# Interface: Monitor

Imperative controller for a WebGPU signal monitor canvas.

## Remarks

The controller owns its renderer resources, but borrows both the device and
canvas supplied to [createMonitor](../index.md#createmonitor). Call [Monitor.destroy](#destroy)
before releasing either borrowed resource.

## Methods

### clear()

> **clear**(): `void`

Clear the loaded series and blank the monitor.

#### Returns

`void`

***

### destroy()

> **destroy**(): `void`

Release event handlers, canvas configuration, and renderer resources.

#### Returns

`void`

***

### extend()

> **extend**(`validFrames`, `values?`): `void`

Advance the committed frame frontier.

Pass `values` to replace the loaded sample buffer; otherwise mutate the
existing buffer in place before calling.

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `validFrames` | `number` | Number of frames ready to draw, clamped to the series length. |
| `values?` | `Float32Array`\<`ArrayBufferLike`\> | Optional replacement buffer with the same length as the loaded series. |

#### Returns

`void`

#### Throws

Error when no series is loaded or the replacement buffer length differs.

***

### load()

> **load**(`series`, `signal?`): `void`

Bind a series and schedule its committed frames for painting.

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `series` | [`Series`](Series.md) | Packed monitor samples and time coordinates. |
| `signal?` | `number` | Initial signal index. Default: `0`. |

#### Returns

`void`

#### Throws

Error when the series shape or signal index is invalid.

***

### on()

> **on**\<`K`\>(`event`, `handler`): () => `void`

Subscribe to a monitor event and receive an unsubscribe callback.

#### Type Parameters

| Type Parameter |
| :------ |
| `K` *extends* keyof [`Events`](../index.md#events) |

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `event` | `K` | Event name to observe. |
| `handler` | (`payload`) => `void` | Callback invoked with the event payload. |

#### Returns

A function that removes the handler.

() => `void`

***

### pause()

> **pause**(): `void`

Pause painting and pointer hover work until resumed.

#### Returns

`void`

***

### resume()

> **resume**(): `void`

Resume painting after a consumer pause.

#### Returns

`void`

***

### setColormap()

> **setColormap**(`fn`): `void`

Replace the transfer function used for trace color.

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `fn` | (`t`) => readonly \[`number`, `number`, `number`\] | Function mapping normalized values in `[0, 1]` to RGB channels in `[0, 1]`. |

#### Returns

`void`

***

### setFocus()

> **setFocus**(`element`): `void`

Highlight one element with a foreground trace, or pass null to clear focus.

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `element` | `number` \| `null` | Element index to focus, or `null` to clear focus. |

#### Returns

`void`

***

### setSignal()

> **setSignal**(`signal`): `void`

Switch the displayed signal.

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `signal` | `number` | Signal index in `[0, series.signalCount)`. |

#### Returns

`void`

#### Throws

Error when no series is loaded or the signal index is invalid.

***

### setValueRange()

> **setValueRange**(`range`): `void`

Override the value domain, or pass null to return to auto-fit.

#### Parameters

| Parameter | Type | Description |
| :------ | :------ | :------ |
| `range` | readonly \[`number`, `number`\] \| `null` | Fixed `[min, max]` domain, or `null` for auto-fit. |

#### Returns

`void`