taler-ios

iOS apps for GNU Taler (wallet)
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QRGeneratorView.swift (3955B)

      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 struct QRGeneratorView: View {
     25     let text: String
     26     let size: CGFloat
     27     let logo: Image?
     28     let logoSize: CGFloat
     29     @Binding var image: UIImage?
     30 
     31     @State private var failed = false
     32 
     33     // a QR code which cannot be generated must not look like an empty area to scan
     34     private var failedText: Text {
     35         Text("Cannot create QR code", comment: "shown instead of the QR code")
     36     }
     37 
     38     var body: some View {
     39         ZStack {
     40             if let image {
     41                 Image(uiImage: image)
     42                     .interpolation(.none)
     43                     .resizable()
     44                     .scaledToFit()
     45                     .frame(width: size, height: size)
     46                 if let logo {
     47                     logo
     48                         .resizable()
     49                         .scaledToFit()
     50                         .frame(width: logoSize * 2, height: logoSize)
     51                 }
     52             } else if failed {
     53                 failedText
     54                     .talerFont(.title2)
     55                     .frame(width: size, height: size)
     56             } else {
     57                 EmptyView()
     58             }
     59         }
     60         .accessibilityElement(children: .combine)
     61         .accessibilityLabel(failed ? failedText : Text("QR Code", comment: "a11y"))
     62         .onAppear {
     63 //          if let uiImage = getQRCode(text: text) {
     64             if let data = getQRCodeData(text: text),
     65                let uiImage = UIImage(data: data)  {
     66                 image = uiImage
     67             } else {
     68                 failed = true
     69             }
     70         }
     71     }
     72 
     73 //    func getQRCode(text: String) -> UIImage? {
     74     func getQRCodeData(text: String) -> Data? {
     75         guard let filter = CIFilter(name: "CIQRCodeGenerator") else { return nil }
     76         let data = text.data(using: .ascii, allowLossyConversion: false)
     77         filter.setValue(data, forKey: "inputMessage")
     78         filter.setValue("Q", forKey: "inputCorrectionLevel")    // 4 levels: L M Q H 
     79         guard let ciimage = filter.outputImage else { return nil }
     80         let transform = CGAffineTransform(scaleX: 10, y: 10)
     81         let scaledCIImage = ciimage.transformed(by: transform)
     82         // a UIImage(ciImage:) has no bitmap representation, so pngData() would return nil
     83         guard let cgImage = CIContext().createCGImage(scaledCIImage, from: scaledCIImage.extent)
     84         else { return nil }
     85         return UIImage(cgImage: cgImage).pngData()
     86     }
     87 }
     88 
     89 //#Preview {      // 'Previewable()' is only available in iOS 17.0 or newer
     90 //    @Previewable @State var image: UIImage?
     91 //    VStack {
     92 //        QRGeneratorView(text: "Hello World!", size: 200, image: $image)
     93 //        QRGeneratorView(text: "taler://pay-pull/exchange.demo.taler.net/7J7SNHYMCCAZ1ARY9YCB5Z9FTY0YZP8F2KDRXV94KZCQ6WAVMTX0",
     94 //                        size: 200, image: $image)
     95 //    }
     96 //}