textual/FAQ.md

Frequently Asked Questions

• Does Textual support images?
• How can I fix ImportError cannot import name ComposeResult from textual.app ?
• How do I center a widget in a screen?
• How do I pass arguments to an app?

Does Textual support images?

Textual doesn't have built in support for images yet, but it is on the Roadmap.

See also the rich-pixels project for a Rich renderable for images that works with Textual.

How can I fix ImportError cannot import name ComposeResult from textual.app ?

You likely have an older version of Textual. You can install the latest version by adding the -U switch which will force pip to upgrade.

The following should do it:

pip install "textual[dev]" -U

How do I center a widget in a screen?

To center a widget within a container use align. But remember that align works on the children of a container, it isn't something you use on the child you want centered.

For example, here's an app that shows a Button in the middle of a Screen:

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

class ButtonApp(App):

    CSS = """
    Screen {
        align: center middle;
    }
    """

    def compose(self) -> ComposeResult:
        yield Button("PUSH ME!")

if __name__ == "__main__":
    ButtonApp().run()

How do I pass arguments to an app?

When creating your App class, override __init__ as you would when inheriting normally. For example:

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

class Greetings(App[None]):

    def __init__(self, greeting: str="Hello", to_greet: str="World") -> None:
        self.greeting = greeting
        self.to_greet = to_greet
        super().__init__()

    def compose(self) -> ComposeResult:
        yield Static(f"{self.greeting}, {self.to_greet}")

Then the app can be run, passing in various arguments; for example:

# Running with default arguments.
Greetings().run()

# Running with a keyword arguyment.
Greetings(to_greet="davep").run()

# Running with both positional arguments.
Greetings("Well hello", "there").run()

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