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painter.rs
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painter.rs
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use crate::{CursorConfig, PromptEditMode, PromptViMode};
use {
super::utils::{coerce_crlf, line_width},
crate::{
menu::{Menu, ReedlineMenu},
painting::PromptLines,
Prompt,
},
crossterm::{
cursor::{self, MoveTo, RestorePosition, SavePosition},
style::{Attribute, Print, ResetColor, SetAttribute, SetForegroundColor},
terminal::{self, Clear, ClearType},
QueueableCommand,
},
std::io::{Result, Write},
};
#[cfg(feature = "external_printer")]
use {crate::LineBuffer, crossterm::cursor::MoveUp};
// Returns a string that skips N number of lines with the next offset of lines
// An offset of 0 would return only one line after skipping the required lines
fn skip_buffer_lines(string: &str, skip: usize, offset: Option<usize>) -> &str {
let mut matches = string.match_indices('\n');
let index = if skip == 0 {
0
} else {
matches
.clone()
.nth(skip - 1)
.map(|(index, _)| index + 1)
.unwrap_or(string.len())
};
let limit = match offset {
Some(offset) => {
let offset = skip + offset;
matches
.nth(offset)
.map(|(index, _)| index)
.unwrap_or(string.len())
}
None => string.len(),
};
string[index..limit].trim_end_matches('\n')
}
/// the type used by crossterm operations
pub type W = std::io::BufWriter<std::io::Stderr>;
/// Implementation of the output to the terminal
pub struct Painter {
// Stdout
stdout: W,
prompt_start_row: u16,
terminal_size: (u16, u16),
last_required_lines: u16,
large_buffer: bool,
}
impl Painter {
pub(crate) fn new(stdout: W) -> Self {
Painter {
stdout,
prompt_start_row: 0,
terminal_size: (0, 0),
last_required_lines: 0,
large_buffer: false,
}
}
/// Height of the current terminal window
pub fn screen_height(&self) -> u16 {
self.terminal_size.1
}
/// Width of the current terminal window
pub fn screen_width(&self) -> u16 {
self.terminal_size.0
}
/// Returns the available lines from the prompt down
pub fn remaining_lines(&self) -> u16 {
self.screen_height() - self.prompt_start_row
}
/// Sets the prompt origin position and screen size for a new line editor
/// invocation
///
/// Not to be used for resizes during a running line editor, use
/// [`Painter::handle_resize()`] instead
pub(crate) fn initialize_prompt_position(&mut self) -> Result<()> {
// Update the terminal size
self.terminal_size = {
let size = terminal::size()?;
// if reported size is 0, 0 -
// use a default size to avoid divide by 0 panics
if size == (0, 0) {
(80, 24)
} else {
size
}
};
// Cursor positions are 0 based here.
let (column, row) = cursor::position()?;
// Assumption: if the cursor is not on the zeroth column,
// there is content we want to leave intact, thus advance to the next row
let new_row = if column > 0 { row + 1 } else { row };
// If we are on the last line and would move beyond the last line due to
// the condition above, we need to make room for the prompt.
// Otherwise printing the prompt would scroll of the stored prompt
// origin, causing issues after repaints.
let new_row = if new_row == self.screen_height() {
self.print_crlf()?;
new_row.saturating_sub(1)
} else {
new_row
};
self.prompt_start_row = new_row;
Ok(())
}
/// Main pain painter for the prompt and buffer
/// It queues all the actions required to print the prompt together with
/// lines that make the buffer.
