Remap System-Level Keybindings

[dorianpercic]

Hello everyone!

I'm curious if it's possible to override system-level key bindings for the Input widget in Textual. I tried adding a custom binding for ctrl+a like this:

BINDINGS = [Binding("ctrl+a", "select_all", "Select All")]
def action_select_all(self):
    self.log("Here") # This does not get executed

However, pressing Ctrl+a simply moves the cursor to the start of the input, just as if the terminal itself received it. It looks like the terminal emulator (konsole) intercepts this, so Textual never gets the event.
Is remapping ctrl+a within the Input widget possible given this behavior?

• Terminal Emulator: konsole 22.12.3
• Textual version: 4.0.0
• Python version: 3.11.2
• OS: Debian GNU/Linux 12 (bookworm)

[TomJGooding]

Where are you defining your bindings? This works for me:

from textual.app import App, ComposeResult
from textual.binding import Binding
from textual.widgets import Input


class CustomInput(Input):
    BINDINGS = [Binding("ctrl+a", "select_all", "Select All")]

    def action_select_all(self) -> None:
        self.notify("Select all", title="TODO")


class ExampleApp(App):
    def compose(self) -> ComposeResult:
        yield CustomInput()


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

[dorianpercic]

Hi @TomJGooding, thanks for your reply! I am defining it like shown below, and executing it in konsole. From the on_key method it works however, maybe that could be my workaround. :)

class UserInput(Static):
    BINDINGS = [Binding("ctrl+a", "select_all", "Select All")]

    class Submitted(Message):
        def __init__(self, message: str):
            super().__init__()
            self.message = message

    def __init__(self):
        super().__init__()

    def on_mount(self) -> None:
        self.input.focus()
        self.scroll_visible()

    def action_select_all(self):
        self.log("From action_select_all") # This is not triggered... 

    def on_key(self, event: events.Key):
        if event.key == "ctrl+a":
            self.log("from on_key") # This is triggered! 
            self.input.text_select_all()

    @on(Input.Submitted)
    def on_input_submitted(self, message: Input.Submitted) -> None:
        self.post_message(self.Submitted(message.value))

    def compose(self) -> ComposeResult:
        self.input = Input(placeholder="Enter message...", type="text", id="user-input")
        yield self.input

[TomJGooding]

Why are you wrapping the Input inside a Static widget?

When you press a key, Textual will first check for a matching binding in the BINDINGS list of the currently focused widget.¹ The problem in your application is that the Input is focused widget.

Footnotes

1. https://textual.textualize.io/guide/input/#bindings ↩

[willmcgugan]

You're extending a Static there, with an Input inside of it. If you want a custom Input, then you can extend the Input class as Tom has done.

I think that may be the root of the problem. But note that bindings won't work unless a widget is focusable. You can make a widget focusable by setting can_focus=True.

[dorianpercic]

Alright, thank you very much guys, this works now!

class UserInput(Input, can_focus=True):
    BINDINGS = [Binding("ctrl+a", "select_all", "Select All", show=False)]

    def __init__(self):
        super().__init__()

    def on_mount(self) -> None:
        self.scroll_visible()
        self.focus()

    def action_select_all(self):
        self.selection = Selection(0, len(self.value))

[willmcgugan]

You won't need the can_focus=True in this instance, since it is already set by the base class.