title descriptors (#2213)

* title descriptors

* add extra line around titles

* changelog

* snapshots

* comment

* Fix border refresh

* simplify typing

* test for None case

CHANGELOG.md

@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+
+### Changed
+
+- Allowed border_title and border_subtitle to accept Text objects
+- Added additional line around titles
+
 ## [0.18.0] - 2023-04-04
 
 ### Added

src/textual/_border.py

@@ -283,7 +283,7 @@ def get_box(
 
 
 def render_border_label(
-    label: str,
+    label: Text,
     is_title: bool,
     name: EdgeType,
     width: int,
@@ -323,12 +323,10 @@ def render_border_label(
     # How many cells do we need to reserve for surrounding blanks and corners?
     corners_needed = has_left_corner + has_right_corner
     cells_reserved = 2 * corners_needed
-    if not label or width <= cells_reserved:
+    if not label.cell_len or width <= cells_reserved:
         return
 
-    text_label = Text.from_markup(label)
-    if not text_label.cell_len:
-        return
+    text_label = label.copy()
     text_label.truncate(width - cells_reserved, overflow="ellipsis")
     segments = text_label.render(console)
 
@@ -401,13 +399,15 @@ def render_row(
     elif not label_length:
         yield Segment(box2.text * space_available, box2.style)
     elif label_alignment == "left" or label_alignment == "right":
-        edge = Segment(box2.text * space_available, box2.style)
+        edge = Segment(box2.text * (space_available - 1), box2.style)
         if label_alignment == "left":
+            yield Segment(box2.text, box2.style)
             yield from label_segments_list
             yield edge
         else:
             yield edge
             yield from label_segments_list
+            yield Segment(box2.text, box2.style)
     elif label_alignment == "center":
         length_on_left = space_available // 2
         length_on_right = space_available - length_on_left

src/textual/_styles_cache.py

@@ -7,6 +7,7 @@ from typing import TYPE_CHECKING, Callable, Iterable
 from rich.console import Console
 from rich.segment import Segment
 from rich.style import Style
+from rich.text import Text
 
 from ._border import get_box, render_border_label, render_row
 from ._opacity import _apply_opacity
@@ -115,8 +116,8 @@ class StylesCache:
             background,
             widget.render_line,
             widget.app.console,
-            widget.border_title,
-            widget.border_subtitle,
+            widget._border_title,
+            widget._border_subtitle,
             content_size=widget.content_region.size,
             padding=styles.padding,
             crop=crop,
@@ -146,8 +147,8 @@ class StylesCache:
         background: Color,
         render_content_line: RenderLineCallback,
         console: Console,
-        border_title: str,
-        border_subtitle: str,
+        border_title: Text | None,
+        border_subtitle: Text | None,
         content_size: Size | None = None,
         padding: Spacing | None = None,
         crop: Region | None = None,
@@ -228,8 +229,8 @@ class StylesCache:
         background: Color,
         render_content_line: Callable[[int], Strip],
         console: Console,
-        border_title: str,
-        border_subtitle: str,
+        border_title: Text | None,
+        border_subtitle: Text | None,
     ) -> Strip:
         """Render a styled line.
 
@@ -310,7 +311,7 @@ class StylesCache:
                     border_label,
                     is_top,
                     border_edge_type,
-                    width,
+                    width - 2,
                     inner,
                     outer,
                     border_color_as_style,

src/textual/app.py

@@ -1011,6 +1011,8 @@ class App(Generic[ReturnType], DOMNode):
                 )
 
         try:
+            app._loop = asyncio.get_running_loop()
+            app._thread_id = threading.get_ident()
             await app._process_messages(
                 ready_callback=None if auto_pilot is None else app_ready,
                 headless=headless,

src/textual/widget.py

@@ -188,6 +188,34 @@ class PseudoClasses(NamedTuple):
     hover: bool
 
 
+class _BorderTitle:
+    """Descriptor to set border titles."""
+
+    def __set_name__(self, owner: Widget, name: str) -> None:
+        # The private name where we store the real data.
+        self._internal_name = f"_{name}"
+
+    def __set__(self, obj: Widget, title: str | Text | None) -> None:
+        """Setting a title accepts a str, Text, or None."""
+        if title is None:
+            setattr(obj, self._internal_name, None)
+        else:
+            # We store the title as Text
+            new_title = obj.render_str(title)
+            new_title.expand_tabs(4)
+            new_title = new_title.split()[0]
+            setattr(obj, self._internal_name, new_title)
+        obj.refresh()
+
+    def __get__(self, obj: Widget, objtype: type[Widget] | None = None) -> str | None:
+        """Getting a title will return None or a str as console markup."""
+        title: Text | None = getattr(obj, self._internal_name, None)
+        if title is None:
+            return None
+        # If we have a title, convert from Text to console markup
+        return title.markup
+
+
 @rich.repr.auto
 class Widget(DOMNode):
     """
@@ -241,10 +269,6 @@ class Widget(DOMNode):
     """Widget will highlight links automatically."""
     disabled = Reactive(False)
     """The disabled state of the widget. `True` if disabled, `False` if not."""
-    border_title = Reactive("")
-    """The one-line border title, which may contain markup to be parsed."""
-    border_subtitle = Reactive("")
-    """The one-line border subtitle, which may contain markup to be parsed."""
 
