TextArea

Added in version 0.38.0

A widget for editing text which may span multiple lines. Supports syntax highlighting for a selection of languages.

• Focusable
• Container

Guide

Syntax highlighting dependencies

To enable syntax highlighting, you'll need to install the syntax extra dependencies:

pippoetry

pip install "textual[syntax]"

poetry add "textual[syntax]"

This will install tree-sitter and tree-sitter-languages. These packages are distributed as binary wheels, so it may limit your applications ability to run in environments where these wheels are not supported.

Loading text

In this example we load some initial text into the TextArea, and set the language to "python" to enable syntax highlighting.

Outputtext_area_example.py

from textual.app import App, ComposeResult
from textual.widgets import TextArea

TEXT = """\
def hello(name):
    print("hello" + name)

def goodbye(name):
    print("goodbye" + name)
"""


class TextAreaExample(App):
    def compose(self) -> ComposeResult:
        yield TextArea(TEXT, language="python")


app = TextAreaExample()
if __name__ == "__main__":
    app.run()

To load content into the TextArea after it has already been created, use the load_text method.

To update the parser used for syntax highlighting, set the language reactive attribute:

# Set the language to Markdown
text_area.language = "markdown"

Note

Syntax highlighting is unavailable on Python 3.7.

Note

More built-in languages will be added in the future. For now, you can add your own.

Reading content from TextArea

There are a number of ways to retrieve content from the TextArea:

• The TextArea.text property returns all content in the text area as a string.
• The TextArea.selected_text property returns the text corresponding to the current selection.
• The TextArea.get_text_range method returns the text between two locations.

In all cases, when multiple lines of text are retrieved, the document line separator will be used.

Editing content inside TextArea

The content of the TextArea can be updated using the replace method. This method is the programmatic equivalent of selecting some text and then pasting.

Some other convenient methods are available, such as insert, delete, and clear.

Working with the cursor

Moving the cursor

The cursor location is available via the cursor_location property, which represents the location of the cursor as a tuple (row_index, column_index). These indices are zero-based. Writing a new value to cursor_location will immediately update the location of the cursor.

>>> text_area = TextArea()
>>> text_area.cursor_location
(0, 0)
>>> text_area.cursor_location = (0, 4)
>>> text_area.cursor_location
(0, 4)

cursor_location is a simple way to move the cursor programmatically, but it doesn't let us select text.

Selecting text

To select text, we can use the selection reactive attribute. Let's select the first two lines of text in a document by adding text_area.selection = Selection(start=(0, 0), end=(2, 0)) to our code:

Outputtext_area_selection.py

from textual.app import App, ComposeResult
from textual.widgets import TextArea
from textual.widgets.text_area import Selection

TEXT = """\
def hello(name):
    print("hello" + name)

def goodbye(name):
    print("goodbye" + name)
"""


class TextAreaSelection(App):
    def compose(self) -> ComposeResult:
        text_area = TextArea(TEXT, language="python")
        text_area.selection = Selection(start=(0, 0), end=(2, 0))  # (1)!
        yield text_area


app = TextAreaSelection()
if __name__ == "__main__":
    app.run()

1. Selects the first two lines of text.

Note that selections can happen in both directions, so Selection((2, 0), (0, 0)) is also valid.

Tip

The end attribute of the selection is always equal to TextArea.cursor_location. In other words, the cursor_location attribute is simply a convenience for accessing text_area.selection.end.

More cursor utilities

There are a number of additional utility methods available for interacting with the cursor.

Location information

A number of properties exist on TextArea which give information about the current cursor location. These properties begin with cursor_at_, and return booleans. For example, cursor_at_start_of_line tells us if the cursor is at a start of line.

We can also check the location the cursor would arrive at if we were to move it. For example, get_cursor_right_location returns the location the cursor would move to if it were to move right. A number of similar methods exist, with names like get_cursor_*_location.

Cursor movement methods

The move_cursor method allows you to move the cursor to a new location while selecting text, or move the cursor and scroll to keep it centered.

# Move the cursor from its current location to row index 4,
# column index 8, while selecting all the text between.
text_area.move_cursor((4, 8), select=True)

The move_cursor_relative method offers a very similar interface, but moves the cursor relative to its current location.

Common selections

There are some methods available which make common selections easier:

• select_line selects a line by index. Bound to F6 by default.
• select_all selects all text. Bound to F7 by default.

Themes

TextArea ships with some builtin themes, and you can easily add your own.

Themes give you control over the look and feel, including syntax highlighting, the cursor, selection, gutter, and more.

Using builtin themes

The initial theme of the TextArea is determined by the theme parameter.

# Create a TextArea with the 'dracula' theme.
yield TextArea("print(123)", language="python", theme="dracula")

You can check which themes are available using the available_themes property.

>>> text_area = TextArea()
>>> print(text_area.available_themes)
{'dracula', 'github_light', 'monokai', 'vscode_dark'}

After creating a TextArea, you can change the theme by setting the theme attribute to one of the available themes.

text_area.theme = "vscode_dark"

On setting this attribute the TextArea will immediately refresh to display the updated theme.

Custom themes

Using custom (non-builtin) themes is two-step process:

1. Create an instance of TextAreaTheme.
2. Register it using TextArea.register_theme.

1. Creating a theme

Let's create a simple theme, "my_cool_theme", which colors the cursor blue, and the cursor line yellow. Our theme will also syntax highlight strings as red, and comments as magenta.

from rich.style import Style
from textual.widgets.text_area import TextAreaTheme
# ...
my_theme = TextAreaTheme(
    # This name will be used to refer to the theme...
    name="my_cool_theme",
    # Basic styles such as background, cursor, selection, gutter, etc...
    cursor_style=Style(color="white", bgcolor="blue"),
    cursor_line_style=Style(bgcolor="yellow"),
    # `syntax_styles` is for syntax highlighting.
    # It maps tokens parsed from the document to Rich styles.
    syntax_styles={
        "string": Style(color="red"),
        "comment": Style(color="magenta"),
    }
)

Attributes like cursor_style and cursor_line_style apply general language-agnostic styling to the widget.

