taler-ios

iOS apps for GNU Taler (wallet)
Log | Files | Refs | README | LICENSE

QRGeneratorView.swift (3493B)

      1 /* MIT License
      2  * Copyright (c) 2020 Jeeva Tamilselvan
      3  *
      4  * Permission is hereby granted, free of charge, to any person obtaining a copy
      5  * of this software and associated documentation files (the "Software"), to deal
      6  * in the Software without restriction, including without limitation the rights
      7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
      8  * copies of the Software, and to permit persons to whom the Software is
      9  * furnished to do so, subject to the following conditions:
     10  *
     11  * The above copyright notice and this permission notice shall be included in all
     12  * copies or substantial portions of the Software.
     13  *
     14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     20  * SOFTWARE.
     21  */
     22 import SwiftUI
     23 
     24 public func QRCode(from text: String) -> UIImage? {
     25     guard let filter = CIFilter(name: "CIQRCodeGenerator") else { return nil }
     26     let data = text.data(using: .utf8, allowLossyConversion: false)
     27     filter.setValue(data, forKey: "inputMessage")
     28     filter.setValue("Q", forKey: "inputCorrectionLevel")    // 4 levels: L M Q H
     29     guard let ciimage = filter.outputImage else { return nil }
     30     let transform = CGAffineTransform(scaleX: 10, y: 10)
     31     let scaledCIImage = ciimage.transformed(by: transform)
     32     // a UIImage(ciImage:) has no bitmap representation, so pngData() would return nil
     33     guard let cgImage = CIContext().createCGImage(scaledCIImage,
     34                                             from: scaledCIImage.extent) else { return nil }
     35     return UIImage(cgImage: cgImage)
     36 }
     37 // MARK: -
     38 struct QRGeneratorView: View {
     39     let image: UIImage?
     40     let size: CGFloat
     41     let logo: Image?
     42     let logoSize: CGFloat
     43 
     44     // a QR code which cannot be generated must not look like an empty area to scan
     45     private var failedText: Text {
     46         Text("Cannot create QR code", comment: "shown instead of the QR code")
     47     }
     48 
     49     var body: some View {
     50         ZStack {
     51             if let image {
     52                 Image(uiImage: image)
     53                     .interpolation(.none)
     54                     .resizable()
     55                     .scaledToFit()
     56                     .frame(width: size, height: size)
     57                 if let logo {
     58                     logo
     59                         .resizable()
     60                         .scaledToFit()
     61                         .frame(width: logoSize * 2, height: logoSize)
     62                 }
     63             } else {
     64                 failedText
     65                     .talerFont(.title2)
     66                     .frame(width: size, height: size)
     67             }
     68         }
     69         .accessibilityElement(children: .combine)
     70         .accessibilityLabel(image == nil ? failedText : Text("QR Code", comment: "a11y"))
     71     }
     72 }
     73 
     74 //#Preview {      // 'Previewable()' is only available in iOS 17.0 or newer
     75 //    @Previewable @State var image: UIImage?
     76 //    VStack {
     77 //        QRGeneratorView(text: "Hello World!", size: 200, image: $image)
     78 //        QRGeneratorView(text: "taler://pay-pull/exchange.demo.taler.net/7J7SNHYMCCAZ1ARY9YCB5Z9FTY0YZP8F2KDRXV94KZCQ6WAVMTX0",
     79 //                        size: 200, image: $image)
     80 //    }
     81 //}