workings-book/entries/2014-12-18.md

Thursday, December 18, 2014

screencast gifs

Looking to make some GIFs of things that happen on my screen, found byzanz.

$ sudo apt-get install byzanz
byzanz-record -x 1 -y 1 --delay=4 -h 150 -w 700 hello_world.gif

Options:

• -x and -y set origin of capture on screen
• -h and -w set height and width to capture

I think I need a more clever way to trigger / manage this than just fiddling with CLI options, but it works really well and produces lightweight image files.

I think it would be cool if there were a utility that let me use arrow keys / hjkl / the mouse cursor to visually select a region of the screen. It could return x, y, height, and width, then I'd let byzanz handle the capture.

That can't be the hardest thing in the world to do.

-> ☆ <-

xdotool seems like kind of a swiss army knife, and has a getmouselocation command. Theoretically, at least, you can have it respond to events, including a mouse click. I can't quite wrap my head around how this is supposed to work, and my first few attempts fall flat.

GNU xnee might also be promising, but I don't really get anywhere with it.

Eventually I find an Ask Ubuntu thread on creating screencast gifs, which points to xrectsel, a tool for returning the coordinates and size of a screen region selected with the mouse:

brennen@desiderata 22:06:28 /var/www/workings-book (master) ★  xrectsel "%x %y %w %h"
432 130 718 575%

I wind up with gif_sel:

#!/usr/bin/env bash

# requires:
# https://github.com/lolilolicon/xrectsel.git

eval `xrectsel "BYZANZ_X=%x; BYZANZ_Y=%y; BYZANZ_WIDTH=%w; BYZANZ_HEIGHT=%h"`
byzanz-record -x $BYZANZ_X -y $BYZANZ_Y --delay=4 -h $BYZANZ_HEIGHT -w $BYZANZ_WIDTH ~/screenshots/screencast-`date +"%Y-%m-%d-%T"`.gif

I'll probably wind up with a couple of wrappers for this for different lengths of recording (for starting with dmenu), though it would be nice if I could just have it record until I press some hotkey.