Merge pull request #592 from ryuta46/imp/zoom-scale-improvements

feat: Improvements about zoom scale value and ultra-wide camera

@@ -138,6 +138,7 @@ class MobileScanner(
         torch: Boolean,
         detectionSpeed: DetectionSpeed,
         torchStateCallback: TorchStateCallback,
+        zoomScaleStateCallback: ZoomScaleStateCallback,
         mobileScannerStartedCallback: MobileScannerStartedCallback,
         detectionTimeout: Long
     ) {
@@ -201,6 +202,11 @@ class MobileScanner(
                 torchStateCallback(state)
             }
 
+            // Register the zoom scale listener
+            camera!!.cameraInfo.zoomState.observe(activity) { state ->
+                zoomScaleStateCallback(state.linearZoom.toDouble())
+            }
+
 
             // Enable torch if provided
             camera!!.cameraControl.enableTorch(torch)
@@ -283,4 +289,12 @@ class MobileScanner(
         camera!!.cameraControl.setLinearZoom(scale.toFloat())
     }
 
+    /**
+     * Reset the zoom rate of the camera.
+     */
+    fun resetScale() {
+        if (camera == null) throw ZoomWhenStopped()
+        camera!!.cameraControl.setZoomRatio(1f)
+    }
+
 }

@@ -6,4 +6,5 @@ typealias MobileScannerCallback = (barcodes: List<Map<String, Any?>>, image: Byt
 typealias AnalyzerCallback = (barcodes: List<Map<String, Any?>>?) -> Unit
 typealias MobileScannerErrorCallback = (error: String) -> Unit
 typealias TorchStateCallback = (state: Int) -> Unit
+typealias ZoomScaleStateCallback = (zoomScale: Double) -> Unit
 typealias MobileScannerStartedCallback = (parameters: MobileScannerStartParameters) -> Unit
\ No newline at end of file

@@ -70,6 +70,10 @@ class MobileScannerHandler(
         barcodeHandler.publishEvent(mapOf("name" to "torchState", "data" to state))
     }
 
+    private val zoomScaleStateCallback: ZoomScaleStateCallback = {zoomScale: Double ->
+        barcodeHandler.publishEvent(mapOf("name" to "zoomScaleState", "data" to zoomScale))
+    }
+
     init {
         methodChannel = MethodChannel(binaryMessenger,
             "dev.steenbakker.mobile_scanner/scanner/method")
@@ -115,6 +119,7 @@ class MobileScannerHandler(
             "stop" -> stop(result)
             "analyzeImage" -> analyzeImage(call, result)
             "setScale" -> setScale(call, result)
+            "resetScale" -> resetScale(call, result)
             "updateScanWindow" -> updateScanWindow(call)
             else -> result.notImplemented()
         }
@@ -152,7 +157,7 @@ class MobileScannerHandler(
         val detectionSpeed: DetectionSpeed = DetectionSpeed.values().first { it.intValue == speed}
 
         try {
-            mobileScanner!!.start(barcodeScannerOptions, returnImage, position, torch, detectionSpeed, torchStateCallback, mobileScannerStartedCallback = {
+            mobileScanner!!.start(barcodeScannerOptions, returnImage, position, torch, detectionSpeed, torchStateCallback, zoomScaleStateCallback, mobileScannerStartedCallback = {
                 result.success(mapOf(
                     "textureId" to it.id,
                     "size" to mapOf("width" to it.width, "height" to it.height),
@@ -229,6 +234,15 @@ class MobileScannerHandler(
         }
     }
 
+    private fun resetScale(call: MethodCall, result: MethodChannel.Result) {
+        try {
+            mobileScanner!!.resetScale()
+            result.success(null)
+        } catch (e: ZoomWhenStopped) {
+            result.error("MobileScanner", "Called resetScale() while stopped!", null)
+        }
+    }
+
     private fun updateScanWindow(call: MethodCall) {
         mobileScanner!!.scanWindow = call.argument<List<Float>?>("rect")
     }

