ImagePlug

ImagePlug is an image optimization server, written as a Plug.

Uses the image library under the hood.

Probably not quite ready for prime time yet.

Name not final!

Transforms

Transforms are passed through the query parameter transform. Multiple transforms can be supplied by separating them with a semicolon, and the transforms will be executed from left to right.

E.g. ?transform=scale=500;crop=50px50p will first scale the image to a width of 500 pixels, and then crop it from the center to 50% of the width and height.

More transforms are coming.

Crop

Crops the image from the center of the current focus, or growing from the top left corner set using the optionally supplied <left>x<top> coordinate. Can use pixel values (e.g. 330) or percent values (e.g. 25.5p)

Parameters

Crop with the center of the crop at the current focus. By default the center of the image unless supplied through the focus transform.

crop=<width>x<height>

Crop and set the top left corner of the crop area.

crop=<width>x<height>[@<left>x<top>]

Scale

Scales the image using pixel values (e.g. 250) or percent values (e.g. 45.2p).

Set width and height.

scale=<width>x<height>

Set height. Automatic width based on aspect ratio.

scale=*x<height>

Set width. Automatic height based on aspect ratio.

scale=<width>x*

Set width. Automatic height based on aspect ratio.

scale=<width>

Focus

By default :center, but can be set to a pixel coordinate using this transform. Is reset back to :center after any operation that alters the image size (i.e. crop & scale).

focus=<left>x<top>

Usage example

defmodule ImagePlug.SimpleServer do
  use Plug.Router

  plug Plug.Static,
    at: "/",
    from: {:the_app_name, "priv/static"},
    only: ~w(images)

  plug :match
  plug :dispatch

  forward "/process",
    to: ImagePlug,
    init_opts: [root_url: "http://localhost:4000"]

  match _ do
    send_resp(conn, 404, "404 Not Found")
  end
end