d3dshot_screen_grabber

Overview

This Python script implements a rospy ROS node which uses d3dshot to make screenshots of a Windows desktop and publishes those both as sensor_msgs/Images as well as sensor_msgs/CompressedImages (JPEG compression). sensor_msgs/CameraInfo messages are also published.

Supported OS and Python versions

As d3dshot only works on Windows, this node only works on Windows.

Only Windows 10 has been tested.

The authors have only used Python 3.8.x.

Installation

This is not a regular ROS package, as it is intended to be used with rospypi/simple, the pure Python, minimalistic package index for ROS 1 packages. The index provides a convenient way to setup venvs for rospy and related packages, which greatly reduces the overhead of running ROS 1 on Windows.

Users are encouraged to create a venv and install all dependencies in that venv (update paths below as required):

REM create the venv
python -m venv venv_d3dshot_screen_grabber

REM activate the venv
venv_d3dshot_screen_grabber\Scripts\activate.bat

REM update pip itself
pip install -U pip wheel

Dependencies

By default, the node will install and use opencv-python-headless, which is a CPU only version of OpenCV. If you already have OpenCV installed (important: the Python bindings are required), or will install another version of OpenCV in the venv, run the following command:

pip install -r path\to\d3dshot_screen_grabber\requirements_no_cv.txt

If you do not have OpenCV installed and just want to use the default (ie: opencv-python-headless), run:

pip install -r path\to\d3dshot_screen_grabber\requirements.txt

General usage

To start the node, make sure a roscore is running (locally, or on remote PC) and:

REM make sure the venv is active
venv_d3dshot_screen_grabber\Scripts\activate.bat

REM setup the environment
set ROS_IP=<ip of this PC>
set ROS_MASTER_URI=http://<ip of the PC running roscore>:11311

REM start the node
python path\to\d3dshot_screen_grabber\node.py WINDOW_NAME

Alternatively, specify the local IP and URI of the ROS master using command line arguments:

python path\to\d3dshot_screen_grabber\node.py WINDOW_NAME __ip:=<ip of this PC> __master:=http://<ip of the PC running roscore>:11311

It may be convenient to create a .bat or .cmd to easily start the node with the required command line arguments (note: ^ is the line-continuation character):

path\to\venv_d3dshot_screen_grabber\Scripts\python.exe ^
  path\to\d3dshot_screen_grabber\node.py ^
  __ip:=<ip of this PC> ^
  __master:=http://<ip of the PC running roscore>:11311 ^
  WINDOW_NAME

See --help for the usage specification and additional command line arguments.

Example

This example shows how to capture the full window of the Calculator application and publish it on /capture/calculator/image_rect_color (the namespace is provided as a command line argument, the topic name is default in accordance with naming practices of ROS topics for cameras).

Follow the steps in the previous section to activate the venv, setup the environment and then:

REM start the calculator
calc

REM start the node:
REM
REM   -f   : push the Calculator window to the foreground
REM   --ns : override the default namespace
python path\to\d3dshot_screen_grabber\node.py -f --ns="capture/calculator" "Calculator"

On the receiving side, start either an image_view node or RViz and subscribe to the /capture/calculator/image_rect_color topic.

tud-cor / d3dshot_screen_grabber