The syntax_styles attribute of TextAreaTheme is used for syntax highlighting and depends on the language currently in use. For more details, see syntax highlighting.

If you wish to build on an existing theme, you can obtain a reference to it using the TextAreaTheme.get_builtin_theme classmethod:

from textual.widgets.text_area import TextAreaTheme

monokai = TextAreaTheme.get_builtin_theme("monokai")

2. Registering a theme

Our theme can now be registered with the TextArea instance.

text_area.register_theme(my_theme)

After registering a theme, it'll appear in the available_themes:

>>> print(text_area.available_themes)
{'dracula', 'github_light', 'monokai', 'vscode_dark', 'my_cool_theme'}

We can now switch to it:

text_area.theme = "my_cool_theme"

This immediately updates the appearance of the TextArea:

Indentation

The character(s) inserted when you press tab is controlled by setting the indent_type attribute to either tabs or spaces.

If indent_type == "spaces", pressing Tab will insert up to indent_width spaces in order to align with the next tab stop.

Line separators

When content is loaded into TextArea, the content is scanned from beginning to end and the first occurrence of a line separator is recorded.

This separator will then be used when content is later read from the TextArea via the text property. The TextArea widget does not support exporting text which contains mixed line endings.

Similarly, newline characters pasted into the TextArea will be converted.

You can check the line separator of the current document by inspecting TextArea.document.newline:

>>> text_area = TextArea()
>>> text_area.document.newline
'\n'

Line numbers

The gutter (column on the left containing line numbers) can be toggled by setting the show_line_numbers attribute to True or False.

Setting this attribute will immediately repaint the TextArea to reflect the new value.

Extending TextArea

Sometimes, you may wish to subclass TextArea to add some extra functionality. In this section, we'll briefly explore how we can extend the widget to achieve common goals.

Hooking into key presses

You may wish to hook into certain key presses to inject some functionality. This can be done by over-riding _on_key and adding the required functionality.

Example - closing parentheses automatically

Let's extend TextArea to add a feature which automatically closes parentheses and moves the cursor to a sensible location.

from textual import events
from textual.app import App, ComposeResult
from textual.widgets import TextArea


class ExtendedTextArea(TextArea):
    """A subclass of TextArea with parenthesis-closing functionality."""

    def _on_key(self, event: events.Key) -> None:
        if event.character == "(":
            self.insert("()")
            self.move_cursor_relative(columns=-1)
            event.prevent_default()


class TextAreaKeyPressHook(App):
    def compose(self) -> ComposeResult:
        yield ExtendedTextArea(language="python")


app = TextAreaKeyPressHook()
if __name__ == "__main__":
    app.run()

This intercepts the key handler when "(" is pressed, and inserts "()" instead. It then moves the cursor so that it lands between the open and closing parentheses.

Typing def hello( into the TextArea results in the bracket automatically being closed:

Advanced concepts

Syntax highlighting

Syntax highlighting inside the TextArea is powered by a library called tree-sitter.

Each time you update the document in a TextArea, an internal syntax tree is updated. This tree is frequently queried to find location ranges relevant to syntax highlighting. We give these ranges names, and ultimately map them to Rich styles inside TextAreaTheme.syntax_styles.

To illustrate how this works, lets look at how the "Monokai" TextAreaTheme highlights Markdown files.

When the language attribute is set to "markdown", a highlight query similar to the one below is used (trimmed for brevity).

(heading_content) @heading
(link) @link

This highlight query maps heading_content nodes returned by the Markdown parser to the name @heading, and link nodes to the name @link.

Inside our TextAreaTheme.syntax_styles dict, we can map the name @heading to a Rich style. Here's a snippet from the "Monokai" theme which does just that:

TextAreaTheme(
    name="monokai",
    base_style=Style(color="#f8f8f2", bgcolor="#272822"),
    gutter_style=Style(color="#90908a", bgcolor="#272822"),
    # ...
    syntax_styles={
        # Colorise @heading and make them bold
        "heading": Style(color="#F92672", bold=True),
        # Colorise and underline @link
        "link": Style(color="#66D9EF", underline=True),
        # ...
    },
)

To understand which names can be mapped inside syntax_styles, we recommend looking at the existing themes and highlighting queries (.scm files) in the Textual repository.

Tip

You may also wish to take a look at the contents of TextArea._highlights on an active TextArea instance to see which highlights have been generated for the open document.

Adding support for custom languages

To add support for a language to a TextArea, use the register_language method.

To register a language, we require two things:

1. A tree-sitter Language object which contains the grammar for the language.
2. A highlight query which is used for syntax highlighting.

Example - adding Java support

The easiest way to obtain a Language object is using the py-tree-sitter-languages package. Here's how we can use this package to obtain a reference to a Language object representing Java:

from tree_sitter_languages import get_language
java_language = get_language("java")

Note

py-tree-sitter-languages may not be available on some architectures (e.g. Macbooks with Apple Silicon running Python 3.7).

The exact version of the parser used when you call get_language can be checked via the repos.txt file in the version of py-tree-sitter-languages you're using. This file contains links to the GitHub repos and commit hashes of the tree-sitter parsers. In these repos you can often find pre-made highlight queries at queries/highlights.scm, and a file showing all the available node types which can be used in highlight queries at src/node-types.json.

Since we're adding support for Java, lets grab the Java highlight query from the repo by following these steps:

1. Open repos.txt file from the py-tree-sitter-languages repo.
2. Find the link corresponding to tree-sitter-java and go to the repo on GitHub (you may also need to go to the specific commit referenced in repos.txt).
3. Go to queries/highlights.scm to see the example highlight query for Java.

Be sure to check the license in the repo to ensure it can be freely copied.

Warning

It's important to use a highlight query which is compatible with the parser in use, so pay attention to the commit hash when visiting the repo via repos.txt.

