camera_start_viewfinder()

Start the viewfinder on the camera

Synopsis:

#include <camera/camera_api.h>

camera_error_t camera_start_viewfinder(camera_handle_t handle,
                                       void(*viewfinder_callback)(camera_handle_t,
                                       camera_buffer_t *,
                                       void *),
                                       void(*status_callback)(camera_handle_t,
                                       camera_devstatus_t,
                                       uint16_t,
                                       void *),
                                       void *arg)

Arguments:

handle

The handle returned by a call to the camera_open() function.

viewfinder_callback

A function pointer to a function with the following signature:

void function_name( camera_handle_t,
                    camera_buffer_t*,
                    void* );

The function is a callback that is invoked when an image buffer becomes available. Set this argument to NULL if no function needs to be called. For information about the callback arguments, see "Callback mode" in the Camera Library Developer's Guide.

status_callback

A function pointer to a function with the following signature:

void function_name( camera_handle_t,
                    camera_devstatus_t,
                    uint16_t,
                    void* );

The function is a callback that is invoked when status events occur. Set this argument to NULL if no function needs to be called. For information about the callback arguments, see "Callback mode" in the Camera Library Developer's Guide.

arg

The argument passed to all callback functions, which is the last argument in the callback functions.

Library:

libcamapi

Description:

Use this function to start the viewfinder on the camera. Only call this function if the viewfinder mode has been set to a value other than CAMERA_VFMODE_DEFAULT using camera_set_vf_mode().

Before calling this function, ensure that you:

Use the camera_set_vf_property() function to configure the viewfinder.
If ::camera_imgprop_createwindow is set to 1, you can create a screen window to be the parent of the child viewfinder window that's created by this call.

Once the viewfinder is running, you can adjust zoom levels, and other camera operations. In addition, you can reposition or resize the viewfinder window using the Screen API. In order to retrieve a window handle to the viewfinder window that is created, you must listen for the appropriate SCREEN_EVENT_CREATE event using the Screen API. For more information, see the "Screen library reference" in the Screen Developer's Guide.

Note:

It is important that your application follows the guidelines for resource management described in "Resource management" in the Camera Library Developer's Guide. If you do not observe these guidelines, your application is at risk of crashing due to memory access errors when resource arbitration is performed by the operating system.

Returns:

CAMERA_EOK when the function successfully completes, otherwise another camera_error_t value that provides the reason that the call failed.