implemented AutoZoom feature for Android

Author: sartajroshan

README.md

@@ -38,6 +38,7 @@ See the example app for detailed implementation information.
 | analyzeImage (Gallery) | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark:   | :x: |
 | returnImage            | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark:   | :x: |
 | scanWindow             | :heavy_check_mark: | :heavy_check_mark: | :heavy_check_mark:   | :x: |
+| autoZoom               | :heavy_check_mark: | :x: | :x:   | :x: |
 
 ## Platform Support
 

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScanner.kt

@@ -499,6 +499,11 @@ class MobileScanner(
         camera?.cameraControl?.setLinearZoom(scale.toFloat())
     }
 
+    fun setZoomRatio(zoomRatio: Double) {
+        if (camera == null) throw ZoomWhenStopped()
+        camera?.cameraControl?.setZoomRatio(zoomRatio.toFloat())
+    }
+
     /**
      * Reset the zoom rate of the camera.
      */

android/src/main/kotlin/dev/steenbakker/mobile_scanner/MobileScannerHandler.kt

@@ -1,6 +1,9 @@
 package dev.steenbakker.mobile_scanner
 
 import android.app.Activity
+import android.content.Context
+import android.hardware.camera2.CameraCharacteristics
+import android.hardware.camera2.CameraManager
 import android.net.Uri
 import android.os.Handler
 import android.os.Looper
@@ -18,6 +21,7 @@ import io.flutter.plugin.common.PluginRegistry.RequestPermissionsResultListener
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding
 import io.flutter.view.TextureRegistry
 import java.io.File
+import com.google.mlkit.vision.barcode.ZoomSuggestionOptions
 
 class MobileScannerHandler(
     private val activity: Activity,
@@ -138,13 +142,14 @@ class MobileScannerHandler(
         val timeout: Int = call.argument<Int>("timeout") ?: 250
         val cameraResolutionValues: List<Int>? = call.argument<List<Int>>("cameraResolution")
         val useNewCameraSelector: Boolean = call.argument<Boolean>("useNewCameraSelector") ?: false
+        val enableAutoZoom: Boolean = call.argument<Boolean>("autoZoom") ?: false
         val cameraResolution: Size? = if (cameraResolutionValues != null) {
             Size(cameraResolutionValues[0], cameraResolutionValues[1])
         } else {
             null
         }
 
-        val barcodeScannerOptions: BarcodeScannerOptions? = buildBarcodeScannerOptions(formats)
+        val barcodeScannerOptions: BarcodeScannerOptions? = buildBarcodeScannerOptions(formats, enableAutoZoom)
 
         val position =
             if (facing == 0) CameraSelector.DEFAULT_FRONT_CAMERA else CameraSelector.DEFAULT_BACK_CAMERA
@@ -230,7 +235,7 @@ class MobileScannerHandler(
 
         mobileScanner!!.analyzeImage(
             Uri.fromFile(File(filePath)),
-            buildBarcodeScannerOptions(formats),
+            buildBarcodeScannerOptions(formats, false),
             analyzeImageSuccessCallback,
             analyzeImageErrorCallback)
     }
@@ -253,6 +258,14 @@ class MobileScannerHandler(
         }
     }
 
+    private fun setZoomRatio(scale: Float) : Boolean {
+        try {
+            mobileScanner!!.setZoomRatio(scale.toDouble())
+            return true
+        } catch (e: ZoomWhenStopped) { }
+        return false
+    }
+
     private fun resetScale(result: MethodChannel.Result) {
         try {
             mobileScanner!!.resetScale()
@@ -269,25 +282,54 @@ class MobileScannerHandler(
         result.success(null)
     }
 
-    private fun buildBarcodeScannerOptions(formats: List<Int>?): BarcodeScannerOptions? {
+    private fun buildBarcodeScannerOptions(formats: List<Int>?, enableAutoZoom: Boolean): BarcodeScannerOptions? {
+        val builder : BarcodeScannerOptions.Builder?
         if (formats == null) {
-            return null
+           builder = BarcodeScannerOptions.Builder()
+        } else {
+            val formatsList: MutableList<Int> = mutableListOf()
+
+            for (formatValue in formats) {
+                formatsList.add(BarcodeFormats.fromRawValue(formatValue).intValue)
+            }
+
+            if (formatsList.size == 1) {
+                builder = BarcodeScannerOptions.Builder().setBarcodeFormats(formatsList.first())
+            } else {
+                builder = BarcodeScannerOptions.Builder().setBarcodeFormats(
+                    formatsList.first(),
+                    *formatsList.subList(1, formatsList.size).toIntArray()
+                )
+            }
         }
 
