Weston keyboard shortcuts

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Weston is the reference implementation of a Wayland compositor.

The table below lists the actions that can be performed through Weston keyboard shortcuts, when the development board is connected to a keyboard.

It must be noted that:

• <modifier-key> in the table below corresponds to the key used for common bindings. It is defined by binding-modifier=<modifier-key> in the /etc/xdg/weston/weston.ini file. Possible values for <modifier-key> are:
  • "super", i.e. Windows key between "ctrl" and "alt" (default Weston value)
  • "ctrl" (default value in STMicroelectronics images)
  • "alt"
  • "none"
• The shortcuts are defined in desktop-shell/shell.c^[1] file (shell_add_bindings() function)
• Some shortcuts require that both a keyboard and a mouse are connected to the development board
• Some shortcuts require that several workspaces are defined. The number of workspaces is defined by num-workspaces=<num-workspaces> in the /etc/xdg/weston/weston.ini file. The maximum number of workspaces is 6. If num-workspaces is not set, one single workspace is configured.
• The left mouse button allows the activation of a window.

Before proceeding, it is recommended to

• check the <modifier-key> value:

  grep binding-modifier /etc/xdg/weston/weston.ini                                             
binding-modifier=ctrl

• check the <num-workspaces> value:

 grep num-workspaces /etc/xdg/weston/weston.ini                                             
num-workspaces=6

Additional shortcuts can be found on internet.

1 Capturing a screenshot

1. Refer to the table above for the command to be used.
2. The captured picture (PNG format) is automatically stored in /wayland-screenshot-2018-01-06_01-48-19.png.
3. Copy the screenshot from the board to the host PC in the <file-path> directory (for example with the scp command).

 scp root@<ip address>:/wayland-screenshot-*.png <file-path>/

Note: a screenshot capture is also named a snapshot or a screen capture.

2 Recording a screencast

1. Refer to the table above for the command to be used.
2. The recorded screencast (WCAP format) is automatically stored in /capture.wcap. The WCAP format is a lossless video format specific to Weston (only the frame differences are recorded).
3. To play the recorded screencast, convert it to a format that can be interpreted by any video player (e.g. VP8). Three steps are required:

• On the board, convert the WCAP file into a YUV file using wcap-decode:

 wcap-decode capture.wcap --yuv4mpeg2 > capture.y4m

• Copy the YUV file from the board to the host PC in the <file-path> directory (for example with the scp command):

 scp root@<ip address>:/capture.y4m <file-path>/

• On the host PC, transcode the YUV file to any other well-known format (e.g. VP8) using ffmpeg:

 ffmpeg -i capture.y4m -c:v libvpx -b:v 1M capture.webm

• Optionally, choose a higher bitrate (-b:v 1M means a target bitrate of 1 MBit/s) if a better quality is required. Optionally, use the transpose parameter when a 90 degree clockwise rotation is needed:

 ffmpeg -i capture.y4m -vf transpose=1 -c:v libvpx -b:v 1M capture.webm

Information

Note that the YUV file size might be huge if the recording is long (see example below).

Example:

• On the board: a 5-second screencast is recorded

 wcap-decode capture.wcap --yuv4mpeg2 > capture.y4m
wcap file: size 720x1280, 192 frames
 ls -l capture.*
-rw-r--r-- 1   8246868 Dec 13 14:58 capture.wcap
-rw-r--r-- 1 167821312 Dec 13 14:59 capture.y4m

• On the host PC

 scp root@<ip address>:/capture.y4m .
 ffmpeg -i capture.y4m -vf transpose=1 -c:v libvpx -b:v 1M capture.webm
 ls -l capture.*
-rw-r--r-- 1    104470 Feb  8 11:01 capture.webm
-rw-r--r-- 1 167821312 Feb  8 10:56 capture.y4m

References list: