Feature request: Persistent zoom

[mrelg]

Keep preview zoom parameters fixed while refreshing after changing processing options/parameters for easy comparison and adjustment of effects.

[pablogventura]

This was fixed in PR #108 (merge of 1.1.1 improvements) and follow-up PR #109 (Windows threshold overflow fix). Please close this issue.

[pablogventura]

Persistent zoom across page changes / sessions is a feature request — not implemented from this ticket alone.

Note whether you mean per-filter zoom or global UI zoom — storage might use ApplicationSettings.

Open.

[gorgobacka]

@pablogventura What do you mean with "per-filter zoom or global UI zoom"?

[pablogventura]

Thanks for asking for clarification.

• Per-filter zoom: the zoom level you use while working inside one pipeline stage (e.g. Deskew, Select Content, Output) could in principle be remembered only for that stage when you switch pages or come back later.

• Global UI zoom: the same idea but one zoom level shared across all stages (or even the whole app session), so the main image view feels consistent everywhere.

Today ScanTailor mostly treats zoom as per view / session and does not persist it the way you might expect from a document editor—that is why #21 stayed open as a feature request. If we implement something here, we would need to decide which of those behaviours (or both, as a setting) matches user expectations best.

[gorgobacka]

@pablogventura Have you used the software? (Sorry for my stupid question. Or am I talking to a LLM here?)

Each pipeline stage already preserves their "individual" zoom level. That is fine.

This issue is about the last stage: Output.

Let me rephrase it:
Usually, to inspect the effect of the chosen settings the user zooms in to analyze the details of the image. Then he wants to finetune the result and adjusts the settings. After settings are changed, the full image is displayed again (zoom level is not preserved) and the user needs to zoom in again. This is a bit annoying and not ideal for simple comparison.

The expected behavior is that the zoom level is preserved after changing any settings in the "Output" stage.

[pablogventura]

Thanks for the detailed clarification — that helps a lot, and sorry for the earlier framing that didn’t match what you care about here.

Understood: this is specifically about the Output stage, where changing any setting triggers a refresh that resets the zoom (typically back to a full-page view), which makes it tedious to compare fine detail before/after tweaks.

The earlier note about PR #108/#109 was not meant to claim this behaviour was fixed; those changes were unrelated to Output preview zoom. I’ll treat #21 as still open for preserving zoom (and ideally the same viewport / pan) across Output setting changes.

Next step on our side: trace where the Output preview is rebuilt when parameters change and whether we can reapply the previous zoom level (or the previous transform) instead of resetting to “fit whole page”. If you have a minimal repro (which Output controls reliably trigger the reset, and your typical zoom level), that will speed up validation once a patch exists.

And yes — I’m a real person with a regular squishy meat brain, not an automated reply 😄

[pablogventura]

Hello everyone,

We have opened a small pull request that tries to address the behaviour discussed here (keeping the Output preview zoom and scroll position when settings trigger a reload):

PR: #123

If you have a moment to try a build from that branch, we would really appreciate your feedback—especially on real projects and with the controls you normally use in the Output stage. If anything still feels off (or if you notice a regression in another filter’s image view), please let us know so we can adjust.

Thank you for the clear reports and patience, and thanks in advance for any testing you can do.

Kind regards