We now have our Language and our highlight query, so we can register Java as a language.

from pathlib import Path

from tree_sitter_languages import get_language

from textual.app import App, ComposeResult
from textual.widgets import TextArea

java_language = get_language("java")
java_highlight_query = (Path(__file__).parent / "java_highlights.scm").read_text()
java_code = """\
class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}
"""


class TextAreaCustomLanguage(App):
    def compose(self) -> ComposeResult:
        text_area = TextArea(text=java_code)
        text_area.cursor_blink = False

        # Register the Java language and highlight query
        text_area.register_language(java_language, java_highlight_query)

        # Switch to Java
        text_area.language = "java"
        yield text_area


app = TextAreaCustomLanguage()
if __name__ == "__main__":
    app.run()

Running our app, we can see that the Java code is highlighted. We can freely edit the text, and the syntax highlighting will update immediately.

Recall that we map names (like @heading) from the tree-sitter highlight query to Rich style objects inside the TextAreaTheme.syntax_styles dictionary. If you notice some highlights are missing after registering a language, the issue may be:

1. The current TextAreaTheme doesn't contain a mapping for the name in the highlight query. Adding a new to syntax_styles should resolve the issue.
2. The highlight query doesn't assign a name to the pattern you expect to be highlighted. In this case you'll need to update the highlight query to assign to the name.

Tip

The names assigned in tree-sitter highlight queries are often reused across multiple languages. For example, @string is used in many languages to highlight strings.

Reactive attributes

Name	Type	Default	Description
language	str | None	None	The language to use for syntax highlighting.
theme	str | None	TextAreaTheme.default()	The theme to use for syntax highlighting.
selection	Selection	Selection()	The current selection.
show_line_numbers	bool	True	Show or hide line numbers.
indent_width	int	4	The number of spaces to indent and width of tabs.
match_cursor_bracket	bool	True	Enable/disable highlighting matching brackets under cursor.
cursor_blink	bool	True	Enable/disable blinking of the cursor when the widget has focus.

Messages

• TextArea.Changed
• TextArea.SelectionChanged

Bindings

The TextArea widget defines the following bindings:

Key(s)	Description
escape	Focus on the next item.
up	Move the cursor up.
down	Move the cursor down.
left	Move the cursor left.
ctrl+left	Move the cursor to the start of the word.
ctrl+shift+left	Move the cursor to the start of the word and select.
right	Move the cursor right.
ctrl+right	Move the cursor to the end of the word.
ctrl+shift+right	Move the cursor to the end of the word and select.
home,ctrl+a	Move the cursor to the start of the line.
end,ctrl+e	Move the cursor to the end of the line.
shift+home	Move the cursor to the start of the line and select.
shift+end	Move the cursor to the end of the line and select.
pageup	Move the cursor one page up.
pagedown	Move the cursor one page down.
shift+up	Select while moving the cursor up.
shift+down	Select while moving the cursor down.
shift+left	Select while moving the cursor left.
shift+right	Select while moving the cursor right.
backspace	Delete character to the left of cursor.
ctrl+w	Delete from cursor to start of the word.
delete,ctrl+d	Delete character to the right of cursor.
ctrl+f	Delete from cursor to end of the word.
ctrl+x	Delete the current line.
ctrl+u	Delete from cursor to the start of the line.
ctrl+k	Delete from cursor to the end of the line.
f6	Select the current line.
f7	Select all text in the document.

Component classes

The TextArea widget defines no component classes.

Styling should be done exclusively via TextAreaTheme.

See also

• Input - for single-line text input.
• TextAreaTheme - for theming the TextArea.
• The tree-sitter documentation website.
• The tree-sitter Python bindings repository.
• py-tree-sitter-languages repository (provides binary wheels for a large variety of tree-sitter languages).

---

textual.widgets._text_area.TextArea class

def __init__(
    self,
    text="",
    *,
    language=None,
    theme=None,
    name=None,
    id=None,
    classes=None,
    disabled=False
):

Bases: ScrollView

Parameters

Parameter	Default	Description
text str	''	The initial text to load into the TextArea.
language str | None	None	The language to use.
theme str | None	None	The theme to use.
name str | None	None	The name of the TextArea widget.
id str | None	None	The ID of the widget, used to refer to it from Textual CSS.
classes str | None	None	One or more Textual CSS compatible class names separated by spaces.
disabled bool	False	True if the widget is disabled.

BINDINGS instance-attribute class-attribute

BINDINGS = [
    Binding(
        "escape",
        "screen.focus_next",
        "Shift Focus",
        show=False,
    ),
    Binding("up", "cursor_up", "cursor up", show=False),
    Binding(
        "down", "cursor_down", "cursor down", show=False
    ),
    Binding(
        "left", "cursor_left", "cursor left", show=False
    ),
    Binding(
        "right", "cursor_right", "cursor right", show=False
    ),
    Binding(
        "ctrl+left",
        "cursor_word_left",
        "cursor word left",
        show=False,
    ),
    Binding(
        "ctrl+right",
        "cursor_word_right",
        "cursor word right",
        show=False,
    ),
    Binding(
        "home,ctrl+a",
        "cursor_line_start",
        "cursor line start",
        show=False,
    ),
    Binding(
        "end,ctrl+e",
        "cursor_line_end",
        "cursor line end",
        show=False,
    ),
    Binding(
        "pageup",
        "cursor_page_up",
        "cursor page up",
        show=False,
    ),
    Binding(
        "pagedown",
        "cursor_page_down",
        "cursor page down",
        show=False,
    ),
    Binding(
        "ctrl+shift+left",
        "cursor_word_left(True)",
        "cursor left word select",
        show=False,
    ),
    Binding(
        "ctrl+shift+right",
        "cursor_word_right(True)",
        "cursor right word select",
        show=False,
    ),
    Binding(
        "shift+home",
        "cursor_line_start(True)",
        "cursor line start select",
        show=False,
    ),
    Binding(
        "shift+end",
        "cursor_line_end(True)",
        "cursor line end select",
        show=False,
    ),
    Binding(
        "shift+up",
        "cursor_up(True)",
        "cursor up select",
        show=False,
    ),
    Binding(
        "shift+down",
        "cursor_down(True)",
        "cursor down select",
        show=False,
    ),
    Binding(
        "shift+left",
        "cursor_left(True)",
        "cursor left select",
        show=False,
    ),
    Binding(
        "shift+right",
        "cursor_right(True)",
        "cursor right select",
        show=False,
    ),
    Binding("f6", "select_line", "select line", show=False),
    Binding("f7", "select_all", "select all", show=False),
    Binding(
        "backspace",
        "delete_left",
        "delete left",
        show=False,
    ),
    Binding(
        "ctrl+w",
        "delete_word_left",
        "delete left to start of word",
        show=False,
    ),
    Binding(
        "delete,ctrl+d",
        "delete_right",
        "delete right",
        show=False,
    ),
    Binding(
        "ctrl+f",
        "delete_word_right",
        "delete right to start of word",
        show=False,
    ),
    Binding(
        "ctrl+x", "delete_line", "delete line", show=False
    ),
    Binding(
        "ctrl+u",
        "delete_to_start_of_line",
        "delete to line start",
        show=False,
    ),
    Binding(
        "ctrl+k",
        "delete_to_end_of_line",
        "delete to line end",
        show=False,
    ),
]

