All posts by Dominik

Dominik is a PhD student at the Control Theory and Robotics Lab, TU Darmstadt, as part of the Research Training Group GKMM (GRK1362). My research focuses on state estimation in distributed systems. As hobby, I contribute to the KDE project and work on the Kate application and editor component.

Join Kate Development!

The Wheel of Time turns… meaning that the Kate Project has quite along history by now. The Kate Project was started back in December 2000, so it’s almost 10 years old. Development sometimes continues with a fast pace; and at other times there is almost no progress for weeks. But all in all, looking back at those 10 years, we can proudly tell you that the project is very much alive. Let’s take a look at the traffic of our mailing list:

The traffic itself does not say much about the development. It probably tells us that there are quite a lot of people using Kate and reporting wishes and bugs. This is a good thing :) The commit statistics for Kate, KWrite and the KTextEditor interfaces look like this:

Before 2000, Kate did not exist yet. Instead, so these commits come from the KWrite days. The commit rate is quite constant according to this statistic. In fact, there usually are always several developers working on Kate. Some only for a short period to implement single features or fix some bugs, and some long-term contributors. A very nice trend is given by the fact that the core team of Kate grew from about 4 to 7 developers over the last two years. So the Kate Project is very healthy – nice! And of course we are happy for every single contribution. So if you want to get involved in Kate development, join us!

Kate: Scripted Actions

Finally, I came around to implement scripted actions for Kate in KDE SC 4.6. Let’s take a look at how this works. When Kate starts, it searches for $KDEDIRS/share/apps/katepart/script/ for *.js files. As example, let’s take a look at utils.js there:

/* kate-script
 * author: Dominik Haumann
 * license: LGPL
 * revision: 3
 * kate-version: 3.4
 * type: commands
 * functions: moveLinesDown
 */

function moveLinesDown()
{
  var fromLine = -1;
  var toLine = -1;

  var selectionRange = view.selection();
  if (selectionRange.isValid() &&
      selectionRange.end.line < document.lines() - 1)
  {
    toLine = selectionRange.start.line;
    fromLine = selectionRange.end.line + 1;
  } else if (view.cursorPosition().line < document.lines() - 1) {
    toLine = view.cursorPosition().line;
    fromLine = toLine + 1;
  }

  if (fromLine != -1 && toLine != -1) {
    var text = document.line(fromLine);

    document.editBegin();
    document.removeLine(fromLine);
    document.insertLine(toLine, text);
    document.editEnd();
  }
}

function action(cmd)
{
  var a = new Object();
  if (cmd == "moveLinesDown") {
    a.text = i18n("Move Lines Down");
    a.icon = "";
    a.category = "";
    a.interactive = false;
    a.shortcut = "";
  }

  return a;
}

function help(cmd)
{
  if (cmd == "moveLinesDown") {
    return i18n("Move selected lines down.");
  }
}

What happens is the following:

  1. the header tells kate that there is an exported function “moveLinesDown”
  2. so when Kate Part is loaded, it calls “action(moveLinesDown)” to check whether this function should be exposed in the GUI. Here, we return the action info that includes the displayed text, an icon, a category, whether the script needs user input (interactive) and a default shortcut. Of course, you can change the shortcuts, and also configure the toolbars to show the actions.

With this, every user is able to script arbitrary editing functions for Kate Part. We don’t have to implement all those helpers in C++ anymore. The result looks like this:
You can have this already now, you just have to use the development version of Kate :)

Enjoying Tampere

As always, the KDE conference has its funny sides, as you can see on the photo: 4 Kate developers shaping the future of the (as you all know) most awesome application: Kate :-)