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
The thresholds are only for detecting if a specific side of the image is in the viewport.
For the check if the image fills the whole viewport, the thresholds incorrectly detect this depending on the readers reading direction.
E.g. in the continuous horizontal pager with theme direction LTR and reader reading direction RTL, the left threshold will be the total width of the viewport plus one which will lead to out of view images to be detected as completely filling the viewport
Both hardcoded thresholds (MIN_VISIBLE_PX 0 or 1) break the "first visible image" detection in different kind of ways.
With 1 it always incorrectly jumps to the next page when resuming a chapter, since the page to resume will bet at 0px.
With 0 it fails to detect the correct first visible image when scrolling (automatically not via wheel or touch) to another page.
This happens when there is no gap between the pages because in this case the start of the current image and the end of the previous image are at the same coordinate.
Thus, the previous image is still incorrectly detected as visible since the end still aligns with the viewports start/end
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
Depending on the set reader width, the auto margin of the images took effect and separated the double pages.
However, for double pages, only the margin left/right depending on the page should be set, to properly center the pages without a gap between them
Depending on the screen size and e.g. the set "reader width" pages might not have filled out the full img elements size due to "object-fit contain".
This was caused due to the image wrappers flex container "align-items center" which slightly reduced the images width to some ".xy" number (e.g. instead of wrappers width 258px, the images were something like 257.83px)
In case two pages were displayed with different dimensions, the bigger page might take up more than 50% of the screen.
In this case the bigger page got limited to 50% which caused in to unintentionally get reduced in size
Due to the way the pages got scrolled into view, the current page was not changed to the new page.
This then prevented the previous/next page to get opened via click/hotkey actions
