hyperion.ng/libsrc/grabber/x11/X11Grabber.cpp

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// STL includes
#include <iostream>
#include <cstdint>
// X11 includes
#include <X11/Xutil.h>
// X11Grabber includes
#include <grabber/X11Grabber.h>
X11Grabber::X11Grabber(int cropLeft, int cropRight, int cropTop, int cropBottom, int horizontalPixelDecimation, int verticalPixelDecimation) :
_imageResampler(),
_cropLeft(cropLeft),
_cropRight(cropRight),
_cropTop(cropTop),
_cropBottom(cropBottom),
_x11Display(nullptr),
_screenWidth(0),
_screenHeight(0),
_croppedWidth(0),
_croppedHeight(0),
_image(0,0)
{
_imageResampler.setHorizontalPixelDecimation(horizontalPixelDecimation);
_imageResampler.setVerticalPixelDecimation(verticalPixelDecimation);
_imageResampler.setCropping(0, 0, 0, 0); // cropping is performed by XShmGetImage
}
X11Grabber::~X11Grabber()
{
if (_x11Display != nullptr)
{
freeResources();
XCloseDisplay(_x11Display);
}
}
void X11Grabber::freeResources()
{
// Cleanup allocated resources of the X11 grab
XShmDetach(_x11Display, &_shminfo);
XDestroyImage(_xImage);
shmdt(_shminfo.shmaddr);
shmctl(_shminfo.shmid, IPC_RMID, 0);
}
void X11Grabber::setupResources()
{
_xImage = XShmCreateImage(_x11Display, _windowAttr.visual,
_windowAttr.depth, ZPixmap, NULL, &_shminfo,
_croppedWidth, _croppedHeight);
_shminfo.shmid = shmget(IPC_PRIVATE, _xImage->bytes_per_line * _xImage->height, IPC_CREAT|0777);
_shminfo.shmaddr = _xImage->data = (char*)shmat(_shminfo.shmid,0,0);
_shminfo.readOnly = False;
XShmAttach(_x11Display, &_shminfo);
}
bool X11Grabber::Setup()
{
_x11Display = XOpenDisplay(NULL);
if (_x11Display == nullptr)
{
std::cerr << "Unable to open display";
if (getenv("DISPLAY"))
std::cerr << " " << std::string(getenv("DISPLAY")) << std::endl;
else
std::cerr << ". DISPLAY environment variable not set" << std::endl;
return false;
}
_window = DefaultRootWindow(_x11Display);
return true;
}
Image<ColorRgb> & X11Grabber::grab()
{
updateScreenDimensions();
XShmGetImage(_x11Display, _window, _xImage, _cropLeft, _cropTop, 0x00FFFFFF);
if (_xImage == nullptr)
{
std::cerr << "Grab failed" << std::endl;
return _image;
}
_imageResampler.processImage(reinterpret_cast<const uint8_t *>(_xImage->data), _xImage->width, _xImage->height, _xImage->bytes_per_line, PIXELFORMAT_BGR32, _image);
return _image;
}
int X11Grabber::updateScreenDimensions()
{
const Status status = XGetWindowAttributes(_x11Display, _window, &_windowAttr);
if (status == 0)
{
std::cerr << "Failed to obtain window attributes" << std::endl;
return -1;
}
if (_screenWidth == unsigned(_windowAttr.width) && _screenHeight == unsigned(_windowAttr.height))
{
// No update required
return 0;
}
std::cout << "Update of screen resolution: [" << _screenWidth << "x" << _screenHeight <<"] => ";
if (_screenWidth || _screenHeight)
freeResources();
_screenWidth = _windowAttr.width;
_screenHeight = _windowAttr.height;
std::cout << "[" << _screenWidth << "x" << _screenHeight <<"]" << std::endl;
if (_screenWidth > unsigned(_cropLeft + _cropRight))
_croppedWidth = _screenWidth - _cropLeft - _cropRight;
else
_croppedWidth = _screenWidth;
if (_screenHeight > unsigned(_cropTop + _cropBottom))
_croppedHeight = _screenHeight - _cropTop - _cropBottom;
else
_croppedHeight = _screenHeight;
setupResources();
return 0;
}