gradient

Gradient

Library for dealing with color gradients in ruby

Usage

Gradient works by placing point vectors along a one dimensional plane. Start by creating a few points and pass them to a gradient map.

gradient = Gradient::Map.new(
  Gradient::Point.new(0, Color::RGB.new(32, 36, 196), 1.0),
  Gradient::Point.new(0.49, Color::RGB.new(14, 250, 211), 0.1),
  Gradient::Point.new(0.50, Color::RGB.new(171, 25, 12), 0.7),
  Gradient::Point.new(1, Color::RGB.new(15, 212, 162), 0.3)
)
# => #<Gradient Map #<Point 0 #2024c4ff> #<Point 49.0 #0efad31a> #<Point 50.0 #ab190cb3> #<Point 100 #0fd4a24d>>

Convert to CSS

If you use ruby to serve web content you can use Gradient to convert gradient maps in to CSS3 Gradients

gradient.to_css
# => "background:linear-gradient(to right, rgba(30,87,153,1.0) 0%, rgba(41,137,216,0.02) 49%, rgba(37,131,209,0.0) 50%, rgba(32,124,202,0.02) 51%, rgba(125,185,232,1.0) 100%);"

gradient.to_css(property: "border-image")
# => "border-image:linear-gradient(to right, rgba(30,87,153,1.0) 0%, rgba(41,137,216,0.02) 49%, rgba(37,131,209,0.0) 50%, rgba(32,124,202,0.02) 51%, rgba(125,185,232,1.0) 100%);"

If you want some more control of the css generation you can invoke the CSS Printer manually.

printer = Gradient::CSSPrinter.new(gradient)
printer.linear
# => "linear-gradient(to right, rgba(30,87,153,1.0) 0%, rgba(41,137,216,0.02) 49%, rgba(37,131,209,0.0) 50%, rgba(32,124,202,0.02) 51%, rgba(125,185,232,1.0) 100%)"

printer.linear(direction: "to bottom")
# => "linear-gradient(to bottom, rgba(30,87,153,1.0) 0%, rgba(41,137,216,0.02) 49%, rgba(37,131,209,0.0) 50%, rgba(32,124,202,0.02) 51%, rgba(125,185,232,1.0) 100%)"

printer.radial(shape: :circle)
# => "radial-gradient(circle, rgba(30,87,153,1.0) 0%, rgba(41,137,216,0.02) 49%, rgba(37,131,209,0.0) 50%, rgba(32,124,202,0.02) 51%, rgba(125,185,232,1.0) 100%)"

Serialize & deserialize gradients

To store your gradients in something like a document database, you're able to convert a gradient to primitives using Gradient::Map#serialize.

Gradient::Map.new(
  Gradient::Point.new(0, Color::RGB.new(221, 189, 82), 1.0),
  Gradient::Point.new(1, Color::RGB.new(89, 12, 72), 0.3)
).serialize
# => [[0, "rgb", [221, 189, 82], 1.0], [1, "rgb", [89, 12, 72], 0.3]]

You can easily turn them back in to ruby objects by using Gradient::Map.deserialize.

Gradient::Map.deserialize([[0, "rgb", [221, 189, 82], 1.0], [1, "rgb", [89, 12, 72], 0.3]])
# => #<Gradient Map #<Point 0 #ddbd52ff> #<Point 100 #590c484d>>

Import Adobe Photoshop gradient (.grd) files

For many artists, a preferred way of creating gradients is through Photoshop. You are able to parse .grd files and turn them in to a hash of Gradient::Map objects.

Gradient::GRD.read("./kiwi.grd")
# => {
#   "Kiwi"=> #<Gradient Map #<Point 0.0 #3d1103ff> #<Point 38.6 #29860dff> #<Point 84.0 #a0cb1bff> #<Point 92.7 #f3f56eff> #<Point 100.0 #ffffffff>>
# }

Import SVG gradients

SVG images can contain multiple gradients, and these can be extracted in the same way as for .grd files.

Gradient::SVG.read("./lemon-lime.svg")
# => {
#   "Lemon-Lime"=> #<Gradient Map #<Point 0.0 #ffff00ff> #<Point 20.0 #ffff00ff> #<Point 50.0 #00ff00ff> #<Point 80.0 #ffff00ff> #<Point 100.0 #ffff00ff>>}"
# }

Separate point vectors for opacity and color

You're able to control the point vectors for color and opacity separately by using a point merger.

color_points = [
  Gradient::ColorPoint.new(0, Color::RGB.new(30, 87, 153)),
  Gradient::ColorPoint.new(0.49, Color::RGB.new(41, 137, 216)),
  Gradient::ColorPoint.new(0.51, Color::RGB.new(32, 124, 202)),
  Gradient::ColorPoint.new(1, Color::RGB.new(125, 185, 232)),
]

opacity_points = [
  Gradient::OpacityPoint.new(0, 1),
  Gradient::OpacityPoint.new(0.5, 0),
  Gradient::OpacityPoint.new(1, 1)
]

points = Gradient::PointMerger.new(color_points, opacity_points).call

gradient = Gradient::Map.new(points)
# => #<Gradient Map #<Point 0 #1e5799ff> #<Point 49.0 #2989d805> #<Point 50.0 #2583d100> #<Point 51.0 #207cca05> #<Point 100 #7db9e8ff>>

Interpolation

One can find the color and opacity at an arbitrary location using the #at method, which returns a new Gradient::Point.

map = Gradient::Map.new(
  Gradient::Point.new(0, Color::RGB.new(0, 128, 255), 1.0),
  Gradient::Point.new(1, Color::RGB.new(255, 128, 0), 0.0)
)
map.at(0.5)
# => #<Point 50.0 #80808080>

Installation

Add this line to your application's Gemfile:

gem "gradient"

And then execute:

$ bundle

Or install it yourself as:

$ gem install gradient

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment. To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/zeeraw/gradient. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Acknowledgments

Valek Filippov and the RE-lab team decoded the .grd file format and provided an initial parser implementation. Andy Boughton later created an implementation in python which is the base for this library's implementation.