# useComputerKeyboard

> The computer's keyboard as a keyboard of notes, as in a DAW: the middle row from A plays the white keys and the row above the black ones, by where the keys sit; Z and X move an octave, C and V the velocity.

```bash
npx shadcn@latest add @audio-ui/use-computer-keyboard
```

```ts
import { useComputerKeyboard } from "@/hooks/use-computer-keyboard";
```

- Files: `hooks/use-computer-keyboard.ts`, `lib/computer-keyboard.ts`
- Depends on: nothing; npm: nothing
- Used by: nothing

| Export | Kind | What it is |
| --- | --- | --- |
| `UseComputerKeyboardOptions` | interface |  |
| `useComputerKeyboard` | function | Plays notes from the computer's keyboard while `enabled` (`noteOfKey`'s layout): a key held is one note, released when the key is, or when the keys are turned off or the window loses focus. |

## Usage

The computer's keys as a keyboard of notes while `enabled`: the middle row from A plays the white keys from middle C and the row above the black ones, by the key's `code`, so any layout works. Z and X move an octave, C and V the velocity.

```tsx
import { useComputerKeyboard } from "@/hooks/use-computer-keyboard";

const keys = useComputerKeyboard({
  enabled: armed,
  onNoteOff: (note) => voices.noteOff(`key-${note}`),
  onNoteOn: (note, velocity) => voices.noteOn({ frequency: midiToHz(note), velocity }, `key-${note}`),
});
// keys.octave, keys.velocity for a readout
```

A key held is one note, released when the key is, when the keys are turned off, or when the window loses focus, so no note sticks. Keys typed into a field, or held with Cmd, Ctrl or Alt, are left to the page. `lib/computer-keyboard` (installed with it) has the layout, `noteOfKey`.