Class for capturing video from camera devices. More...

#include <gcg.h>

Inheritance diagram for gcgVIDEOCAPTURE:

Public Member Functions
	gcgVIDEOCAPTURE ()
	Constructs a valid video capture object. The capture actually starts with calls to setCallBackFunction() and openCamera(). More...

virtual	~gcgVIDEOCAPTURE ()
	Releases all video capture resources by calling destroyVideo(). More...

virtual bool	destroyVideo ()
	Releases all resources of this video capture object. More...

virtual int	getNumberOfCameras ()
	Returns the number of valid cameras installed in the system. More...

virtual bool	getCameraName (unsigned int id, char *pCameraName, unsigned int maxName)
	Gets the human readable name of the capture device given its integer identification. More...

virtual bool	openCamera (unsigned int id, unsigned int width, unsigned int height, unsigned char bpp, float fps)
	Opens the capture device and makes it ready to start image retrieval. More...

virtual bool	start ()
	Starts synchronous capturing. If successful, the capture starts from the device indicated by the previous call to openCamera() and the frames are delivered to the callback set by setCallBackFunction(). More...

virtual bool	stop ()
	Stops synchronous capturing. If successful, the capture stops. It generally releases some video resources. For a faster restart, use pause() instead. More...

virtual bool	resume ()
	Resumes synchronous capturing. If successful, the capture restarts. More...

virtual bool	pause ()
	Pauses the synchronous capturing. More...

virtual bool	isCapturing ()
	Returns true if the object is currently capturing, i.e., not stoped. More...

virtual bool	setCallBackFunction (void(callback)(gcgVIDEOCAPTURE ))
	Sets the callback function for the current object. It should be called before start(). Changing the internal function during the capture might give undesirable results. The callback function receives a pointer of the gcgVIDEOCAPTURE object that is delivering the new frame. The callback must return as fast as possible otherwise the video capture stream will be delayed. This might result in frame losses or instability depending on the system. More...

virtual double	copyFrameTo (gcgIMAGE *dstimg)
	Copies the last delivered frame into a gcgIMAGE object. It is generally used during a call to the callback function defined by setCallBackFunction() in order to get a copy of the new frame. More...

Public Member Functions inherited from gcgVIDEO
	gcgVIDEO ()
	Constructs a valid but empty image. The image can be used as destiny image in any gcgIMAGE method or GCGlib function. More...

virtual	~gcgVIDEO ()
	Releases all video resources by deleting the video handler. More...

Public Member Functions inherited from gcgCLASS
void *	operator new (size_t size)
	Defines a new operator to be used by instatiations of GCGlib classes instead the global one. More...

void *	operator new (size_t size, const std::nothrow_t &) throw ()
	Defines a new operator to be used by instantiations of GCGlib classes instead the global one. Returns a NULL pointer instead of throwing an exception if an error occurs. More...

void *	operator new[] (size_t size)
	Defines a new operator to be used by GCGlib array allocations instead the global one. More...

void *	operator new[] (size_t size, const std::nothrow_t &) throw ()
	Defines a new operator to be used by vector allocations instead the global one. More...

void	operator delete (void *p)
	Defines a delete operator to free instances of GCGlib classes instead the global one. It is designed to match the new operator. More...

void	operator delete (void *p, const std::nothrow_t &) throw ()
	Defines a delete operator to free instances of GCGlib classes instead the global one. It is designed to match the new operator. More...

void	operator delete[] (void *p)
	Defines a delete operator to free instances of arrays for GCGlib classes instead the global one. It is designed to match the new[] operator. More...

void	operator delete[] (void *p, const std::nothrow_t &) throw ()
	Defines a delete operator to free instances of arrays for GCGlib classes instead the global one. It is designed to match the new[] operator. More...

Detailed Description

Class for capturing video from camera devices.

The gcgVIDEOCAPTURE class is the main interface of GCGlib with camera devices. It uses platform specific objects and APIs. The camera is identified by its sequencial integer number. The capture mechanism is synchronous using a callback funtion. The video frames are provided by gcgIMAGE objects. Do not change any attributes unless you are absolutely sure about you are doing.

Since: 0.01.6

Constructor & Destructor Documentation

◆ gcgVIDEOCAPTURE()

gcgVIDEOCAPTURE::gcgVIDEOCAPTURE ( )

Constructs a valid video capture object. The capture actually starts with calls to setCallBackFunction() and openCamera().

See also: openCamera(); setCallBackFunction(); ~gcgVIDEOCAPTURE()

◆ ~gcgVIDEOCAPTURE()

virtual gcgVIDEOCAPTURE::~gcgVIDEOCAPTURE ( )

virtual

Releases all video capture resources by calling destroyVideo().

See also: destroyVideo(); gcgVIDEOCAPTURE()

Member Function Documentation

◆ copyFrameTo()

virtual double gcgVIDEOCAPTURE::copyFrameTo ( gcgIMAGE * dstimg )

virtual

Copies the last delivered frame into a gcgIMAGE object. It is generally used during a call to the callback function defined by setCallBackFunction() in order to get a copy of the new frame.

