hyperion.ng/libsrc/dispmanx-grabber/DispmanxFrameGrabber.cpp

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#include "DispmanxFrameGrabber.h"
DispmanxFrameGrabber::DispmanxFrameGrabber(const unsigned width, const unsigned height) :
_vc_display(0),
_vc_resource(0),
_width(width),
_height(height)
{
// Initiase BCM
bcm_host_init();
{
// Check if the display can be opened and display the current resolution
// Open the connection to the display
_vc_display = vc_dispmanx_display_open(0);
assert(_vc_display > 0);
// Obtain the display information
DISPMANX_MODEINFO_T vc_info;
int result = vc_dispmanx_display_get_info(_vc_display, &vc_info);
// Keep compiler happy in 'release' mode
(void)result;
assert(result == 0);
std::cout << "Display opened with resolution: " << vc_info.width << "x" << vc_info.height << std::endl;
// Close the displaye
vc_dispmanx_display_close(_vc_display);
}
// Create the resources for capturing image
uint32_t vc_nativeImageHandle;
_vc_resource = vc_dispmanx_resource_create(
VC_IMAGE_RGB888,
width,
height,
&vc_nativeImageHandle);
assert(_vc_resource);
// Define the capture rectangle with the same size
vc_dispmanx_rect_set(&_rectangle, 0, 0, width, height);
}
DispmanxFrameGrabber::~DispmanxFrameGrabber()
{
// Clean up resources
vc_dispmanx_resource_delete(_vc_resource);
// De-init BCM
bcm_host_deinit();
}
void DispmanxFrameGrabber::grabFrame(RgbImage& image)
{
// Sanity check of the given image size
assert(image.width() == _width && image.height() == _height);
// Open the connection to the display
_vc_display = vc_dispmanx_display_open(0);
// Create the snapshot (incl down-scaling)
vc_dispmanx_snapshot(_vc_display, _vc_resource, VC_IMAGE_ROT0);
// Read the snapshot into the memory
void* image_ptr = image.memptr();
const unsigned destPitch = _width * 3;
vc_dispmanx_resource_read_data(_vc_resource, &_rectangle, image_ptr, destPitch);
// Close the displaye
vc_dispmanx_display_close(_vc_display);
}