Key(s)	Description
escape	Focus on the next item.
up	Move the cursor up.
down	Move the cursor down.
left	Move the cursor left.
ctrl+left	Move the cursor to the start of the word.
ctrl+shift+left	Move the cursor to the start of the word and select.
right	Move the cursor right.
ctrl+right	Move the cursor to the end of the word.
ctrl+shift+right	Move the cursor to the end of the word and select.
home,ctrl+a	Move the cursor to the start of the line.
end,ctrl+e	Move the cursor to the end of the line.
shift+home	Move the cursor to the start of the line and select.
shift+end	Move the cursor to the end of the line and select.
pageup	Move the cursor one page up.
pagedown	Move the cursor one page down.
shift+up	Select while moving the cursor up.
shift+down	Select while moving the cursor down.
shift+left	Select while moving the cursor left.
shift+right	Select while moving the cursor right.
backspace	Delete character to the left of cursor.
ctrl+w	Delete from cursor to start of the word.
delete,ctrl+d	Delete character to the right of cursor.
ctrl+f	Delete from cursor to end of the word.
ctrl+x	Delete the current line.
ctrl+u	Delete from cursor to the start of the line.
ctrl+k	Delete from cursor to the end of the line.
f6	Select the current line.
f7	Select all text in the document.

available_languages property

available_languages: set[str]

A list of the names of languages available to the TextArea.

The values in this list can be assigned to the language reactive attribute of TextArea.

The returned list contains the builtin languages plus those registered via the register_language method. Builtin languages will be listed before user-registered languages, but there are no other ordering guarantees.

available_themes property

available_themes: set[str]

A list of the names of the themes available to the TextArea.

The values in this list can be assigned theme reactive attribute of TextArea.

You can retrieve the full specification for a theme by passing one of the strings from this list into TextAreaTheme.get_by_name(theme_name: str).

Alternatively, you can directly retrieve a list of TextAreaTheme objects (which contain the full theme specification) by calling TextAreaTheme.builtin_themes().

cursor_at_end_of_line property

cursor_at_end_of_line: bool

True if and only if the cursor is at the end of a row.

cursor_at_end_of_text property

cursor_at_end_of_text: bool

True if and only if the cursor is at the very end of the document.

cursor_at_first_line property

cursor_at_first_line: bool

True if and only if the cursor is on the first line.

cursor_at_last_line property

cursor_at_last_line: bool

True if and only if the cursor is on the last line.

cursor_at_start_of_line property

cursor_at_start_of_line: bool

True if and only if the cursor is at column 0.

cursor_at_start_of_text property

cursor_at_start_of_text: bool

True if and only if the cursor is at location (0, 0)

cursor_blink instance-attribute class-attribute

cursor_blink: Reactive[bool] = reactive(True)

True if the cursor should blink.

cursor_location property writable

cursor_location: Location

The current location of the cursor in the document.

This is a utility for accessing the end of TextArea.selection.

cursor_screen_offset property

cursor_screen_offset: Offset

The offset of the cursor relative to the screen.

document instance-attribute

document: DocumentBase = Document(text)

The document this widget is currently editing.

gutter_width property

gutter_width: int

The width of the gutter (the left column containing line numbers).

Returns

Type	Description
int	The cell-width of the line number column. If show_line_numbers is False returns 0.

indent_type instance-attribute

indent_type: Literal['tabs', 'spaces'] = 'spaces'

Whether to indent using tabs or spaces.

indent_width instance-attribute class-attribute

indent_width: Reactive[int] = reactive(4)

The width of tabs or the multiple of spaces to align to on pressing the tab key.

If the document currently open contains tabs that are currently visible on screen, altering this value will immediately change the display width of the visible tabs.

is_syntax_aware property

is_syntax_aware: bool

True if the TextArea is currently syntax aware - i.e. it's parsing document content.

language instance-attribute class-attribute

language: Reactive[str | None] = language

The language to use.

This must be set to a valid, non-None value for syntax highlighting to work.

If the value is a string, a built-in language parser will be used if available.

If you wish to use an unsupported language, you'll have to register it first using TextArea.register_language.

match_cursor_bracket instance-attribute class-attribute

match_cursor_bracket: Reactive[bool] = reactive(True)

If the cursor is at a bracket, highlight the matching bracket (if found).

selected_text property

selected_text: str

The text between the start and end points of the current selection.

selection instance-attribute class-attribute

selection: Reactive[Selection] = reactive(
    Selection(), always_update=True, init=False
)

The selection start and end locations (zero-based line_index, offset).

This represents the cursor location and the current selection.

The Selection.end always refers to the cursor location.

If no text is selected, then Selection.end == Selection.start is True.

The text selected in the document is available via the TextArea.selected_text property.

show_line_numbers instance-attribute class-attribute

show_line_numbers: Reactive[bool] = reactive(True)

True to show the line number column on the left edge, otherwise False.

