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Separate the scroll state

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This commit is contained in:
mo8it 2024-08-27 00:03:50 +02:00
parent 0f71a150ff
commit dd52e9cd72
3 changed files with 135 additions and 74 deletions
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1
src/list.rs
View file

@ -16,6 +16,7 @@ use crate::app_state::AppState;
use self::state::{Filter, ListState};
mod scroll_state;
mod state;
fn handle_list(app_state: &mut AppState, stdout: &mut StdoutLock) -> Result<()> {

104
src/list/scroll_state.rs Normal file
View file

@ -0,0 +1,104 @@
pub struct ScrollState {
n_rows: usize,
max_n_rows_to_display: usize,
selected: Option<usize>,
offset: usize,
scroll_padding: usize,
max_scroll_padding: usize,
}
impl ScrollState {
pub fn new(n_rows: usize, selected: Option<usize>, max_scroll_padding: usize) -> Self {
Self {
n_rows,
max_n_rows_to_display: 0,
selected,
offset: selected.map_or(0, |selected| selected.saturating_sub(max_scroll_padding)),
scroll_padding: 0,
max_scroll_padding,
}
}
#[inline]
pub fn offset(&self) -> usize {
self.offset
}
fn update_offset(&mut self) {
let Some(selected) = self.selected else {
return;
};
let min_offset = (selected + self.scroll_padding)
.saturating_sub(self.max_n_rows_to_display.saturating_sub(1));
let max_offset = selected.saturating_sub(self.scroll_padding);
let global_max_offset = self.n_rows.saturating_sub(self.max_n_rows_to_display);
self.offset = self
.offset
.max(min_offset)
.min(max_offset)
.min(global_max_offset);
}
#[inline]
pub fn selected(&self) -> Option<usize> {
self.selected
}
fn set_selected(&mut self, selected: usize) {
self.selected = Some(selected);
self.update_offset();
}
pub fn select_next(&mut self) {
if let Some(selected) = self.selected {
self.set_selected((selected + 1).min(self.n_rows - 1));
}
}
pub fn select_previous(&mut self) {
if let Some(selected) = self.selected {
self.set_selected(selected.saturating_sub(1));
}
}
pub fn select_first(&mut self) {
if self.n_rows > 0 {
self.set_selected(0);
}
}
pub fn select_last(&mut self) {
if self.n_rows > 0 {
self.set_selected(self.n_rows - 1);
}
}
pub fn set_n_rows(&mut self, n_rows: usize) {
self.n_rows = n_rows;
if self.n_rows == 0 {
self.selected = None;
return;
}
self.set_selected(self.selected.map_or(0, |selected| selected.min(n_rows - 1)));
}
#[inline]
fn update_scroll_padding(&mut self) {
self.scroll_padding = (self.max_n_rows_to_display / 4).min(self.max_scroll_padding);
}
#[inline]
pub fn max_n_rows_to_display(&self) -> usize {
self.max_n_rows_to_display
}
pub fn set_max_n_rows_to_display(&mut self, max_n_rows_to_display: usize) {
self.max_n_rows_to_display = max_n_rows_to_display;
self.update_scroll_padding();
self.update_offset();
}
}

