add fromRawValue constructors to camera_facing, detection_speed and torch_state enums

@@ -8,6 +8,17 @@ enum CameraFacing {
 
   const CameraFacing(this.rawValue);
 
+  factory CameraFacing.fromRawValue(int value) {
+    switch (value) {
+      case 0:
+        return CameraFacing.front;
+      case 1:
+        return CameraFacing.back;
+      default:
+        throw ArgumentError.value(value, 'value', 'Invalid raw value.');
+    }
+  }
+
   /// The raw value for the camera facing direction.
   final int rawValue;
 }

@@ -18,6 +18,19 @@ enum DetectionSpeed {
 
   const DetectionSpeed(this.rawValue);
 
+  factory DetectionSpeed.fromRawValue(int value) {
+    switch (value) {
+      case 0:
+        return DetectionSpeed.noDuplicates;
+      case 1:
+        return DetectionSpeed.normal;
+      case 2:
+        return DetectionSpeed.unrestricted;
+      default:
+        return DetectionSpeed.normal;
+    }
+  }
+
   /// The raw value for the detection speed.
   final int rawValue;
 }

@@ -8,6 +8,17 @@ enum TorchState {
 
   const TorchState(this.rawValue);
 
+  factory TorchState.fromRawValue(int value) {
+    switch (value) {
+      case 0:
+        return TorchState.off;
+      case 1:
+        return TorchState.on;
+      default:
+        throw ArgumentError.value(value, 'value', 'Invalid raw value.');
+    }
+  }
+
   /// The raw value for the torch state.
   final int rawValue;
 }