Talking with Thread

With another search on the web.. I have found the answer I was searching on yesterday: Queue with thread.

How? you can read here a good guide.
So anytime the code need to fetch data from the web, there is a good thread who can manage it.

I would like to see a urllib2 library completely asynchronous.. but for now.. you need threads.

Other things I did..a lot of bugfixing and a little bit of code cleaning.

I have also found another bug while displaying data on the chart.
Next step, will be chart improvements... and than..

first alpha will be out!

Baby, did a bad, bad thing

Yesterday I wasted a little bit of time searching to find a bug: I had to delete a selected element from the list of registered stocks in the main screen, and also from the internal db.
Everytime I searched to delete one element from the list, the deletion of that element from internal db doesn't work... instead it was deleting another element.
The code was something like that:

1. get the iterator and model , for the selected element of the treeview.
2. remove the element from the model giving the iterator.
3. the iterator became invalid...(yes it is deleted!) so I did the same thing of step 1.
4. remove the element form the db getting the key from the iterator.

The bug was simple but it takes some time.. at point 4, the selection to the treeview changed to the previous element in the list!
So the code changed like this:

1. get the iterator and model , for the selected element of the treeview.
   
2. remove the element form the db getting the key from the iterator.
3. remove the element from the model giving the iterator.

Now add and delete of stocks works.

The other problem is with pygtk and thread.. As I mentioned before.. everytime the application try to connect to the web the interface freeze until this operation is complete.
This happened because retrieving data from the net, it is a blocking operation, and block the main thread where the GTK engine runs.. so the application freeze.

I read so many pages about which is the best way to implements a Thread.. and I hope to be near to a solution.. but not yet!

About Dialogs and Gtk.TreeView

Just finished working on this: open a new dialog with a simple treeview inside and other widgets.
This dialog will be used for searching inside the stock quote table(see the previous post)

First problem first
Adding a new dialog to your project it is easier than you think.. if you know that you should use Quickly (and if your project is quickly based)!

Quickly team make easy to add a new dialog to your project.. just follow this answer.
I wasted an hour searching for an answer on how to manage it with glade3 and finally I found that post.
I like this solution... it is easy to add a new dialog and it manage files for you.. just quickly.

After a dialog finish his task, it return a response code; a list of response code is here.

Second problem.. Treeview, pygtk and Glade
This is a complicated task... information on the net are poor or refers to old version.. but you can do a lot with glade3.
You need to create a TreeView and the associated ListStore.
On the treeview you should define:

• column list with information
• the renderer for every column you need like Text, Image or other widget available

On the liststore you have to define:

•  the column to use with the type for every column (for text gchararray is enough)
• eventually, any static information you need in the list when the treeview start.

ListStore need to be connected with Treestore and also you need to map every cellrenderer to an attribute on the liststore! For this last point, there is a "Text" property in the tab General of a CellRenderer element.
If you don't map the attribute and you have elements on the liststore, you will probably see 0 lenght string on the treeview.

What now?
Now, I have enough informations to stop hacking and start designing the app.
Also I will try to include the feautres that someone asked on reddit :).
Need to sleep now, it is a working day tomorrow and it's too late!

Data downloading... complete!

Ok here it is again.
Today, I'm happier than yesterday.. just because the things went as expected and I can go to sleep earlier...

This is how it looks the new experiment:

That chart display google stock quote (on a predefined period) integrated with pycha library and gtk3!

What I learnt
If you want to:

• draw on a GTK3 drawing area, you need to register to "draw" event.The "expose" event doesn't exist anymore.
• update a drawing area widget, you must call queue_draw on that widget
• get the dimension and position of a widget, you can call the methoed "get_allocation()" on that widget. This methoed give back a Rectangle object with this properties: x,y,width,height.
• plot with pycha, you have to create a context from the drawing area widget and from the context a surface, than pass the surface to pycha. More info on this point soon.

Yahoo Finance and Stock Quote Data
The stock quote data is obtained from Yahoo Finance, thanks to a web services present on their portal.
Thanks to Corey Goldberg with his library ystockquote obtain these data is a pretty easy task.
I have only to understand how much deep I can go with this script and if it is enough for what I'm looking for...
I also don't know where I can find the right keyword for stock quote companies: Google is GOOG , Apple is AAPL but I don't know where to find a list of these keywords.. or better a webservices to query.

