feat(qr-code): return raw barcode data if available (#1904)

Author: cozmo

android/src/main/java/org/reactnative/camera/events/BarCodeReadEvent.java

@@ -12,6 +12,7 @@
 import com.google.zxing.ResultPoint;
 
 import java.util.Date;
+import java.util.Formatter;
 
 public class BarCodeReadEvent extends Event<BarCodeReadEvent> {
   private static final Pools.SynchronizedPool<BarCodeReadEvent> EVENTS_POOL =
@@ -68,6 +69,14 @@ private WritableMap serializeEventData() {
 
     event.putInt("target", getViewTag());
     event.putString("data", mBarCode.getText());
+
+    Formatter formatter = new Formatter();
+    for (byte b : mBarCode.getRawBytes()) {
+      formatter.format("%02x", b);
+    }
+    event.putString("rawData", formatter.toString());
+    formatter.close();
+
     event.putString("type", mBarCode.getBarcodeFormat().toString());
     WritableArray resultPoints = Arguments.createArray();
     ResultPoint[] points = mBarCode.getResultPoints();

docs/RNCamera.md

@@ -319,7 +319,10 @@ Function to be called when native code emit onPictureTaken event, when camera ha
 
 Will call the specified method when a barcode is detected in the camera's view.
 
-Event contains `data` (the data in the barcode) and `type` (the type of the barcode detected).
+Event contains the following fields
+- `data` - a textual representation of the barcode, if available
+- `rawData` - The raw data encoded in the barcode, if available
+- `type` - the type of the barcode detected
 
 The following barcode types can be recognised:
 
@@ -337,8 +340,6 @@ The following barcode types can be recognised:
 - `itf14` (when available)
 - `datamatrix` (when available)
 
-The barcode type is provided in the `data` object.
-
 
 #### `barCodeTypes`
 

ios/RN/RNCamera.m

@@ -869,22 +869,58 @@ - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:
             for (id barcodeType in self.barCodeTypes) {
                 if ([metadata.type isEqualToString:barcodeType]) {
                     AVMetadataMachineReadableCodeObject *transformed = (AVMetadataMachineReadableCodeObject *)[_previewLayer transformedMetadataObjectForMetadataObject:metadata];
-                    NSDictionary *event = @{
-                                            @"type" : codeMetadata.type,
-                                            @"data" : codeMetadata.stringValue,
-                                            @"bounds": @{
-                                                @"origin": @{
-                                                    @"x": [NSString stringWithFormat:@"%f", transformed.bounds.origin.x],
-                                                    @"y": [NSString stringWithFormat:@"%f", transformed.bounds.origin.y]
-                                                },
-                                                @"size": @{
-                                                    @"height": [NSString stringWithFormat:@"%f", transformed.bounds.size.height],
-                                                    @"width": [NSString stringWithFormat:@"%f", transformed.bounds.size.width]
-                                                }
-                                            }
-                                            };
-
-                    [self onCodeRead:event];
+                    NSMutableDictionary *event = [NSMutableDictionary dictionaryWithDictionary:@{
+                        @"type" : codeMetadata.type,
+                        @"data" : [NSNull null],
+                        @"rawData" : [NSNull null],
+                        @"bounds": @{
+                            @"origin": @{
+                                    @"x": [NSString stringWithFormat:@"%f", transformed.bounds.origin.x],
+                                    @"y": [NSString stringWithFormat:@"%f", transformed.bounds.origin.y]
+                                    },
+                            @"size": @{
+                                    @"height": [NSString stringWithFormat:@"%f", transformed.bounds.size.height],
+                                    @"width": [NSString stringWithFormat:@"%f", transformed.bounds.size.width]
+                                    }
+                            }
+                        }
+                    ];
+
+                    NSData *rawData;
+                    // If we're on ios11 then we can use `descriptor` to access the raw data of the barcode.
+                    // If we're on an older version of iOS we're stuck using valueForKeyPath to peak at the
+                    // data.
+                    if (@available(iOS 11, *)) {
+                        // descriptor is a CIBarcodeDescriptor which is an abstract base class with no useful fields.
+                        // in practice it's a subclass, many of which contain errorCorrectedPayload which is the data we
+                        // want. Instead of individually checking the class types, just duck type errorCorrectedPayload
+                        if ([codeMetadata.descriptor respondsToSelector:@selector(errorCorrectedPayload)]) {
+                            rawData = [codeMetadata.descriptor performSelector:@selector(errorCorrectedPayload)];
+                        }
+                    } else {
+                        rawData = [codeMetadata valueForKeyPath:@"_internal.basicDescriptor.BarcodeRawData"];
+                    }
+
+                    // Now that we have the raw data of the barcode translate it into a hex string to pass to the JS
+                    const unsigned char *dataBuffer = (const unsigned char *)[rawData bytes];
+                    if (dataBuffer) {
+                        NSMutableString     *rawDataHexString  = [NSMutableString stringWithCapacity:([rawData length] * 2)];
+                        for (int i = 0; i < [rawData length]; ++i) {
+                            [rawDataHexString appendString:[NSString stringWithFormat:@"%02lx", (unsigned long)dataBuffer[i]]];
+                        }
+                        [event setObject:[NSString stringWithString:rawDataHexString] forKey:@"rawData"];
+                    }
+
+                    // If we were able to extract a string representation of the barcode, attach it to the event as well
+                    // else just send null along.
+                    if (codeMetadata.stringValue) {
+                        [event setObject:codeMetadata.stringValue forKey:@"data"];
+                    }
+
+                    // Only send the event if we were able to pull out a binary or string representation
+                    if ([event objectForKey:@"data"] != [NSNull null] || [event objectForKey:@"rawData"] != [NSNull null]) {
+                        [self onCodeRead:event];
+                    }
                 }
             }
         }

types/index.d.ts

@@ -89,6 +89,7 @@ export interface RNCameraProps {
     googleVisionBarcodeType?: keyof GoogleVisionBarcodeType;
     onBarCodeRead?(event: {
         data: string,
+        rawData?: string,
         type: keyof BarCodeType,
         /**
          * @description For Android use `[Point<string>, Point<string>]`