Changing this value will immediately re-render the TextArea.

text property writable

text: str

The entire text content of the document.

theme instance-attribute class-attribute

theme: Reactive[str | None] = theme

The name of the theme to use.

Themes must be registered using TextArea.register_theme before they can be used.

Syntax highlighting is only possible when the language attribute is set.

Changed class

Bases: Message

Posted when the content inside the TextArea changes.

Handle this message using the on decorator - @on(TextArea.Changed) or a method named on_text_area_changed.

control property

control: TextArea

The TextArea that sent this message.

text_area instance-attribute

text_area: TextArea

The text_area that sent this message.

SelectionChanged class

Bases: Message

Posted when the selection changes.

This includes when the cursor moves or when text is selected.

selection instance-attribute

selection: Selection

The new selection.

text_area instance-attribute

text_area: TextArea

The text_area that sent this message.

action_cursor_down method

def action_cursor_down(self, select=False):

Move the cursor down one cell.

Parameters

Parameter	Default	Description
select bool	False	If True, select the text while moving.

action_cursor_left method

def action_cursor_left(self, select=False):

Move the cursor one location to the left.

If the cursor is at the left edge of the document, try to move it to the end of the previous line.

Parameters

Parameter	Default	Description
select bool	False	If True, select the text while moving.

action_cursor_line_end method

def action_cursor_line_end(self, select=False):

Move the cursor to the end of the line.

action_cursor_line_start method

def action_cursor_line_start(self, select=False):

Move the cursor to the start of the line.

action_cursor_page_down method

def action_cursor_page_down(self):

Move the cursor and scroll down one page.

action_cursor_page_up method

def action_cursor_page_up(self):

Move the cursor and scroll up one page.

action_cursor_right method

def action_cursor_right(self, select=False):

Move the cursor one location to the right.

If the cursor is at the end of a line, attempt to go to the start of the next line.

Parameters

Parameter	Default	Description
select bool	False	If True, select the text while moving.

action_cursor_up method

def action_cursor_up(self, select=False):

Move the cursor up one cell.

Parameters

Parameter	Default	Description
select bool	False	If True, select the text while moving.

action_cursor_word_left method

def action_cursor_word_left(self, select=False):

Move the cursor left by a single word, skipping trailing whitespace.

Parameters

Parameter	Default	Description
select bool	False	Whether to select while moving the cursor.

action_cursor_word_right method

def action_cursor_word_right(self, select=False):

Move the cursor right by a single word, skipping leading whitespace.

action_delete_left method

def action_delete_left(self):

Deletes the character to the left of the cursor and updates the cursor location.

If there's a selection, then the selected range is deleted.

action_delete_line method

def action_delete_line(self):

Deletes the lines which intersect with the selection.

action_delete_right method

def action_delete_right(self):

Deletes the character to the right of the cursor and keeps the cursor at the same location.

If there's a selection, then the selected range is deleted.

action_delete_to_end_of_line method

def action_delete_to_end_of_line(self):

Deletes from the cursor location to the end of the line.

action_delete_to_start_of_line method

def action_delete_to_start_of_line(self):

Deletes from the cursor location to the start of the line.

action_delete_word_left method

def action_delete_word_left(self):

Deletes the word to the left of the cursor and updates the cursor location.

action_delete_word_right method

def action_delete_word_right(self):

Deletes the word to the right of the cursor and keeps the cursor at the same location.

Note that the location that we delete to using this action is not the same as the location we move to when we move the cursor one word to the right. This action does not skip leading whitespace, whereas cursor movement does.

action_select_all method

def action_select_all(self):

Select all the text in the document.

action_select_line method

def action_select_line(self):

Select all the text on the current line.

cell_width_to_column_index method

def cell_width_to_column_index(self, cell_width, row_index):

Return the column that the cell width corresponds to on the given row.

Parameters

Parameter	Default	Description
cell_width int	required	The cell width to convert.
row_index int	required	The index of the row to examine.

Returns

Type	Description
int	The column corresponding to the cell width on that row.

clamp_visitable method

def clamp_visitable(self, location):

Clamp the given location to the nearest visitable location.

Parameters

Parameter	Default	Description
location Location	required	The location to clamp.

Returns

Type	Description
Location	The nearest location that we could conceivably navigate to using the cursor.

clear method

def clear(self):

Delete all text from the document.

delete method

def delete(self, start, end, *, maintain_selection_offset=True):

Delete the text between two locations in the document.

Parameters

Parameter	Default	Description
start Location	required	The start location.
end Location	required	The end location.
maintain_selection_offset bool	True	If True, the active Selection will be updated such that the same text is selected before and after the selection, if possible. Otherwise, the cursor will jump to the end point of the edit.

Returns

Type	Description
EditResult	An EditResult containing information about the edit.

edit method

def edit(self, edit):

Perform an Edit.

Parameters

Parameter	Default	Description
edit Edit	required	The Edit to perform.

Returns

Type	Description
Any	Data relating to the edit that may be useful. The data returned
Any	may be different depending on the edit performed.

find_matching_bracket method

def find_matching_bracket(self, bracket, search_from):

If the character is a bracket, find the matching bracket.

Parameters

Parameter	Default	Description
bracket str	required	The character we're searching for the matching bracket of.
search_from Location	required	The location to start the search.

Returns

Type	Description
Location | None	The Location of the matching bracket, or None if it's not found.
Location | None	If the character is not available for bracket matching, None is returned.

get_column_width method

def get_column_width(self, row, column):

Get the cell offset of the column from the start of the row.

Parameters

Parameter	Default	Description
row int	required	The row index.
column int	required	The column index (codepoint offset from start of row).

Returns

Type	Description
int	The cell width of the column relative to the start of the row.

get_cursor_down_location method

def get_cursor_down_location(self):

Get the location the cursor will move to if it moves down.

Returns

Type	Description
Location	The location the cursor will move to if it moves down.

get_cursor_left_location method

def get_cursor_left_location(self):

Get the location the cursor will move to if it moves left.