/// Using the prompt lines object in this function it is estimated how the
/// prompt should scroll up and how much space is required to print all the
/// lines for the buffer
///
/// Note. The `ScrollUp` operation in `crossterm` deletes lines from the top of
/// the screen.
pub(crate) fn repaint_buffer(
&mut self,
prompt: &dyn Prompt,
lines: &PromptLines,
prompt_mode: PromptEditMode,
menu: Option<&ReedlineMenu>,
use_ansi_coloring: bool,
cursor_config: &Option<CursorConfig>,
) -> Result<()> {
self.stdout.queue(cursor::Hide)?;
let screen_width = self.screen_width();
let screen_height = self.screen_height();
// Lines and distance parameters
let remaining_lines = self.remaining_lines();
let required_lines = lines.required_lines(screen_width, menu);
// Marking the painter state as larger buffer to avoid animations
self.large_buffer = required_lines >= screen_height;
// Moving the start position of the cursor based on the size of the required lines
if self.large_buffer {
self.prompt_start_row = 0;
} else if required_lines >= remaining_lines {
let extra = required_lines.saturating_sub(remaining_lines);
self.queue_universal_scroll(extra)?;
self.prompt_start_row = self.prompt_start_row.saturating_sub(extra);
}
// Moving the cursor to the start of the prompt
// from this position everything will be printed
self.stdout
.queue(cursor::MoveTo(0, self.prompt_start_row))?
.queue(Clear(ClearType::FromCursorDown))?;
if self.large_buffer {
self.print_large_buffer(prompt, lines, menu, use_ansi_coloring)?;
} else {
self.print_small_buffer(prompt, lines, menu, use_ansi_coloring)?;
}
// The last_required_lines is used to move the cursor at the end where stdout
// can print without overwriting the things written during the painting
self.last_required_lines = required_lines;
self.stdout.queue(RestorePosition)?;
if let Some(shapes) = cursor_config {
let shape = match &prompt_mode {
PromptEditMode::Emacs => shapes.emacs,
PromptEditMode::Vi(PromptViMode::Insert) => shapes.vi_insert,
PromptEditMode::Vi(PromptViMode::Normal) => shapes.vi_normal,
_ => None,
};
if let Some(shape) = shape {
self.stdout.queue(shape)?;
}
}
self.stdout.queue(cursor::Show)?;
self.stdout.flush()
}
fn print_right_prompt(&mut self, lines: &PromptLines) -> Result<()> {
let prompt_length_right = line_width(&lines.prompt_str_right);
let start_position = self
.screen_width()
.saturating_sub(prompt_length_right as u16);
let screen_width = self.screen_width();
let input_width = lines.estimate_right_prompt_line_width(screen_width);
let mut row = self.prompt_start_row;
if lines.right_prompt_on_last_line {
row += lines.prompt_lines_with_wrap(screen_width);
}
if input_width <= start_position {
self.stdout
.queue(SavePosition)?
.queue(cursor::MoveTo(start_position, row))?
.queue(Print(&coerce_crlf(&lines.prompt_str_right)))?
.queue(RestorePosition)?;
}
Ok(())
}
fn print_menu(
&mut self,
menu: &dyn Menu,
lines: &PromptLines,
use_ansi_coloring: bool,
) -> Result<()> {
let screen_width = self.screen_width();
let screen_height = self.screen_height();
let cursor_distance = lines.distance_from_prompt(screen_width);
// If there is not enough space to print the menu, then the starting
// drawing point for the menu will overwrite the last rows in the buffer
let starting_row = if cursor_distance >= screen_height.saturating_sub(1) {
screen_height.saturating_sub(menu.min_rows())
} else {
self.prompt_start_row + cursor_distance + 1
};
let remaining_lines = screen_height.saturating_sub(starting_row);
let menu_string = menu.menu_string(remaining_lines, use_ansi_coloring);
self.stdout
.queue(cursor::MoveTo(0, starting_row))?
.queue(Clear(ClearType::FromCursorDown))?
