Smooth Scroll

[ilyadegroeve]

Adding the feature "Smooth Scroll". Currently scrolling in Sumatra PDF is low fps and very scratchy, smooth scrolling would solve this issue.

[GitHubRulesOK]

Scroll behaviour is 2 parts so hardware and software have a different effect for each user. Personally I use smooth auto scroll that is built into my mouse, (same one I use in browser to make that smooth) but each mouse may have different "smoothness" Note it is reasonably smooth enough even though SumatraPDF advanced settings are currently SmoothScroll = false

The software limit is that the rendering needs to be built lines at a time so often a page may stutter as each text high line is rendered since PDF are not like an image format which can show scan line by line.

Comparatively in my hardware Acrobat and SumatraPDF are equally smooth.

[ilyadegroeve]

I am talking about auto scroll (middle mouse button). For some reason, Firefox PDF reader offers smooth scroll while it is very scratchy and the speed is limited on Sumatra PDF. I do love the dark mode though.

[GitHubRulesOK]

FireFox PDF reader ? if you mean Mozilla PDFasAnIMG.js then that is not a normal binary (Use Adobe Reader as a Compliant yardstick)
If you inspect the Firefox page is is scanlines I.E it is a picture of a PDF just like GoogleViewer or FlipBooks are NOT a PDF so images will always scroll by exceptionally small steps compared to vector based rendering.

And even this knackered $1 mouse autoscroll in SumatraPDF is as smooth as here in Edge. The Powered by Adobe viewer in edge looks jerkier to me than using SumatraPDF in old Firefox or other newer current browsers.

Acrobat Reader DC in FireFox variants is way smoother than Powered by Acrobat in Chromium Edge And if I switch Reader DC on in Edge it is amazingly fast (as its lighter that standalone!) even looks as fast as SumatraPDF

[kjk]

Sadly, smooth scroll is not easy to implement. Web browsers have very sophisticated rendering engine that required lots of people and lots of time to implement. I'm one person and I don't see an easy way to improve scrolling.