     hover_style: Reactive[Style] = Reactive(Style, repaint=False)
     highlight_link_id: Reactive[str] = Reactive("")
@@ -270,6 +294,9 @@ class Widget(DOMNode):
         self._horizontal_scrollbar: ScrollBar | None = None
         self._scrollbar_corner: ScrollBarCorner | None = None
 
+        self._border_title: Text | None = None
+        self._border_subtitle: Text | None = None
+
         self._render_cache = RenderCache(Size(0, 0), [])
         # Regions which need to be updated (in Widget)
         self._dirty_regions: set[Region] = set()
@@ -321,6 +348,11 @@ class Widget(DOMNode):
     show_vertical_scrollbar = Reactive(False, layout=True)
     show_horizontal_scrollbar = Reactive(False, layout=True)
 
+    border_title = _BorderTitle()
+    """A title to show in the top border (if there is one)."""
+    border_subtitle = _BorderTitle()
+    """A title to show in the bottom border (if there is one)."""
+
     @property
     def siblings(self) -> list[Widget]:
         """Get the widget's siblings (self is removed from the return list).
@@ -2429,20 +2461,6 @@ class Widget(DOMNode):
         """Update the styles of the widget and its children when disabled is toggled."""
         self._update_styles()
 
-    def validate_border_title(self, title: str) -> str:
-        """Ensure we only use a single line for the border title."""
-        if not title:
-            return title
-        first, *_ = title.splitlines()
-        return first
-
-    def validate_border_subtitle(self, subtitle: str) -> str:
-        """Ensure we only use a single line for the border subtitle."""
-        if not subtitle:
-            return subtitle
-        first, *_ = subtitle.splitlines()
-        return first
-
     def _size_updated(
         self, size: Size, virtual_size: Size, container_size: Size, layout: bool = True
     ) -> bool:

tests/test_border.py

@@ -2,6 +2,7 @@ import pytest
 from rich.console import Console
 from rich.segment import Segment
 from rich.style import Style
+from rich.text import Text
 
 from textual._border import render_border_label, render_row
 from textual.widget import Widget
@@ -37,6 +38,11 @@ def test_border_title_single_line():
     """The border_title gets set to a single line even when multiple lines are provided."""
     widget = Widget()
 
+    assert widget.border_title is None
+
+    widget.border_title = None
+    assert widget.border_title == None
+
     widget.border_title = ""
     assert widget.border_title == ""
 
@@ -50,7 +56,10 @@ def test_border_title_single_line():
     assert widget.border_title == "Sorry you "
 
     widget.border_title = "[red]This also \n works with markup \n involved.[/]"
-    assert widget.border_title == "[red]This also "
+    assert widget.border_title == "[red]This also [/red]"
+
+    widget.border_title = Text.from_markup("[bold]Hello World")
+    assert widget.border_title == "[bold]Hello World[/bold]"
 
 
 def test_border_subtitle_single_line():
@@ -70,7 +79,10 @@ def test_border_subtitle_single_line():
     assert widget.border_subtitle == "Sorry you "
 
     widget.border_subtitle = "[red]This also \n works with markup \n involved.[/]"
-    assert widget.border_subtitle == "[red]This also "
+    assert widget.border_subtitle == "[red]This also [/red]"
+
+    widget.border_subtitle = Text.from_markup("[bold]Hello World")
+    assert widget.border_subtitle == "[bold]Hello World[/bold]"
 
 
 @pytest.mark.parametrize(
@@ -93,7 +105,7 @@ def test_render_border_label_empty_label_skipped(
 
     assert [] == list(
         render_border_label(
-            "",
+            Text(""),
             True,
             "round",
             width,
@@ -130,7 +142,7 @@ def test_render_border_label_skipped_if_narrow(
 
     assert [] == list(
         render_border_label(
-            label,
+            Text.from_markup(label),
             True,
             "round",
             width,
@@ -168,7 +180,7 @@ def test_render_border_label_wide_plain(label: str):
         True,
         True,
     )
-    left, original_text, right = render_border_label(label, *args)
+    left, original_text, right = render_border_label(Text.from_markup(label), *args)
 
     assert left == _BLANK_SEGMENT
     assert right == _BLANK_SEGMENT
@@ -188,7 +200,7 @@ def test_render_border_empty_text_with_markup(label: str):
     """Test label rendering if there is no text but some markup."""
     assert [] == list(
         render_border_label(
-            label,
+            Text.from_markup(label),
             True,
             "round",
             999,
@@ -210,7 +222,7 @@ def test_render_border_label():
 
     # Implicit test on the number of segments returned:
     blank1, what, is_up, with_you, blank2 = render_border_label(
-        label,
+        Text.from_markup(label),
         True,
         "round",
         9999,
@@ -239,7 +251,7 @@ def test_render_border_label():
     assert with_you == expected_with_you
 
     blank1, what, blank2 = render_border_label(
-        label,
+        Text.from_markup(label),
         True,
         "round",
         5 + 4,  # 5 where "What…" fits + 2 for the blank spaces + 2 for the corners.