default_screen.py

"""An example showing how to use a default main screen.

Simple Textual apps place a lot of logic in the `App` class, but you can also
use a `Screen` as the main screen. This example shows how to do that, and how to
push modal screens from the main screen, and show a modal confirmation screen
when quitting the app. You'll never leave the main screen until you quit the
application, but you can still use the `App` class to manage a (few)
application-wide bindings.
"""

from textual import on
from textual.app import App, ComposeResult
from textual.containers import HorizontalGroup, VerticalGroup
from textual.screen import ModalScreen, Screen
from textual.widgets import Button, Footer, Label


class HelpModal(ModalScreen[None]):
    BINDINGS = [("escape", "dismiss", "Dismiss")]

    def compose(self) -> ComposeResult:
        yield Footer()
        yield Label("Just your regular help screen, dismiss with escape")


class MainScreen(Screen[None]):
    BINDINGS = [
        ("a", "add_item", "Add Item"),
        ("r", "remove_item", "Remove Item"),
        ("h", "show_help", "Help"),
    ]

    items: list[str] = []

    def compose(self) -> ComposeResult:
        yield Footer()
        yield Label()

    def on_mount(self) -> None:
        self.update_label()

    def action_add_item(self) -> None:
        self.items.append("💡")
        self.update_label()

    def action_remove_item(self) -> None:
        if self.items:
            self.items.pop()
            self.update_label()

    def update_label(self) -> None:
        widget = self.query_one(Label)
        if self.items:
            widget.update("".join(self.items))
        else:
            widget.update("Empty")

    def action_show_help(self) -> None:
        self.app.push_screen(HelpModal())


class ConfirmQuitScreen(ModalScreen[bool]):
    BINDINGS = [("escape", "dismiss", "Dismiss")]

    def compose(self) -> ComposeResult:
        yield Footer()
        with VerticalGroup():
            yield Label("Are you sure you want to quit?")
            yield HorizontalGroup(
                Button("Yes", id="yes_button", variant="success"),
                Button("No", id="no_button", variant="error"),
            )

    @on(Button.Pressed)
    def confirm(self, event: Button.Pressed) -> None:
        if event.button.id == "yes_button":
            self.dismiss(True)
        else:
            self.dismiss(False)


class MainApp(App[None]):
    BINDINGS = [("q", "confirm_quit", "Quit")]

    CSS = """
        MainScreen Label {
            width: 100%;
            text-align: center;
            padding-top: 5;
        }

        HelpModal {
            align: center middle;
            & Label {
                border: $primary hkey;
                background: $panel;
                padding: 1 2;
                margin-top: 3;
            }
        }

        ConfirmQuitScreen {
            align: center middle;
            & VerticalGroup {
                width: auto;

                & Label {
                    width: 100%;
                    text-align: center;
                }

                & HorizontalGroup {
                    width: auto;

                    & Button {
                        margin: 1 2;
                    }
                }
            }
        }
    """

    def get_default_screen(self) -> Screen[None]:
        return MainScreen()

    def action_confirm_quit(self) -> None:
        def callback(is_confirmed: bool | None) -> None:
            if is_confirmed:
                self.exit()

        self.push_screen(ConfirmQuitScreen(), callback=callback)


MainApp().run()