-        val formatsList: MutableList<Int> = mutableListOf()
-
-        for (formatValue in formats) {
-            formatsList.add(BarcodeFormats.fromRawValue(formatValue).intValue)
+        if (enableAutoZoom) {
+            builder.setZoomSuggestionOptions(
+                ZoomSuggestionOptions.Builder {
+                    setZoomRatio(it)
+                }.setMaxSupportedZoomRatio(getMaxZoomRatio())
+                    .build())
         }
 
-        if (formatsList.size == 1) {
-            return BarcodeScannerOptions.Builder().setBarcodeFormats(formatsList.first())
-                .build()
-        }
+        return builder.build()
+    }
+
+    private fun getMaxZoomRatio(): Float {
+        val cameraManager = activity.getSystemService(Context.CAMERA_SERVICE) as CameraManager
+        var maxZoom = 1.0F
+
+        try {
+            for (cameraId in cameraManager.cameraIdList) {
+                val characteristics = cameraManager.getCameraCharacteristics(cameraId)
 
-        return BarcodeScannerOptions.Builder().setBarcodeFormats(
-            formatsList.first(),
-            *formatsList.subList(1, formatsList.size).toIntArray()
-        ).build()
+                val maxZoomRatio = characteristics.get(CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM)
+                if (maxZoomRatio != null && maxZoomRatio > maxZoom) {
+                    maxZoom = maxZoomRatio
+                }
+            }
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+        return maxZoom
     }
 }

example/lib/barcode_scanner_controller.dart

@@ -19,6 +19,7 @@ class _BarcodeScannerWithControllerState
     autoStart: false,
     torchEnabled: true,
     useNewCameraSelector: true,
+    enableAutoZoom: true
   );
 
   Barcode? _barcode;

lib/src/mobile_scanner_controller.dart

@@ -26,6 +26,7 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
     this.returnImage = false,
     this.torchEnabled = false,
     this.useNewCameraSelector = false,
+    this.enableAutoZoom = false
   })  : detectionTimeoutMs =
             detectionSpeed == DetectionSpeed.normal ? detectionTimeoutMs : 0,
         assert(
@@ -96,6 +97,11 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
   /// Only supported on Android.
   final bool useNewCameraSelector;
 
+  /// Whether the Camera should auto zoom.
+  ///
+  /// Only supported on Android.
+  final bool enableAutoZoom;
+
   /// The internal barcode controller, that listens for detected barcodes.
   final StreamController<BarcodeCapture> _barcodesController =
       StreamController.broadcast();
@@ -283,6 +289,7 @@ class MobileScannerController extends ValueNotifier<MobileScannerState> {
       returnImage: returnImage,
       torchEnabled: torchEnabled,
       useNewCameraSelector: useNewCameraSelector,
+      enableAutoZoom: enableAutoZoom
     );
 
     try {

lib/src/objects/start_options.dart

@@ -15,6 +15,7 @@ class StartOptions {
     required this.returnImage,
     required this.torchEnabled,
     required this.useNewCameraSelector,
+    required this.enableAutoZoom
   });
 
   /// The direction for the camera.
@@ -43,6 +44,11 @@ class StartOptions {
   /// This option is only supported on Android. Other platforms will ignore this option.
   final bool useNewCameraSelector;
 
+  /// Whether the Camera should auto zoom.
+  ///
+  /// This option is only supported on Android. Other platforms will ignore this option.
+  final bool enableAutoZoom;
+
   Map<String, Object?> toMap() {
     return <String, Object?>{
       if (cameraResolution != null)
@@ -58,6 +64,7 @@ class StartOptions {
       'timeout': detectionTimeoutMs,
       'torch': torchEnabled,
       'useNewCameraSelector': useNewCameraSelector,
+      'autoZoom' : enableAutoZoom
     };
   }
 }