Low pre-rendered Version of PdfPage

[LukasKompatscher]

Use case

When scrolling through the pages on a slow device, the white loading screen makes the pdf viewer seem kind of slow. A prerendered but very low quality version of page already rendered would make it seem a lot more fast and also a lot better instead of the white page or even the loading indicator.

Proposal

When going thorough the pages with snapping, and reaching the next page, instead of a loading indicator there should be a low quality version rendered page, which then transforms into the better rendered version if the page has finished loading. This ensures better flow and better UI.

[Deepak1799]

Hi @LukasKompatscher ,

Implementing blurred preview rendering can lead to memory-related issues, particularly in large documents, as it increases memory usage during rendering. Given the limited resources on mobile devices, this approach is not well-suited for mobile platforms. Similar behavior can be observed in other products, where only a white page is initially rendered, followed by the page in full quality.

This approach not only impacts memory but also increases rendering time. Since page rendering operations cannot be performed concurrently, we would need to sequentially retrieve the page image—first rendering a low-quality version, then the full-quality image. This further increases the time required to display pages in full quality.

For this reason, to provide visual feedback while a page is loading, we have opted to use a loading indicator instead. So, we do not have any plans to implement the support for low pre-rendered version of PDF pages.