Move QR code reader and generator classes in their own module.

Riot/Modules/QRCode/QRCodeGenerator.swift

@@ -0,0 +1,50 @@
+/*
+ Copyright 2020 New Vector Ltd
+ 
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+ 
+ http://www.apache.org/licenses/LICENSE-2.0
+ 
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+ */
+
+import Foundation
+
+final class QRCodeGenerator {
+    
+    // MARK: - Constants
+    
+    private enum Constants {
+        static let qrCodeGeneratorFilter = "CIQRCodeGenerator"
+        static let qrCodeInputCorrectionLevel = "M"
+    }
+    
+    // MARK: - Public
+    
+    func generateCode(from data: Data, with size: CGSize) -> UIImage? {
+        guard let filter = CIFilter(name: Constants.qrCodeGeneratorFilter) else {
+            return nil
+        }
+        
+        filter.setValue(data, forKey: "inputMessage")
+        filter.setValue(Constants.qrCodeInputCorrectionLevel, forKey: "inputCorrectionLevel") // Be sure to use same error resilience level as other platform
+        
+        guard let ciImage = filter.outputImage else {
+            return nil
+        }
+        
+        let scaleX = size.width/ciImage.extent.size.width
+        let scaleY = size.height/ciImage.extent.size.height
+        
+        let transform = CGAffineTransform(scaleX: scaleX, y: scaleY)
+            
+        let transformedCIImage = ciImage.transformed(by: transform)
+        return UIImage(ciImage: transformedCIImage)
+    }
+}