# Utility Library

To assist with the usage of this Extension, a [utility library](https://www.npmjs.com/package/@invertase/image-processing-api) exists
to help provide a typed API interface for easily constructing operations to send to the API.

## Installation

```bash
npm i --save @invertase/image-processing-api
```

## Usage

Once installed, import the `builder` function from the library:

```ts
import { builder } from '@invertase/image-processing-api';
```

The `builder` function returns a new `ImageProcessingApi` instance which provides a API for constructing operations to send to the API.
At a minimum, you must provide an `input` and `output` operation as required by the extension itself:

```ts
import { builder } from '@invertase/image-processing-api';

const build = builder()
  .input({
    url: 'https://example.com/image.jpg',
  })
  .output({
    format: 'png',
  });
```

To provide additional operations, you can chain them together. For example,
to apply a blur, grayscale and flip the provided input image, and return a new PNG image:

```ts
const output = builder()
  .input({
    url: 'https://example.com/image.jpg',
  })
  .blur()
  .grayscale()
  .flip()
  .output({
    format: 'png',
  });
```

Please refer to the [operations](/operations) documentation for a full list of available operations, their API and examples.

Once you have constructed your operations, you can return the operations as JSON, a JSON string or encoded JSON string value:

```ts
const json = output.toJSON();
const jsonString = output.toJSONString();
const encodedJsonString = output.toEncodedJSONString();
```

The encoded JSON string value can be passed directly to the extension as the `operations` parameter:

```ts
const encodedJsonString = output.toEncodedJSONString();

const url = `https://{LOCATION}-{PROJECT_ID}.cloudfunctions.net/ext-image-processing-api-handler/process?operations=${encodedJsonString}`;
```