Loomy 🧶

The friendly pixel-weaver for Ruby.

Loomy is a modern, high-performance image processing engine for Ruby. Think of it as a master weaver for your images: it takes raw layers (the threads) and weaves them into complex compositions using a smart, declarative DSL.

Built on top of libvips, Loomy doesn't just process images; it optimizes the entire "weaving" process (AST) to ensure your pipelines are as light and fast as silk.

• High Performance: Built on libvips with a custom Batch Composition engine that flattens operations into a single efficient pipeline.
• Hierarchical Groups: Nest layers and groups to create complex layouts with shared effects.
• Intelligent DSL: Declarative, block-based syntax. Define properties naturally without complex argument lists.
• AST Optimizer: A smart "pre-weaving" layer that prunes invisible layers and pre-calculates geometry before rendering.
• Extensible Effects: Dynamic registry to add your own image processing strategies.

Add this line to your application's Gemfile:

gem 'loomy'

And then execute:

bundle install

Loomy offers two ways to get your results: render (write to file) and generate (get a Vips::Image object).

Loomy.render("output.png", size: [1200, 630]) do
  layer "background.jpg"
end

# Returns a Vips::Image object
image = Loomy.generate(size: [1200, 630]) do
  layer "background.jpg"
end

# Get binary buffer for HTTP response or S3
buffer = image.write_to_buffer(".png")

Group layers to apply effects or positioning to a set of nodes collectively.

Loomy.render("banner.png", size: [800, 400]) do
  group x: 50, y: 50 do
    layer "icon.png", width: 50
    layer "text.png", x: 60

    # Apply blur to the entire group
    blur radius: 2
  end
end

Forget about complex argument lists. Describe your image layout naturally:

require 'loomy'

Loomy.render("output.png", size: [1200, 630]) do
  # Background
  layer "background.jpg" do
    fit :cover
    blur radius: 10
  end

  # Overlay
  layer "avatar.png" do
    x :center
    y :center
    width "20%"
    trim true # Auto-crop transparent borders
  end
end

Define common looks and apply them anywhere.

# Define a style
Loomy.define_style :hero_layer do
  x 50
  y 100
  blend :overlay
end

Loomy.render("post.png", size: [1000, 1000]) do
  layer "texture.png" do
    use :hero_layer # Apply the style
    width 500       # Override or extend
  end
end

Loomy is extensible. You can register your own libvips processors:

# Register a custom effect
Loomy.register_effect(MyCustomEffectClass, ->(img, effect_node) {
  img.my_vips_operation(effect_node.param)
})

Loomy is designed for scale. Leveraging libvips' streaming architecture and our proprietary AST optimization, Loomy delivers exceptional throughput:

• Full support for relative geometry (%, vh, vw)
• Rounded corners and masking
• SVG support as layers
• Smart Saliency Masking (Background Removal)

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