BarcodeDecoder QML Type

Capture, read and decode barcodes through image files. More...

• List of all members, including inherited members

Properties

• barcode : string
• barcodeType : BarcodeType
• barcodeTypeString : string
• boundingRect : rect
• decodeHints : int
• points : object
• source : url
• status : Status

Methods

• clear()
• decode(url source)
• decode(url source, rect boundingRect)
• string getBarcodeTypeString(barcodetype barcodeType_)

Detailed Description

The BarcodeDecoder component provides specialized tools to read and decode a wide variety of barcode types. This component is specifically designed to be used with images, making a dedicated external barcode scanner unnecessary.

BarcodeDecoder works through scanning images, such as from a file or an image object, for valid barcodes. These images can then be edited or processed futher by other components or applications. Consider the BarcodeFilter component for faster detection through a video stream.

This code sample outlines the functions a barcode decoder to a pre-existing camera object. The camera takes a photo every quarter of a second, searching for a readable barcode. Once found, the image is captured and the barcode decoded.

Item {
    BarcodeDecoder {
        id: barcodeDecoder

        property int _decodeHints: BarcodeDecoder.DecodeHintQR_CODE
                                   | BarcodeDecoder.DecodeHintTryHarder

        property bool rotated: false
        property bool has1D: (decodeHints &
                             (BarcodeDecoder.DecodeHintCODABAR
                              | BarcodeDecoder.DecodeHintCODE_39
                              | BarcodeDecoder.DecodeHintCODE_93
                              | BarcodeDecoder.DecodeHintCODE_128
                              | BarcodeDecoder.DecodeHintEAN_8
                              | BarcodeDecoder.DecodeHintEAN_13
                              | BarcodeDecoder.DecodeHintITF
                              | BarcodeDecoder.DecodeHintMAXICODE
                              | BarcodeDecoder.DecodeHintRSS_14
                              | BarcodeDecoder.DecodeHintRSS_EXPANDED
                              | BarcodeDecoder.DecodeHintUPC_A
                              | BarcodeDecoder.DecodeHintUPC_E
                              | BarcodeDecoder.DecodeHintUPC_EAN_EXTENSION
                              )) !== 0

        decodeHints: _decodeHints

        onStatusChanged: {
            if (status === BarcodeDecoder.Error) {
                if (has1D && !rotated) {
                    imageObject.rotate(90, imageObject.width >> 1, imageObject.height >> 1);
                    rotated = true;
                    decode(imageObject.url);
                    return;
                }
                scanFailed();
                return;
            }

            if (status !== BarcodeDecoder.Decoding && barcode.length !== 0) {
                console.log("codeScanned:", barcode, "type:", barcodeTypeString)

                if (debugMode) {
                    scanMessage.show(barcodeTypeString + "\n" + barcode, 5000, "white");
                } else {
                    scanMessage.show(barcode, undefined, "green");
                    codeScanned(barcode);
                }
            }
        }
    }

    FileFolder {
        id: captureFolder

        path: AppFramework.standardPaths.writableLocation(StandardPaths.TempLocation)
    }

    Timer {
        id: retryTimer

        running: false
        repeat: false
        triggeredOnStart: false
        interval: 250

        onTriggered: {
            scan();
        }
    }

    function scan() {
        barcodeDecoder.clear();
        if (flashActive || scanMode === scanModeCapture) {
            scanCapture();
        }
    }

        function scanCapture() {
        camera.imageCapture.captureToLocation(captureFolder.filePath("code.jpg"));
    }

    function decodeCapture(path) {
        imageObject.load(path);
        var captureFrameD = Math.min(imageObject.size.width, imageObject.size.height) * 9/ 10;
        var captureFrameX = (imageObject.size.width - captureFrameD) >> 1;
        var captureFrameY = (imageObject.size.height - captureFrameD) >> 1;
        imageObject.clip(captureFrameX, captureFrameY, captureFrameD, captureFrameD);
        barcodeDecoder.rotated = false;
        barcodeDecoder.decode(imageObject.url);
    }
}

Enumerations

Status enumeration

BarcodeType enumeration

DecodeHint enumeration

Property Documentation

Method Documentation