After this research.. I need to pass to design & a bit of mockups!
 

Lack of documentation

Yesterday I spent a lot of time trying to plot a Chart in a Gtk Drawing Area, using quickly, Glade3, pygtk and pycha.

Some criticism about these tools:

• "hackish" style... you fix some problem thanks god to people like this: http://somethingididnotknow.wordpress.com/2012/01/27/retrieve-the-window-object-from-widgets-with-pygobject-gtk3.
• general lack of documentation. what you find around the web is usually deprecated and it doesn't work when you try it
• the gtk documentation is mainly in C, not in python, and sometimes have a C function called pippo() doesn't mean it exists the equivalent python function pippo()..but something like pyPippo()....
• when you need a library for a simple task, like plotting on a screen, you can find a lot of solutions, but find the one that just works , it is hard. Many library examples just doesn't work.. you have to find the solution. Read this http://detrasproject.wordpress.com/2011/04/04/show-graphs-using-pygtk/ Also if you don't want plot chart, read the post to understand what I mean. It's not coding.. it's hacking.
• Trying to plot a line chart inside a drawing area...it has been a bad experience.. and the result not satisfying for now... it looks good but there are a lot of bug to fix.

 

a prototype.

Quickly, pygtk, glade etc are great tool.. but Ubuntu need documentation, keeping it updated with examples and easy to find tutorial on "how to solve a simple task" or a page with the most important and working library for solve a task.
The hackish approach is not for all, we are in 2012.

This is not an attack to ubuntu community or in general to opensource.
Instead it is an important point, where community should think and improve.

I will post later the recipe for plot a pycha inside a GTK window made with Glade.

Planning and some code

For many reasons, the only way I had to find a place for ubuntu 12.04 was some space on Virtualbox.
Ubuntu on Virtualbox is quite fast to don't regret a real machine.

I have seen some parts of the video recorded from UbuntuDevelopers on this youtube channel: http://www.youtube.com/user/ubuntudevelopers
If you are new to pygtk, glade and quickly I suggest to follow those videos.

Planning
From now on, I have around 15 days to produce something good for the competition..
The 15 days will be splitted like this:

• 3 days experimenting, searching and understand new library in python: fetch webservices,  plot graphs (at least lines) and tools pygtk/glade, quickly.
• 4 days for design
• 4 days for programming
• 1 day for testing
• 1 day for submission
• 2 days extra time.. I know those days will be used in some way.

1st Problem
Yes, 1st problem: I desperately need to find a way to plot "cool" graphs with python.

I searched a bit and what I've found is not satisfying me enough.

I don't have the time to create a new library for plot graphs like I want..

Maybe, at the beginning I will use matplotlib (see this tutorial http://www.thetechrepo.com/main-articles/465-how-to-create-a-graph-in-python ) and I will try to improve how graphs looks on the screen only if I will have the time to do it..
I hope matplotlib is able to draw directly on a Gtk Drawing Area... I don't want to save on disk the image than load an image on the Gtk Drawing Area..... it is a sad approach.

A Stock Quotes App for Ubuntu

I will do a simple stock quotes application with Quickly for Ubuntu 12.04 but first of all..

Why did I choose to make a stock quotes app for Ubuntu?
Everything started some day ago, while I was playing with the new beta of IOS 6, I found the IOS default app for trace stock quotes information:

It was the first time that I ran that app.

I like the way it works:

• built to be easy
• fast manipulation of information: add/remove stocks quote
• fast searching for stock quotes
• interface without noise
• smooth animation and graphics

I've never been interested in stock quotes, markets, etc.. but when you find an application like this and you feel how it is designed...you are captured by how it guides you.

After that I see there is an Ubuntu competition and I have thinked to make something similar for Ubuntu.
I am an Ubuntu user since 4.10 and I would like to give some of my contribute back to the community (I did in other way in the past but I never did a program for the community).
I see there are other stock quote application but I don't like it.. and I have some idea on how to create something different... I would like to create a "wow" effect app.. maybe
I will use quickly (as suggest in the competition) and I will use this blog to document my progress.
I hope the future informations posted on this blog will be useful for others.