singularity-forge/docs/dev/pi-ui-tui/18-ime-support-the-focusable-interface.md

IME Support — The Focusable Interface

For components that display a text cursor and need IME (Input Method Editor) support for CJK languages:

import { CURSOR_MARKER, type Component, type Focusable } from "@mariozechner/pi-tui";

class MyInput implements Component, Focusable {
  focused: boolean = false;  // Set by TUI when focus changes

  render(width: number): string[] {
    const marker = this.focused ? CURSOR_MARKER : "";
    return [`> ${beforeCursor}${marker}\x1b[7m${atCursor}\x1b[27m${afterCursor}`];
  }
}

Container with Embedded Input

If your container contains an Input or Editor child, propagate focus:

class SearchDialog extends Container implements Focusable {
  private searchInput: Input;
  private _focused = false;

  get focused(): boolean { return this._focused; }
  set focused(value: boolean) {
    this._focused = value;
    this.searchInput.focused = value;  // Propagate!
  }

  constructor() {
    super();
    this.searchInput = new Input();
    this.addChild(this.searchInput);
  }
}

Without this, IME candidate windows (Chinese, Japanese, Korean input) appear in the wrong position.

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