104
src/list/state.rs
View file

@ -17,7 +17,8 @@ use crate::{
MAX_EXERCISE_NAME_LEN,
};
const MAX_SCROLL_PADDING: usize = 5;
use super::scroll_state::ScrollState;
// +1 for column padding.
const SPACE: &[u8] = &[b' '; MAX_EXERCISE_NAME_LEN + 1];
@ -39,19 +40,14 @@ pub struct ListState<'a> {
/// Footer message to be displayed if not empty.
pub message: String,
app_state: &'a mut AppState,
scroll_state: ScrollState,
name_col_width: usize,
filter: Filter,
n_rows_with_filter: usize,
/// Selected row out of the filtered ones.
selected_row: Option<usize>,
row_offset: usize,
term_width: u16,
term_height: u16,
separator_line: Vec<u8>,
narrow_term: bool,
show_footer: bool,
max_n_rows_to_display: usize,
scroll_padding: usize,
}
impl<'a> ListState<'a> {
@ -70,50 +66,29 @@ impl<'a> ListState<'a> {
let n_rows_with_filter = app_state.exercises().len();
let selected = app_state.current_exercise_ind();
let (width, height) = terminal::size()?;
let scroll_state = ScrollState::new(n_rows_with_filter, Some(selected), 5);
let mut slf = Self {
message: String::with_capacity(128),
app_state,
scroll_state,
name_col_width,
filter,
n_rows_with_filter,
selected_row: Some(selected),
row_offset: selected.saturating_sub(MAX_SCROLL_PADDING),
// Set by `set_term_size`
term_width: 0,
term_height: 0,
separator_line: Vec::new(),
narrow_term: false,
show_footer: true,
max_n_rows_to_display: 0,
scroll_padding: 0,
};
let (width, height) = terminal::size()?;
slf.set_term_size(width, height);
slf.draw(stdout)?;
Ok(slf)
}
fn update_offset(&mut self) {
let Some(selected) = self.selected_row else {
return;
};
let min_offset = (selected + self.scroll_padding)
.saturating_sub(self.max_n_rows_to_display.saturating_sub(1));
let max_offset = selected.saturating_sub(self.scroll_padding);
let global_max_offset = self
.n_rows_with_filter
.saturating_sub(self.max_n_rows_to_display);
self.row_offset = self
.row_offset
.max(min_offset)
.min(max_offset)
.min(global_max_offset);
}
pub fn set_term_size(&mut self, width: u16, height: u16) {
self.term_width = width;
self.term_height = height;
@ -124,7 +99,7 @@ impl<'a> ListState<'a> {
let wide_help_footer_width = 95;
// The help footer is shorter when nothing is selected.
self.narrow_term = width < wide_help_footer_width && self.selected_row.is_some();
self.narrow_term = width < wide_help_footer_width && self.scroll_state.selected().is_some();
let header_height = 1;
// 2 separator, 1 progress bar, 1-2 footer message.
@ -135,13 +110,10 @@ impl<'a> ListState<'a> {
self.separator_line = "─".as_bytes().repeat(width as usize);
}
self.max_n_rows_to_display = height
.saturating_sub(header_height + u16::from(self.show_footer) * footer_height)
as usize;
self.scroll_padding = (self.max_n_rows_to_display / 4).min(MAX_SCROLL_PADDING);
self.update_offset();
self.scroll_state.set_max_n_rows_to_display(
height.saturating_sub(header_height + u16::from(self.show_footer) * footer_height)
as usize,
);
}
fn draw_rows(
@ -150,15 +122,16 @@ impl<'a> ListState<'a> {
filtered_exercises: impl Iterator<Item = (usize, &'a Exercise)>,
) -> io::Result<usize> {
let current_exercise_ind = self.app_state.current_exercise_ind();
let row_offset = self.scroll_state.offset();
let mut n_displayed_rows = 0;
for (exercise_ind, exercise) in filtered_exercises
.skip(self.row_offset)
.take(self.max_n_rows_to_display)
.skip(row_offset)
.take(self.scroll_state.max_n_rows_to_display())
{
let mut writer = MaxLenWriter::new(stdout, self.term_width as usize);
if self.selected_row == Some(self.row_offset + n_displayed_rows) {
if self.scroll_state.selected() == Some(row_offset + n_displayed_rows) {
writer.stdout.queue(SetBackgroundColor(Color::Rgb {
r: 40,
g: 40,
@ -225,7 +198,7 @@ impl<'a> ListState<'a> {
Filter::None => self.draw_rows(stdout, iter)?,
};
for _ in 0..self.max_n_rows_to_display - n_displayed_rows {
for _ in 0..self.scroll_state.max_n_rows_to_display() - n_displayed_rows {
next_ln(stdout)?;
}
@ -247,7 +220,7 @@ impl<'a> ListState<'a> {
let mut writer = MaxLenWriter::new(stdout, self.term_width as usize);
if self.message.is_empty() {
// Help footer message
if self.selected_row.is_some() {
if self.scroll_state.selected().is_some() {
writer.write_str("↓/j ↑/k home/g end/G | <c>ontinue at | <r>eset exercise")?;
if self.narrow_term {
next_ln(stdout)?;
@ -298,13 +271,8 @@ impl<'a> ListState<'a> {
stdout.queue(EndSynchronizedUpdate)?.flush()
}
fn set_selected(&mut self, selected: usize) {
self.selected_row = Some(selected);
self.update_offset();
}
fn update_rows(&mut self) {
self.n_rows_with_filter = match self.filter {
let n_rows = match self.filter {
Filter::Done => self
.app_state
.exercises()
@ -320,15 +288,7 @@ impl<'a> ListState<'a> {
Filter::None => self.app_state.exercises().len(),
};
if self.n_rows_with_filter == 0 {
self.selected_row = None;
return;
}
self.set_selected(
self.selected_row
.map_or(0, |selected| selected.min(self.n_rows_with_filter - 1)),
);
self.scroll_state.set_n_rows(n_rows);
}
#[inline]
@ -341,28 +301,24 @@ impl<'a> ListState<'a> {
self.update_rows();
}
#[inline]
pub fn select_next(&mut self) {
if let Some(selected) = self.selected_row {
self.set_selected((selected + 1).min(self.n_rows_with_filter - 1));
}
self.scroll_state.select_next();
}
#[inline]
pub fn select_previous(&mut self) {
if let Some(selected) = self.selected_row {
self.set_selected(selected.saturating_sub(1));
}
self.scroll_state.select_previous();
}
#[inline]
pub fn select_first(&mut self) {
if self.n_rows_with_filter > 0 {
self.set_selected(0);
}
self.scroll_state.select_first();
}
#[inline]
pub fn select_last(&mut self) {
if self.n_rows_with_filter > 0 {
self.set_selected(self.n_rows_with_filter - 1);
}
self.scroll_state.select_last();
}
fn selected_to_exercise_ind(&self, selected: usize) -> Result<usize> {
@ -390,7 +346,7 @@ impl<'a> ListState<'a> {
}
pub fn reset_selected(&mut self) -> Result<()> {
let Some(selected) = self.selected_row else {
let Some(selected) = self.scroll_state.selected() else {
self.message.push_str("Nothing selected to reset!");
return Ok(());
};
@ -408,7 +364,7 @@ impl<'a> ListState<'a> {
// Return `true` if there was something to select.
pub fn selected_to_current_exercise(&mut self) -> Result<bool> {
let Some(selected) = self.selected_row else {
let Some(selected) = self.scroll_state.selected() else {
self.message.push_str("Nothing selected to continue at!");
return Ok(false);
};