@ -2,31 +2,123 @@ use crate::node::Node;
use serde ::{ Deserialize , Serialize } ;
use time ::OffsetDateTime ;
#[ derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize) ]
pub struct ScrollState {
current_focus : usize ,
pub last_focus : Option < usize > ,
pub skipped_rows : usize ,
/* The number of visible next lines when scrolling towards either ends of the view port */
pub initial_preview_cushion : usize ,
}
impl ScrollState {
pub fn set_focus ( & mut self , current_focus : usize ) {
self . last_focus = Some ( self . current_focus ) ;
self . current_focus = current_focus ;
}
pub fn get_focus ( & self ) -> usize {
self . current_focus
}
pub fn calc_skipped_rows (
& self ,
height : usize ,
total : usize ,
vimlike_scrolling : bool ,
) -> usize {
let preview_cushion = if height > = self . initial_preview_cushion * 3 {
self . initial_preview_cushion
} else if height > = 9 {
3
} else if height > = 3 {
1
} else {
0
} ;
let current_focus = self . current_focus ;
let last_focus = self . last_focus ;
let first_visible_row = self . skipped_rows ;
// Calculate the cushion rows at the start and end of the view port
let start_cushion_row = first_visible_row + preview_cushion ;
let end_cushion_row = ( first_visible_row + height )
. saturating_sub ( preview_cushion + 1 )
. min ( total . saturating_sub ( preview_cushion + 1 ) ) ;
if ! vimlike_scrolling {
height * ( self . current_focus / height . max ( 1 ) )
} else if last_focus . is_none ( ) {
// Just entered the directory
0
} else if current_focus = = 0 {
// When focus goes to first node
0
} else if current_focus = = total . saturating_sub ( 1 ) {
// When focus goes to last node
total . saturating_sub ( height )
} else if ( start_cushion_row ..= end_cushion_row ) . contains ( & current_focus ) {
// If within cushioned area; do nothing
first_visible_row
} else if current_focus > last_focus . unwrap ( ) {
// When scrolling down the cushioned area
if current_focus > total . saturating_sub ( preview_cushion + 1 ) {
// When focusing the last nodes; always view the full last page
total . saturating_sub ( height )
} else {
// When scrolling down the cushioned area without reaching the last nodes
current_focus . saturating_sub ( height . saturating_sub ( preview_cushion + 1 ) )
}
} else if current_focus < last_focus . unwrap ( ) {
// When scrolling up the cushioned area
if current_focus < preview_cushion {
// When focusing the first nodes; always view the full first page
0
} else if current_focus > end_cushion_row {
// When scrolling up from the last rows; do nothing
first_visible_row
} else {
// When scrolling up the cushioned area without reaching the first nodes
current_focus . saturating_sub ( preview_cushion )
}
} else {
// If nothing matches; do nothing
first_visible_row
}
}
}
#[ derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize) ]
pub struct DirectoryBuffer {
pub parent : String ,
pub nodes : Vec < Node > ,
pub total : usize ,
pub focus : usize ,
pub scroll_state: ScrollStat e,
#[ serde(skip, default = " now " ) ]
pub explored_at : OffsetDateTime ,
}
impl DirectoryBuffer {
pub fn new ( parent : String , nodes : Vec < Node > , focus : usize ) -> Self {
pub fn new ( parent : String , nodes : Vec < Node > , current_ focus: usize ) -> Self {
let total = nodes . len ( ) ;
Self {
parent ,
nodes ,
total ,
focus ,
scroll_state : ScrollState {
current_focus ,
last_focus : None ,
skipped_rows : 0 ,
initial_preview_cushion : 5 ,
} ,
explored_at : now ( ) ,
}
}
pub fn focused_node ( & self ) -> Option < & Node > {
self . nodes . get ( self . focus )
self . nodes . get ( self . scroll_state. current_ focus)
}
}
@ -35,3 +127,112 @@ fn now() -> OffsetDateTime {
. ok ( )
. unwrap_or_else ( OffsetDateTime ::now_utc )
}
#[ cfg(test) ]
mod tests {
use super ::* ;
#[ test ]
fn test_calc_skipped_rows_non_vimlike_scrolling ( ) {
let state = ScrollState {
current_focus : 10 ,
last_focus : Some ( 8 ) ,
skipped_rows : 0 ,
initial_preview_cushion : 5 ,
} ;
let height = 5 ;
let total = 20 ;
let vimlike_scrolling = false ;
let result = state . calc_skipped_rows ( height , total , vimlike_scrolling ) ;
assert_eq! ( result , height * ( state . current_focus / height . max ( 1 ) ) ) ;
}
#[ test ]
fn test_calc_skipped_rows_entered_directory ( ) {
let state = ScrollState {
current_focus : 10 ,
last_focus : None ,
skipped_rows : 0 ,
initial_preview_cushion : 5 ,
} ;
let height = 5 ;
let total = 20 ;
let vimlike_scrolling = true ;
let result = state . calc_skipped_rows ( height , total , vimlike_scrolling ) ;
assert_eq! ( result , 0 ) ;
}
#[ test ]
fn test_calc_skipped_rows_top_of_directory ( ) {
let state = ScrollState {
current_focus : 0 ,
last_focus : Some ( 8 ) ,
skipped_rows : 5 ,
initial_preview_cushion : 5 ,
} ;
let height = 5 ;
let total = 20 ;
let vimlike_scrolling = true ;
let result = state . calc_skipped_rows ( height , total , vimlike_scrolling ) ;
assert_eq! ( result , 0 ) ;
}
#[ test ]
fn test_calc_skipped_rows_bottom_of_directory ( ) {
let state = ScrollState {
current_focus : 19 ,
last_focus : Some ( 18 ) ,
skipped_rows : 15 ,
initial_preview_cushion : 5 ,
} ;
let height = 5 ;
let total = 20 ;
let vimlike_scrolling = true ;
let result = state . calc_skipped_rows ( height , total , vimlike_scrolling ) ;
assert_eq! ( result , 15 ) ;
}
#[ test ]
fn test_calc_skipped_rows_scrolling_down ( ) {
let state = ScrollState {
current_focus : 12 ,
last_focus : Some ( 10 ) ,
skipped_rows : 10 ,
initial_preview_cushion : 5 ,
} ;
let height = 5 ;
let total = 20 ;
let vimlike_scrolling = true ;
let result = state . calc_skipped_rows ( height , total , vimlike_scrolling ) ;
assert_eq! ( result , 10 ) ;
}
#[ test ]
fn test_calc_skipped_rows_scrolling_up ( ) {
let state = ScrollState {
current_focus : 8 ,
last_focus : Some ( 10 ) ,
skipped_rows : 10 ,
initial_preview_cushion : 5 ,
} ;
let height = 5 ;
let total = 20 ;
let vimlike_scrolling = true ;
let result = state . calc_skipped_rows ( height , total , vimlike_scrolling ) ;
assert_eq! ( result , 7 ) ;
}
// Add more tests for other scenarios...
}
Arijit Basu
4 weeks ago
committed by
GitHub