Webcam Library Reference Documentation

Libs/libwebcam/libwebcam.h File Reference

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Detailed Description

Webcam library declarations.

#include <assert.h>

Go to the source code of this file.

Data Structures
struct	_Control
	An internal control description associated with a device. More...
struct	_ControlList
	Base structure that contains a list of controls and associated data. More...
struct	_Device
	Internal device information. More...
struct	_DeviceList
	Base structure that contains a list of devices and associated data. More...
struct	_Handle
	Information associated with a device handle. More...
struct	_HandleList
	Base structure that contains an array of device handles and associated data. More...
Defines
#define	USE_UVCVIDEO
	Whether private controls of the Linux UVC driver should be used or not.
#define	USE_LOGITECH_DYNCTRL
	Whether or not to include the automatically generated Logitech dynamic controls header file.
#define	ENABLE_V4L2_ADVANCED_CONTROL_ENUMERATION
	Whether to use the V4L2_CTRL_FLAG_NEXT_CTRL flag when enumerating V4L2 controls.
#define	DYNCTRL_IGNORE_EEXIST_AFTER_PASS1
	Ignore EEXIST errors for the UVCIOC_CTRL_ADD and UVCIOC_CTRL_MAP ioctls for all but the first device.
#define	MAX_HANDLES   32
	The maximum number (plus 1) of handles libwebcam supports.
#define	DISABLE_LOCKING   1
	Debug option to disable locking.
#define	DEBUG_LOCKING   1
	Debug option to add verbosity to locking and unlocking.
#define	UNKNOWN_CONTROL_NAME   "Unknown control"
	The name used for controls whose name could not be retrieved.
#define	CONTROL_IO_ERROR_RETRIES   2
	Number of retries for failed V4L2 ioctl requests.
#define	GET_HANDLE(handle)   (handle_list.handles[(handle)])
	Returns the given handle structure.
#define	HANDLE_OPEN(handle)   ((handle) < MAX_HANDLES && GET_HANDLE(handle).open)
	Returns true if the given handle is open (valid or invalid).
#define	HANDLE_VALID(handle)   (HANDLE_OPEN(handle) && GET_HANDLE(handle).device)
	Returns true if the given handle is open and valid.
#define	V4L2_MENU_CTRL_MAX_NAME_SIZE   sizeof(((struct v4l2_querymenu *)NULL)->name)
	Returns the maximum number of characters that a menu-type control choice can have in V4L2.
#define	MAKE_FOURCC(c1, c2, c3, c4)   (unsigned int)((long)c1 | (long)c2 << 8 | (long)c3 << 16 | (long)c4 << 24)
	Converts the given characters into a FourCC code.
Typedefs
typedef _Control	Control
	An internal control description associated with a device.
typedef _ControlList	ControlList
	Base structure that contains a list of controls and associated data.
typedef _Device	Device
	Internal device information.
typedef _DeviceList	DeviceList
	Base structure that contains a list of devices and associated data.
typedef _Handle	Handle
	Information associated with a device handle.
typedef _HandleList	HandleList
	Base structure that contains an array of device handles and associated data.
Functions
int	open_v4l2_device (char *device_name)
static CResult	lock_mutex (pthread_mutex_t *mutex)
	Acquire a mutex.
static void	unlock_mutex (pthread_mutex_t *mutex)
	Release a mutex.
static void	copy_string_to_buffer (char **target, char *source, void *buffer, unsigned int *offset)
	Copies a variable-length string to the part of an enumeration buffer that is reserved for dynamic data.
Variables
int	initialized
	A flag indicating whether the library was initialized.
HandleList	handle_list
	The fixed size list of file handles.

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Define Documentation

#define CONTROL_IO_ERROR_RETRIES   2

Number of retries for failed V4L2 ioctl requests. This is a workaround for faulty devices.

#define DYNCTRL_IGNORE_EEXIST_AFTER_PASS1

Ignore EEXIST errors for the UVCIOC_CTRL_ADD and UVCIOC_CTRL_MAP ioctls for all but the first device. This is required if the driver uses global controls instead of per-device controls.

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Typedef Documentation

typedef struct _Handle Handle

Information associated with a device handle. Note that a handle can have three different states: Closed/free: The device handle is not being used by an application. Valid: The device handle is open by an application and points to a valid device. Invalid: The device handle is open by an application but does not point to a (valid) device anymore. This happens when a device is removed from the system but there are still open handles around. An "open" handle can be both valid or invalid.

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Function Documentation

static void copy_string_to_buffer (  char **  target, char *  source, void *  buffer, unsigned int *  offset )  [inline, static]

Copies a variable-length string to the part of an enumeration buffer that is reserved for dynamic data. This function is used by the enumeration functions.

static CResult lock_mutex (  pthread_mutex_t *  mutex  )  [inline, static]

Acquire a mutex. This function is identical to pthread_mutex_lock except that it has different return values and supports some debug flags. Returns: C_SUCCESS if the mutex was successfully acquired C_SYNC_ERROR if an error occured while trying to acquire the mutex

static void unlock_mutex (  pthread_mutex_t *  mutex  )  [inline, static]

Release a mutex. This function is identical to pthread_mutex_unlock except that it has different return values and supports some debug flags. Returns: C_SUCCESS if the mutex was successfully released C_SYNC_ERROR if an error occured while trying to release the mutex

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