SharedMemoryCamera Class Reference

Shared memory camera. More...

#include <cams/shmem.h>

Inheritance diagram for SharedMemoryCamera:

Inheritance graph
[legend]

List of all members.


Public Member Functions

 SharedMemoryCamera (const char *image_id, bool deep_copy=false)
 Constructor.
 SharedMemoryCamera (const CameraArgumentParser *cap)
 Constructor.
 ~SharedMemoryCamera ()
 Destructor.
virtual void open ()
 Open the camera.
virtual void start ()
 Start image transfer from the camera.
virtual void stop ()
 Stop image transfer from the camera.
virtual void close ()
 Close camera.
virtual void flush ()
 Flush image queue.
virtual void capture ()
 Capture an image.
virtual void print_info ()
 Print out camera information.
virtual bool ready ()
 Camera is ready for taking pictures.
virtual unsigned char * buffer ()
 Get access to current image buffer.
virtual unsigned int buffer_size ()
 Size of buffer.
virtual void dispose_buffer ()
 Dispose current buffer.
virtual unsigned int pixel_width ()
 Width of image in pixels.
virtual unsigned int pixel_height ()
 Height of image in pixels.
virtual colorspace_t colorspace ()
 Colorspace of returned image.
virtual fawkes::Time * capture_time ()
 Get the Time of the last successfully captured image.
virtual void set_image_number (unsigned int n)
 Set image number to retrieve.
SharedMemoryImageBuffer * shared_memory_image_buffer ()
 Get the shared memory image buffer.
virtual void lock_for_read ()
 Lock image for reading.
virtual bool try_lock_for_read ()
 Try to lock for reading.
virtual void lock_for_write ()
 Lock image for writing.
virtual bool try_lock_for_write ()
 Try to lock for reading.
virtual void unlock ()
 Unlock buffer.

Detailed Description

Shared memory camera.

Camera to retrieve images from a shared memory segment.

The camera can operate in a so-called deep-copy mode. In this mode a local internal buffer is created of the size of the image. On capture() the image is copied from the shared memory buffer to the local buffer with the shared memory segment locked for reading. This can be used if the image writing and the image reading processess run asynchronously. While locking would suffice the copying will account for only short locking times so that the interference between the two processes is minimal.

Author:
Tim Niemueller

Definition at line 33 of file shmem.h.

Constructor & Destructor Documentation

SharedMemoryCamera::SharedMemoryCamera ( const char *  image_id,
bool  deep_copy = false 
)

Constructor.

Parameters:
image_id image ID to open
deep_copy true to operate in deep-copy mode, false otherwise

Definition at line 55 of file shmem.cpp.

SharedMemoryCamera::SharedMemoryCamera ( const CameraArgumentParser *  cap  ) 

Constructor.

Take configuration data from camera argument parser. The following options are supported.

  • image_id=ID, where ID is the image ID
    Parameters:
    cap camera argument parser

Definition at line 76 of file shmem.cpp.

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

SharedMemoryCamera::~SharedMemoryCamera (  ) 

Destructor.

Definition at line 101 of file shmem.cpp.

Member Function Documentation

unsigned char * SharedMemoryCamera::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 Camera.

Definition at line 167 of file shmem.cpp.

References SharedMemoryImageBuffer::buffer().

unsigned int SharedMemoryCamera::buffer_size (  )  [virtual]

Size of buffer.

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

Returns:
size of buffer in bytes

Implements Camera.

Definition at line 177 of file shmem.cpp.

References SharedMemoryImageBuffer::colorspace(), SharedMemoryImageBuffer::height(), and SharedMemoryImageBuffer::width().

void SharedMemoryCamera::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 Camera.

Definition at line 155 of file shmem.cpp.

References SharedMemoryImageBuffer::buffer(), SharedMemoryImageBuffer::capture_time(), fawkes::SharedMemory::data_size(), fawkes::SharedMemory::lock_for_read(), fawkes::Time::set_time(), and fawkes::SharedMemory::unlock().

fawkes::Time * SharedMemoryCamera::capture_time (  )  [virtual]

Get the Time of the last successfully captured image.

Returns a Time representing the time when the last image was captured successfully. Note that calling this function is only valid after capture() and before dispose_buffer() has been called -- it is only valid when an image is currently available.

Returns:
Time of the currently processed image. The pointer shall be valid at least until the next call to dispose_buffer().
Exceptions:
NotImplementedException thrown if Camera does not support time stamping

Reimplemented from Camera.

Definition at line 215 of file shmem.cpp.

void SharedMemoryCamera::close (  )  [virtual]

Close camera.

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

Implements Camera.

Definition at line 185 of file shmem.cpp.

colorspace_t SharedMemoryCamera::colorspace (  )  [virtual]

Colorspace of returned image.

Returns:
colorspace of image returned by buffer()

Implements Camera.

Definition at line 208 of file shmem.cpp.

References SharedMemoryImageBuffer::colorspace().

void SharedMemoryCamera::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 Camera.

Definition at line 190 of file shmem.cpp.

void SharedMemoryCamera::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 Camera.

Definition at line 222 of file shmem.cpp.

void SharedMemoryCamera::lock_for_read (  )  [virtual]

Lock image for reading.

Aquire the lock to read images.

Definition at line 255 of file shmem.cpp.

References fawkes::SharedMemory::lock_for_read().

void SharedMemoryCamera::lock_for_write (  )  [virtual]

Lock image for writing.

Aquire the lock to write images.

Definition at line 275 of file shmem.cpp.

References fawkes::SharedMemory::lock_for_write().

void SharedMemoryCamera::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 Camera.

Definition at line 134 of file shmem.cpp.

unsigned int SharedMemoryCamera::pixel_height (  )  [virtual]

Height of image in pixels.

Returns:
height of image in pixels

Implements Camera.

Definition at line 201 of file shmem.cpp.

References SharedMemoryImageBuffer::height().

unsigned int SharedMemoryCamera::pixel_width (  )  [virtual]

Width of image in pixels.

Returns:
width of image in pixels

Implements Camera.

Definition at line 195 of file shmem.cpp.

References SharedMemoryImageBuffer::width().

void SharedMemoryCamera::print_info (  )  [virtual]

Print out camera information.

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

Implements Camera.

Definition at line 150 of file shmem.cpp.

bool SharedMemoryCamera::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 Camera.

Definition at line 238 of file shmem.cpp.

void SharedMemoryCamera::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:
n image number to set

Implements Camera.

Definition at line 245 of file shmem.cpp.

SharedMemoryImageBuffer * SharedMemoryCamera::shared_memory_image_buffer (  ) 

Get the shared memory image buffer.

Returns:
shared memory image buffer used to access image

Definition at line 231 of file shmem.cpp.

void SharedMemoryCamera::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 Camera.

Definition at line 140 of file shmem.cpp.

void SharedMemoryCamera::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 Camera.

Definition at line 145 of file shmem.cpp.

bool SharedMemoryCamera::try_lock_for_read (  )  [virtual]

Try to lock for reading.

Returns:
true if the lock has been aquired, false otherwise

Definition at line 265 of file shmem.cpp.

References fawkes::SharedMemory::try_lock_for_read().

bool SharedMemoryCamera::try_lock_for_write (  )  [virtual]

Try to lock for reading.

Returns:
true if the lock has been aquired, false otherwise

Definition at line 285 of file shmem.cpp.

References fawkes::SharedMemory::try_lock_for_write().

void SharedMemoryCamera::unlock (  )  [virtual]

Unlock buffer.

Definition at line 293 of file shmem.cpp.

References fawkes::SharedMemory::unlock().

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