GrabbaFingerprintAPI Class Reference

Description

Provides access to Grabba fingerprint functionality, such as enrolling fingerprints.

Callbacks to user-provided code may be triggered in response to relevant events, e.g. successful enrolment of a fingerprint. Refer to the GrabbaFingerprintListener class for the details of these callbacks and how to enable them.

Calls to this class will not succeed until a connection to a Grabba device has been established. Refer to the GrabbaCoreAPI class for details of how to establish or query this connection.

Thread safety: This class is fully thread-safe.

Inheritance diagram for GrabbaFingerprintAPI:

Instance Methods
(instancetype _Nullable)	- init
	Not callable (NS_UNAVAILABLE) since this is a static class. More...

Class Methods
(void)	+ abortWithBlocking:
	Abort any asynchronous operations which are currently in progress. More...
(void)	+ captureWithTemplateType:imageType:repeatCapture:error:
(BOOL)	+ supported
	Query whether there is currently a connected Grabba device with fingerprint functionality. More...
(BOOL)	+ V1CompressionSupported
	Query whether there is currently a connected Grabba device with V1 compression support. More...
(void)	+ verifyWithData:templateType:error:
(BOOL)	+ WSQ_CompressionSupported
	Query whether there is currently a connected Grabba device with WSQ compression support. More...

Method Documentation

abortWithBlocking:()

+ (void) abortWithBlocking:

(BOOL)

blocking

Abort any asynchronous operations which are currently in progress.

If either of the capture or verify operations are currently in progress, then they will be aborted. If no such operations are currently active then this call will have no effect.

This operation may be performed either synchronously or asynchronously:

• Synchronous mode: This call will block until any ongoing fingerprint reader operations have been aborted.
• Asynchronous mode: This call is non-blocking; it will signal ongoing processes but not wait for them to abort.

The asynchronous mode does not guarantee immediate termination; it is still possible for an operation which had nearly completed to finish a short time after the abort call is triggered.

Parameters

blocking

If set, this operation will run synchronously (blocking until complete); otherwise, it will run asynchronously

captureWithTemplateType:imageType:repeatCapture:error:()

+ (void) captureWithTemplateType:		(GrabbaFingerprintTemplateTypeID)	templateType
imageType:		(GrabbaFingerprintImageTypeID)	imageType
repeatCapture:		(BOOL)	repeatCapture
error:		(GrabbaErrorCode *_Nonnull)	error

Attempt to capture a fingerprint If the supplied error code indicates no prior errors, then an attempt will be made to capture a fingerprint. This operation will occur asynchronously; only error conditions which can be detected immediately (e.g. lack of hardware support) will be returned by this function.

If the capture starts, then the returned error code will be set to GrabbaNoError; results are provided as callbacks to GrabbaFingerprintListener objects. Note that only one image/template callback will be provided; if the repeatCapture parameter is set true, then the template returned will be a consolidation of the three captures, and the image returned will be that of the third (last) capture.

Once captured, the fingerprint may subsequently be used with the verify function.

Parameters

templateType	The type of fingerprint template to pass to the listener object(s) after enrolment
imageType	The type of fingerprint image to pass to the listener object(s) after enrolment
repeatCapture	If true, each print is captured three times, otherwise it is only captured once. Notes: If only an image is required, then a single acquisition may suffice, particularly if the user can be notified of the quality (or lack thereof) If a capture is being performed for the purpose of verification, then a single capture is likely to suffice If a template is being captured for the purpose of database enrolment, then it is often preferable to obtain three captures, since the template is a consolidation of multiple reads of the same print
error	Error code; operation proceeds only if set to GrabbaNoError. If an error is detected when starting the operation, then this will be updated with the details.

init()

- (instancetype _Nullable) init

Not callable (NS_UNAVAILABLE) since this is a static class.

supported()

+ (BOOL) supported

Query whether there is currently a connected Grabba device with fingerprint functionality.

This is a non-blocking call; device capabilities are cached internally by the driver.

Returns

YES if there is a connected Grabba device and that device supports fingerprint functionality; NO otherwise.

V1CompressionSupported()

+ (BOOL) V1CompressionSupported

Query whether there is currently a connected Grabba device with V1 compression support.

This is a non-blocking call; device capabilities are cached internally by the driver.

Note that this can only return true when Supported() also returns true; however, not all Grabba devices with fingerprint readers have V1 compression support.

Returns

YES if there is a connected Grabba device and that device supports fingerprint images with V1 compression; NO otherwise.

verifyWithData:templateType:error:()

+ (void) verifyWithData:		(NSData *_Nonnull)	data
templateType:		(GrabbaFingerprintTemplateTypeID)	templateType
error:		(GrabbaErrorCode *_Nonnull)	error

Attempt to capture a fingerprint, then verify it against a given template If the supplied error code indicates no prior errors, then an attempt will be made to capture a fingerprint, and if successful then verify it against the given template. This operation will occur asynchronously; only error conditions which can be detected immediately (e.g. lack of hardware support) will be returned by this function.

If the capture starts, then the returned error code will be set to GrabbaNoError; results are provided as callbacks to API_Types::FingerprintListener objects.

Typically this function is used in conjunction with capture, which can generate templates to verify against.

Parameters

data	Template data for comparison
templateType	Type of templateData
error	Error code; operation proceeds only if set to GrabbaNoError. If an error is detected when starting the operation, then this will be updated with the details.

WSQ_CompressionSupported()

+ (BOOL) WSQ_CompressionSupported

Query whether there is currently a connected Grabba device with WSQ compression support.

This is a non-blocking call; device capabilities are cached internally by the driver.

Note that this can only return true when Supported() also returns true; however, not all Grabba devices with fingerprint readers have WSQ compression support.

Returns

YES if there is a connected Grabba device and that device supports fingerprint images with WSQ compression; NO otherwise.