feat: Query if ScrollViewState is_at_bottom()

[Teufelchen1]

Hey 🐅,

this aims to fix #72

It is close to what was discussed but I made the additional decision to respect the page size. I believe this is the right way to do it as not respecting the page size feels very odd to the user, example:

let state = ...;
// our content is 5 rows
assert_eq!(state.size.unwrap().height, 5);
// our page size is 3
assert_eq!(state.page_size.unwrap().height, 3);

// Scrolling down 5 times
state.scroll_down();
state.scroll_down();
state.scroll_down();
state.scroll_down();
state.scroll_down();

// Render it
scroll_view.render(...);

// Are we at the bottom?
assert!(state.is_at_bottom()); // FAILS!
// This is because rendering resets our offset to cater for the page size
assert_eq!(state.offset.unwrap().y, 2);

See scroll_view.rs:210-232 for why that is.

Since that felt wrong to me, I made the judgment call for is_at_bottom() to consider the page size. So technically it is now a are_we_scrolled_down_enough_so_it_behaves_and_looks_like_we_are_at_the_bottom() 🥸

I added a unit test.

Feedback? :)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 74.36%. Comparing base (59a01f7) to head (cbfbe82).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #75      +/-   ##
==========================================
+ Coverage   73.90%   74.36%   +0.46%     
==========================================
  Files          16       16              
  Lines        2667     2672       +5     
==========================================
+ Hits         1971     1987      +16     
+ Misses        696      685      -11     

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[Teufelchen1]

@joshka any actions required from my side? If not, just slam an emoji on my message and I will know you are just busy.