README.md

# imglab

`imglab` is the official Elixir library to integrate with imglab services.

## Installation

Add `imglab` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [
    {:imglab, "~> 0.2"}
  ]
end
```

And run:

```sh
$ mix deps.get
```

## Elixir compatibility

`imglab` has been successfully tested on the following Elixir versions: `1.13`, `1.12`, `1.11`, `1.10`, `1.9`, `1.8`, `1.7`, `1.6`, `1.5`, and `1.4`.

## Generating URLs

You can use `Imglab.url/3` function to generate imglab compatible URLs for your application.

The easiest way to generate a URL is to specify the `source_name`, `path` and required `parameters`:

```elixir
Imglab.url("assets", "image.jpeg", width: 500, height: 600)
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600"

Imglab.url("avatars", "user-01.jpeg", width: 300, height: 300, mode: :crop, crop: :face, format: :webp)
"https://avatars.imglab-cdn.net/user-01.jpeg?width=300&height=300&mode=crop&crop=face&format=webp"
```

If some specific settings are required for the source you can use a `Imglab.Source` struct instead of a `string` source name:

```elixir
Imglab.url(Imglab.Source.new("assets"), "image.jpeg", width: 500, height: 600)
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600"
```

### Using secure image sources

For sources that require signed URLs you can specify `secure_key` and `secure_salt` attributes:

```elixir
"assets"
|> Imglab.Source.new(secure_key: "assets-secure-key", secure_salt: "assets-secure-salt")
|> Imglab.url("image.jpeg", width: 500, height: 600)
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&signature=generated-signature"
```

`signature` query parameter will be automatically generated and attached to the returned URL.

> Note: `secure_key` and `secure_salt` attributes are secrets that should not be added to a code repository. Please use environment vars or other secure method to use them in your application.

### Using HTTP instead of HTTPS

In the case that HTTP schema is required instead of HTTPS you can set `https` attribute to `false` when creating the source:

```elixir
"assets"
|> Imglab.Source.new(https: false)
|> Imglab.url("image.jpeg", width: 500, height: 600)
"http://assets.imglab-cdn.net/image.jpeg?width=500&height=600"
```

> Note: HTTPS is the default and recommended way to generate URLs with imglab.

### Specifying parameters

Any parameter from the imglab API can be used to generate URLs with `Imglab.url/3` function. For parameters that required dashes characters like `trim-color` you can use regular underscore Elixir atoms like `:trim_color` those will be normalized in the URL generation to it's correct form:

```elixir
Imglab.url("assets", "image.jpeg", trim: "color", trim_color: "black")
"https://assets.imglab-cdn.net/image.jpeg?trim=color&trim-color=black"
```

It is possible to use quoted atoms too:

```elixir
Imglab.url("assets", "image.jpeg", trim: "color", "trim-color": "black")
"https://assets.imglab-cdn.net/image.jpeg?trim=color&trim-color=black"
```

### Specifying color parameters

Some imglab parameters can receive a color as value. It is possible to specify these color values as strings:

```elixir
# Specifying a RGB color as string
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: :contain, background_color: "255,0,0")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=255%2C0%2C0"

# Specifying a RGBA color as string
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: :contain, background_color: "255,0,0,128")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=255%2C0%2C0%2C128"

# Specifying a named color as string
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: :contain, background_color: "red")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=red"

# Specifying a hexadecimal color as string
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: :contain, background_color: "F00")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=F00"
```

You can additionally use `Imglab.Color` macros to specify these color values:

```elixir
# Remember to import Imglab.Color before use these macros
import Imglab.Color

# Using color macro for a RGB color
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: "contain", background_color: color(255, 0, 0))
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=255%2C0%2C0"

# Using color macro for a RGBA color
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: "contain", background_color: color(255, 0, 0, 128))
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=255%2C0%2C0%2C128"

# Using color macro for a named color
Imglab.url("assets", "image.jpeg", width: 500, height: 600, mode: "contain", background_color: color("red"))
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&mode=contain&background-color=red"
```

> Note: specify hexadecimal color values using `Imglab.Color` macros is not allowed. You can use strings instead.

### Specifying position parameters

Some imglab parameters can receive a position as value. It is possible to specify these values using strings:

```elixir
# Specifying a horizontal and vertical position as string
Imglab.url("assets", "image.jpeg", width: 500, height: 500, mode: "crop", crop: "left,top")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=500&mode=crop&crop=left%2Ctop"

# Specifying a vertical and horizontal position as string
Imglab.url("assets", "image.jpeg", width: 500, height: 500, mode: "crop", crop: "top,left")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=500&mode=crop&crop=top%2Cleft"

