[native_pdf_view] Add Zooming without pixel loss about packages.flutter

[SergeShkurko]

added in pdfx

[SergeShkurko]

in version 1.5.0 added crop attributes in render options

[deakjahn]

Yes, the crop is there but the view makes no attempt at reloading the contents when the zoom changes. :-)

[deakjahn]

I found a possible solution, if you would like to check it out. Instead of ExtendedImage, you might want to switch to FlutterMap. Yep, I know, it seems strange at first. But, although it's conceived for maps, it could be used all right. It has full support for tiling smaller parts to show a larger picture, with pinch zoom and everything. And a FileTileProvider that you could extend to return the actual tiles of the PDF. When at zoom level 1, nothing would change but at higher zoom levels, you could generate (and cache) the smaller tiles using the crop approach.

I tried to experiment with it a little but I don't know if I can dedicate enough time to it right now. So I thought I'd mention it up front if you think you're interested to look into it. :-)

[SergeShkurko]

@deakjahn ExtendedImage uses also for image switch

[deakjahn]

No, I didn't mean that. ExtendedImage can just replace it with a larger image but if you want to allow higher zoom levels without quality loss, you simply cannot generate ten times the size, the bitmap would be too large. Using tiled images would mean that only the part the user is actually looking at gets generated.

[SergeShkurko]

I understand your idea, it's just that this library is used not only for scaling, but also for turning pages. This is also quite an important factor.

[deakjahn]

Yes, sure. I would think about a PageView, just like now, where each page is a FlutterMap. I'll try to come up with something if I have the time. :-)

[SergeShkurko]

I will be glad to any help :)

[SergeShkurko]

I start work on this issue

see #238