@@ -13,6 +13,7 @@ import MLKitBarcodeScanning
 
 typealias MobileScannerCallback = ((Array<Barcode>?, Error?, UIImage) -> ())
 typealias TorchModeChangeCallback = ((Int?) -> ())
+typealias ZoomScaleChangeCallback = ((Double?) -> ())
 
 public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate, FlutterTexture {
     /// Capture session of the camera
@@ -36,6 +37,9 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
     /// When torch mode is changes, this callback will be called
     let torchModeChangeCallback: TorchModeChangeCallback
 
+    /// When zoom scale is changes, this callback will be called
+    let zoomScaleChangeCallback: ZoomScaleChangeCallback
+
     /// If provided, the Flutter registry will be used to send the output of the CaptureOutput to a Flutter texture.
     private let registry: FlutterTextureRegistry?
 
@@ -47,10 +51,13 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
 
     var detectionSpeed: DetectionSpeed = DetectionSpeed.noDuplicates
 
-    init(registry: FlutterTextureRegistry?, mobileScannerCallback: @escaping MobileScannerCallback, torchModeChangeCallback: @escaping TorchModeChangeCallback) {
+    var standardZoomFactor: CGFloat = 1
+
+    init(registry: FlutterTextureRegistry?, mobileScannerCallback: @escaping MobileScannerCallback, torchModeChangeCallback: @escaping TorchModeChangeCallback, zoomScaleChangeCallback: @escaping ZoomScaleChangeCallback) {
         self.registry = registry
         self.mobileScannerCallback = mobileScannerCallback
         self.torchModeChangeCallback = torchModeChangeCallback
+        self.zoomScaleChangeCallback = zoomScaleChangeCallback
         super.init()
     }
 
@@ -133,6 +140,21 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         }
 
         device.addObserver(self, forKeyPath: #keyPath(AVCaptureDevice.torchMode), options: .new, context: nil)
+        device.addObserver(self, forKeyPath: #keyPath(AVCaptureDevice.videoZoomFactor), options: .new, context: nil)
+
+        // Check the zoom factor at switching from ultra wide camera to wide camera.
+        standardZoomFactor = 1
+        if #available(iOS 13.0, *) {
+            for (index, actualDevice) in device.constituentDevices.enumerated() {
+                if (actualDevice.deviceType != .builtInUltraWideCamera) {
+                    if index > 0 && index <= device.virtualDeviceSwitchOverVideoZoomFactors.count {
+                        standardZoomFactor = CGFloat(truncating: device.virtualDeviceSwitchOverVideoZoomFactors[index - 1])
+                    }
+                    break
+                }
+            }
+        }
+
         do {
             try device.lockForConfiguration()
             if device.isFocusModeSupported(.continuousAutoFocus) {
@@ -181,6 +203,13 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         } catch {
             print("Failed to set initial torch state.")
         }
+
+        do {
+            try resetScale()
+        } catch {
+            print("Failed to reset zoom scale")
+        }
+
         let dimensions = CMVideoFormatDescriptionGetDimensions(device.activeFormat.formatDescription)
 
         return MobileScannerStartParameters(width: Double(dimensions.height), height: Double(dimensions.width), hasTorch: device.hasTorch, textureId: textureId)
@@ -199,6 +228,7 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
             captureSession.removeOutput(output)
         }
         device.removeObserver(self, forKeyPath: #keyPath(AVCaptureDevice.torchMode))
+        device.removeObserver(self, forKeyPath: #keyPath(AVCaptureDevice.videoZoomFactor))
         registry?.unregisterTexture(textureId)
         textureId = nil
         captureSession = nil
@@ -228,6 +258,10 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
             // off = 0; on = 1; auto = 2;
             let state = change?[.newKey] as? Int
             torchModeChangeCallback(state)
+        case "videoZoomFactor":
+            let zoomFactor = change?[.newKey] as? CGFloat ?? 1
+            let zoomScale = (zoomFactor - 1) / 4
+            zoomScaleChangeCallback(Double(zoomScale))
         default:
             break
         }
@@ -252,7 +286,7 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
             actualScale = min(maxZoomFactor, actualScale)
             
