Adjusting the Distance Moved in PDF on Tap

[Rand Brittain]

Is there a setting in KOreader that lets me change how far forward I move down the page when I tap the screen while reading a PDF? Right now, when I read in landscape, a single tap moves me almost to the bottom of the page, but not quite, so that making it just a little farther on each tap would cut the number of refreshes per PDF in half.

I've found the settings for adjusting how to tap, but not the ones that determines what happens when I do.

[NiLuJe]

That's probably related to https://github.com/koreader/koreader...ts.lua#L50-L51 (the intent being that you keep 30px of the previous screen visible, for clarity in general, and in particular if the bottom of the screen happens to cut through a line ).

You can tweak that as part of the "Advanced settings" UI. ([Tools] > More tools > Advanced setting).

What you're asking should be doable by using a value closer or equal to 0.

Fair warning: continuous mode is a giant can of worms, expect stuff to break in fun and interesting ways depending on zoom modes & factors and whatnot (and I'm not actually sure anybody ever validated what happens at 0).

[Rand Brittain]

I'll give it a try! I don't think I was in continuous mode; at least, not on purpose.

(Continuous mode for reading books really bugs me and I'm very sad that the one Android PDF app that I sort of like for devices that aren't eInk seems to insist on either continuous mode with vertical scroll, or page mode but I can't fit to width. Why! Why!

But that's not a you thing.

[Rand Brittain]

Hm, I made the adjustment and it didn't seem to have any effect. Honestly, I can still see plenty of pixels that were visible from the previous position, so I don't think the issue is actually related to the overlap setting. I just wish I could set it to go a little bit more when I tap it because right now it hits just short of moving to the next page.

[NiLuJe]

Oh, if you're *not* in continuous mode, then this has no effect at all ;o).

But if you're in paged mode, then you'll have to detail which zoom & layout options you're using. I imagine you want something like fit to content height?

[Rand Brittain]

Originally Posted by NiLuJe

Oh, if you're *not* in continuous mode, then this has no effect at all ;o).

But if you're in paged mode, then you'll have to detail which zoom & layout options you're using. I imagine you want something like fit to content height?

Well, I have it on fit-to-width with no zoom applied, which is how I want it so I can read comfortably in landscape, and the screen of the Tab Ultra is big enough that in this mode it shows about 2/3 of the height of a normal letter-sized page. A tap on the screen scrolls me down almost to the bottom of the page, but not quite, so I have to tap it again and have the screen do an unnecessary refresh on each page.

[NiLuJe]

Then it just depends on the actual content or page size (depending on if you fit to page or content), and doing it any other way would go against your chosen fit mode, so it's kind of a catch-22 there .

[Rand Brittain]

Hm, that doesn't seem quite right—why would fit-to-width constrain the amount of vertical movement?—which makes me wonder if I'm explaining it correctly.

Come to think of it, how does KOreader determine how far to scroll down on a PDF when you tap it?

[NiLuJe]

Depends on the aspect ratio of what you're asking to "fit" to. If it's (it being page or content, depending on your settings) a perfect square, fit to width == fit to height, so a page turn will turn by a screenful of content, which will also mean a page of "it" .

But that will probably never happen, because mostly, you'll be reading content that's Portrait-ish; i.e., taller than it is wide. So, if you fit to width, you're left with a bit of "it" offscreen at the bottom, so a page turn will let you actually *see* that leftover instead of skipping over it.

The vertical movement is always worth (roughly) a screenful, whatever the screen currently displays, so whether or not you get overlap actually depends on the content (and how much of the content you get to see in a single screen depends on your settings).

As a mildly related example, for a CBZ use-case, on a large screen, I target a 1:1 experience, so I preprocess my content to target the *exact* dimensions of my screen, and then fit to page height (or 1:1, it'll be the same anyway).