Drawing Library for Ruby

Question

I am trying to code a flowchart generator for a language using Ruby.

I wanted to know if there were any libraries that I could use to draw various shapes for the various flowchart elements and write out text to those shapes.

I would really prefer not having to write code for drawing basic shapes, if I can help it.

Can someone could point me to some reference documentation with examples of using that library?

I had the same question, Let me know id there is anything comparable to System.Drawing namespace in .net — Zasz, Aug 28 '11 at 11:11

score 17 · Answer 1 · edited Feb 08 '17 at 14:09

Write up your flowchart as a directed or undirected graph in Graphviz. Graphviz has a language, dot that makes it easy to generate graphs. Just generate the dot file, run it through Graphiviz, and you get your image.

graph {
  A -- B -- C;
  B -- D;
  C -- D [constraint=false];
}

renders as

digraph {
  A [label="start"];
  B [label="eat"];
  C [label="drink"];
  D [label="be merry"];

  A -> B -> C;
  C -> D [constraint=false];
  B -> D [ arrowhead=none, arrowtail=normal]; // reverse this edge
}

renders as

You can control node shapes and much more in Graphviz.

score 3 · Answer 2 · edited Jun 16 '17 at 16:12

It sounds like you're going to be limited mainly by the capabilities of whatever user agent you're building for; if this is a web project, drawing capabilities are going to be dependent on the browser. Since Ruby is running server-side, you would at minimum need some JavaScript to allow dragging/zooming, etc. There's plenty of examples of JavaScript being used for vector drawing (just google "javascript graphics library"), but all require coding, and I haven't seen any library that abstracts this elegantly.

ImageMagick has a Ruby binding called RMagick (sometimes known by other names, depending on the repository). (Link) I haven't used it myself, but I believe it will do what you're looking for. You will need to do some coding, but it's along the lines of

draw.rectangle(x1, y1, x2, y2)
draw.polygon(x1, y1,...,xN, yN)

score 2 · Accepted Answer · edited Dec 04 '14 at 05:43

The simple answer is that (at time of writing) what you want almost certainly didn't exist. Sorry!

If you're Windows-based then I'd look for a product in the .NET space, where I expect you'd find something. You're probably going to have to pay real money though. I suppose, if you're brave, you may be able to talk to it using IronRuby.

From a non-MS environment I would be hoping for a Java-based solution. As already mentioned, within the Web world, you're going to be hoping some something JavaScript-based, or probably more likely, something from the Flash (or maybe even Silverlight?) world.

Actually, if you want to stay in Ruby and don't mind some risk, Silverlight might be a way to go - assuming the DLR stuff actually works (no experience here). Ruby - much as I love it - hardly has the most mature GUI structure around it.

Update: Since writing this (approaching 5 years ago) the situation has improved - a little. While I'm still not aware of any specific Ruby graph-drawing libraries, there is improved support for Graphviz here (Github) or by gem install ruby-graphviz. I've found that for simple graphs, it's quite possible to write the script directly from Ruby.

Some libraries do exist for ruby. Although you would have to work only with basic elements. As Nathan pointed out, there's https://rubygems.org/gems/rmagick, but there's also https://rubygems.org/gems/cairo. Here's a simple tutorial http://www.hokstad.com/simple-drawing-in-ruby-with-cairo.html. And here's another that uses GTK http://zetcode.com/tutorials/rubygtktutorial/cairo/. I would have to agree that it's not the best API, but it's a start. — Gaston, Feb 01 '12 at 18:14

score 0 · Answer 4 · answered Dec 23 '08 at 07:31

0

I am totally sure, but check out cairo bindings for ruby. Pango for text. I am investigating then currently and came across this page.

answered Dec 23 '08 at 07:31

Drawing Library for Ruby

4 Answers4