Corunet. El blog http://blog.corunet.com Diseño web Thu, 21 Jun 2007 19:06:13 +0000 http://wordpress.org/?v=2.0.3 en Automatic CSS: The stylizator http://blog.corunet.com/english/automatic-css-the-stylizator http://blog.corunet.com/english/automatic-css-the-stylizator#comments Wed, 20 Jun 2007 20:15:15 +0000 david English CSS and Javascript http://blog.corunet.com/english/automatic-css-the-stylizator Writing CSS is good fun, but analyzing an html document to find how the page is structured us, at the very least, tiring. If you have ever had to write CSS for a blog or CMS template, you already know how time-consuming is to find every ID and CLASS in a large document. We’re going to write a simple script that takes an HTML file as input and gives us two things:

  • First, some CSS and Javascript to generate a visual structure with all the names like the one that can be seen at the top image (and a javascript only version!!).
  • Second, a CSS file without any rules, but with every ID and class in the document.

Let’s go:

The tools

We need to use any scripting language to read the HTML and act accordingly. This time we’re going to use perl, since it’s a simple and powerful language for text managing. It’s available in most operating systems and for windows users, it’s downloadable from http://activestate.com/ .

It should be possible to write in ruby, python, java or any other programming language. Take it as a guideline or, if you just want to use it, grab the code
We’re going to use some CSS and Javascript too. Let’s get wet…

Reading and parsing HTML

First of all, we need an HTML document to be parsed. As I’ll recall later, I used HTML code from csszengarden to try the code.
First thing to do is read the html from a file. The script we’re going starts the following way:

Code: stylizator.1.pl

This first part opens a file, reads it and assign the contents to a variable. Now, we need to find all the id’s present in the file. To do that we could use a full-fledged HTML parser, but since many documents in the real world are not correct and our necessities are quite easy, there’s a simpler solution. So, regular expressions to the rescue.
Regular expressions find patterns in a file. We can tell perl to find things like /\w+/ and it will match alphanumeric characters. Probably to find named elements it should be enough to write:


/id=\"?\w+\"?/i

Where “id=” means exactly that, \”? means a possible quotation mark, (\w+) is a group of letters or numbers, another possible quote and the last “i” tells us to ignore the case of the text. In this particular case, we’re going to use a slightly more complicated expression, to take into acount possible missing quotes and so on:


/id\s*=\s*"?([^"\s>]+)/

Creating the CSS template

We’re going to write an empty CSS file. I like to use a previously written template that includes links to my CSS-reset file and some more files I always use. Then, for every named element, we need a line:


#namedelement{

}

Code: stylizator.2.pl

and every time we find a class, since they are not unique, we need to filter it, creating a hash (associative array) with its name. And then, the same thing we’ve done with the IDs. Some more code:

Code: stylizator.3.pl

With all that code, we already have a CSS template. You could start right now editing it to suit your needs. But we don’t know yet what the structure is. Why don’t we create a new HTML file that shows us how the document is laid? OK. Let’s write some more code

Javascript: The magic

Here is where the fun begins. Probably, I’ll need to wite another post about this piece of code, since there are a couple of sleights of hand, but, briefly, the following piece of code removes all the stylesheets and the inline CSS rules, then takes all the elements in the dom and finds the ones that have an ID, and adds a P element with the ID name to each one.

Code: stylizator.js

As you can see, there are only two functions. The first one, removeSheets(), disables every stylesheet included from the HTML, and then calls the other one, findNamedElements(), This function gets all the elements in the DOM (getElementsByTagName(’*')) and iterates over them, doing a couple of things:

  • First, remove inline style elements (allElements[i].style.cssText = ‘’)
  • For the elements with an ID, some styles are added (a silver box around them)
  • A child P tag with the ID text is created too, giving it a class ’sign’

Then, we create a new stylesheet only for that class. We have to code a different way for Explorer and Firefox/Opera/Others because of compatibility issues.
Last, the function is called with removesheets(). You can even save the code as a bookmarklet and apply it to any website. It’s truly portable.

Now we need some perl code to insert the javascript into the HTML file, just before the </body>: tag.
Update: My pal Félix has just tol me that I need to add an “s” in the javascript substitution, to cope with multi-line javascript. Thanks, Félix

Code: stylizator.4.pl

When you run the full script, another HTML file will be generated, that shows how the document is laid.