Returns

Type	Description
Location	The location of the cursor if it moves left.

get_cursor_line_end_location method

def get_cursor_line_end_location(self):

Get the location of the end of the current line.

Returns

Type	Description
Location	The (row, column) location of the end of the cursors current line.

get_cursor_line_start_location method

def get_cursor_line_start_location(self):

Get the location of the start of the current line.

Returns

Type	Description
Location	The (row, column) location of the start of the cursors current line.

get_cursor_right_location method

def get_cursor_right_location(self):

Get the location the cursor will move to if it moves right.

Returns

Type	Description
Location	the location the cursor will move to if it moves right.

get_cursor_up_location method

def get_cursor_up_location(self):

Get the location the cursor will move to if it moves up.

Returns

Type	Description
Location	The location the cursor will move to if it moves up.

get_cursor_word_left_location method

def get_cursor_word_left_location(self):

Get the location the cursor will jump to if it goes 1 word left.

Returns

Type	Description
Location	The location the cursor will jump on "jump word left".

get_cursor_word_right_location method

def get_cursor_word_right_location(self):

Get the location the cursor will jump to if it goes 1 word right.

Returns

Type	Description
Location	The location the cursor will jump on "jump word right".

get_target_document_location method

def get_target_document_location(self, event):

Given a MouseEvent, return the row and column offset of the event in document-space.

Parameters

Parameter	Default	Description
event MouseEvent	required	The MouseEvent.

Returns

Type	Description
Location	The location of the mouse event within the document.

get_text_range method

def get_text_range(self, start, end):

Get the text between a start and end location.

Parameters

Parameter	Default	Description
start Location	required	The start location.
end Location	required	The end location.

Returns

Type	Description
str	The text between start and end.

insert method

def insert(
    self,
    text,
    location=None,
    *,
    maintain_selection_offset=True
):

Insert text into the document.

Parameters

Parameter	Default	Description
text str	required	The text to insert.
location Location | None	None	The location to insert text, or None to use the cursor location.
maintain_selection_offset bool	True	If True, the active Selection will be updated such that the same text is selected before and after the selection, if possible. Otherwise, the cursor will jump to the end point of the edit.

Returns

Type	Description
EditResult	An EditResult containing information about the edit.

load_document method

def load_document(self, document):

Load a document into the TextArea.

Parameters

Parameter	Default	Description
document DocumentBase	required	The document to load into the TextArea.

load_text method

def load_text(self, text):

Load text into the TextArea.

This will replace the text currently in the TextArea.

Parameters

Parameter	Default	Description
text str	required	The text to load into the TextArea.

move_cursor method

def move_cursor(
    self,
    location,
    select=False,
    center=False,
    record_width=True,
):

Move the cursor to a location.

Parameters

Parameter	Default	Description
location Location	required	The location to move the cursor to.
select bool	False	If True, select text between the old and new location.
center bool	False	If True, scroll such that the cursor is centered.
record_width bool	True	If True, record the cursor column cell width after navigating so that we jump back to the same width the next time we move to a row that is wide enough.

move_cursor_relative method

def move_cursor_relative(
    self,
    rows=0,
    columns=0,
    select=False,
    center=False,
    record_width=True,
):

Move the cursor relative to its current location.

Parameters

Parameter	Default	Description
rows int	0	The number of rows to move down by (negative to move up)
columns int	0	The number of columns to move right by (negative to move left)
select bool	False	If True, select text between the old and new location.
center bool	False	If True, scroll such that the cursor is centered.
record_width bool	True	If True, record the cursor column cell width after navigating so that we jump back to the same width the next time we move to a row that is wide enough.

record_cursor_width method

def record_cursor_width(self):

Record the current cell width of the cursor.

This is used where we navigate up and down through rows. If we're in the middle of a row, and go down to a row with no content, then we go down to another row, we want our cursor to jump back to the same offset that we were originally at.

register_language method

def register_language(self, language, highlight_query):

Register a language and corresponding highlight query.

Calling this method does not change the language of the TextArea. On switching to this language (via the language reactive attribute), syntax highlighting will be performed using the given highlight query.

If a string name is supplied for a builtin supported language, then this method will update the default highlight query for that language.

Registering a language only registers it to this instance of TextArea.

Parameters

Parameter	Default	Description
language str | 'Language'	required	A string referring to a builtin language or a tree-sitter Language object.
highlight_query str	required	The highlight query to use for syntax highlighting this language.

register_theme method

def register_theme(self, theme):

Register a theme for use by the TextArea.

After registering a theme, you can set themes by assigning the theme name to the TextArea.theme reactive attribute. For example text_area.theme = "my_custom_theme" where "my_custom_theme" is the name of the theme you registered.

If you supply a theme with a name that already exists that theme will be overwritten.

replace method

def replace(
    self,
    insert,
    start,
    end,
    *,
    maintain_selection_offset=True
):

Replace text in the document with new text.

Parameters

Parameter	Default	Description
insert str	required	The text to insert.
start Location	required	The start location
end Location	required	The end location.
maintain_selection_offset bool	True	If True, the active Selection will be updated such that the same text is selected before and after the selection, if possible. Otherwise, the cursor will jump to the end point of the edit.

Returns

Type	Description
EditResult	An EditResult containing information about the edit.

scroll_cursor_visible method

def scroll_cursor_visible(self, center=False, animate=False):

Scroll the TextArea such that the cursor is visible on screen.

Parameters

Parameter	Default	Description
center bool	False	True if the cursor should be scrolled to the center.
animate bool	False	True if we should animate while scrolling.

Returns

Type	Description
Offset	The offset that was scrolled to bring the cursor into view.

select_all method

def select_all(self):

Select all of the text in the TextArea.

select_line method

def select_line(self, index):

Select all the text in the specified line.

Parameters

Parameter	Default	Description
index int	required	The index of the line to select (starting from 0).

---

Highlight module-attribute

Highlight = Tuple[StartColumn, EndColumn, HighlightName]

A tuple representing a syntax highlight within one line.

