Visual Servoing Platform  version 3.5.1 under development (2022-07-05)
#include <visp3/gui/vpDisplayGDI.h>
#include <visp3/gui/vpDisplayOpenCV.h>
#include <visp3/gui/vpDisplayX.h>
#include <visp3/detection/vpDetectorFace.h>
#include <visp3/io/vpVideoReader.h>
int main(int argc, const char *argv[])
try {
std::string opt_face_cascade_name = "./haarcascade_frontalface_alt.xml";
std::string opt_video = "video.mp4";
for (int i = 0; i < argc; i++) {
if (std::string(argv[i]) == "--haar")
opt_face_cascade_name = std::string(argv[i + 1]);
else if (std::string(argv[i]) == "--video")
opt_video = std::string(argv[i + 1]);
else if (std::string(argv[i]) == "--help" || std::string(argv[i]) == "-h") {
std::cout << "Usage: " << argv[0] << " [--haar <haarcascade xml filename>] [--video <input video file>]"
<< " [--help] [-h]" << std::endl;
return 0;
#if defined(VISP_HAVE_X11)
vpDisplayX d(I);
#elif defined(VISP_HAVE_GDI)
#elif defined(VISP_HAVE_OPENCV)
vpDisplay::setTitle(I, "ViSP viewer");
vpDetectorFace face_detector;
bool exit_requested = false;
while (!g.end() && !exit_requested) {
bool face_found = face_detector.detect(I);
if (face_found) {
std::ostringstream text;
text << "Found " << face_detector.getNbObjects() << " face(s)";
vpDisplay::displayText(I, 10, 10, text.str(), vpColor::red);
for (size_t i = 0; i < face_detector.getNbObjects(); i++) {
vpRect bbox = face_detector.getBBox(i);
vpDisplay::displayText(I, (int)bbox.getTop() - 10, (int)bbox.getLeft(),
"Message: \"" + face_detector.getMessage(i) + "\"", vpColor::red);
vpDisplay::displayText(I, (int)I.getHeight() - 25, 10, "Click to quit...", vpColor::red);
if (vpDisplay::getClick(I, false)) // a click to exit
exit_requested = true;
if (!exit_requested)
} catch (const vpException &e) {
std::cout << e.getMessage() << std::endl;
static const vpColor red
Definition: vpColor.h:217
static const vpColor green
Definition: vpColor.h:220
Display for windows using GDI (available on any windows 32 platform).
Definition: vpDisplayGDI.h:129
The vpDisplayOpenCV allows to display image using the OpenCV library. Thus to enable this class OpenC...
Use the X11 console to display images on unix-like OS. Thus to enable this class X11 should be instal...
Definition: vpDisplayX.h:135
static bool getClick(const vpImage< unsigned char > &I, bool blocking=true)
static void display(const vpImage< unsigned char > &I)
static void setTitle(const vpImage< unsigned char > &I, const std::string &windowtitle)
static void flush(const vpImage< unsigned char > &I)
static void displayRectangle(const vpImage< unsigned char > &I, const vpImagePoint &topLeft, unsigned int width, unsigned int height, const vpColor &color, bool fill=false, unsigned int thickness=1)
static void displayText(const vpImage< unsigned char > &I, const vpImagePoint &ip, const std::string &s, const vpColor &color)
error that can be emited by ViSP classes.
Definition: vpException.h:72
const char * getMessage() const
Definition: vpException.cpp:87
unsigned int getHeight() const
Definition: vpImage.h:188
Defines a rectangle in the plane.
Definition: vpRect.h:80
double getLeft() const
Definition: vpRect.h:174
double getTop() const
Definition: vpRect.h:193
Class that enables to manipulate easily a video file or a sequence of images. As it inherits from the...
void acquire(vpImage< vpRGBa > &I)
void open(vpImage< vpRGBa > &I)
void setFileName(const std::string &filename)