Fawkes API  Fawkes Development Version
firevision::V4LCamera Class Reference

General Video4Linux camera implementation. More...

#include <>>

Inheritance diagram for firevision::V4LCamera:

Public Member Functions

 V4LCamera (const char *device_name="/dev/video0")
 Constructor. More...
 
 V4LCamera (const CameraArgumentParser *cap)
 Constructor. More...
 
virtual ~V4LCamera ()
 Destructor. More...
 
virtual void open ()
 Open the camera. More...
 
virtual void start ()
 Start image transfer from the camera. More...
 
virtual void stop ()
 Stop image transfer from the camera. More...
 
virtual void close ()
 Close camera. More...
 
virtual void flush ()
 Flush image queue. More...
 
virtual void capture ()
 Capture an image. More...
 
virtual void print_info ()
 Print out camera information. More...
 
virtual bool ready ()
 Camera is ready for taking pictures. More...
 
virtual unsigned char * buffer ()
 Get access to current image buffer. More...
 
virtual unsigned int buffer_size ()
 Size of buffer. More...
 
virtual void dispose_buffer ()
 Dispose current buffer. More...
 
virtual unsigned int pixel_width ()
 Width of image in pixels. More...
 
virtual unsigned int pixel_height ()
 Height of image in pixels. More...
 
virtual colorspace_t colorspace ()
 Colorspace of returned image. More...
 
virtual void set_image_number (unsigned int n)
 Set image number to retrieve. More...
 
- Public Member Functions inherited from firevision::Camera
virtual ~Camera ()
 Virtual empty destructor. More...
 
virtual fawkes::Timecapture_time ()
 Get the Time of the last successfully captured image. More...
 

Detailed Description

General Video4Linux camera implementation.

Maintains backwards compatibility. Chooses on the fly whether v4l1 or v4l2 is needed for a given device.

Author
Tobias Kellner

Definition at line 37 of file v4l.h.

Constructor & Destructor Documentation

◆ V4LCamera() [1/2]

firevision::V4LCamera::V4LCamera ( const char *  device_name = "/dev/video0")

Constructor.

Parameters
device_namedevice file name (e.g. /dev/video0)

Definition at line 60 of file v4l.cpp.

◆ V4LCamera() [2/2]

firevision::V4LCamera::V4LCamera ( const CameraArgumentParser cap)

Constructor.

Initialize camera with parameters from camera argument parser. Supported arguments:

  • device=DEV, device file, for example /dev/video0
    Parameters
    capcamera argument parser

Definition at line 73 of file v4l.cpp.

References firevision::CameraArgumentParser::get(), and firevision::CameraArgumentParser::has().

◆ ~V4LCamera()

firevision::V4LCamera::~V4LCamera ( )
virtual

Destructor.

Definition at line 81 of file v4l.cpp.

Member Function Documentation

◆ buffer()

unsigned char * firevision::V4LCamera::buffer ( )
virtual

Get access to current image buffer.

This will return a pointer to the current buffer. The buffer contains an image of the given colorspace, width and height.

Returns
pointer to image buffer

Implements firevision::Camera.

Definition at line 172 of file v4l.cpp.

References firevision::Camera::buffer().

◆ buffer_size()

unsigned int firevision::V4LCamera::buffer_size ( )
virtual

Size of buffer.

Gets the size in bytes of the buffer returned by buffer().

Returns
size of buffer in bytes

Implements firevision::Camera.

Definition at line 178 of file v4l.cpp.

References firevision::Camera::buffer_size().

◆ capture()

void firevision::V4LCamera::capture ( )
virtual

Capture an image.

Although cameras shall operate with a continuous image flow where possible sometimes capturing an image means copying a buffer or advancing a buffer list pointer. This shall be done in this method. For a camera-using application it is mandatory to call capture() just before accessing the image buffer.

Implements firevision::Camera.

Definition at line 154 of file v4l.cpp.

