> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mentraglass.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Input

> Glasses button presses and touchpad gestures.

`session.input` delivers the physical controls on the glasses: button presses and
touchpad gestures. The starter scaffold wires a button press to the display, so a
short press shows a text wall.

```typescript src/background/index.ts theme={null}
import { registerMiniapp } from "@mentra/miniapp/background";

registerMiniapp((session) => {
  session.input.onButtonPress((press) => {
    session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: `${press.buttonId}: ${press.pressType}`}]);
  });
});
```

Button events only reach glasses that have a button. Declare a `BUTTON` hardware
requirement in your [manifest](/app-devs/core-concepts/miniapp-manifest) to gate
the miniapp to those glasses.

## Button presses

`onButtonPress` fires on every press of a physical button:

```typescript theme={null}
session.input.onButtonPress((press) => {
  if (press.pressType === "long") session.display.render([]);
});
```

Each `ButtonPressData` has:

| Field       | Type                | Notes               |
| ----------- | ------------------- | ------------------- |
| `buttonId`  | `string`            | Which button fired. |
| `pressType` | `"short" \| "long"` | Press duration.     |

## Touch gestures

`onTouch` subscribes to touchpad gestures. Pass a handler for every gesture, a
single gesture name to filter, or an array of names for one subscription across
several gestures.

```typescript theme={null}
// Every touch gesture.
session.input.onTouch((touch) => {
  session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: touch.kind}]);
});

// One gesture.
session.input.onTouch("single_tap", () => {
  session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: "Tap"}]);
});

// Several gestures, one subscription.
session.input.onTouch(["swipe_up", "swipe_down"], (touch) => {
  // touch.kind tells you which one.
});
```

Each `TouchData` has:

| Field  | Type     | Notes                              |
| ------ | -------- | ---------------------------------- |
| `kind` | `string` | The gesture. See the values below. |

The gesture values the runtime reports:

| `kind`         | Gesture                       |
| -------------- | ----------------------------- |
| `"single_tap"` | A single tap on the touchpad. |
| `"double_tap"` | Two quick taps.               |
| `"triple_tap"` | Three quick taps.             |
| `"long_press"` | A press and hold.             |
| `"swipe_up"`   | A swipe up.                   |
| `"swipe_down"` | A swipe down.                 |

Glasses can send other `kind` strings, so `kind` is typed as `string`. Match the
values you handle and ignore the rest.

## Cleaning up

`onButtonPress` and every `onTouch` form return an unsubscribe function:

```typescript theme={null}
const off = session.input.onTouch("single_tap", handler);
off(); // stop listening
```

Calling `onTouch` with an array returns one unsubscribe function that drops all of
the gestures it registered.