Count characters or words in the X selection from Python (Shallow Thoughts)

Akkana's Musings on Open Source Computing, Science, and Nature.

Fri, 09 Sep 2011

Count characters or words in the X selection from Python

This post is, above all, a lesson in doing a web search first. Even when what you're looking for is so obscure you're sure no one else has wanted it. But the script I got out of it might turn out to be useful.

It started with using Bitlbee for Twitter. I love bitlbee -- it turns a Twitter stream into just another IRC channel tab in the xchat I'm normally running anyway.

The only thing I didn't love about bitlbee is that, unlike the twitter app I'd previously used, I didn't have any way to keep track of when I neared the 140-character limit. There were various ways around that, mostly involving pasting the text into other apps before submitting it. But they were all too many steps.

It occurred to me that one way around this was to select-all, then run something that would show me the number of characters in the X selection. That sounded like an easy app to write.

Getting the X selection from Python

I was somewhat surprised to find that Python has no way of querying the X selection. It can do just about everything else -- even simulate X events. But there are several command-line applications that can print the selection, so it's easy enough to run xsel or xclip from Python and read the output.

I ended up writing a little app that brings up a dialog showing the current count, then hangs around until you dismiss it, querying the selection once a second and updating the count. It's called countsel.

Of course, if you don't want to write a Python script you can use commandline tools directly. Here are a couple of examples, using xclip instead of xsel: xterm -title 'lines words chars' -geometry 25x2 -e bash -c 'xclip -o | wc; read -n 1' pops up a terminal showing the "wc" counts of the selection once, and xterm -title 'lines words chars' -geometry 25x1 -e watch -t 'xclip -o | wc' loops over those counts printing them once a second.

Binding commands to a key is different for every window manager. In Openbox, I added this to rc.xml to call up my program whenever I type W-t (short for Twitter):

    <keybind key="W-t">
      <action name="Execute">
        <execute>/home/akkana/bin/countsel</execute>
      </action>
    </keybind>

Now, any time I needed to check my character count, I could triple-click or type Shift-Home, then hit W-t to call up the dialog and get a count. Then I could leave the dialog up, and whenever I wanted a new count, just Shift-Home or triple-click again, and the dialog updates automatically. Not perfect, but not bad.

Xchat plug-in for a much more elegant solution

Only after getting countsel working did it occur to me to wonder if anyone else had the same Bitlbee+xchat+twitter problem. And a web search found exactly what I needed: xchat-inputcount.pl, a wonderful xchat script that adds a character-counter next to the input box as you're typing. It's a teensy bit buggy, but still, it's far better than my solution. I had no idea you could add user-interface elements to xchat like that!

But that's okay. Countsel didn't take long to write. And I've added word counting to countsel, so I can use it for word counts on anything I'm writing.

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[ 11:32 Sep 09, 2011    More programming | permalink to this entry | comments ]
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