Fixed zoom level implementation (partially done)

[Tmarinus]

I created a beginning for an issue I was having with Zotero on android.
See forum posts:
https://forums.zotero.org/discussion/129087/pdf-zoom-uniform-over-multiple-pages-mostly-on-android#latest https://forums.zotero.org/discussion/126456/feature-request-android-fixed-zoom/p1

What this code does is add 3 buttons to the annotation bar. Two buttons for previous and next page, and then one that locks the zoom. When the zoom is locked, scrolling and zooming is disabled. Using the buttons for prev and next will allow you to go to the next page with exactly the same zoom level and location.

I think this solves my and the other forum request.

However due to my lack of understanding (this is my first attempt to help with anything android related).

• I was unable to make a nice icon and let the icon of locking the zoom switch based on the state.
• Instead of having buttons for prev and next page, a swipe (two finger?) would maybe be a nice addition or alternative
• This fills up the annotation bar a bit, and it is not part of annotation so maybe the buttons should be somewhere else. (This can also be solved with adding the buttons to a settings field somewhere.

Please let me know if this is worth continuing. The code like this has been tested on emulator and my ereader.
I am willing to fix it further if someone helps me a little bit on how to do it.

Additionally I wanted to ask if I just wanted to use this feature for myself, will I be required to own a pspdfkit license? Now I have these big warning letters.

You can see the code below.

master...Tmarinus:zotero-android:add_prev_next_buttons

[dstillman]

Thanks, but the fix here should just be to support page changing via the screen edge when zoomed and to preserve the zoom:

#253

It's just a bug that that doesn't work when zoomed in on Android, and it's a bug that the iOS app doesn't preserve the zoom on edge tap.

[Tmarinus]

Thank you for the reply. I tried to look into it, but as far as I can see this is not really a bug. There is not feature implemented that should allow the side pressing to cause a page switch. It works when zoomed out because it is a feature of pspdfkit.

What would you suggest as to approach this. I looked at PdfReaderScreen.kt, but handling keys there will be tricky cause it will interfere with the UI elements.

Two other logical locations are onDocumentClick and onPageClick of the documentListener of PdfReaderViewModel.

onDocumentClick does not provide event x,y click positions so clicking outside of the pdf page I do not see how to detect if it was right or left.
onPageClick seems to be a good option, having a pagePosition: PointF? indicating where the click was. This could converted to a view click position to know if it was left or right side of the page. However that the click will need to happen on the page.

If you want me to try and help further with this, can you point me to the right direction where this problem could be solved?