User`s guide

5 Acquiring Image Data

5-20

Frame Acquisition Loop

The frame acquisition loop is where your adaptor acquires frames from the device and

sends them to the engine. This process involves the following steps:

Check whether the specified number of frames has been acquired. The

frame acquisition loop acquires frames from the device until the specified

number of frames has been acquired. Use the IAdaptor member function

isAcquisitionNotComplete() to determine if more frames are needed.

If your adaptor supports hardware triggers, you would check whether a hardware

trigger is configured here — “Supporting Hardware Triggers” on page 5-27.

Grab a frame from the device. This code is completely dependent on your device

SDK's API. With many device SDKs, you allocate a buffer and the device fills it with

image data. See your device's API documentation to learn how to get frames from

your device.

Check whether you need to send the acquired frame to the engine, using the

IAdaptor member function isSendFrame(). This is how the toolbox implements

the FrameGrabInterval property, where users can specify that they only want to

acquire every other frame, for example.

If you need to send a frame to the engine, package the frame in an IAdaptorFrame

object; otherwise, skip to step 5.

Create a frame object, using the IEngine object makeFrame() member

function. You must specify the image frame dimensions and frame type when

you create the frame object.

Put the acquired image data into the frame object, using the IAdaptorFrame

object setImage() member function. You specify a pointer to the buffer that

contains the image data, the frame width and height and any offsets from the

upper left corner of the image.

Note For information about specifying frame width, height, and offset with

ROIs, see “Supporting ROIs” on page 5-24.

Log the time of the acquisition in the frame object, using the IAdaptorFrame

member function setTime(). Device SDKs sometimes provide access to time

stamp information, but you can also use the adaptor kit getCurrentTime()

function.