There can be cases where when scrolling backward/forward the first/last page never gets visible in the viewport due to a large width/height of another page.
In that case the intersection observer would never trigger and thus, the chapter wouldn't get changed.
By using the Pager, which always takes up the full width/height, this problem will not be possible, since the start/end of the Pager always enters or leaves the viewport.
The viewers can have different sizes which caused theme to not be properly centered.
E.g. for the "vertical mode" in case "chapter 1" is greater in width than "chapter 2", the pages of "chapter 2" were not correctly centered due to the "viewers" having different widths.
Seems like not all browsers handle
width/height: 100%
min-width/min-height: fit-content
correctly.
the "min" setting just never applies and the size is stuck at 100%.
In case many chapters are rendered, even just the HOC wrapper component re-render due to the context change increases the render time.
Thus, getting rid of these HOC wrapper re-renders by moving the context usage up to the ReaderViewer decreases the render time.
In case many chapters are rendered, even just the HOC wrapper component re-render due to the context change increases the render time.
Thus, getting rid of these HOC wrapper re-renders by moving the context usage up to the ReaderViewer decreases the render time.
Preparation for infinite scroll, since there will be a wrapper which fits its content in width and height, thus, percentage based dimension won't work anymore
By the time the scroll area got scrolled to the start of the visible pages, the previous/next page wasn't yet shown and thus, the scrollable area wasn't updated yet.
Thus, in case the scrollable area grew in width due to the page change, the start never got scrolled into view due to triggering the logic too early.
Instead of immediately updating the value once the page count changed, it got updated after "pagesToSpreadState" changed, which was after the rendering finished.
This was the actual root cause of what was tried to be fixed with 9ab6ec89c7
I was unable to find a fix for this problem, thus, the only solution I see is disabling this functionality for the continuous readers.
Due to preloading leading pages, the layout got shifted once the pages got loaded.
This messed with the scroll position which caused the top of the scrolled into views pages to not be at the top of the viewport anymore.
For continuous pagers the chapter transition page is always visible regardless of the current "transitionPageMode".
However, this was not properly checked and thus, it wasn't considered to be visible and instead of opening the previous/next chapter, the transition page got set to be visible first and only with the second hotkey press did the chapter get opened
Since "pagesToSpreadState" isn't part of the dependency array and also would decrease the render performance if it was (see reasoning of c79f7cc874), the array reference might be out of date and thus, the guard might not work correctly
In case the current page changed after selecting a page, the previously selected page couldn't be selected again since the "pageToScrollToIndex" was still set to this page
After changes in e4253633c9 the transition page content wasn't properly centered anymore in the single/double reading mode depending on the applied reader settings (scale type, stretch, reader width)
Due to handling an "offset spread page" change as if the "double page" mode got activated, the index of the secondary page was set, which resulted in opening the next page
