On iOS we find pages are blurry for some time, before they look correct. Is there a suggested setting in the PDF or optimisation to avoid this ‘bluriness’?
The blurry images that you see are low res place holder images, that are replaced by high res ones afterwards. The time to go from low to high res image is dependent on the page complexity, and hardware. So on mobile it is expected that this low resolution placeholder will be on screen longer then would be the case on desktop.
Is there a suggested setting in the PDF or optimisation to avoid this ‘bluriness’?
If you are able to pre-process the PDF files, then you can add high resolution thumbnails to the document, and set PDFViewCtrl to use the ones in the document. This will give a better user experience, though the files will be larger. If this is something you would like to persue then let me know and I can advise further.
To generate the thumbnails, and use them in the PDF, you can simply call PDFDoc.GenerateThumbnails passing in the max dimension, say 512, or 1024, to start with. Then you would save as e_linearized or e_remove_unused.
Then to at runtime you call the following after instantiating your PDFViewCtrl object, PDFViewCtrl.SetupThumbnails(true, true, true, 250, /* current_default_is_256MB_on_mobile_and_512MB_desktop */, 0.1);
Above could will use your embedded ones if present, and since the second boolean is true, it will also auto generate for any files that do not have embedded. Though, if a file has a bad/incorrect embedded thumbnails those would be used. There isn’t a way to differentiate between thumbs you generated and pre-existing ones.
Beyond that, the default settings of PDFNet and PDFViewCtrl are setup to maximize performance.