Class Grabber

The grabber object is the core component used when working with video capture devices.

Grabber objects are created using the constructor Grabber().

After creation, the most common operation on a grabber is to open a device. A device can be opened directly by

• passing string identifying a device to DeviceOpen(string)
• passing a DeviceInfo object to DeviceOpen(DeviceInfo)

A device can also be selected and configured from a previously saved device state by

• passing the file name of a device state file to DeviceOpenFromState(string)
• passing a byte array contains device state data to DeviceOpenFromState(byte[])
• passing a Stream containing device state data to DeviceOpenFromState(Stream)

To establish a data stream from the opened video capture device, call StreamSetup(Sink, IDisplay, StreamSetupOption).

A Sink is required if the program needs to access, process, or store image data. There are several sink types available to choose from, which are useful depending on the application, e.g. QueueSink or SnapSink.

A IDisplay can be used to automatically display all images from the video capture device.

After the data stream has been set up, call AcquisitionStart() to begin the transfer of images.

See Grabber States for a discussion of the internal states of the grabber object during its lifetime.

Some object references, e.g. ImageBuffer, can keep the device and/or driver opened as long as they exist, since they point into device driver memory. To free all device-related resources, all objects references have to be released.

The property map returned from this function is the origin for all device feature manipulation operations.

The property map returned from this function is the origin for driver-related feature operations.

In contrast to IsStreaming, this additionally checks whether the device was instructed to begin image acquisition.

See Grabber States for a discussion of the internal states of the grabber object during its lifetime.

See Grabber States for a discussion of the internal states of the grabber object during its lifetime.

There are multiple reasons for why this function may return false:

• No device has been opened
• The device was disconnected
• There is a loose hardware connection
• There was an internal error in the video capture device
• There was a driver error

If the currently opened device becomes invalid, the DeviceLost event is raised.

See Grabber States for a discussion of the internal states of the grabber object during its lifetime.

See Grabber States for a discussion of the internal states of the grabber object during its lifetime.

This operation is only valid after a data stream was established once.

A data stream has to be established before calling this function by calling StreamSetup(Sink, IDisplay, StreamSetupOption) or one of its overloads.

This operation is equivalent to executing the AcquisitionStart command on the device's PropertyMap.

The acquisition of images has to be started, for example by calling AcquisitionStart() or passing AcquisitionStart during stream setup, before calling this function.

This operation is equivalent to executing the AcquisitionStop command on the device's PropertyMap.

If the device is closed, all its resouces are released:

• If image acquisition is active, it is stopped.
• If a data stream was set up, it is stopped.
• References to data stream-related objects are released, possibly destroying the sink and/or display.
• Property objects retrieved from the DevicePropertyMap become invalid.

ImageBuffer objects and their memory stay allocated until they are disposed. References to image buffers can keep the video capture device open, if they point into driver memory.

If there are multiple devices matching the specified model name, unique name or serial, the function will fail and throw a IC4Exception with the error code set to Ambiguous.

If there is no device with the specified model name, unique name or serial, the function will fail and throw a IC4Exception with the error code set to DeviceNotFound.

If the memory buffer contains settings for properties that could not be written, the function will fail and throw a IC4Exception with the error code set to Incomplete.

To restore the device state at a later time, use DeviceOpenFromState(byte[]).

In addition to serializing the device's properties (like Serialize() would), this function also saves the currently opened video capture device so that it can be re-opened at a later time with all settings restored.

To restore the device state at a later time, use DeviceOpenFromState(string).

In addition to serializing the device's properties (like Serialize(string) would), this function also saves the currently opened video capture device so that it can be re-opened at a later time with all settings restored.

A device has to be opened before calling this function.

The grabber takes references to the passed display, tying its lifetime to the grabber until the data stream is stopped.

To stop the data stream at a later time, call StreamStop()

A device has to be opened before calling this function.

The grabber takes references to the passed sink and display, tying their lifetime to the grabber until the data stream is stopped.

To stop the data stream at a later time, call StreamStop()

A device has to be opened before calling this function.

The grabber takes references to the passed sink, tying its lifetime to the grabber until the data stream is stopped.

To stop the data stream at a later time, call StreamStop()

This function releases the sink and/or display references that were used to setup the data stream. If there are no additional references to the sink or display, the sink or display is destroyed.

There are multiple reasons for why event may happen:

• The device was disconnected
• There is a loose hardware connection
• There was an internal error in the video capture device
• There was a driver error