Merge pull request #1333 from Textualize/textlog-docs

textlog documentation

docs/api/text_log.md

@@ -0,0 +1 @@
+::: textual.widgets.TextLog

docs/examples/widgets/text_log.py

@@ -0,0 +1,66 @@
+import csv
+import io
+
+from rich.table import Table
+from rich.syntax import Syntax
+
+from textual.app import App, ComposeResult
+from textual import events
+from textual.widgets import TextLog
+
+
+CSV = """lane,swimmer,country,time
+4,Joseph Schooling,Singapore,50.39
+2,Michael Phelps,United States,51.14
+5,Chad le Clos,South Africa,51.14
+6,László Cseh,Hungary,51.14
+3,Li Zhuhao,China,51.26
+8,Mehdy Metella,France,51.58
+7,Tom Shields,United States,51.73
+1,Aleksandr Sadovnikov,Russia,51.84"""
+
+
+CODE = '''\
+def loop_first_last(values: Iterable[T]) -> Iterable[tuple[bool, bool, T]]:
+    """Iterate and generate a tuple with a flag for first and last value."""
+    iter_values = iter(values)
+    try:
+        previous_value = next(iter_values)
+    except StopIteration:
+        return
+    first = True
+    for value in iter_values:
+        yield first, False, previous_value
+        first = False
+        previous_value = value
+    yield first, True, previous_value\
+'''
+
+
+class TextLogApp(App):
+    def compose(self) -> ComposeResult:
+        yield TextLog(highlight=True, markup=True)
+
+    def on_ready(self) -> None:
+        """Called  when the DOM is ready."""
+        text_log = self.query_one(TextLog)
+
+        text_log.write(Syntax(CODE, "python", indent_guides=True))
+
+        rows = iter(csv.reader(io.StringIO(CSV)))
+        table = Table(*next(rows))
+        for row in rows:
+            table.add_row(*row)
+
+        text_log.write(table)
+        text_log.write("[bold magenta]Write text or any Rich renderable!")
+
+    def on_key(self, event: events.Key) -> None:
+        """Write Key events to log."""
+        text_log = self.query_one(TextLog)
+        text_log.write(event)
+
+
+if __name__ == "__main__":
+    app = TextLogApp()
+    app.run()

docs/widgets/text_log.md

@@ -0,0 +1,44 @@
+# TextLog
+
+A TextLog is a widget which displays scrollable content that may be appended to in realtime.
+
+Call [TextLog.write][textual.widgets.TextLog.write] with a string or [Rich Renderable](https://rich.readthedocs.io/en/latest/protocol.html) to write content to the end of the TextLog. Call [TextLog.clear][textual.widgets.TextLog.clear] to clear the content.
+
+- [X] Focusable
+- [ ] Container
+
+## Example
+
+The example below shows each placeholder variant.
+
+=== "Output"
+
+    ```{.textual path="docs/examples/widgets/text_log.py" press="_,H,i"}
+    ```
+
+=== "text_log.py"
+
+    ```python
+    --8<-- "docs/examples/widgets/text_log.py"
+    ```
+
+
+
+## Reactive Attributes
+
+| Name        | Type   | Default | Description                                                  |
+| ----------- | ------ | ------- | ------------------------------------------------------------ |
+| `highlight` | `bool` | `False` | Automatically highlight content.                             |
+| `markup`    | `bool` | `False` | Apply Rich console markup.                                   |
+| `max_lines` | `int`  | `None`  | Maximum number of lines in the log or `None` for no maximum. |
+| `min_width` | `int`  | 78      | Minimum width of renderables.                                |
+| `wrap`      | `bool` | `False` | Enable word wrapping.                                        |
+
+## Messages
+
+This widget sends no messages.
+
+
+## See Also
+
+* [TextLog](../api/textlog.md) code reference

mkdocs.yml

@@ -92,6 +92,7 @@ nav:
       - "widgets/button.md"
       - "widgets/checkbox.md"
       - "widgets/data_table.md"
+      - "widgets/text_log.md"
       - "widgets/directory_tree.md"
       - "widgets/footer.md"
       - "widgets/header.md"
@@ -109,6 +110,7 @@ nav:
     - "api/color.md"
     - "api/containers.md"
     - "api/data_table.md"
+    - "api/text_log.md"
     - "api/directory_tree.md"
     - "api/dom_node.md"
     - "api/events.md"

src/textual/app.py

@@ -356,6 +356,7 @@ class App(Generic[ReturnType], DOMNode):
         )
         self._screenshot: str | None = None
         self._dom_lock = asyncio.Lock()
+        self._dom_ready = False
 
     @property
     def return_value(self) -> ReturnType | None:

src/textual/events.py

@@ -140,6 +140,10 @@ class Hide(Event, bubble=False):
     """
 
 
+class Ready(Event, bubble=False):
+    """Sent to the app when the DOM is ready."""
+
+
 @rich.repr.auto
 class MouseCapture(Event, bubble=False):
     """Sent when the mouse has been captured.

src/textual/screen.py

@@ -379,8 +379,6 @@ class Screen(Widget):
 
             for widget in hidden:
                 widget.post_message_no_wait(Hide(self))
-            for widget in shown:
-                widget.post_message_no_wait(Show(self))
 
             # We want to send a resize event to widgets that were just added or change since last layout
             send_resize = shown | resized
@@ -401,11 +399,17 @@ class Screen(Widget):
                         ResizeEvent(self, region.size, virtual_size, container_size)
                     )
 
+            for widget in shown:
+                widget.post_message_no_wait(Show(self))
+
         except Exception as error:
             self.app._handle_exception(error)
             return
         display_update = self._compositor.render(full=full)
         self.app._display(self, display_update)
+        if not self.app._dom_ready:
+            self.app.post_message_no_wait(events.Ready(self))
+            self.app._dom_ready = True
 
     async def _on_update(self, message: messages.Update) -> None:
         message.stop()

src/textual/widgets/_text_log.py

@@ -4,6 +4,7 @@ from typing import cast
 
 from rich.console import RenderableType
 from rich.highlighter import ReprHighlighter
+from rich.measure import measure_renderables
 from rich.pretty import Pretty
 from rich.protocol import is_renderable
 from rich.segment import Segment
@@ -73,22 +74,31 @@ class TextLog(ScrollView, can_focus=True):
         else:
             if isinstance(content, str):
                 if self.markup:
-                    content = Text.from_markup(content)
-                if self.highlight:
-                    renderable = self.highlighter(content)
+                    renderable = Text.from_markup(content)
                 else:
                     renderable = Text(content)
+                if self.highlight:
+                    renderable = self.highlighter(content)
             else:
                 renderable = cast(RenderableType, content)
 
         console = self.app.console
-        width = max(self.min_width, self.size.width or self.min_width)
+        render_options = console.options
 
-        render_options = console.options.update_width(width)
-        if not self.wrap:
+        if isinstance(renderable, Text) and not self.wrap:
             render_options = render_options.update(overflow="ignore", no_wrap=True)
-        segments = self.app.console.render(renderable, render_options.update_width(80))
+
+        width = max(
+            self.min_width,
+            measure_renderables(console, render_options, [renderable]).maximum,
+        )
+
+        segments = self.app.console.render(
+            renderable, render_options.update_width(width)
+        )
         lines = list(Segment.split_lines(segments))
+        if not lines:
+            return
 
         self.max_width = max(
             self.max_width,