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fix(terminal): insert_before() now accepts lines > terminal height an…
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…d doesn't add an extra blank line (#596)

Fixes issue with inserting content with height>viewport_area.height and adds
the ability to insert content of height>terminal_height

- Adds TestBackend::append_lines() and TestBackend::clear_region() methods to
  support testing the changes
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@danny-burrows
danny-burrows committed Nov 8, 2023
1 parent 59b9c32 commit df0eb1f
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Showing 4 changed files with 538 additions and 29 deletions.
2 changes: 1 addition & 1 deletion src/backend.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -228,7 +228,7 @@ pub trait Backend {
/// [`get_cursor`]: Backend::get_cursor
fn set_cursor(&mut self, x: u16, y: u16) -> io::Result<()>;

/// Clears the whole terminal scree
/// Clears the whole terminal screen
///
/// # Example
///
Expand Down
357 changes: 354 additions & 3 deletions src/backend/test.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use std::{
use unicode_width::UnicodeWidthStr;

use crate::{
backend::{Backend, WindowSize},
backend::{Backend, ClearType, WindowSize},
buffer::{Buffer, Cell},
layout::{Rect, Size},
};
Expand Down Expand Up @@ -179,6 +179,71 @@ impl Backend for TestBackend {
Ok(())
}

fn clear_region(&mut self, clear_type: super::ClearType) -> io::Result<()> {
match clear_type {
ClearType::All => self.clear()?,
ClearType::AfterCursor => {
let index = self.buffer.index_of(self.pos.0, self.pos.1) + 1;
self.buffer.content[index..].fill(Cell::default());
}
ClearType::BeforeCursor => {
let index = self.buffer.index_of(self.pos.0, self.pos.1);
self.buffer.content[..index].fill(Cell::default());
}
ClearType::CurrentLine => {
let line_start_index = self.buffer.index_of(0, self.pos.1);
let line_end_index = self.buffer.index_of(self.width - 1, self.pos.1);
self.buffer.content[line_start_index..=line_end_index].fill(Cell::default());
}
ClearType::UntilNewLine => {
let index = self.buffer.index_of(self.pos.0, self.pos.1);
let line_end_index = self.buffer.index_of(self.width - 1, self.pos.1);
self.buffer.content[index..=line_end_index].fill(Cell::default());
}
}
Ok(())
}

/// Inserts n line breaks at the current cursor position.
///
/// After the insertion, the cursor x position will be incremented by 1 (unless it's already
/// at the end of line). This is a common behaviour of terminals in raw mode.
///
/// If the number of lines to append is fewer than the number of lines in the buffer after the
/// cursor y position then the cursor is moved down by n rows.
///
/// If the number of lines to append is greater than the number of lines in the buffer after
/// the cursor y position then that number of empty lines (at most the buffer's height in this
/// case but this limit is instead replaced with scrolling in most backend implementations) will
/// be added after the current position and the cursor will be moved to the last row.
fn append_lines(&mut self, n: u16) -> io::Result<()> {
let (cur_x, cur_y) = self.get_cursor()?;

// the next column ensuring that we don't go past the last column
let new_cursor_x = cur_x.saturating_add(1).min(self.width.saturating_sub(1));

let max_y = self.height.saturating_sub(1);
let lines_after_cursor = max_y.saturating_sub(cur_y);
if n > lines_after_cursor {
let rotate_by = n.saturating_sub(lines_after_cursor).min(max_y);

if rotate_by == self.height - 1 {
self.clear()?;
}

self.set_cursor(0, rotate_by)?;
self.clear_region(ClearType::BeforeCursor)?;
self.buffer
.content
.rotate_left((self.width * rotate_by).into());
}

let new_cursor_y = cur_y.saturating_add(n).min(max_y);
self.set_cursor(new_cursor_x, new_cursor_y)?;

Ok(())
}

fn size(&self) -> Result<Rect, io::Error> {
Ok(Rect::new(0, 0, self.width, self.height))
}
Expand Down Expand Up @@ -310,13 +375,299 @@ mod tests {

