added barcode false positive detection

Author: ajungg

CHANGELOG.md

@@ -1,18 +1,23 @@
 # Changelog  
 All notable changes to this project will be documented in this file. 
 
+## [0.10.3]
+
+### Added
+- Barcode false positive detection
+
 ## [0.10.2]
 
-## Fixed
+### Fixed
 - Fixed checkout cancelling
 - Product search item cells should now scale with multiline text 
 
 ## [0.10.1] 
 
-## Added
+### Added
 - Experimental support for IKEA vendor specific codes
 
-## Changed
+### Changed
 - ITF code detection is now restricted to ITF14
 
 ## [0.10.0]

ui/src/main/java/io/snabble/sdk/ui/scanner/BarcodeScannerView.java

@@ -98,6 +98,7 @@ public class BarcodeScannerView extends FrameLayout implements TextureView.Surfa
     private int bitsPerPixel;
     private boolean indicatorEnabled = true;
     private FrameLayout splashView;
+    private FalsePositiveFilter falsePositiveFilter = new FalsePositiveFilter();
 
     public BarcodeScannerView(Context context) {
         super(context);
@@ -227,6 +228,7 @@ public void resume() {
         cameraHandler.post(new Runnable() {
             @Override
             public void run() {
+                resetFalsePositiveFilter();
                 isPaused = false;
 
                 if (!running) {
@@ -264,6 +266,7 @@ private void startIfRequested() {
             return;
         }
 
+        resetFalsePositiveFilter();
         setupZXing();
 
         showError(false);
@@ -393,6 +396,15 @@ public void run() {
         }
     }
 
+    private void resetFalsePositiveFilter() {
+        barcodeProcessingHandler.post(new Runnable() {
+            @Override
+            public void run() {
+                falsePositiveFilter.reset();
+            }
+        });
+    }
+
     private void chooseOptimalPreviewSize(Camera.Parameters parameters) {
         Camera.Size optimalSize = getOptimalPreviewSize();
 
@@ -675,8 +687,11 @@ public void run() {
                                             finalResult.getText(),
                                             finalResult.getTimestamp());
 
-                                    Logger.d("Detected barcode: " + barcode.toString());
-                                    callback.onBarcodeDetected(barcode);
+                                    Barcode filtered = falsePositiveFilter.filter(barcode);
+                                    if (filtered != null) {
+                                        Logger.d("Detected barcode: " + barcode.toString());
+                                        callback.onBarcodeDetected(barcode);
+                                    }
                                 }
                             }
                         });

ui/src/main/java/io/snabble/sdk/ui/scanner/FalsePositiveFilter.java

@@ -0,0 +1,37 @@
+package io.snabble.sdk.ui.scanner;
+
+import io.snabble.sdk.utils.Logger;
+
+public class FalsePositiveFilter {
+    private final static int REPEATS_NEEDED = 2;
+
+    private Barcode lastBarcode;
+    private int repeats = 0;
+
+    public FalsePositiveFilter() {
+
+    }
+
+    public synchronized void reset() {
+        repeats = 0;
+        lastBarcode = null;
+    }
+
+    public synchronized Barcode filter(Barcode barcode) {
+        if (lastBarcode == null
+        || (lastBarcode.getText().equals(barcode.getText())
+         && lastBarcode.getFormat().equals(barcode.getFormat()))) {
+            repeats++;
+            lastBarcode = barcode;
+        } else {
+            Logger.d("Filtered false positive: %s OR %s", lastBarcode, barcode);
+            reset();
+        }
+
+        if (repeats >= REPEATS_NEEDED) {
+            return barcode;
+        }
+
+        return null;
+    }
+}