gpui-focus-handle

Overview

GPUI's focus system enables keyboard navigation and focus management.

Key Concepts:

• FocusHandle: Reference to focusable element
• Focus tracking: Current focused element
• Keyboard navigation: Tab/Shift-Tab between elements
• Focus events: on_focus, on_blur

Quick Start

Creating Focus Handles

struct FocusableComponent {
    focus_handle: FocusHandle,
}

impl FocusableComponent {
    fn new(cx: &mut Context<Self>) -> Self {
        Self {
            focus_handle: cx.focus_handle(),
        }
    }
}

Making Elements Focusable

impl Render for FocusableComponent {
    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        div()
            .track_focus(&self.focus_handle)
            .on_action(cx.listener(Self::on_enter))
            .child("Focusable content")
    }

    fn on_enter(&mut self, _: &Enter, cx: &mut Context<Self>) {
        // Handle Enter key when focused
        cx.notify();
    }
}

Focus Management

impl MyComponent {
    fn focus(&mut self, cx: &mut Context<Self>) {
        self.focus_handle.focus(cx);
    }

    fn is_focused(&self, cx: &App) -> bool {
        self.focus_handle.is_focused(cx)
    }

    fn blur(&mut self, cx: &mut Context<Self>) {
        cx.blur();
    }
}

Focus Events

Handling Focus Changes

impl Render for MyInput {
    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let is_focused = self.focus_handle.is_focused(cx);

        div()
            .track_focus(&self.focus_handle)
            .on_focus(cx.listener(|this, _event, cx| {
                this.on_focus(cx);
            }))
            .on_blur(cx.listener(|this, _event, cx| {
                this.on_blur(cx);
            }))
            .when(is_focused, |el| {
                el.bg(cx.theme().focused_background)
            })
            .child(self.render_content())
    }
}

impl MyInput {
    fn on_focus(&mut self, cx: &mut Context<Self>) {
        // Handle focus gained
        cx.notify();
    }

    fn on_blur(&mut self, cx: &mut Context<Self>) {
        // Handle focus lost
        cx.notify();
    }
}

Keyboard Navigation

Tab Order

Elements with track_focus() automatically participate in Tab navigation.

div()
    .child(
        input1.track_focus(&focus1)  // Tab order: 1
    )
    .child(
        input2.track_focus(&focus2)  // Tab order: 2
    )
    .child(
        input3.track_focus(&focus3)  // Tab order: 3
    )

Focus Within Containers

impl Container {
    fn focus_first(&mut self, cx: &mut Context<Self>) {
        if let Some(first) = self.children.first() {
            first.update(cx, |child, cx| {
                child.focus_handle.focus(cx);
            });
        }
    }

    fn focus_next(&mut self, cx: &mut Context<Self>) {