Trying it out

The best example I can think of is CSSzengarden, a site where a default layout is given to designers to skin it the better they can. I downloaded the HTML code (CC license, by-nc-sa) and called he script over it:


$> perl stylizator.pl csszengarden.html

And I got a csszengarden CSS file, with all the named tags, and a csszengarden.structure.html file with the visual structure of the site.

Code: csszengarden.html
Code: csszengarden.structure.html
Code: csszengarden.css

Something like this. Click to expand(PNG 239KB):

The code

Download this file, unzip it in the same folder and call it via >perl stylizator.pl yourhtmlfile.html
It’ll create a file named yourhtmlfile.css and another one called yourhtmlfile.structure.html

Further work

There’s so much to be done. It could be possible to create a firefox extension that gives us the same visual result at the press of a button, or a system that keeps only structural CSS, discarding type and colors. The regular expressions could be better, too, to allow not-so-well-defined documents. If you have any further questions, drop me a line to david@corunet.com.

Have fun.

]]> http://blog.corunet.com/english/automatic-css-the-stylizator/feed/ Three column layout with full page height http://blog.corunet.com/english/three-column-layout-with-full-page-height http://blog.corunet.com/english/three-column-layout-with-full-page-height#comments Thu, 14 Jun 2007 19:36:56 +0000 david English CSS and Javascript http://blog.corunet.com/english/three-column-layout-with-full-page-height Sometimes I wish I could do things that were easily done with table-based layouts but quite hard using just CSS.
Following a couple of posts in a CSS related Spanish mailing list (Ovillo), a guy called Zafonic showed me how to use negative margins and positive paddings to make equal sized columns. With a couple javascript functions, I patched it to fill the full browser window. Let’s see how…
Update: Error in code solved. Thanks to the testers

The problem

We’re going to write a three-column plus footer layout that covers all the browser space. The requisites are the following:

  • The three columns will have different background colors
  • We’re not going to use background images (so, no faux-columns)
  • We want the page to cover the full height of the browser. So, the footer will be at the bottom of the screen.
  • The layout has to degrade gracefully for javascript disabled browsers
  • All the code has to be valid and accesible

The beginning

The first part is simple. We need some html that defines three columns and a footer. Lets wrap the three columns within a div (called, by the way, container) and call the three columns col1, col2 and col3. The html code will be something like:

Code: body.html

We need to give the columns a width and float them to the left. The css would be:

Code: first.css

So, we already have a three column layout, but each column has a diferent height and the footer is far from the bottom:

first version

Negative margins to the rescue

As I already told you, I had’t heard about creating layouts using negative margins (I should have read this article from A List Apart some time ago). In a nutshell, it says that you can use a large negative margin and the opposite positive padding to “make room for the columns”. I recommend to read it if you haven’t, it’s very useful.
So, let’s go on the code. We’re going to add a -5000 pixel margin-bottom and a 5000 pixel padding-bottom to each column:

Code: second.css

This way we get same height columns. This looks much better:

second version

but we don’t have 100% height yet. Internet explorer supports 100% height but all the other browsers don’t. So, we’ll need to use javascript to solve it:

Filling the screen - Here comes Javascript

The first thing we need is to find the height of the browser window. I use a small javascript function that takes into account the diferent behaviours of the different browsers:

Code: height.js

This function returns the height of the browser window. It does one thing and does it well… Using this new knokledge, we can set the height of the columns, making them the browser’s window height minus the footer, to fill the screen completely. The other function we’ll need is:

Code: fill.js

This function works by calling the last one (windowHeight) and substracting the footer size. If we’re in Explorer, we use style.height to modify the height of the columns and in all other browsers, minHeight, since Explorer doesn’t support that attribute. We’re going to call that function via onload.
And we get this:

third version

If the window is not tall enough to fit the column height, the page behaves normally:

small screen

The full code

Putting all together, this is what we get:

Code: 3.html

If you use it in a production environment, it’d be wise to split the javascript and the CSS into their own files, and review all the code, since it’s done in a quick and dirty way.

