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Composite Codes

The Scandit Data Capture SDK supports scanning of all GS1 Composite Codes. The specification defines three different types: A, B and C.

note

Composite codes are only supported in SDCBarcodeCapture.

For composite codes Type A and B the 2d component is always a SDCSymbologyMicroPDF417 and the 1d component can be any of the following symbologies:

  • SDCSymbologyEAN13UPCA
  • SDCSymbologyEAN8
  • SDCSymbologyUPCE
  • SDCSymbologyGS1Databar
  • SDCSymbologyGS1DatabarExpanded
  • SDCSymbologyGS1DatabarLimited

For composite codes of Type C the 2d component is always SDCSymbologyPDF417 while the 1d component is SDCSymbologyCode128.

Enabling Composite Codes​

Composite code scanning is enabled in the SDCBarcodeCaptureSettings as follows:

  • One or more composite types need to be enabled via enabledCompositeTypes
  • The symbologies associated with those composite types need to be enabled through enableSymbologiesForCompositeTypes:.

For example, to enable scanning of composite code A:

  • First SDCCompositeTypeA is enabled with a call to enabledCompositeTypes
  • A call to enableSymbologiesForCompositeTypes: passing SDCCompositeTypeA the following symbologies will be enabled:
    • SDCSymbologyEAN13UPCA
    • SDCSymbologyEAN8
    • SDCSymbologyUPCE
    • SDCSymbologyGS1Databar
    • SDCSymbologyGS1DatabarExpanded
    • SDCSymbologyGS1DatabarLimited
    • SDCSymbologyMicroPDF417

The same can be accomplished by individually enabling all of these symbologies with setSymbology:enabled:.

enableSymbologiesForCompositeTypes: is a convenience function to enable all at once for a certain composite type. If you only want to scan a subset of the possible symbologies of a composite type then you should only enable those. It is not possible to disable a specific symbology, like SDCSymbologyGS1DatabarExpanded for SDCCompositeTypeA but keep it enabled for SDCCompositeTypeB, it is either enabled for both or neither.

The following lines of code show you how this is done to enable scanning of composite codes A and C. Composite code B will not be recognized in these examples as SDCCompositeTypeB is not enabled:

let settings = BarcodeCaptureSettings()

let compositeTypes: CompositeType = [.a, .c]
settings.enableSymbologies(forCompositeTypes: compositeTypes)
settings.enabledCompositeTypes = compositeTypes
note

Enabling composite codes will slow down the recognition of non-composite codes slightly. You should only enable composite codes if you expect them to be present.

Improving Composite Code Recognition​

The SDCSymbologyMicroPDF417 is contained in all composite codes A and B but is generally not very easy to recognize in a large scan area because of its compressed size.

To improve the recognition rate it is advised to restrict the scan area when scanning Composite Code A and B, which is best done through a rectangular location selection.

Reading Composite Code Data​

When composite codes are enabled the Scandit Data Capture SDK automatically couples the composites to the main code and returns the composite’s data through SDCBarcode.compositeData and SDCBarcode.compositeRawData.

There are two potential cases when a barcode of a symbology with enabled composite extension is returned:

  • The barcode has a composite and is returned with composite data
  • The barcode does not have an composite and is returned without composite data

Inside SDCBarcodeCaptureListener.barcodeCapture:didScanInSession:frameData: the data can be retrieved from the recognized barcode as follows:

let barcode = session.newlyRecognizedBarcode[0]

let data = barcode.data
let compositeData = barcode.compositeData
if let compositeData = compositeData {
    // Do something with the data & compositeData.
} else {
    // Do something with just the data.
}

Avoiding the Scanning of Barcodes without Composite​

For a use-case where only barcodes with add-ons should be scanned, the same type of rejection as shown in the BarcodeCaptureRejectSample (available from the Samples page of your preferred framework) can be used.

If composite data is available:

  • Manually emit feedback
  • Change the overlay’s brush to the default

If no composite data is available:

  • Don’t emit any feedback
  • Change the overlay’s brush to transparent