#[test]
fn clear() {
let mut backend = TestBackend::new(10, 2);
let mut backend = TestBackend::new(10, 4);
let mut cell = Cell::default();
cell.set_symbol("a");
backend.draw([(0, 0, &cell)].into_iter()).unwrap();
backend.draw([(0, 1, &cell)].into_iter()).unwrap();
backend.clear().unwrap();
backend.assert_buffer(&Buffer::with_lines(vec![" "; 2]));
backend.assert_buffer(&Buffer::with_lines(vec![
" ",
" ",
" ",
" ",
]));
}

#[test]
fn clear_region_all() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]);

backend.clear_region(ClearType::All).unwrap();
backend.assert_buffer(&Buffer::with_lines(vec![
" ",
" ",
" ",
" ",
" ",
]));
}

#[test]
fn clear_region_after_cursor() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]);

backend.set_cursor(3, 2).unwrap();
backend.clear_region(ClearType::AfterCursor).unwrap();
backend.assert_buffer(&Buffer::with_lines(vec![
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaa ",
" ",
" ",
]));
}

#[test]
fn clear_region_before_cursor() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]);

backend.set_cursor(5, 3).unwrap();
backend.clear_region(ClearType::BeforeCursor).unwrap();
backend.assert_buffer(&Buffer::with_lines(vec![
" ",
" ",
" ",
" aaaaa",
"aaaaaaaaaa",
]));
}

#[test]
fn clear_region_current_line() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]);

backend.set_cursor(3, 1).unwrap();
backend.clear_region(ClearType::CurrentLine).unwrap();
backend.assert_buffer(&Buffer::with_lines(vec![
"aaaaaaaaaa",
" ",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]));
}

#[test]
fn clear_region_until_new_line() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]);

backend.set_cursor(3, 0).unwrap();
backend.clear_region(ClearType::UntilNewLine).unwrap();
backend.assert_buffer(&Buffer::with_lines(vec![
"aaa ",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
"aaaaaaaaaa",
]));
}

#[test]
fn append_lines_not_at_last_line() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]);

backend.set_cursor(0, 0).unwrap();

// If the cursor is not at the last line in the terminal the addition of a
// newline simply moves the cursor down and to the right

backend.append_lines(1).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (1, 1));

backend.append_lines(1).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (2, 2));

backend.append_lines(1).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (3, 3));

backend.append_lines(1).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (4, 4));

// As such the buffer should remain unchanged
backend.assert_buffer(&Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]));
}

#[test]
fn append_lines_at_last_line() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]);

// If the cursor is at the last line in the terminal the addition of a
// newline will scroll the contents of the buffer
backend.set_cursor(0, 4).unwrap();

backend.append_lines(1).unwrap();

backend.buffer = Buffer::with_lines(vec![
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
" ",
]);

// It also moves the cursor to the right, as is common of the behaviour of
// terminals in raw-mode
assert_eq!(backend.get_cursor().unwrap(), (1, 4));
}

#[test]
fn append_multiple_lines_not_at_last_line() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]);

backend.set_cursor(0, 0).unwrap();

// If the cursor is not at the last line in the terminal the addition of multiple
// newlines simply moves the cursor n lines down and to the right by 1

backend.append_lines(4).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (1, 4));

// As such the buffer should remain unchanged
backend.assert_buffer(&Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]));
}

#[test]
fn append_multiple_lines_past_last_line() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]);

backend.set_cursor(0, 3).unwrap();

backend.append_lines(3).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (1, 4));

backend.assert_buffer(&Buffer::with_lines(vec![
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
" ",
" ",
]));
}

#[test]
fn append_multiple_lines_where_cursor_at_end_appends_height_lines() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]);

backend.set_cursor(0, 4).unwrap();

backend.append_lines(5).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (1, 4));

backend.assert_buffer(&Buffer::with_lines(vec![
" ",
" ",
" ",
" ",
" ",
]));
}

#[test]
fn append_multiple_lines_where_cursor_appends_height_lines() {
let mut backend = TestBackend::new(10, 5);
backend.buffer = Buffer::with_lines(vec![
"aaaaaaaaaa",
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
]);

backend.set_cursor(0, 0).unwrap();

backend.append_lines(5).unwrap();
assert_eq!(backend.get_cursor().unwrap(), (1, 4));

backend.assert_buffer(&Buffer::with_lines(vec![
"bbbbbbbbbb",
"cccccccccc",
"dddddddddd",
"eeeeeeeeee",
" ",
]));
}

#[test]
Expand Down

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