How to respond_to PNG or JPG in Rails and generate image from HTML?

Question

I am looking for a gem or solution to generate image in controller response.

It would be nice if it's possible to do in controller like that:

respond_to :html, :png

def show
  ...
  respond_to do |format|
    format.html
    format.png { ??? }  # some html to png converter 
  end
end

When the png format is requested the response handles with template:

#show.png.haml
%h1
  Some title
%p
  Some content

The result should be an image.

I know about pdf generation solutions PDFKit, prawn and am looking for image generation.

Does anybody know working solution/example? Any starting point would be very appreciated.

Answer 1

Check out here: http://weblog.rubyonrails.org/2006/12/19/using-custom-mime-types

Mime::Type.register "image/png", :png

# then in your controller action
def show
  respond_to do |format|
    format.html { }
    format.png { }
  end
end

UPD

What about image generating. If you need to convert your HTML page into image. You can use wkhtmltoimage
http://code.google.com/p/wkhtmltopdf/downloads/detail?name=wkhtmltoimage-0.10.0_beta2-static-amd64.tar.bz2&can=4&q=

There is no gem like pdfkit for wkhtmltopdf but it is easy to use.

Also you can use pdfKIT gem and after that convert PDF to PNG with imagemagick. That is quite easy too.

UPD

Istead of using SnapShot I prefer to use IMGKit gem

https://github.com/csquared/IMGKit