Writing images to PDF using PDFKit in Swift results in blurry images

Question

I have the following classes:

import Foundation
import PDFKit
import SwiftUI

struct PDFPreviewView  : View {
    @State private var showShareSheet : Bool = false
    
    var pdfData: Data? {
        LabelPDFCreator().pdfData()
    }
    
    var body: some View {
        VStack {
            PdfViewUI(data: pdfData)
        }
        .navigationTitle(Text("Your Labels"))
        .navigationBarTitleDisplayMode(.inline)
        .sheet(isPresented: $showShareSheet, content: {
            if let data = pdfData {
                ShareView(activityItems: [data])
            }
        })
        .toolbar {
            Button {
                self.showShareSheet.toggle()
            } label: {
                Label("Options", systemImage: "square.and.arrow.up")
            }
        }
    }
}

struct PdfViewUI : UIViewRepresentable {

    private var data: Data?
    
    private let autoScales : Bool
    
    init(data : Data?, autoScales : Bool = true ) {
        self.data = data
        self.autoScales = autoScales
    }

    func makeUIView(context: Context) -> PDFView {
        let pdfView = PDFView()

        pdfView.autoScales =  self.autoScales
       
        if let data = self.data {
            pdfView.document = PDFDocument(data: data)
        }
        
        return pdfView
    }

    func updateUIView(_ uiView: PDFView, context: Context) {
        // Empty
    }
}

class LabelPDFCreator : NSObject {
    static let DPI = 72.0
    
    private var pageRect : CGRect
    private var renderer : UIGraphicsPDFRenderer?
    
    let context = CIContext()
    let filter = CIFilter.qrCodeGenerator()

    override init() {
        let format = UIGraphicsPDFRendererFormat()
        
        let pageRect = CGRect(x: 0, y: 0, width: (8.5 * LabelPDFCreator.DPI), height: (11.0 * LabelPDFCreator.DPI))
        self.pageRect = pageRect
        self.renderer = UIGraphicsPDFRenderer(bounds: self.pageRect,
                                             format: format)
        super.init()
    }
    
    func pdfData() -> Data? {
        if let renderer = self.renderer {
            let data = renderer.pdfData { ctx in
                ctx.beginPage()

                let image = generateQRCode(from: UUID().uuidString)
                let imageWidthHeight = 1.0 * LabelPDFCreator.DPI
                                    
                image.draw(in: CGRect(x: LabelPDFCreator.DPI, y : LabelPDFCreator.DPI, width: imageWidthHeight, height: imageWidthHeight))
            }
            return data
        }
        return nil
    }
    
    func generateQRCode(from id: String) -> UIImage {
        filter.message = Data(id.utf8)
        
        if let outputImage = filter.outputImage {
            if let cgImage = context.createCGImage(outputImage, from: outputImage.extent) {
                return UIImage(cgImage: cgImage)
            }
        }
        
        return UIImage(systemName: "xmark.circle") ?? UIImage()
    }
}

I have simplified the code down to the core functionality that I am experiencing issues with.

Within LabelPDFCreator, you can see that I am generate a QR code UIImage from a UUID string, and then drawing that image onto a page of a PDF using PDFKit.

The draw is successful, however the QR code winds up being very blurry. Am I able to adjust this code in a way that will result in a sharper display of the QR code in the PDF?

I have tried to scale up both the bounds of the UIGraphicsPDFRenderer, and the width and height of the image being drawn into the PDF, but this effort was unsuccessful.

Writing images to PDF using PDFKit in Swift results in blurry images

0 Answers0