feat: add barcode scanner plugin (#536)

plugins/barcode-scanner/ios/Sources/CameraView.swift

@@ -0,0 +1,57 @@
+// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
+import AVFoundation
+import UIKit
+
+class CameraView: UIView {
+  var videoPreviewLayer: AVCaptureVideoPreviewLayer?
+
+  func interfaceOrientationToVideoOrientation(_ orientation: UIInterfaceOrientation)
+    -> AVCaptureVideoOrientation
+  {
+    switch orientation {
+    case UIInterfaceOrientation.portrait:
+      return AVCaptureVideoOrientation.portrait
+    case UIInterfaceOrientation.portraitUpsideDown:
+      return AVCaptureVideoOrientation.portraitUpsideDown
+    case UIInterfaceOrientation.landscapeLeft:
+      return AVCaptureVideoOrientation.landscapeLeft
+    case UIInterfaceOrientation.landscapeRight:
+      return AVCaptureVideoOrientation.landscapeRight
+    default:
+      return AVCaptureVideoOrientation.portraitUpsideDown
+    }
+  }
+
+  override func layoutSubviews() {
+    super.layoutSubviews()
+    if let sublayers = self.layer.sublayers {
+      for layer in sublayers {
+        layer.frame = self.bounds
+      }
+    }
+
+    if let interfaceOrientation = UIApplication.shared.windows.first(where: { $0.isKeyWindow })?
+      .windowScene?.interfaceOrientation
+    {
+      self.videoPreviewLayer?.connection?.videoOrientation = interfaceOrientationToVideoOrientation(
+        interfaceOrientation)
+    }
+  }
+
+  func addPreviewLayer(_ previewLayer: AVCaptureVideoPreviewLayer?) {
+    previewLayer!.videoGravity = AVLayerVideoGravity.resizeAspectFill
+    previewLayer!.frame = self.bounds
+    self.layer.addSublayer(previewLayer!)
+    self.videoPreviewLayer = previewLayer
+  }
+
+  func removePreviewLayer() {
+    if self.videoPreviewLayer != nil {
+      self.videoPreviewLayer!.removeFromSuperlayer()
+      self.videoPreviewLayer = nil
+    }
+  }
+}