Location module-attribute

Location = Tuple[int, int]

A location (row, column) within the document. Indexing starts at 0.

Document class

def __init__(self, text):

Bases: DocumentBase

A document which can be opened in a TextArea.

line_count property

line_count: int

Returns the number of lines in the document.

lines property

lines: list[str]

Get the document as a list of strings, where each string represents a line.

Newline characters are not included in at the end of the strings.

The newline character used in this document can be found via the Document.newline property.

newline property

newline: Newline

Get the Newline used in this document (e.g. ' ', ' '. etc.)

text property

text: str

Get the text from the document.

get_index_from_location method

def get_index_from_location(self, location):

Given a location, returns the index from the document's text.

Parameters

Parameter	Default	Description
location Location	required	The location in the document.

Returns

Type	Description
int	The index in the document's text.

get_line method

def get_line(self, index):

Returns the line with the given index from the document.

Parameters

Parameter	Default	Description
index int	required	The index of the line in the document.

Returns

Type	Description
str	The string representing the line.

get_location_from_index method

def get_location_from_index(self, index):

Given an index in the document's text, returns the corresponding location.

Parameters

Parameter	Default	Description
index int	required	The index in the document's text.

Returns

Type	Description
Location	The corresponding location.

get_size method

def get_size(self, tab_width):

The Size of the document, taking into account the tab rendering width.

Parameters

Parameter	Default	Description
tab_width int	required	The width to use for tab indents.

Returns

Type	Description
Size	The size (width, height) of the document.

get_text_range method

def get_text_range(self, start, end):

Get the text that falls between the start and end locations.

Returns the text between start and end, including the appropriate line separator character as specified by Document._newline. Note that _newline is set automatically to the first line separator character found in the document.

Parameters

Parameter	Default	Description
start Location	required	The start location of the selection.
end Location	required	The end location of the selection.

Returns

Type	Description
str	The text between start (inclusive) and end (exclusive).

replace_range method

def replace_range(self, start, end, text):

Replace text at the given range.

Parameters

Parameter	Default	Description
start Location	required	A tuple (row, column) where the edit starts.
end Location	required	A tuple (row, column) where the edit ends.
text str	required	The text to insert between start and end.

Returns

Type	Description
EditResult	The EditResult containing information about the completed replace operation.

DocumentBase class

Bases: ABC

Describes the minimum functionality a Document implementation must provide in order to be used by the TextArea widget.

line_count property abstractmethod

line_count: int

Returns the number of lines in the document.

newline property abstractmethod

newline: Newline

Return the line separator used in the document.

text property abstractmethod

text: str

The text from the document as a string.

get_line abstractmethod

def get_line(self, index):

Returns the line with the given index from the document.

This is used in rendering lines, and will be called by the TextArea for each line that is rendered.

Parameters

Parameter	Default	Description
index int	required	The index of the line in the document.

Returns

Type	Description
str	The str instance representing the line.

get_size abstractmethod

def get_size(self, indent_width):

Get the size of the document.

The height is generally the number of lines, and the width is generally the maximum cell length of all the lines.

Parameters

Parameter	Default	Description
indent_width int	required	The width to use for tab characters.

Returns

Type	Description
Size	The Size of the document bounding box.

get_text_range abstractmethod

def get_text_range(self, start, end):

Get the text that falls between the start and end locations.

Parameters

Parameter	Default	Description
start Location	required	The start location of the selection.
end Location	required	The end location of the selection.

Returns

Type	Description
str	The text between start (inclusive) and end (exclusive).

query_syntax_tree method

def query_syntax_tree(
    self, query, start_point=None, end_point=None
):

Query the tree-sitter syntax tree.

The default implementation always returns an empty list.

To support querying in a subclass, this must be implemented.

Parameters

Parameter	Default	Description
query Query	required	The tree-sitter Query to perform.
start_point tuple[int, int] | None	None	The (row, column byte) to start the query at.
end_point tuple[int, int] | None	None	The (row, column byte) to end the query at.

Returns

Type	Description
list[tuple[Node, str]]	A tuple containing the nodes and text captured by the query.

replace_range abstractmethod

def replace_range(self, start, end, text):

Replace the text at the given range.

Parameters

Parameter	Default	Description
start Location	required	A tuple (row, column) where the edit starts.
end Location	required	A tuple (row, column) where the edit ends.
text str	required	The text to insert between start and end.

Returns

Type	Description
EditResult	The new end location after the edit is complete.

Edit class

Implements the Undoable protocol to replace text at some range within a document.

from_location instance-attribute

from_location: Location

The start location of the insert.

maintain_selection_offset instance-attribute

maintain_selection_offset: bool

If True, the selection will maintain its offset to the replacement range.

text instance-attribute

text: str

The text to insert. An empty string is equivalent to deletion.

to_location instance-attribute

to_location: Location

The end location of the insert

after method

def after(self, text_area):

Possibly update the cursor location after the widget has been refreshed.

Parameters

Parameter	Default	Description
text_area TextArea	required	The TextArea this operation was performed on.

do method

def do(self, text_area):

Perform the edit operation.

Parameters

Parameter	Default	Description
text_area TextArea	required	The TextArea to perform the edit on.

Returns

Type	Description
EditResult	An EditResult containing information about the replace operation.

undo method

def undo(self, text_area):

Undo the edit operation.

Parameters

Parameter	Default	Description
text_area TextArea	required	The TextArea to undo the insert operation on.

Returns

Type	Description
EditResult	An EditResult containing information about the replace operation.

EditResult class

Contains information about an edit that has occurred.

end_location instance-attribute

end_location: Location

The new end Location after the edit is complete.

replaced_text instance-attribute

replaced_text: str

The text that was replaced.

LanguageDoesNotExist class

Bases: Exception

Raised when the user tries to use a language which does not exist. This means a language which is not builtin, or has not been registered.