.queue(Print(menu_string.trim_end_matches('\n')))?;
Ok(())
}
fn print_small_buffer(
&mut self,
prompt: &dyn Prompt,
lines: &PromptLines,
menu: Option<&ReedlineMenu>,
use_ansi_coloring: bool,
) -> Result<()> {
// print our prompt with color
if use_ansi_coloring {
self.stdout
.queue(SetForegroundColor(prompt.get_prompt_color()))?;
}
self.stdout
.queue(Print(&coerce_crlf(&lines.prompt_str_left)))?;
let prompt_indicator = match menu {
Some(menu) => menu.indicator(),
None => &lines.prompt_indicator,
};
if use_ansi_coloring {
self.stdout
.queue(SetForegroundColor(prompt.get_indicator_color()))?;
}
self.stdout.queue(Print(&coerce_crlf(prompt_indicator)))?;
if use_ansi_coloring {
self.stdout
.queue(SetForegroundColor(prompt.get_prompt_right_color()))?;
}
self.print_right_prompt(lines)?;
if use_ansi_coloring {
self.stdout
.queue(SetAttribute(Attribute::Reset))?
.queue(ResetColor)?;
}
self.stdout
.queue(Print(&lines.before_cursor))?
.queue(SavePosition)?
.queue(Print(&lines.after_cursor))?;
if let Some(menu) = menu {
self.print_menu(menu, lines, use_ansi_coloring)?;
} else {
self.stdout.queue(Print(&lines.hint))?;
}
Ok(())
}
fn print_large_buffer(
&mut self,
prompt: &dyn Prompt,
lines: &PromptLines,
menu: Option<&ReedlineMenu>,
use_ansi_coloring: bool,
) -> Result<()> {
let screen_width = self.screen_width();
let screen_height = self.screen_height();
let cursor_distance = lines.distance_from_prompt(screen_width);
let remaining_lines = screen_height.saturating_sub(cursor_distance);
// Calculating the total lines before the cursor
// The -1 in the total_lines_before is there because the at least one line of the prompt
// indicator is printed in the same line as the first line of the buffer
let prompt_lines = lines.prompt_lines_with_wrap(screen_width) as usize;
let prompt_indicator = match menu {
Some(menu) => menu.indicator(),
None => &lines.prompt_indicator,
};
let prompt_indicator_lines = prompt_indicator.lines().count();
let before_cursor_lines = lines.before_cursor.lines().count();
let total_lines_before = prompt_lines + prompt_indicator_lines + before_cursor_lines - 1;
// Extra rows represent how many rows are "above" the visible area in the terminal
let extra_rows = (total_lines_before).saturating_sub(screen_height as usize);
// print our prompt with color
if use_ansi_coloring {
self.stdout
.queue(SetForegroundColor(prompt.get_prompt_color()))?;
}
// In case the prompt is made out of multiple lines, the prompt is split by
// lines and only the required ones are printed
let prompt_skipped = skip_buffer_lines(&lines.prompt_str_left, extra_rows, None);
self.stdout.queue(Print(&coerce_crlf(prompt_skipped)))?;
if extra_rows == 0 {
self.print_right_prompt(lines)?;
}
// Adjusting extra_rows base on the calculated prompt line size
let extra_rows = extra_rows.saturating_sub(prompt_lines);
let indicator_skipped = skip_buffer_lines(prompt_indicator, extra_rows, None);
self.stdout.queue(Print(&coerce_crlf(indicator_skipped)))?;
if use_ansi_coloring {
self.stdout.queue(ResetColor)?;
}
// The minimum number of lines from the menu are removed from the buffer if there is no more
// space to print the menu. This will only happen if the cursor is at the last line and
// it is a large buffer
let offset = menu.and_then(|menu| {
if cursor_distance >= screen_height.saturating_sub(1) {
let rows = lines
.before_cursor
.lines()
.count()
.saturating_sub(extra_rows)
.saturating_sub(menu.min_rows() as usize);
Some(rows)
} else {
None
}
});
// Selecting the lines before the cursor that will be printed
let before_cursor_skipped = skip_buffer_lines(&lines.before_cursor, extra_rows, offset);
self.stdout.queue(Print(before_cursor_skipped))?;
self.stdout.queue(SavePosition)?;
if let Some(menu) = menu {
// TODO: Also solve the difficult problem of displaying (parts of)
// the content after the cursor with the completion menu
self.print_menu(menu, lines, use_ansi_coloring)?;
} else {
// Selecting lines for the hint
// The -1 subtraction is done because the remaining lines consider the line where the
// cursor is located as a remaining line. That has to be removed to get the correct offset
// for the after-cursor and hint lines
let offset = remaining_lines.saturating_sub(1) as usize;
// Selecting lines after the cursor
let after_cursor_skipped = skip_buffer_lines(&lines.after_cursor, 0, Some(offset));
self.stdout.queue(Print(after_cursor_skipped))?;
// Hint lines
let hint_skipped = skip_buffer_lines(&lines.hint, 0, Some(offset));
self.stdout.queue(Print(hint_skipped))?;
}
Ok(())
}
/// Updates prompt origin and offset to handle a screen resize event
pub(crate) fn handle_resize(&mut self, width: u16, height: u16) {
let prev_terminal_size = self.terminal_size;
let prev_prompt_row = self.prompt_start_row;
self.terminal_size = (width, height);
if prev_prompt_row < height
&& height <= prev_terminal_size.1
&& width == prev_terminal_size.0
{
// The terminal got smaller in height but the start of the prompt is still visible
// The width didn't change
return;
}
// Either:
// - The terminal got larger in height
// - Note: if the terminal doesn't have sufficient history, this will leave a trail
// of previous prompts currently.
