded = expanded
         self.children.append(node)
         self._tree.invalidate()
         return node
@@ -165,9 +174,10 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
         "tree--highlight-line",
     }
 
-    hover_line: reactive[int] = reactive(-1, repaint=False)
-    cursor_line: reactive[int] = reactive(0, repaint=False)
-    guide_depth: reactive[int] = reactive(4, repaint=False, init=False)
+    hover_line = var(-1)
+    cursor_line = var(-1)
+    guide_depth = var(4, init=False)
+    auto_expand = var(True)
 
     LINES: dict[str, tuple[str, str, str, str]] = {
         "default": (
@@ -216,7 +226,7 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
         self._nodes: dict[NodeID, TreeNode[TreeDataType]] = {}
         self._current_id = 0
         self.root = self._add_node(None, text_label, data)
-        self.root.expanded = True
+        self.root._expanded = True
         self._line_cache: LRUCache[LineCacheKey, list[Segment]] = LRUCache(1024)
         self._tree_lines_cached: list[_TreeLine] | None = None
 
@@ -228,6 +238,17 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
         self._updates += 1
         return node
 
+    def render_label(self, node: TreeNode[TreeDataType]) -> Text:
+        """Render a label for the given node. Override this to modify how labels are rendered.
+
+        Args:
+            node (TreeNode[TreeDataType]): A tree node.
+
+        Returns:
+            Text: A Rich Text object containing the label.
+        """
+        return node.label
+
     def clear(self) -> None:
         """Clear all nodes under root."""
         self._tree_lines_cached = None
@@ -349,7 +370,7 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
         def add_node(path: list[TreeNode], node: TreeNode, last: bool) -> None:
             child_path = [*path, node]
             add_line(_TreeLine(child_path, last))
-            if node.expanded:
+            if node._expanded:
                 for last, child in loop_last(node.children):
                     add_node(child_path, child, last=last)
 
@@ -455,7 +476,8 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
                 guides.append(terminator, style=guide_style)
             else:
                 guides.append(cross, style=guide_style)
-        label = line.path[-1].label.copy()
+
+        label = self.render_label(line.path[-1]).copy()
         label.stylize(self.get_component_rich_style("tree--label", partial=True))
         if self.hover_line == y:
             label.stylize(
@@ -478,14 +500,18 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
         self.invalidate()
         self._line_cache.grow(self.size.height * 2)
 
-    def _on_click(self, event: events.Click) -> None:
+    async def _on_click(self, event: events.Click) -> None:
         meta = event.style.meta
         if "line" in meta:
-            self.cursor_line = meta["line"]
+            cursor_line = meta["line"]
+            if self.cursor_line == cursor_line:
+                await self.action("select_cursor")
+            else:
+                self.cursor_line = cursor_line
 
     def action_cursor_up(self) -> None:
         if self.cursor_line == -1:
-            self.cursor_line = len(self._tree_lines)
+            self.cursor_line = len(self._tree_lines) - 1
         else:
             self.cursor_line -= 1
 
@@ -498,5 +524,7 @@ class Tree(Generic[TreeDataType], ScrollView, can_focus=True):
         except IndexError:
             pass
         else:
+            node = line.path[-1]
+            if self.auto_expand:
+                node.expanded = not node.expanded
             self.emit_no_wait(self.NodeSelected(self, line.path[-1]))
-            self.app.bell()