References firevision::Camera::capture().

◆ close()

void firevision::V4LCamera::close ( )
virtual

Close camera.

This closes the camera device. The camera must have been stopped before calling close().

Implements firevision::Camera.

Definition at line 142 of file v4l.cpp.

References firevision::Camera::close().

◆ colorspace()

colorspace_t firevision::V4LCamera::colorspace ( )
virtual

Colorspace of returned image.

Returns
colorspace of image returned by buffer()

Implements firevision::Camera.

Definition at line 206 of file v4l.cpp.

References firevision::Camera::colorspace().

◆ dispose_buffer()

void firevision::V4LCamera::dispose_buffer ( )
virtual

Dispose current buffer.

Some cameras need disposal of the current buffer (for example to free space in a queue to retrieve the next image). This is done with this method. It has to be called after all work has been done on the image as desired. After dispose_buffer() has been called no further access may happen to the image buffer or undesired behavior may happen.

Implements firevision::Camera.

Definition at line 184 of file v4l.cpp.

References firevision::Camera::dispose_buffer().

◆ flush()

void firevision::V4LCamera::flush ( )
virtual

Flush image queue.

Some cameras may have an image buffer queue. With this it can happen that if the processing of an image took longer than desired it is needed to flush this buffer queue.

Implements firevision::Camera.

Definition at line 148 of file v4l.cpp.

References firevision::Camera::flush().

◆ open()

void firevision::V4LCamera::open ( )
virtual

Open the camera.

The camera is opened, but image transfer not yet started. This can be used to detect general problems with the camera while delaying the real transfer startup until it is needed.

Implements firevision::Camera.

Definition at line 88 of file v4l.cpp.

◆ pixel_height()

unsigned int firevision::V4LCamera::pixel_height ( )
virtual

Height of image in pixels.

Returns
height of image in pixels

Implements firevision::Camera.

Definition at line 198 of file v4l.cpp.

References firevision::Camera::pixel_height().

◆ pixel_width()

unsigned int firevision::V4LCamera::pixel_width ( )
virtual

Width of image in pixels.

Returns
width of image in pixels

Implements firevision::Camera.

Definition at line 190 of file v4l.cpp.

References firevision::Camera::pixel_width().

◆ print_info()

void firevision::V4LCamera::print_info ( )
virtual

Print out camera information.

Shall print out camera information and current setup information on stdout.

Implements firevision::Camera.

Definition at line 160 of file v4l.cpp.

References firevision::Camera::print_info().

◆ ready()

bool firevision::V4LCamera::ready ( )
virtual

Camera is ready for taking pictures.

The camera has been opened and started correctly and may now provide images.

Returns
true, if the camera is ready, false otherwise

Implements firevision::Camera.

Definition at line 166 of file v4l.cpp.

References firevision::Camera::ready().

◆ set_image_number()

void firevision::V4LCamera::set_image_number ( unsigned int  n)
virtual

Set image number to retrieve.

If a camera is able to retrieve several images this method can be used to select the image to be retrieved with the next call to capture().

Parameters
nimage number to set

Implements firevision::Camera.

Definition at line 212 of file v4l.cpp.

References firevision::Camera::set_image_number().

◆ start()

void firevision::V4LCamera::start ( )
virtual

Start image transfer from the camera.

For many cameras opening the camera and starting transmission of images are two tasks. This method will simply initiate the transfer after the camera as been opened. And exception shall be thrown if the camera has not been opened.

Implements firevision::Camera.

Definition at line 126 of file v4l.cpp.

References firevision::Camera::start().

◆ stop()

void firevision::V4LCamera::stop ( )
virtual

Stop image transfer from the camera.

This will stop the image transfer initiated with start(). This can be used to start and stop the image transfer at will without opening and closing operations inbetween.

Implements firevision::Camera.

Definition at line 134 of file v4l.cpp.

References firevision::Camera::stop().


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