fix: unicode truncation bug (#1089)

- Rewrote the line / span rendering code to take into account how
multi-byte / wide emoji characters are truncated when rendering into
areas that cannot accommodate them in the available space
- Added comprehensive coverage over the edge cases
- Adds a benchmark to ensure perf

Fixes: #1032
Co-authored-by: EdJoPaTo <rfc-conform-git-commit-email@funny-long-domain-label-everyone-hates-as-it-is-too-long.edjopato.de>
Co-authored-by: EdJoPaTo <[email protected]>

Cargo.toml

@@ -25,24 +25,24 @@ rust-version = "1.74.0"
 [badges]
 
 [dependencies]
-crossterm = { version = "0.27", optional = true }
-termion = { version = "3.0", optional = true }
-termwiz = { version = "0.22.0", optional = true }
-
-serde = { version = "1", optional = true, features = ["derive"] }
 bitflags = "2.3"
 cassowary = "0.3"
+compact_str = "0.7.1"
+crossterm = { version = "0.27", optional = true }
+document-features = { version = "0.2.7", optional = true }
 indoc = "2.0"
 itertools = "0.12"
+lru = "0.12.0"
 paste = "1.0.2"
+serde = { version = "1", optional = true, features = ["derive"] }
+stability = "0.2.0"
 strum = { version = "0.26", features = ["derive"] }
 time = { version = "0.3.11", optional = true, features = ["local-offset"] }
+termion = { version = "3.0", optional = true }
+termwiz = { version = "0.22.0", optional = true }
 unicode-segmentation = "1.10"
+unicode-truncate = "1"
 unicode-width = "0.1"
-document-features = { version = "0.2.7", optional = true }
-lru = "0.12.0"
-stability = "0.2.0"
-compact_str = "0.7.1"
 
 [dev-dependencies]
 anyhow = "1.0.71"
@@ -163,6 +163,10 @@ harness = false
 name = "block"
 harness = false
 
+[[bench]]
+name = "line"
+harness = false
+
 [[bench]]
 name = "list"
 harness = false

benches/line.rs

@@ -0,0 +1,39 @@
+use std::hint::black_box;
+
+use criterion::{criterion_group, criterion_main, Criterion};
+use ratatui::{
+ buffer::Buffer,
+ layout::{Alignment, Rect},
+ style::Stylize,
+ text::Line,
+ widgets::Widget,
+};
+
+fn line_render(criterion: &mut Criterion) {
+ for alignment in [Alignment::Left, Alignment::Center, Alignment::Right] {
+ let mut group = criterion.benchmark_group(format!("line_render/{alignment}"));
+ group.sample_size(1000);
+
+ let line = &Line::from(vec![
+ "This".red(),
+ " ".green(),
+ "is".italic(),
+ " ".blue(),
+ "SPARTA!!".bold(),
+ ])
+ .alignment(alignment);
+
+ for width in [0, 3, 4, 6, 7, 10, 42] {
+ let area = Rect::new(0, 0, width, 1);
+
+ group.bench_function(width.to_string(), |bencher| {
+ let mut buffer = Buffer::empty(area);
+ bencher.iter(|| black_box(line).render(area, &mut buffer));
+ });
+ }
+ group.finish();
+ }
+}
+
+criterion_group!(benches, line_render);
+criterion_main!(benches);

src/layout/rect.rs

@@ -321,6 +321,18 @@ impl Rect {
  height: self.height,
  }
  }
+
+ /// indents the x value of the `Rect` by a given `offset`
+ ///
+ /// This is pub(crate) for now as we need to stabilize the naming / design of this API.
+ #[must_use]
+ pub(crate) const fn indent_x(self, offset: u16) -> Self {
+ Self {
+ x: self.x.saturating_add(offset),
+ width: self.width.saturating_sub(offset),
+ ..self
+ }
+ }
 }
 
 impl From<(Position, Size)> for Rect {