Animated GIF Screenshots on Ubuntu

Background

I’ve to take screenshots to demonstrate Conky’s visual output.

I’ve chosen Byzanz after reading this answer on Ask Ubuntu.

Peek is more user-friendly, but I prefer CLI’s precision. That’s feasible thanks to a comment mentioning xwininfo.

After typing xwininfo, click on the target window. Switching to adjacent workplace is possible.

$ xwininfo
xwininfo: Please select the window about which you
          would like information by clicking the
          mouse in that window.

xwininfo: Window id: 0x1c0000a "Desktop"

  Absolute upper-left X:  0
  Absolute upper-left Y:  0
  Relative upper-left X:  0
  Relative upper-left Y:  0
  Width: 1920
  Height: 1080
  Depth: 32
  Visual: 0x1a7
  Visual Class: TrueColor
  Border width: 0
  Class: InputOutput
  Colormap: 0x1c00009 (not installed)
  Bit Gravity State: NorthWestGravity
  Window Gravity State: NorthWestGravity
  Backing Store State: NotUseful
  Save Under State: no
  Map State: IsViewable
  Override Redirect State: no
  Corners:  +0+0  -0+0  -0-0  +0-0
  -geometry 1920x1080+0+0

The --x and --y parameters below correspond to the absolute upper-left position of the window.

$ byzanz-record --duration=15 --x=200 --y=300 --width=700 --height=400 \
out.gif

Problem

The window drawn by Conky isn’t regarded as a “window” by xwininfo. It measures the whole desktop wallpaper instead.

Analysis

xwininfo has an -id parameter to allow specifying the target window. This motivates us to look into Conky’s standard output. To simplify things, I’ll kill the Conky instance started since login by issuing kill con<tab>. Oh-My-Zsh (or whatever) then completes the argument with the right PID. Key in conky to start another instance of conky. Luckily, Conky’s messages are useful enough for retriving the right -id parameter for xwininfo.

$ conky
conky: warning: invalid head index, ignoring head settings
conky: warning: invalid head index, ignoring head settings
conky: desktop window (400012) is subwindow of root window (1b1)
conky: window type - normal
conky: drawing to created window (0x1800002)
conky: drawing to double buffer

The hexadecimal numbers 400012 and 1b1 in the parenthesis represent the window IDs for the whole desktop background.

$ xwininfo -id 1b1
X Error: 9: Bad Drawable: 0x1
  Request Major code: 14
  Request serial number: 3
xwininfo: error: No such window with id 0x1

The prefix 0x has to be added to signify that the window ID is a hexadecimal number.

$ xwininfo -id 0x400012

xwininfo: Window id: 0x400012 "mutter guard window"

  Absolute upper-left X:  0
  Absolute upper-left Y:  0
  Relative upper-left X:  0
  Relative upper-left Y:  0
  Width: 1920
  Height: 1080
  Depth: 0
  Visual: 0x41
  Visual Class: TrueColor
  Border width: 0
  Class: InputOnly
  Colormap: 0x0 (not installed)
  Bit Gravity State: ForgetGravity
  Window Gravity State: NorthWestGravity
  Backing Store State: NotUseful
  Save Under State: no
  Map State: IsViewable
  Override Redirect State: yes
  Corners:  +0+0  -0+0  -0-0  +0-0
  -geometry 1920x1080+0+0

In the above message from Conky, the line “drawing to created window (0x1800002)” gives the actual -id.

Solution

1. Use the above hexadecimal number for Conky’s window -id. The -stats option is here to remove the unnecessary details.

    $ xwininfo -id 0x1800002 -stats
   
    xwininfo: Window id: 0x1800002 "conky (vin100-LIFEBOOK-AH557)"
   
      Absolute upper-left X:  1607
      Absolute upper-left Y:  27
      Relative upper-left X:  1607
      Relative upper-left Y:  27
      Width: 313
      Height: 771
      Depth: 32
      Visual: 0xd6
      Visual Class: TrueColor
      Border width: 0
      Class: InputOutput
      Colormap: 0x1800001 (not installed)
      Bit Gravity State: ForgetGravity
      Window Gravity State: NorthWestGravity
      Backing Store State: Always
      Save Under State: no
      Map State: IsViewable
      Override Redirect State: no
      Corners:  +1607+27  -0+27  -0-282  +1607-282
      -geometry 313x771-0+27
   

2. Configure the above byzanz-record command to achieve the goal.

    $ byzanz-record --duration=2 --x=1607 --y=27 --width=313 --height=771 \
    out.gif
   

Edited: It turns out that the main problem has a much simpler solution.

$ xwininfo -tree -root | grep conky
     0x1800002 "conky (vin100-LIFEBOOK-AH557)": ("conky" "conky")  313x771+1607+
27  +1607+27