Posts tagged ‘GTK’

August 20, 2010 Programming , No comments

Pike project – module stub creator

Screenshot of Pike project

I recently began learning how to create Pike modules in C. The Pike module C API seems great and once you’ve sorted things out the modules are easy to build and install. Non the less, when creating a C module from scratch there’s a couple of files you need and some configurations of those before everything is set for go. And here comes “pike-project” into play.

Pike-project is a simple GTK program (works as command line tool also) written in Pike it self. The program will create the basics for a running Pike C module, or a plain installable Pike module. Then it’s just starting programming.

The program is available at my Github repository.

BTW! At the moment it only works on Linux I suppose.

January 19, 2010 Applications, Linux, Programming , , 4 comments

GTK hacking in Pike

Tweepi, the Twitter client written in PikeI’ve found out that it’s great fun programming desktop applications and of course it gets more fun the more you learn. Now I’m doing a Twitter client in Pike – my favorite programming language – mostly because I wanted to try out GTK programming in Pike. I use the good Twitter client Pino – written in Vala – and I have borrowed the concept and layout from it. I call it Tweepi.

The only major difference between Tweepi and Pino – besides they are written in different programming languages – is that Pino uses WebKit to draw the status messages where I am using good old GTK widgets – and I guess there are no bindings to WebKit in Pike for that matter ;)

One thing I noticed is that the Gtk.Label widget sucks at displaying longer texts that line wraps. Since the label widget handles some HTML formatting I thought that it would be suitable for displaying the status messages, but the text looked like shit, line wrapping where ever it felt like. And the Gtk.TextView widget doesn’t handle formatting per default so I Googled some and found that you can format text in Gtk.TextViews by inserting Gtk.TextTags at desired positions. And since Pike has the most awesome HTML parser It was just a matter of sending the text through the parser and create some Gtk.TextTags and inserting them at the same position in the text buffer. (Well, actually it wasn’t that easy but with some help from a Python class I found on the web it was doable).

So now I have a start at something that is a Gtk.HtmlTextView – actually it inherits Gtk.TextView but has an additional method insert_html_text(string text) – and albeit quite simple at the moment it’s worth continuing on. The code for the HtmlTextView is available at my Github repository.

In general I find the GTK implementation in Pike to be pretty OK, but there exist some verbose, and tedious, stuff like getting the text from a Gtk.TextView:

2 lines of Pike
  1. Gtk.TextBuffer b = my_textview->get_buffer();
  2. string text = b->get_text(b->get_start_iter(), b->get_end_iter(), 0);

which in Vala and C# would be done like:

5 lines of Vala
  1. // Vala
  2. string text = my_textview.get_buffer().text;
  4. // C#
  5. string text = myTextView.Buffer.Text;

Anyway! Tweepi isn’t done yet but I think I have solved the most tedious stuff and it’s starting to become useful. It’ll probably be done in a couple of weeks and I will of course release the sources then.

January 14, 2010 Applications, Linux, Roxen , , , , 2 comments

Roxen Application Launcher 0.4.4

This is not the latest version of Roxen Application Launcher. You'll find the latest version at the download page.

So, here’s a new release of the Roxen Application Launcher for Linux (RAL). The previous versions used my home made (sloppy so) HTTP client which didn’t handle redirects or secure connections – thank you tec for the feed back – since I had some major problems getting libsoup working with binary files like images and such. Binary files was heavily scrambled when read from or written to disk so I made my own simple HTTP client that kept the data as a byte array to prevent some underlying libraries (GLib) from fiddling with it.

But I solved the libsoup issue so now the RAL handles redirects and secure connections. This is how I solved it:

The libsoup issue

When uploading a file back to the Roxen server I use IOChannel (g_io_channel in plain C) instead of Gio. So the upload works like this:

13 lines of Vala
  1. var sess = new Soup.SessionSync();
  2. var mess = new Soup.Message("PUT", get_uri());
  3. mess.request_headers.append("Cookie", get_cookie());
  4. mess.request_headers.append("Translate", "f");
  6. IOChannel ch = new IOChannel.file(local_file, "r");
  7. ch.set_encoding(null); // Enables reading of binary data
  8. string data;
  9. size_t len;
  10. ch.read_to_end(out data, out len);
  12. mess.request_body.append(Soup.MemoryUse.COPY, data, len);
  13. sess.send_message(mess);

And that seems to work like a charm!

When downloading data it’s a bit more tricky! Of course I tried using IOChannel in this case also but that made no difference. Downloaded images ended up 4 bytes long! But then I thought: You can make your own C bindings in Vala (remember the Vala compiler generates C code) through what is called Vapi files. So what I did was writing a C function that takes a SoupMessageBody object/struct passed from Vala and writes the data part to a file given as argument.

19 lines of C/C++
  1. gboolean save_soup_data(SoupMessageBody *data, const char *file)
  2. {
  3. FILE *fh;
  5. if ((fh = fopen(file, "w")) == NULL) {
  6. fprintf(stderr, "Unable to open file \"%s\" for writing!\n", file);
  7. return FALSE;
  8. }
  10. int wrote = fwrite(data->data, 1, data->length, fh);
  12. if (wrote != (int)data->length) {
  13. fprintf(stderr, "wrote (%d) != data->length (%d). Data may have been "
  14. "truncated", wrote, (int)data->length);
  15. }
  17. fclose(fh);
  18. return TRUE;
  19. }

And this was then made available to Vala by the following Vapi file:

6 lines of Vala
  1. [CCode (cprefix = "", lower_case_cprefix = "", cheader_filename = "")]
  2. namespace Soppa // Soppa is Swedish for Soup ;)
  3. {
  4. [CCode (cname = "save_soup_data")]
  5. public bool save_soup_data(Soup.MessageBody data, string file);
  6. }

