Feature/zoom scroll

[peshkira]

When a user zooms in a page, and swipes to the end of it, then they cannot scroll to the next page.
This PR changes this by comparing the last known current X or Y Offset (depending on vertical swiping) and then shows the next/previous page. When this happens the zoom is reset, as it seems most apps with similar functionality, do this.

Unfortunately, I had to change the build.grade sdk versions, as Android Studio complained that the build tools version is too low.

Also I saw that there are some API Calls that require API 11, however the min is set to 8

[uugan]

Peshkira I think you should save also zoom. When you swipe zoom goes to default value.
Please merge these commits! PdfView doesn't swipe when zoomed in.

[peshkira]

Thanks @uugan. I am not sure, if the zoom should remain when the page is changed. I took a look at a number of popular apps that render PDFs and they all seem to reset the zoom. It makes sense to me, because you immediately have an overview of the page and you can go through more pages faster (when they are not zoomed). Otherwise it can get confusing.

However, maybe we can make a setting of it and let the developer decide what happens.

[uugan]

@peshkira well i tested some free pdf readers like MuPDF, Adobe Acrobat Reader. It depends on which way to swipe. If you swipe up/down then zoom is stored its value but when swipe right/left then zoom goes to default value.
P.S. 11 Pull requests no answer :(

[Shajeel-Afzal]

Hi, How can we add Zoom Functionality?