I’ve bought myself a Nikon D40 some time ago and finally had enough spare time to shoot some images and post-process them. My environment of choice is Ubuntu Linux so the obvious image management/edit tools were gimp and f-spot.

An first attempt did show some strange behaviour: f-spot did display NEF/RAW images quite different than gimp. It seems as if the (gimp) NEF import step did something to the white-balance and gamma so that imported images did look worse. The worst thing is: while f-spot does display beautiful images it is not able to export them to a more sharable format as JPEG.

GIMP is using ufraw to convert the NEF images, after playing with its parameters I’ve discovered that using a downloaded color profile for the D40 and some custom Gamma and Continuity values does provice a near approximation of the f-spot results. The used values are:

A drawback of using ufraw is it’s slow processing speed. Interestingly using ufraw-batch on the command line does not exhibit this problem, so just use:

ufraw-batch --gamma 0.4 --contuinity 0.02 --wb=camera *.NEF

While not being a problem at all, this is something that should work out-of-the-box, ie. the user should not be irritated by photos being displayed differently between applications.

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Ruby on Rails provides various helpers for generating dynamic web content but sometimes you need documents that users can easily store and share between them. The ubiquitous file format for this is Adobe PDF nowadays.

The common solution fro this problem is Prawn [github, introduction]. Alas it requires a custom DSL for document description, no existing Rails views or partials can be reused. An alternative is princeXML which transforms HTML/CSS into pdf through an external binary. This would allow reuse of existing templates and knowledge (think CSS designers) but has the downside of its price tag of $3800.

The solution

Enters wicked_pdf: it utilizes wkhtmltopdf to create a PDF document from a Rails HTML template. HTML rendering is done through the well-known webkit-engine. This allows developers to do PDFs in the right way™: define the document’s structure through a simple HTML document and theme them through CSS. You’ll get the automatic benefit of themability: exchange the CSS and you have another format. There are also lots of CSS artists out there that can supply you with different designs.

I’ve used this solution with a test Ruby on Rails 3.0-beta application, the steps involved were:

Install wkhtmltopdf:

This program will convert the HTML into the PDF format. To make it work you’ll need at least version 0.9 which isn’t installed in Ubuntu 9.10 by default. Just download the static compiled version from the wkhtmltopdf website and place it under /usr/local/bin.

Install the wicked_pdf plugin:

Just install it in the usual Rails way:

git submodule add git://github.com/mileszs/wicked_pdf.git vendor/plugins/wicked_pdf

Additionally a sample configuration file is needed. You could use the plugin’s generator script for it but alas this didn’t work for me with Rails 3.0. Let’s just copy it form the plugin’s directory into config/initializers.

$ cp vendor/plugins/wicked_pdf/generators/wicked_pdf/templates/wicked_pdf.rb config/initializers

and alter the wkhtmltopdf path within it:

  WICKED_PDF = {
       :exe_path => '/usr/local/bin/wkhtmltopdf-amd64'
  }

Add pdf instructions to your controller..

For example I’m using the invoice#index action to render a simple PDF document.

  format.pdf do
          @example_text = "some text"
          render :pdf => "file_name",
                 :template => 'offers/show.pdf.erb',
                 :layout => 'pdf',
                 :footer => {
                    :center => "Center",
                    :left => "Left",
                    :right => "Right"
                 }
  end

We are rendering the view with a predefined footer containing some sample “center”, “left” and “right” strings. The render :pdf call has various options which can be seen on the wicked_pdf homepage.

.. and create PDF templates

The other half of the PDF templates is the view code consisting of a special layout and template for pdf generation.

The layout (app/views/layouts/pdf.html.erb) resembles a normal Ruby on Rails layout file:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <%= wicked_pdf_stylesheet_link_tag "pdf" %>
  </head>
  <body>
    <div id="content">
      <%= yield %>
    </div>
  </body>
</html>

The view code should not be too surprising, just place it under app/views/offers/index.pdf.erb :

<div id="someid"><%= @example_text %></div>

Lets also create a simple CSS file (public/stylesheets/pdf.css):

#someid {
  margin-left: 430px;
  display: float;
  height: 150px;
  background-color: green;
  width: 250px;
}

This is the whole rendering code.

Reference the PDF view and download it

We still need a reference to the newly created rendernig link, we can easily create this through:

link_to 'Create PDF document', invoice_path(@invoice, :format => :pdf)

When the link is clicked a pdf document will be generated and downloaded.

Conclusion

wicked_pdf allows easy pdf generation in a very Ruby on Rails’ way. It’s free, it works and is easy to employ..

..but not everything is perfect within the wicked_pdf world, especially error handlnig is lacking sometimes. When you’ve debugging initial problems you can expect the only error feedback to be a HTTP return code of 406. Just start with limited controller (rendering) options and double check that you’ve referenced the right view and layout paths and you should be fine.

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The permanent cravings  are gone, conversations with smokers tend to be strain my will but are easily survivable. Standing in the blue smoke still tempts.

But why? I don’t even like the taste. I’ve left behind the illusion that smoking calmes me down or teaches me how to breathe more slowly. My in-official title for smokers, suicidal misanthrope, remains to sound good. Temptation arises from time to time.

Slowly I understand those aggressive ex-smokers. Through a general smoking ban temptations would get rarer. Distrusting collectivism and state-imposed regulations my non-smoking gets a game against myself: do I need higher interventions to finally quit?

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I am using Skype for most of my online communication, mostly because other people are using it and there are strange firewalls at work preventing most other protocols. Alas there’s no support for Skype out of the box and the skype linux crew is kinda slow (Skype 2.1, anyone?). Enters me who needed some diversion from master thesis writing..

indicator-applet with skype

May I introduce indicator-skype-client.py: it’s a small script, written in two or three hours (most of the time spent upon finding strange bugs in python-indicate). It currently provides a list of unread messages. When a username is clicked the corresponding skype window is opened or created. By clicking on the Skype label its main window is displayed. So far it works.. various updates will follow.

