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Taking screenshots on the RaspberryPI

A walk through on how to capture everything displayed by the GPU

Taking a screenshot on the RaspberryPI while you have your favourite app running is not always that easy, is it?

With the advent of new great apps taking advantage of the PIs graphics chip, most screenshot applications like scrot are sometimes not even installable on OpenELEC, Raspbmc and others.

At Kano we have expanded a tool from Andrew Duncan that allows you to take screenshot images of what your app is currently displaying on the screen, regardless of which app that might be. Perhaps you want to take a screenshot of your favourite movie scene? Or your most challenging moment in Minecraft, or Quake? Or your favourite Youtube video still image? Or even your preferred text based console tool?

kano-screenshot can see all of these applications because it reads the graphics chip memory directly, and it can also be invoked from another computer via a remote shell, so for example it can be a great benefit for remote monitoring environments.

On KanoOS, you can trigger it using the Ctrl+PrintScreen combination on regular keyboards, or Ctrl+Alt+= using the Kano Keyboard. You will hear a camera shutter sound and a new PNG file will appear on your “Screenshot” desktop folder. But it can also run on other distributions like Raspbian and media players like OpenELEC or Raspbmc. If the distribution you are using is based on Debian, you can quickly install Kano Screenshot by adding Kano’s package repository amongst your sources, like this:

sudo bash -c "printf 'deb wheezy main contrib\n' > /etc/apt/sources.list.d/kano.list"
sudo apt-get update
sudo apt-get install kano-screenshot

On desktop systems based on the Xserver, kano-screenshot will see your complete desktop, and there is also a useful feature of capturing the area occupied by a specific application. Check out the -l option which will list all your Xserver apps, and -a to capture whichever you like most.

For those who are more adventurous, it’s not difficult to build kano-screenshot from sources and expand it to your specific needs. It has minimal dependencies, namely the libpng library from Raspberry Pi’s firmware package, so you should be up and running pretty easily. We encourage you to submit new improvements and delighted to help you make them into KanoOS!

Written by
Systems developer and Integrator at Kano