// - Note: if the the prompt contains multiple lines, this will leave a trail of
// previous prompts currently.
// - The terminal got smaller in height and the whole prompt is no longer visible
// - Note: if the the prompt contains multiple lines, this will leave a trail of
// previous prompts currently.
// - The width changed
self.prompt_start_row = height.saturating_sub(1);
}
/// Writes `line` to the terminal with a following carriage return and newline
pub(crate) fn paint_line(&mut self, line: &str) -> Result<()> {
self.stdout.queue(Print(line))?.queue(Print("\r\n"))?;
self.stdout.flush()
}
/// Goes to the beginning of the next line
///
/// Also works in raw mode
pub(crate) fn print_crlf(&mut self) -> Result<()> {
self.stdout.queue(Print("\r\n"))?;
self.stdout.flush()
}
/// Clear the screen by printing enough whitespace to start the prompt or
/// other output back at the first line of the terminal.
pub(crate) fn clear_screen(&mut self) -> Result<()> {
self.stdout.queue(cursor::Hide)?;
let (_, num_lines) = terminal::size()?;
for _ in 0..2 * num_lines {
self.stdout.queue(Print("\n"))?;
}
self.stdout.queue(MoveTo(0, 0))?;
self.stdout.queue(cursor::Show)?;
self.stdout.flush()?;
self.initialize_prompt_position()
}
pub(crate) fn clear_scrollback(&mut self) -> Result<()> {
self.stdout
.queue(crossterm::terminal::Clear(ClearType::All))?
.queue(crossterm::terminal::Clear(ClearType::Purge))?
.queue(cursor::MoveTo(0, 0))?
.flush()?;
self.initialize_prompt_position()
}
// The prompt is moved to the end of the buffer after the event was handled
// If the prompt is in the middle of a multiline buffer, then the output to stdout
// could overwrite the buffer writing
pub(crate) fn move_cursor_to_end(&mut self) -> Result<()> {
let final_row = self.prompt_start_row + self.last_required_lines;
let scroll = final_row.saturating_sub(self.screen_height() - 1);
if scroll != 0 {
self.queue_universal_scroll(scroll)?;
}
self.stdout
.queue(MoveTo(0, final_row.min(self.screen_height() - 1)))?;
self.stdout.flush()
}
/// Prints an external message
///
/// This function doesn't flush the buffer. So buffer should be flushed
/// afterwards perhaps by repainting the prompt via `repaint_buffer()`.
