prawn-shadings

Prawn Shadings

This is a Prawn extension that implements advanced PDF shadings.

Specifically, it a bit refactors already implemented linear and radial gradients and adds a few more advanced ones.

Currently implemented shadings:

• Axial Shadings (or linear gradients) (PDF Type 2 Shading)
• Radial Shading (PDF Type 3 Shading)
• Free-Form Gouraud-Shaded Triangle Meshes (PDF Type 4 Shading)
• Lattice-Form Gouraud-Shaded Triangle Meshes (PDF Type 5 Shading)
• Coons Patch Meshes (PDF Type 6 Shading)
• Tensor-Product Patch Meshes (PDF Type 7 Shading)

API is simple but you need to know what data to supply. Please get familiar with Section 4.6.3 of PDF Reference.

A Word of Warning

Please note that this gem gives you ability use all these shadings in your generated PDF but gives no guarantee that PDF will be rendered correctly.

Just a few examples:

• OS X Preview has problems with flags other than 0 in Type 4, 6 and 7 type shadings.
• OS X Previews renders Type 7 shadings exactly the same as Type 6 shadings ignoring all 4 extra control points.
• PDF.js can not render pretty much any of these.

Installation

gem install prawn-shadings

Usage

require 'prawn/shadings'

Testing

To run the tests:

$ rake

Contributing

1. Fork it.
2. Create a branch (git checkout -b my_shading)
3. Commit your changes (git commit -am "Added Shading")
4. Push to the branch (git push origin my_shading)
5. Open a Pull Request