# Specifying a position as string
Imglab.url("assets", "image.jpeg", width: 500, height: 500, mode: "crop", crop: "left")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=500&mode=crop&crop=left"
```

You can additionally use `Imglab.Position` macros to specify these position values:

```elixir
# Remember to import Imglab.Position before use these macros
import Imglab.Position

# Using position macro for a horizontal and vertical position
Imglab.url("assets", "image.jpeg", width: 500, height: 500, mode: "crop", crop: position("left", "top"))
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=500&mode=crop&crop=left%2Ctop"

# Using position macro for a vertical and horizontal position
Imglab.url("assets", "image.jpeg", width: 500, height: 500, mode: "crop", crop: position("top", "left"))
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=500&mode=crop&crop=top%2Cleft"

# Using position macro for a position
Imglab.url("assets", "image.jpeg", width: 500, height: 500, mode: "crop", crop: position("left"))
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=500&mode=crop&crop=left"
```

### Specifying URL parameters

Some imglab parameters can receive URLs as values. It is possible to specify these parameter values as strings.

```elixir
Imglab.url("assets", "image.jpeg", width: 500, height: 600, watermark: "logo.svg")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&watermark=logo.svg"
```

And even use parameters if required:

```elixir
Imglab.url("assets", "image.jpeg", width: 500, height: 600, watermark: "logo.svg?width=100&format=png")
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&watermark=logo.svg%3Fwidth%3D100%26format%3Dpng"
```

Additionally you can use nested `Imglab.url/3` calls to specify these URL values:

```elixir
Imglab.url(
  "assets",
  "image.jpeg",
  width: 500,
  height: 600,
  watermark: Imglab.url("assets", "logo.svg", width: 100, format: "png")
)
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&watermark=https%3A%2F%2Fassets.imglab-cdn.net%2Flogo.svg%3Fwidth%3D100%26format%3Dpng"
```

If the resource is located in a different source we can specify it using `Imglab.url/3`:

```elixir
Imglab.url(
  "assets",
  "image.jpeg",
  width: 500,
  height: 600,
  watermark: Imglab.url("marketing", "logo.svg", width: 100, format: "png")
)
"https://assets.imglab-cdn.net/image.jpeg?width=500&height=600&watermark=https%3A%2F%2Fmarketing.imglab-cdn.net%2Flogo.svg%3Fwidth%3D100%26format%3Dpng"
```

Using secure sources for URLs parameter values is possible too:

```elixir
marketing_source = Imglab.Source.new("marketing", secure_key: "marketing-secure-key", secure_salt: "marketing-secure-salt")

Imglab.url(
  "assets",
  "image.jpeg",
  width: 500,
  height: 600,
  watermark: Imglab.url(marketing_source, "logo.svg", width: 100, format: "png")
)
```

`signature` query parameter will be automatically generated and attached to the nested URL value.

## Generating URLs for on-premises imglab server

For on-premises imglab server is possible to define custom sources pointing to your server location.

* `:https` - a `boolean` value specifying if the source should use https or not (default: `true`)
* `:host` - a `string` specifying the host where the imglab server is located. (default: `imglab-cdn.net`)
* `:port` - a `:inet.port_number` specifying a port where the imglab server is located.
* `:subdomains` - a `boolean` value specifying if the source should be specified using subdomains instead of using the path. (default: `true`)

If we have our on-premises imglab server at `http://my-company.com:8080` with a source named `images` we can use the following source settings to access a `logo.png` image:

```elixir
"images"
|> Imglab.Source.new(https: false, host: "my-company.com", port: 8080)
|> Imglab.url("logo.png", width: 300, height: 300, format: "png")
"http://images.my-company.com:8080/logo.png?width=300&height=300&format=png"
```

It is possible to use secure sources too:

```elixir
"images"
|> Imglab.Source.new(https: false, host: "my-company.com", port: 8080, secure_key: "images-secure-key", secure_salt: "images-secure-salt")
|> Imglab.url("logo.png", width: 300, height: 300, format: "png")
"http://images.my-company.com:8080/logo.png?width=300&height=300&format=png&signature=generated-signature"
```

### Using sources with disabled subdomains

In the case that your on-premises imglab server is configured to use source names as paths instead of subdomains you can set `subdomains` attribute to `false`:

```elixir
"images"
|> Imglab.Source.new(https: false, host: "my-company.com", port: 8080, subdomains: false)
|> Imglab.url("logo.png", width: 300, height: 300, format: "png")
"http://my-company.com:8080/images/logo.png?width=300&height=300&format=png"
```

## License

imglab source code is released under [MIT License](LICENSE).