CODEWITHSUNDEEP
iosswiftperformancepdfkit
SwiftedMind
SwiftedMind

Reputation: 4297

PDFKit - PDFView using pageViewController - page rendering slow when swiping to next page

I have a PDFView that's set to use a pageViewController:

    let pdfView = PDFView()
    let pdfDoc = PDFDocument(url: Bundle.main.url(forResource: "test", withExtension: "pdf")!)
    pdfView.document = pdfDoc
    pdfView.autoScales = true
    pdfView.displayDirection = .horizontal
    pdfView.usePageViewController(true, withViewOptions: [:])

Whenever I swipe to get to the next page, said next page is blurry for half a second before it's rendered sharply. That is quite annoying. Can I somehow preload the pages? I haven't found any attributes/methods in the documentation.

(Interestingly, I have the exact same problem in Preview on MacOS when it's in fullscreen mode [since forever, on every mac I own])

It's not reliant on pdf (file) size. The problem occurs with every pdf I tried.

Thanks for any help

Upvotes: 12

Views: 5568

Answers (3)

Adrian
Adrian

Reputation: 324

Did you try to change the interpolationQuality option ?

The interpolation quality for images drawn into the PDFView context.

Possible values are

  • none
  • low
  • high

Maybe you could try something like

pdfView.interpolationQuality = .low

or 

pdfView.interpolationQuality = .none

Upvotes: 0

Abhishek
Abhishek

Reputation: 3604

Please make sure to add values of .maxScaleFactor .minScaleFactor also as per your requirement and see if it makes any difference in the loading time. e.g. 

.maxScaleFactor = 4.0;
.minScaleFactor = self.scaleFactorForSizeToFit;

Upvotes: 1

Jeremie
Jeremie

Reputation: 2421

I think this is due to the high resolution of your PDF and the way PDFView renders PDF. Do you have more information on your PDF?

Could you try with a PDF with less heavy images? It should render fine. If so, it's not your code which is at fault, but the resources needed to display and render it to the view.

UPDATE

You can try using the PDFView without PageViewController and see you it behaves. You could do this:

pdfView = PDFView(frame: view.frame)
pdfView.backgroundColor = UIColor.white

var documentName: String = "test"

if let documentURL = Bundle.main.url(forResource: documentName, withExtension: "pdf") {
    if let document = PDFDocument(url: documentURL) {
        pdfView.autoScales = true
        pdfView.displayDirection = .horizontal
        pdfView.displayMode = .singlePageContinuous
        pdfView.document = document
    }
}

self.view.addSubview(pdfView)

Does it behave differently? I've notice that the option usePageViewController loads the document faster for big PDF documents. Something to take into consideration when implementing.

I hope this helps

Upvotes: 1

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