You can download the code using this link. People without javascript don’t get the full height but the site is equally usable and visually pleasant. I you have any further questions or just want to talk, drop me a line to david@corunet.com

]]> http://blog.corunet.com/english/three-column-layout-with-full-page-height/feed/ Clickmaps in sourceforge http://blog.corunet.com/english/clickmaps-in-sourceforge http://blog.corunet.com/english/clickmaps-in-sourceforge#comments Mon, 21 Aug 2006 16:55:49 +0000 david English Usability http://blog.corunet.com/english/clickmaps-in-sourceforge Today, all the code for creating clickmaps has been uploaded to sourceforge and made public under a GPL license. You can find it at http://sourceforge.net/projects/clickmaps

Thanks to jerret, the code now uses RMagick calls and it’s usable with logs sporting more than ten thousand clicks per page.

]]> http://blog.corunet.com/english/clickmaps-in-sourceforge/feed/ The definitive heatmap http://blog.corunet.com/english/the-definitive-heatmap http://blog.corunet.com/english/the-definitive-heatmap#comments Wed, 16 Aug 2006 18:39:21 +0000 david English Usability http://blog.corunet.com/english/the-definitive-heatmap After the interest shown about the clickmaps / heatmaps articles, I’ve decided to gather all the information into an easy to use system. What we are going to make is a complete solution that allows collecting, analyzing and showing the click information our users give us. Now, it works in web pages not center aligned and is quite a bit more robust. Read on…

What?

If you are a webmaster, you had probably thought about what do users do in your website. Beyond usual statistics, clickmaps allow you to find where your users are clicking. This is quite useful to find areas in needing of change, layouts that don’t work as intended or anchors that aren’t being understood as you would like.

You’re going to be able to find every single click your users make in your website, being over a link or even in blank areas. We are going to do it the following way:

The proccess

We need to divide the full proccess into some manageable steps that use some open source tools. Since I work both in windows and linux systems, I’ll be OS agnostic and use only tools available in most systems, including Mac OSX.
The main steps and the tools they use are the following:

  1. The collecting (javascript and apache)
  2. The processing (ruby and imageMagick)
  3. The showing (javascript)

The collecting

We are going to use a small snippet of unobtrusive javascript to allow the client to tell our server the click positions. Just place this small javascript file at the very end of your template, right before the closing <body> tag:

Code: registerclicks.js

The code adds a onMouseDown handler to the document, executes a function for every click and returns true, since we want the user to follow the normal navigation. Then, when the user clicks any part of the page, a tiny request is going to get sent on the background to our server. The script has to calculate the offsett of the first element inside the <body> tag, because most pages arent aligned to the top-right corner. In liquid layouts the system is not going to work at all

The request is sent via a HttpRequest object that calls a file in the server. In last version, I used a small GCI written in perl to log the request and return an empty document, but since we want to serve so many request, there’s a better method to apply. Using a perl CGI, in a modern server, we get the following results benchmarking with apache bench (100 requests, 10 concurrent ones):


Concurrency Level: 10
Time taken for tests: 6.537187 seconds
Complete requests: 100
Failed requests: 0
Write errors: 0
Total transferred: 17100 bytes
HTML transferred: 0 bytes
Requests per second: 15.30 [#/sec] (mean)
Time per request: 653.719 [ms] (mean)
Time per request: 65.372 [ms] (mean, across ...)
Transfer rate: 2.45 [Kbytes/sec] received

Mod_imap

Apache has some modules that work the following way:
You define a handler and what you want to do with it. Some of them are well known, like mod_perl or mod_cgi, but a lesser known one, called mod_imap, does exactly what we want. It’s a module meant to return server-side image maps, but if we use an empty map file, all we get is a 204 status (no data) and a logged transaction. The difference is quite significative. Using Apache Bench with the same configuration, this is what we get:


Concurrency Level: 10
Time taken for tests: 0.106316 seconds
Complete requests: 100
Failed requests: 0
Write errors: 0
Total transferred: 36464 bytes
HTML transferred: 20246 bytes
Requests per second: 940.59 [#/sec] (mean)
Time per request: 10.632 [ms] (mean)
Time per request: 1.063 [ms] (mean, across ...)
Transfer rate: 329.21 [Kbytes/sec] received

That’s 950 requests per second vs 15 with the CGI method!!! We are almost a hundred times faster with this approach!The only thing we have to do to use this mod_imap is to touch a little bit the apache configuration file. Do it carefully because it can hurt your entire server. In the relevant section add the following lines:


AddHandler mod_imap .map
CustomLog /tmp/clicklog clicklog #or modify according to your system

And define a custom log in the same file adding this:

LogFormat "%q,%{Referer}i" clicklog

This way, everything ending in .map is going to be treated as a server-side map, and since the map is empty, it’s not taking your user anywhere. But it logs it, in file /tmp/clicklog (YMMV).