How to install?
Just start the python script while skype is already running. Skype will ask if you want to allow the script to access its data, just answer yes. The script will do the rest. It does not install itself into the user session, so you’ll have to start it if you want skype notifications.

TODOs

• There are various workarounds in the code (for example I needed an empty callback to get things displayed), work out those bugs
• currently there’s a hard refresh every 5 seconds (in addition to incoming message detection). This will have to go and be replaced with a more dynamic scheme.
• detect if an unread conversation was openend within Skype and do not display this conversation
• somehow automatically start the script when Skype or the indication-applet starts

So some things are missing, but the script is already workable. Have fun (and please provide patches if you fix problems (: ).

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I just haven’t enough time at my hands to create regular blog posts. This might change after my master thesis will eventually be finished but letting a web page lying dormant ain’t best style.

As I was down with the flu the last days I wrote a small replacement system: it’s just around 150 lines of rails code that captures my twitter feed and allows me to write write longer posts/memos.

The idea is that tweets are aggregated through the day and presented as formatted RSS feed (so there should be no RSS spamming). Longer stuff (as the typical “how did I get x working under Linux” things that happen from time to time) will be integrated with the tweets (yeah, not done yet).

After all coding it was pretty straightforward and fun.. the only drawback is that the RSS feed URL will change, ie. your newsreader will loose my feed.

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I’ve just discovered an expired life insurance plan which will be reinvested into new stocks. Over the last year I had loses in the one-digit percent range, let’s see how the next year goes.

So far life’s good, I’m stocked up on concert tickets again. You can find me at the following shows:

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I’ve been non-smoking since the Bruce Springsteen concert on July, 5th. So for it has worked out, my initial fears that I’ll loose some valued habits that I associated with cigarettes did not come true. Funny how I was never able to imagine myself in a coffee house or waiting without a cigarette.. and now I do not even know why. I’m still addicted to coffee (and the stays in aforementioned coffee houses to cure my need). What did it make different this time? I started to watch smokers during their daily life — my prejudgement that smoking makes all of us calmer was shattered afterwards. And what other reason to smoke did I ever state (sans the addiction part)?

What kept me occupied? My master thesis mostly. The attending professor did the first review of my thesis and the results were less than joyous. Seems like I’ll have to rewrite most of the thesis to make him happy. But his is one thing about hackers: when we fall down we get up and try to make most out of it. Otherwise no one would ever finish any development project. I’ll have to edit most of my thesis and develop a new storyline for its use cases but at least it seems that the software itself is finished (except the demonstration use cases).

The rest of my time went into SECOQC. A new release is around the porch and will improve various internals as well as provide a new user experience (sounds funny when this means mostly a new command line interface). So I’m doing a bit of user interface development lately: it’s rapid feedback loop is quite redeeming.

And of course I was not able to stay away from concerts. As NiN’s current tour is called “wave goodbye” I had to travel to Budapest for one (hopefully not last) concert. Did you know that you can get shriveled fingertips at a live concert? I didn’t. Thanks to Google Maps on the iPhone we were able to find the Szimpla again after the concert. Great place to hang out if you have some spare time in Budapest, but I never seem able to find the exit..

Hopefully I’ll be able to cover my master thesis with a real announcement soon.. to achieve this I’ve switched to “productive” mode: I’ve locked myself in with a stockpile of pizza and wine (-: code needs to be written.

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sometimes I get the urge to clean out cruft lying around my room, otherwise my mind keeps on thinking about stuff that still needs to be read or repaired.

Cloths get donated, eBay is good for larger stuff. But what about books? They tend to spread around me, some of them just collecting dust and without chance of ever being read again. I’ve used Amazon Marketplace for time to time but did run into some problems lately: their rates seem rise and now I’ve got some problems with them recognizing my banking account for pay-outs.. funny as it is the same account that I’m using for years to pay my book bills on the same site.

So, dear web, are there any alternatives? What I search for is a marketplace for used books, possibly nationally ordered so that I might cut on transportation costs.

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So how did the last year go? It did have its highs and lows but that’s the trade-off of being alive. The first nine month were marked by lots of work, I learned a lot thanks to my coworkers. At the same time excessive party-going was happening, balance got lost. I did not always do the things that would make me feel proud and that would be worth chasing after for the rest of my life. Life had to change.

The last three months have been more quiet. I “really” started to work on my master thesis again, we canceled another master thesis that was stagnating.. overall some open loops have been closed or are currently being worked on. A stealthy “Simplify your life”-operation seems to have occurred in the background, through it my financial situation got clearer — while not alarming the recession did take its share.

Writing helps me to clear my mind, writing in public does wonders for committing myself to something. So what are my goals for the next year?

1. finish master thesis. Actually both of them. They’ve been on my mind far too long.
2. live more healthy: during the last years I’ve done much harm to my body: lack of movement, sleep deprivation, smoking.. the list gets longer and longer. The next goal for the coming year is to stop smoking, and be happy with it. This implies doing more sport which is always a bonus.
3. reconnect to the real world.. seems like I’ve lost human touch from times to times. Also a real vacation is long overdue.. now that I’ve clarified my financial situation I can think about where I want to go and how I can collect the required funds.
4. There’s still that guitar thingie standing in my room.. find time and passion to learn to make it talk

So long and thanks for everything.

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The house has been build.

I’ll be at the next concert.

Badlands you gotta live it every day
Let the broken hearts stand
As the price youve gotta pay
Well keep pushin till its understood
And these badlands start treating us good
Bruce Springsteen – Badlands

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