Parameters

dstimg A pointer to the gcgIMAGE object to which the last frame received by this gcgVIDEOCAPTURE must be copied to. If NULL, a warning is just reported.

Returns: the frame time in seconds. If negative, an error has occurred. Check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: openCamera(); start(); setCallBackFunction()

◆ destroyVideo()

virtual bool gcgVIDEOCAPTURE::destroyVideo ( )

virtual

Releases all resources of this video capture object.

Returns: true if the resources were released. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: gcgVIDEOCAPTURE(); ~gcgVIDEOCAPTURE()

◆ getCameraName()

virtual bool gcgVIDEOCAPTURE::getCameraName	(	unsigned int	id,
		char *	pCameraName,
		unsigned int	maxName
	)

virtual

Gets the human readable name of the capture device given its integer identification.

Parameters

id	The device capture identifier.
pCameraName	Pointer to the char buffer to receive the string. It must be non-null. The maximum number of chars supported by pCameraName must be indicated in maxName.
maxName	Maximum number of characters supported by the buffer pCameraName.

Returns: true if the name was retrieved. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: getNumberOfCameras()

◆ getNumberOfCameras()

virtual int gcgVIDEOCAPTURE::getNumberOfCameras ( )

virtual

Returns the number of valid cameras installed in the system.

Returns: the number of cameras. If negative or zero, no capture devices are available or an error occurred: check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: getCameraName()

◆ isCapturing()

virtual bool gcgVIDEOCAPTURE::isCapturing ( )

virtual

Returns true if the object is currently capturing, i.e., not stoped.

Returns: true if the capture is going on or paused.

See also: start(); stop(); openCamera()

◆ openCamera()

virtual bool gcgVIDEOCAPTURE::openCamera	(	unsigned int	id,
		unsigned int	width,
		unsigned int	height,
		unsigned char	bpp,
		float	fps
	)

virtual

Opens the capture device and makes it ready to start image retrieval.

Parameters

id	The device capture identifier.
width	Desired frame width in pixels. It might not be supported by the device.
height	Desired frame height in pixels. It might not be supported by the device.
bpp	Desired number of bits per pixel of each pixel. It might not be supported by the device.
fps	Desired frames per second rate. It might not be supported by the device.

Returns: true if the camera was successfully opened. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem and make sure the parameters are valid for the given device.

See also: start(); stop(); resume(); pause(); setCallBackFunction()

◆ pause()

virtual bool gcgVIDEOCAPTURE::pause ( )

virtual

Pauses the synchronous capturing.

Returns: true if the capture was paused. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: start(); stop(); resume(); openCamera()

◆ resume()

virtual bool gcgVIDEOCAPTURE::resume ( )

virtual

Resumes synchronous capturing. If successful, the capture restarts.

Returns: true if the capture is resumed. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: start(); stop(); pause(); openCamera()

◆ setCallBackFunction()

virtual bool gcgVIDEOCAPTURE::setCallBackFunction ( void(*)(gcgVIDEOCAPTURE *) callback )

virtual

Sets the callback function for the current object. It should be called before start(). Changing the internal function during the capture might give undesirable results. The callback function receives a pointer of the gcgVIDEOCAPTURE object that is delivering the new frame. The callback must return as fast as possible otherwise the video capture stream will be delayed. This might result in frame losses or instability depending on the system.

Parameters

callback pointer to a function that receives one gcgVIDEOCAPTURE pointer and returns void. When called, the callback function receives the pointer of the object that delivers the new frame. If NULL, a warning is reported and all subsequent frames are discarded.

Returns: true if the callback was correctly set. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: openCamera(); start(); copyFrameTo()

◆ start()

virtual bool gcgVIDEOCAPTURE::start ( )

virtual

Starts synchronous capturing. If successful, the capture starts from the device indicated by the previous call to openCamera() and the frames are delivered to the callback set by setCallBackFunction().

Returns: true if the capture started. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: openCamera(); stop(); resume(); pause()

◆ stop()

virtual bool gcgVIDEOCAPTURE::stop ( )

virtual

Stops synchronous capturing. If successful, the capture stops. It generally releases some video resources. For a faster restart, use pause() instead.

Returns: true if the capture stoped. If it returns false, check GCG_REPORT_MESSAGE(gcgGetReport()) for knowing the problem.

See also: start(); openCamera(); resume(); pause()

The documentation for this class was generated from the following file:

M:/Documentos/Projetos/Projetos/GCGlib/src/gcg.h

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ gcgVIDEOCAPTURE()

◆ ~gcgVIDEOCAPTURE()

Member Function Documentation

◆ copyFrameTo()

◆ destroyVideo()

◆ getCameraName()

◆ getNumberOfCameras()

◆ isCapturing()

◆ openCamera()

◆ pause()

◆ resume()

◆ setCallBackFunction()

◆ start()

◆ stop()