YARP  2.3.68+228-20170410.2+git7d0b2e0
Yet Another Robot Platform

This is the os/image_process.cpp example rewritten as a "module".It inherits better starting up, configuring, and shutting down behavior.

* Copyright: (C) 2010 RobotCub Consortium
* Author: Paul Fitzpatrick
* CopyPolicy: Released under the terms of the LGPLv2.1 or later, see LGPL.TXT
#include <yarp/os/all.h>
#include <yarp/sig/all.h>
using namespace yarp::os;
using namespace yarp::sig;
using namespace yarp::sig::draw;
This example adds a moving circle to an image stream.
It is the same as image_process.cpp, except it is built
as a Yarp "Module". This makes it a bit cleaner to start/stop.
Suppose we have an image source on port /source such as:
yarpdev --device test_grabber --name /source --mode line --framerate 10
And suppose we have an image viewer on port /view:
yarpview --name /view
Then we can hook this program up in between as follows:
./image_process --name /worker
yarp connect /source /worker
yarp connect /worker /view
You should see the normal scrolling line of test_grabber, with a moving
circle overlaid.
class ImageProcessModule : public RFModule {
// Make a port for reading and writing images
Port cmdPort;
int ct;
bool open(Searchable& config) {
ct = 0;
cmdPort.open(getName("cmd")); // optional command port
attach(cmdPort); // cmdPort will work just like terminal
return true;
// try to interrupt any communications or resource usage
bool interruptModule() {
return true;
bool updateModule() {
ImageOf<PixelRgb> *img = port.read();
if (img==NULL) return false;;
// add a blue circle
PixelRgb blue(0,0,255);
ct = (ct+5)%img->width();
// output the image
port.prepare() = *img;
return true;
int main(int argc, char *argv[]) {
// Initialize the yarp network
/* prepare and configure the resource finder */
rf.configure(argc, argv);
// Create and run our module
ImageProcessModule module;
return module.runModule(rf);