Linux上的Android screenshot2工具NullPointerException

Question

I am using:

Java Version: 7

SDK Tools, Revision 24.4.1 (October 2015)

Taking a screenshot with the tool screenshot2 raise a NullPointerException on Ubuntu Server 14.04 and Kali Linux 2.0. It works on Mac OS X 10.11.

Command:

$ screenshot2 -e image.png

(Error happens even with the -s argument or without)

Error:

Exception in thread "main" java.lang.NullPointerException
at com.android.ddmlib.MonitorThread.wakeup(MonitorThread.java:580)
at com.android.ddmlib.MonitorThread.quit(MonitorThread.java:588)
at com.android.ddmlib.AndroidDebugBridge.terminate(AndroidDebugBridge.java:235)
at com.android.screenshot.Screenshot.main(Screenshot.java:198)

Is there a fix or does anyone know the reason for this?

Answer 1

I found a solution that avoid using the screenshot2 tool.

Dependencies for Linux:

sudo apt-get install zlib1g-dev libjpeg-dev

Maybe it works even without on your machine but I don't thing so.

Then you need the python package pillow version 2.9.0

Dependency for Mac AND Linux:

sudo pip install pillow==2.9.0

I made this really basic script that create the screenshot image.

File screenshot.py

from StringIO import StringIO
from PIL import Image
import sys

binary = sys.stdin.read().replace('\r\n', '\n')
stream = StringIO(binary)
image = Image.open(stream)
image.save(sys.argv[1], 'PNG')

Now you can use the command line to simply get a screenshot from the device like I tried above.

Example:

adb shell screencap -p | python screenshot.py image.png

Or with the -s argument for a specific device

adb shell -s emulator-5558 screencap -p | python screenshot.py image.png

Answer 2

For those who don't want to mess with python for a simple screenshot, here is a bash one-liner, without any extra dependencies:

adb exec-out screencap -p >YOUR_FILE.png

You can also make it a bash script for daily use.