#[cfg(feature = "external_printer")]
pub(crate) fn print_external_message(
&mut self,
messages: Vec<String>,
line_buffer: &LineBuffer,
prompt: &dyn Prompt,
) -> Result<()> {
// adding 3 seems to be right for first line-wrap
let prompt_len = prompt.render_prompt_right().len() + 3;
let mut buffer_num_lines = 0_u16;
for (i, line) in line_buffer.get_buffer().lines().enumerate() {
let screen_lines = match i {
0 => {
// the first line has to deal with the prompt
let first_line_len = line.len() + prompt_len;
// at least, it is one line
((first_line_len as u16) / (self.screen_width())) + 1
}
_ => {
// the n-th line, no prompt, at least, it is one line
((line.len() as u16) / self.screen_width()) + 1
}
};
// count up screen-lines
buffer_num_lines = buffer_num_lines.saturating_add(screen_lines);
}
// move upward to start print if the line-buffer is more than one screen-line
if buffer_num_lines > 1 {
self.stdout.queue(MoveUp(buffer_num_lines - 1))?;
}
let erase_line = format!("\r{}\r", " ".repeat(self.screen_width().into()));
for line in messages {
self.stdout.queue(Print(&erase_line))?;
// Note: we don't use `print_line` here because we don't want to
// flush right now. The subsequent repaint of the prompt will cause
// immediate flush anyways. And if we flush here, every external
// print causes visible flicker.
self.stdout.queue(Print(line))?.queue(Print("\r\n"))?;
let new_start = self.prompt_start_row.saturating_add(1);
let height = self.screen_height();
if new_start >= height {
self.prompt_start_row = height - 1;
} else {
self.prompt_start_row = new_start;
}
}
Ok(())
}
/// Queue scroll of `num` lines to `self.stdout`.
///
/// On some platforms and terminals (e.g. windows terminal, alacritty on windows and linux)
/// using special escape sequence '\[e<num>S' (provided by [`ScrollUp`]) does not put lines
/// that go offscreen in scrollback history. This method prints newlines near the edge of screen
/// (which always works) instead. See [here](https://github.com/nushell/nushell/issues/9166)
/// for more info on subject.
///
/// ## Note
/// This method does not return cursor to the original position and leaves it at the first
/// column of last line. **Be sure to use [`MoveTo`] afterwards if this is not the desired
/// location**
fn queue_universal_scroll(&mut self, num: u16) -> Result<()> {
// If cursor is not near end of screen printing new will not scroll terminal.
// Move it to the last line to ensure that every newline results in scroll
self.stdout.queue(MoveTo(0, self.screen_height() - 1))?;
for _ in 0..num {
self.stdout.queue(Print(&coerce_crlf("\n")))?;
}
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use pretty_assertions::assert_eq;
#[test]
fn test_skip_lines() {
let string = "sentence1\nsentence2\nsentence3\n";
assert_eq!(skip_buffer_lines(string, 1, None), "sentence2\nsentence3");
assert_eq!(skip_buffer_lines(string, 2, None), "sentence3");
assert_eq!(skip_buffer_lines(string, 3, None), "");
assert_eq!(skip_buffer_lines(string, 4, None), "");
}
#[test]
fn test_skip_lines_no_newline() {
let string = "sentence1";
assert_eq!(skip_buffer_lines(string, 0, None), "sentence1");
assert_eq!(skip_buffer_lines(string, 1, None), "");
}
#[test]
fn test_skip_lines_with_limit() {
let string = "sentence1\nsentence2\nsentence3\nsentence4\nsentence5";
assert_eq!(
skip_buffer_lines(string, 1, Some(1)),
"sentence2\nsentence3",
);
assert_eq!(
skip_buffer_lines(string, 1, Some(2)),
"sentence2\nsentence3\nsentence4",
);
assert_eq!(
skip_buffer_lines(string, 2, Some(1)),
"sentence3\nsentence4",
);
assert_eq!(
skip_buffer_lines(string, 1, Some(10)),
"sentence2\nsentence3\nsentence4\nsentence5",
);
assert_eq!(
skip_buffer_lines(string, 0, Some(1)),
"sentence1\nsentence2",
);
assert_eq!(skip_buffer_lines(string, 0, Some(0)), "sentence1",);
assert_eq!(skip_buffer_lines(string, 1, Some(0)), "sentence2",);
}
}