And this is how the actual Vala code downloading the files looks like:

15 lines of Vala
  1. var sess = new Soup.SessionSync();
  2. var mess = new Soup.Message("GET", get_uri());
  3. mess.request_headers.append("Cookie", get_cookie());
  4. mess.request_headers.append("Translate", "f");
  5. sess.send_message(mess);
  7. if (mess.status_code == Soup.KnownStatusCode.OK) {
  8. // Here I call the C function made available through the Vapi file
  9. if (Soppa.save_soup_data(mess.response_body, local_file)) {
  10. message("The file was downloaded and written to disk OK");
  11. }
  12. else {
  13. message("Failed writing data to disk!");
  14. }
  15. }

So that’s that on that! ;)

The notification

I also – just for fun – implemented a notification mechanism through libnotify. Since I believe that can be rather annoying it’s not activated by default but can easily be activated by a checkbox in the user interface.

The packages

The Roxen Application Launcher for Linux can be downloaded at the download page at Github where also the work in progress sources is available or downloaded below!

Roxen Application Launcher 0.4.4 23:06, Wed 13 January 2010 :: 373.5 kB

Stay black!

May 04, 2008 Linux, Programming, Roxen , , , , , No comments

Roxen Application Launcher for Linux

There's a new version of The Roxen Application Launcher for Linux written in Vala.

I thought I should broaden my C# knowledge a bit and you know how it is: To learn new stuff you need a real project to work on or else you will lose the fire sooner than later. So I came up with a good project that is actually useful to me: Porting Roxen’s “Application Launcher” to C#. There’s nothing wrong with the original one, written in Pike, except that it uses GTK 1 which is quite hideous (in an aesthetic meaning) compared to the newer GTK 2. And I also though it would be cool to create a panel applet (in the notification area of Gnome so you could put the Application Launcher in the background).

BTW: For those of you not knowing what the heck Roxen’s Application Launcher (AL here after) is here’s a brief explanation: Files in Roxen CMS is stored in a CVS file system which means that you don’t deal with files the way you normally do. To manage files you use a web browser interface (which is a darn good one I might add) but sometimes you actually want to edit files in your standard desktop application. And it is here the AL comes to play. You can download a file through the browser interface so that the file is opened in the AL. AL will then open the file in the desktop application you have associated with the file’s content-type. When you make your changes and saves them the AL will directly upload the changes to the server. So in short I could have said: The Application Launcher is a means to edit files on a remote Roxen server with a preferred desktop application.

The obstacles

I must say I’ve learned a lot from this project!

First off: If you download a file for editing and the AL is already started you don’t want to start a new instance of AL (this is something I have never ever thought about before – in general terms, not just concerning AL) but when you do think about it you find that it’s not a piece of cake to solve. I solved it the way it is solved in the original AL. The first instance of AL that is started also starts a “socket server” that listens for incoming traffic on a given port on the local IP. When a new instance is started it first checks if it can connect to said port and if it can it sends the arguments through the socket to the first instance which then handles the request. The second instance is simply terminated when it has send the data though the socket.

So there I had to do some socket programming. Great fun :)

Secondly: Stuff happens in the background of AL – data send through the socket remember – which means that nothing happens when you try to update the Graphical User Interface. (NOTE! This is the first more advanced desktop application I’ve done.) After “Google-ing” around a bit I came to know that this was a real newbie problem ;) The thing is that the GUI can only be updated through the same thread that started it so when using background threads – implicitly that’s what I’m doing although handled by the asynchronous callback infrastructure of C# – you need to make sure the GUI is updated through the main thread. This is the most simple way so solve it:

3 lines of C#
  1. Gtk.Application.Invoke(delegate{
  2. CallFunctionToUpdateGUI();
  3. });

That’s not too difficult when you know it ;)

Thirdly: The AL is sending data back and forth through the HTTP protocol which means we have to use some sort of HTTP client. C# has a couple of ways to do this but unfortunately they came up short, or I couldn’t use them anyway. I didn’t manage to figure out exactly why I always caught an exception saying something like: A protocol violation occurred!. I’m far from the only one who have fought with this and it has something to do with the headers sent from the remote server. You can invoke “unsafe header parsing” but that was to much of a hassle so I created my own little HTTP client.

One big annoying thing with C# is that is seems almost impossible to turn data from streams into strings without having to use any one of the System.Text.Encoding.* classes/objects which in my case meant that images and files in binary form got seriously fucked up. I manged to solve this my never turning the data into a string but keeping it as a System.Text.Encoding.* all the way from request to response to saving to disk. It was rather irritating but at the same time nice when solved (and I learned a whole bunch about System.Text.Encoding.*, System.Text.Encoding.*, System.Text.Encoding.* and System.Text.Encoding.*.)

Finally: Of course I learned a great deal more about C# but this blog post is starting to get pretty excessive so I will round it off by saying that MonoDevelop is starting to become pretty darn good! I just upgraded to the latest version of Ubuntu and that also meant that I got the latest MonoDevelop and I must say it’s more stable than ever (although it occasionally crashes) and a whole bunch of new features are in place. One I havn’t used before – although it might have existed before – is the “Deployment” stuff. It creates a package with configure and make files for optimal compilation. Really smooth!

Source and screens

I will finish off by adding the source files and a few screen shots:

Roxen Application Launcher 17:31, Sat 17 October 2009 :: 96.7 kB

Screen shot 1: Just a standard view
Roxen Application Launcher 1

Screen shot 2: The panel applet in action
Roxen Application Launcher 2

Screen shot 3: The Application Launcher in Swedish
Roxen Application Launcher 3

Screen shot 4: Adding support for a new content type
Roxen Application Launcher 4