Selection class

Bases: NamedTuple

A range of characters within a document from a start point to the end point. The location of the cursor is always considered to be the end point of the selection. The selection is inclusive of the minimum point and exclusive of the maximum point.

end instance-attribute class-attribute

end: Location = (0, 0)

The end location of the selection.

If you were to click and drag a selection inside a text-editor, this is where you finished dragging.

is_empty property

is_empty: bool

Return True if the selection has 0 width, i.e. it's just a cursor.

start instance-attribute class-attribute

start: Location = (0, 0)

The start location of the selection.

If you were to click and drag a selection inside a text-editor, this is where you started dragging.

cursor classmethod

def cursor(cls, location):

Create a Selection with the same start and end point - a "cursor".

Parameters

Parameter	Default	Description
location Location	required	The location to create the zero-width Selection.

SyntaxAwareDocument class

def __init__(self, text, language):

Bases: Document

A wrapper around a Document which also maintains a tree-sitter syntax tree when the document is edited.

The primary reason for this split is actually to keep tree-sitter stuff separate, since it isn't supported in Python 3.7. By having the tree-sitter code isolated in this subclass, it makes it easier to conditionally import. However, it does come with other design flaws (e.g. Document is required to have methods which only really make sense on SyntaxAwareDocument).

If you're reading this and Python 3.7 is no longer supported by Textual, consider merging this subclass into the Document superclass.

Parameters

Parameter	Default	Description
text str	required	The initial text contained in the document.
language str | Language	required	The language to use. You can pass a string to use a supported language, or pass in your own tree-sitter Language object.

language instance-attribute

language: Language | None = None

The tree-sitter Language or None if tree-sitter is unavailable.

get_line method

def get_line(self, line_index):

Return the string representing the line, not including new line characters.

Parameters

Parameter	Default	Description
line_index int	required	The index of the line.

Returns

Type	Description
str	The string representing the line.

prepare_query method

def prepare_query(self, query):

Prepare a tree-sitter tree query.

Queries should be prepared once, then reused.

To execute a query, call query_syntax_tree.

Parameters

Parameter	Default	Description
query str	required	The string query to prepare.

Returns

Type	Description
Query | None	The prepared query.

query_syntax_tree method

def query_syntax_tree(
    self, query, start_point=None, end_point=None
):

Query the tree-sitter syntax tree.

The default implementation always returns an empty list.

To support querying in a subclass, this must be implemented.

Parameters

Parameter	Default	Description
query Query	required	The tree-sitter Query to perform.
start_point tuple[int, int] | None	None	The (row, column byte) to start the query at.
end_point tuple[int, int] | None	None	The (row, column byte) to end the query at.

Returns

Type	Description
list[tuple['Node', str]]	A tuple containing the nodes and text captured by the query.

replace_range method

def replace_range(self, start, end, text):

Replace text at the given range.

Parameters

Parameter	Default	Description
start Location	required	A tuple (row, column) where the edit starts.
end Location	required	A tuple (row, column) where the edit ends.
text str	required	The text to insert between start and end.

Returns

Type	Description
EditResult	The new end location after the edit is complete.

TextAreaTheme class

A theme for the TextArea widget.

Allows theming the general widget (gutter, selections, cursor, and so on) and mapping of tree-sitter tokens to Rich styles.

For example, consider the following snippet from the markdown.scm highlight query file. We've assigned the heading_content token type to the name heading.

(heading_content) @heading

Now, we can map this heading name to a Rich style, and it will be styled as such in the TextArea, assuming a parser which returns a heading_content node is used (as will be the case when language="markdown").

TextAreaTheme('my_theme', syntax_styles={'heading': Style(color='cyan', bold=True)})

We can register this theme with our TextArea using the TextArea.register_theme method, and headings in our markdown files will be styled bold cyan.

base_style instance-attribute class-attribute

base_style: Style | None = None

The background style of the text area. If None the parent style will be used.

bracket_matching_style instance-attribute class-attribute

bracket_matching_style: Style | None = None

The style to apply to matching brackets. If None, a legible Style will be generated.

cursor_line_gutter_style instance-attribute class-attribute

cursor_line_gutter_style: Style | None = None

The style to apply to the gutter of the line the cursor is on. If None, a legible Style will be generated.

cursor_line_style instance-attribute class-attribute

cursor_line_style: Style | None = None

The style to apply to the line the cursor is on.

cursor_style instance-attribute class-attribute

cursor_style: Style | None = None

The style of the cursor. If None, a legible Style will be generated.

gutter_style instance-attribute class-attribute

gutter_style: Style | None = None

The style of the gutter. If None, a legible Style will be generated.

name instance-attribute

name: str

The name of the theme.

selection_style instance-attribute class-attribute

selection_style: Style | None = None

The style of the selection. If None a default selection Style will be generated.

syntax_styles instance-attribute class-attribute

syntax_styles: dict[str, Style] = field(
    default_factory=dict
)

The mapping of tree-sitter names from the highlight_query to Rich styles.

builtin_themes classmethod

def builtin_themes(cls):

Get a list of all builtin TextAreaThemes.

Returns

Type	Description
list[TextAreaTheme]	A list of all builtin TextAreaThemes.

default classmethod

def default(cls):

Get the default syntax theme.

Returns

Type	Description
TextAreaTheme	The default TextAreaTheme (probably "monokai").

get_builtin_theme classmethod

def get_builtin_theme(cls, theme_name):

Get a TextAreaTheme by name.

Given a theme_name, return the corresponding TextAreaTheme object.

Parameters

Parameter	Default	Description
theme_name str	required	The name of the theme.

Returns

Type	Description
TextAreaTheme | None	The TextAreaTheme corresponding to the name or None if the theme isn't found.

get_highlight method

def get_highlight(self, name):

Return the Rich style corresponding to the name defined in the tree-sitter highlight query for the current theme.

Parameters

Parameter	Default	Description
name str	required	The name of the highlight.

Returns

Type	Description
Style | None	The Style to use for this highlight, or None if no style.

ThemeDoesNotExist class

Bases: Exception

Raised when the user tries to use a theme which does not exist. This means a theme which is not builtin, or has not been registered.