The log analysis

Since we used a logFormat apache directive to write our log, the format should be easy to parse. The query string is written in the log as it comes, and the full lines should be in the following format:


?x=483&y=32&dx10&dy15,http://demo.html
?x=461&y=177&dx10&dy15,http://demo.html
?x=408&y=40&dx10&dy15,http://demo.html
(...)

I decided to write a Ruby script to parse the file and generate the final images, because I hadn’t used ruby before and thought it would be a good way to approach the problem. Last time I had written an structured perl script, but I think that object-oriented is the way to go in this particular situation, since the objects should be well-defined and dividing the program among several coders should be easier too.

Update:Thanks to Jerret, this part has been enhanced using RMagick. Part of the code below can be updated and works some 50 times faster. On top of that, a new sourceforge project has been started at http://sourceforge.net/projects/clickmaps/ under a GPL license. Of course, if you don’t want to install/use RMagick you can still download the original version at the end of this post.

I´ll try to explain the model. It uses five classes:

Conf:
Sets some configuration variables and returns them as a hash. This way, every configuration variable is set in this class and it’s easy to get them later on
Code: conf.rb
Readparsefile
Reads and parses the file defined as logfile in the conf object. For each log line, it stores it into a click object and append it to an array. There are two methods that return all the URLs in the log file (geturls) and all the information for a single URL as a Log object
Code: readparsefile.rb
Click
Stores the data in each log line, including X, Y and URL. Provides a method (xy) that returns an string like “x100y200″ to compare the exact coordinates, useful to extract the maximum number of times a single click is repeated
Code: click.rb
Log
Stores all the values pertinent to a single URL and gives accesors to them. There’s also a “next” method that returns next click within the same URL
Code: log.rb
Image
Receives a log object and the conf object. There are three methods to normalize the spot we’re going to use as a click indicator (normalizespot), compose every click as a dot (iterate) and colorize the final image (colorize)
Code: image.rb

Then, the main program is only eight lines long. It leverages the objects’ methods to be as compact as possible. In fact, the only thing it does is to iterate over each url to create a different image.

conf = Conf.new
file = Readparsefile.new(conf.data['logfile'])
file.geturls.each do |url|
    image = Image.new(file.coordsurl(url),conf)
    image.normalizespot
    image.iterate
    image.colorize
end

Is it better?

You can find another program (this time written in perl) in an older post that does a similar job of making heatmaps. But there has been some modifications that makes this an usable system instead of a proof of concept:

Flexible configuration
Over the harcoded last version, in this one is quite simple to modify the images used in the heatmap generation, or the log name. You only have to modify the Conf definition. It would be so easy to use an external conf file, but doing it this way is quicker for me
Multiple URL support
While last version only let you extract one image, this one makes a heatmap for every URL in your log.
Much faster execution time
Instead of composing the full image everytime, now we create a single ImageMagick sentence to do al the composition for us. That gives us a couple of orders speed advantage. Last version lasted about fifteen minutes for a couple hundred clicks, and now it’s about five seconds. Please note that, for many clicks, the program uses quite a bit of memory. Probably for a production environment it would be neccesary to divide the compose sentence into manageable chuncks, and iterate at the end with them to create the final heatmap.
Manual capture is not needed anymore
Since the last step is to decrement the opacity of the map, we can use a little bit of javascript to overlay the PNG image over the original page. So, the stakeholders can review it without someone manually capturing the screen. This way we don’t need to set an XServer in the production environment
Easier to maintain and extend
The object oriented paradigm doesn’t give us faster code, but much more manageable one. You can extend it as you want

What you get

Now, you’ll have several images. Most of them are OK to delete, but there’s one ending in final.png that’s your heatmap. We’re going to overlay it on top of your web page. That image should be a semi-transparent PNG like this one:

The overlay

This is the final part of the proccess. We already have the overlay image and all we need is a javascript snippet that can be called anytime and that creates a layer on top of your website with the click information. Just like the first step, we’re going to position it over the very first item in the page.
The best way to do that is via a bookmarklet, that is, an small javascript snippet saved as a bookmark. This way, you can have it in your browser and ask for the overlay image when you feel like. The javascript recalculates the offsets of the first element inside the <body> tag and writes the heatmap image on top of it.

Code: overlay.js