How do I create PDFs at the right page size?

[lhr0909]

Hi,

I am checking in after doing integration with the library. So far it is working very well, and we could render very high quality PDFs, which is great!

When we were checking the size of the PDF (width and height), and found that it was way larger than what it was set at render time (A4). We are looking at a number that is almost like a A0 size from MacOS preview.

We found this issue when we were trying to merge existing PDFs together and found that our renders were way larger than A4s.

I am sending an example output from our code:

        let document = PDFViewKit.PDFDocument {
            ReceiptPDFContentView(
                data: exportData,
                attachmentImage: attachmentImage,
                hasPDFAttachment: isPDFAttachment
            )
        }

        try await MainActor.run {
            try PDFRenderer.render(
                document: document,
                to: destinationURL,
                atPageSize: DIN.a4
            )
        }

We now had to scale the attached PDF to make it look right, so it is less than ideal, but not the end of the world.

Please advice if there is a better way to render it. I have been checking the lib source code and we were not wrapping our content view with PDFPage and I am not sure if we need to in order to control the output size. Cheers!

[sgade]

Hej Simon, what OS are you running this on? I assume iOS? Maybe the display DPI is different than 96 DPI by default and could produce a wrong scaling factor. This might be relevant on macOS as well.

See the default assumption here.

If you could try, please adjust the DPI for your device and report if we might need to change how the base DPI is calculated.

[lhr0909]

I have been testing with iPhone 16 Pro Max. How can we change the DPI for the device or for PDFViewKit?

[sgade]

You could try to modify the source line I linked and, for testing, change the value of .display to something that matches the DPI of your device. If that brings the output more in-line with the expected size, then we have identified the culprit.

[lhr0909]

@sgade Got it! We will try to modify the DPI for display scaling and verify if this is the culprit. The device I am testing seems to have 466 ppi. So we will see if this is the DPI we need to set to.

I am currently on vacation so I will update here a little later! Happy holidays and New Year to you too! Cheers!