             // Limit to 1.0 scale
-            device.ramp(toVideoZoomFactor: actualScale, withRate: 5)
+            device.videoZoomFactor = actualScale
             device.unlockForConfiguration()
         } catch {
             throw MobileScannerError.zoomError(error)
@@ -260,6 +294,22 @@ public class MobileScanner: NSObject, AVCaptureVideoDataOutputSampleBufferDelega
         
     }
 
+    /// Reset the zoom factor of the camera
+    func resetScale() throws {
+        if (device == nil) {
+            throw MobileScannerError.zoomWhenStopped
+        }
+
+        do {
+            try device.lockForConfiguration()
+            device.videoZoomFactor = standardZoomFactor
+            device.unlockForConfiguration()
+        } catch {
+            throw MobileScannerError.zoomError(error)
+        }
+    }
+
+
     /// Analyze a single image
     func analyzeImage(image: UIImage, position: AVCaptureDevice.Position, callback: @escaping BarcodeScanningCallback) {
         let image = VisionImage(image: image)

@@ -57,6 +57,8 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
             }
         }, torchModeChangeCallback: { torchState in
             barcodeHandler.publishEvent(["name": "torchState", "data": torchState])
+        }, zoomScaleChangeCallback: { zoomScale in
+            barcodeHandler.publishEvent(["name": "zoomScaleState", "data": zoomScale])
         })
         self.barcodeHandler = barcodeHandler
         super.init()
@@ -85,6 +87,8 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
             analyzeImage(call, result)
         case "setScale":
             setScale(call, result)
+        case "resetScale":
+            resetScale(call, result)
         case "updateScanWindow":
             updateScanWindow(call, result)
         default:
@@ -188,6 +192,27 @@ public class SwiftMobileScannerPlugin: NSObject, FlutterPlugin {
         result(nil)
     }
 
+    /// Reset the zoomScale
+    private func resetScale(_ call: FlutterMethodCall, _ result: @escaping FlutterResult) {
+        do {
+            try mobileScanner.resetScale()
+        } catch MobileScannerError.zoomWhenStopped {
+            result(FlutterError(code: "MobileScanner",
+                                message: "Called resetScale() while stopped!",
+                                details: nil))
+        } catch MobileScannerError.zoomError(let error) {
+            result(FlutterError(code: "MobileScanner",
+                                message: "Error while zooming.",
+                                details: error))
+        } catch {
+            result(FlutterError(code: "MobileScanner",
+                                message: "Error while zooming.",
+                                details: nil))
+        }
+        result(nil)
+    }
+
+
     /// Toggles the torch
     func updateScanWindow(_ call: FlutterMethodCall, _ result: @escaping FlutterResult) {
         let scanWindowData: Array? = (call.arguments as? [String: Any])?["rect"] as? [CGFloat]

@@ -85,6 +85,9 @@ class MobileScannerController {
   late final ValueNotifier<CameraFacing> cameraFacingState =
       ValueNotifier(facing);
 
+  /// A notifier that provides zoomScale.
+  final ValueNotifier<double> zoomScaleState = ValueNotifier(0.0);
+
   bool isStarting = false;
 
   /// A notifier that provides availability of the Torch (Flash)
@@ -318,6 +321,11 @@ class MobileScannerController {
     await _methodChannel.invokeMethod('setScale', zoomScale);
   }
 
+  /// Reset the zoomScale of the camera to use standard scale 1x.
+  Future<void> resetZoomScale() async {
+    await _methodChannel.invokeMethod('resetScale');
+  }
+
   /// Disposes the MobileScannerController and closes all listeners.
   ///
   /// If you call this, you cannot use this controller object anymore.
@@ -337,6 +345,9 @@ class MobileScannerController {
         final state = TorchState.values[data as int? ?? 0];
         torchState.value = state;
         break;
+      case 'zoomScaleState':
+        zoomScaleState.value = data as double? ?? 0.0;
+        break;
       case 'barcode':
         if (data == null) return;
         final parsed = (data as List)