Camera API Technical Report:
Camera Access

Camera Access

In this section basic camera access routines are described. To see structure definitions refer to the later sections lising the header files. Note including a camera specific header file automatically includes the camera-library header file.

#include <camera.h>

int CameraStatus( init_str, cam_class )
char                    *init_str;
CameraClass             cam_class;

Camera CameraInit( init_str, cam_class )
char                    *init_str;
CameraClass             cam_class;

int CameraClose( cam )
Camera  cam;

Camera CameraCopy( cam )
Camera	cam;

int CameraGetList( camera_list )
CameraList      **camera_list;

CameraStatus( init_str, cam_class ) returns zero if the specified camera is present, 1 otherwise. The cam_class is obtained from the camera specific header file or from the camera list (see below). The initialisation string is camera/machine specific and for the iim camera type is the unix device name.

CameraInit( init_str, cam_class ) opens and initialises a camera, initialises a hidden camera structure and returns the Camera pointer. On failure NULL is returned.

CameraClose( cam ) closes the camera and releases any allocated resources. If the camera has been copied using CameraCopy() then the copy will remain valid. Only the last close operation will actually close the device.

CameraCopy( cam ) copies an existing camera structure and attributes. Each copy can have different attribute settings and the library will reset the camera as required when the image is grabbed. Note the camera library also keeps a record in shared memory of which process and which camera attributes are set in the device and so multiple processes can access the camera safely and attributes will be reset if necessary.

CameraGetList( camera_list ) returns the length of the camera record list returned via the camera_list argument. The camera record list is defined:

/* a camera list to enable querying of available cameras */
typedef struct {
    char        *name;
    CameraType  type;
    CameraType  interface_type;
    CameraType  colour_type;
    CameraClass class;
    char        *def_init_str;
} CameraRec, *CameraList;

In each camera record the name and type of camera, camera class pointer and default initialisation string are available. This record and camera class pointer are also available in specific camera header files (see below).