Description

Interface for receiving barcode reader events.

Objects which implement this protocol may receive callbacks when these events occur, via delegation from a GrabbaBarcodeListener object.

Note that this protocol need not be directly implemented; it may be simpler to subclass GrabbaBarcodeListener and thereby receive the events directly.

Thread safety: This interface is intended to be thread-safe; any classes deriving from it should ensure that the relevant methods are callable from any thread.

See also: GrabbaBarcodeAPI for related API functions

Instance Methods
(void)	- cancelEvent
	Callback which is invoked when barcode scanning is cancelled. More...

(void)	- dataEvent:
	Callback which is invoked when a barcode is successfully scanned. More...

(void)	- errorEvent:
	Callback which is invoked when barcode scanning fails. More...

(void)	- startEvent
	Callback which is invoked when either a barcode scan is commenced. More...

(void)	- stopEvent
	Callback which is invoked when barcode scanning is stopped, regardless of the reason. More...

(void)	- timeoutEvent
	Callback which is invoked when barcode scanning times out. More...

Method Documentation

◆ cancelEvent()

- (void) cancelEvent

Callback which is invoked when barcode scanning is cancelled.

Operations may be cancelled by calling stopScan . Note that this callback will only trigger in the event that a running operation was cancelled; if e.g. stopScan is called and there was no scan active at the time, then no callback will be triggered.

Note: Implementations of this method are required to be thread-safe; no guarantees are made about which thread(s) they will be called from.

◆ dataEvent:()

- (void) dataEvent: (GrabbaBarcodeData *_Nonnull) data

Callback which is invoked when a barcode is successfully scanned.

Operations may be commenced by calling startScan. If scanning succeeds, the barcode scanner will be turned off (beyond which point calling stopScan will cease to have any effect), then this callback will be invoked.

Note: Implementations of this method are required to be thread-safe; no guarantees are made about which thread(s) they will be called from.

◆ errorEvent:()

- (void) errorEvent: (GrabbaErrorCode *_Nonnull) error

Callback which is invoked when barcode scanning fails.

Scanning may be commenced by calling startScan. If scanning fails, the barcode scanner will be turned off (beyond which point calling stopScan will cease to have any effect), then this callback will be invoked.

Parameters

error Error code indicating the reasons for the failure

Note: Implementations of this method are required to be thread-safe; no guarantees are made about which thread(s) they will be called from.

◆ startEvent()

- (void) startEvent

Callback which is invoked when either a barcode scan is commenced.

This event may be invoked by calling startScan when a suitable Grabba device is connected.

Note: Implementations of this method are required to be thread-safe; no guarantees are made about which thread(s) they will be called from.

◆ stopEvent()

- (void) stopEvent

Callback which is invoked when barcode scanning is stopped, regardless of the reason.

Scanning may be commenced by calling startScan. If scanning completes, fails, times out or is cancelled, then the barcode reader will be turned off (beyond which point calling stopScan will cease to have any effect), then this callback will be invoked, in addition to another callback specific to the outcome of the operation (success, failure, timeout or cancellation).

No guarantees are provided as to which order the two callbacks will be triggered in, or whether they will be triggered on the same thread.

Note: Implementations of this method are required to be thread-safe; no guarantees are made about which thread(s) they will be called from.

◆ timeoutEvent()

- (void) timeoutEvent

Callback which is invoked when barcode scanning times out.

Scanning may be commenced by calling startScan. If scanning times out, the barcode scanner will be turned off (beyond which point calling stopScan will cease to have any effect), then this callback will be invoked.

Note: Implementations of this method are required to be thread-safe; no guarantees are made about which thread(s) they will be called from.