test(bench): add benchmark for text (#2160)

#2138

---------

Signed-off-by: Shingo OKAWA <shingo.okawa.g.h.c@gmail.com>
Co-authored-by: Shingo OKAWA <shingo.okawa.g.h.c@gmail.com>

ratatui/benches/main.rs

@@ -9,6 +9,7 @@ pub mod main {
     pub mod rect;
     pub mod sparkline;
     pub mod table;
+    pub mod text;
 }
 pub use main::*;
 
@@ -22,5 +23,6 @@ criterion::criterion_main!(
     rect::benches,
     sparkline::benches,
     table::benches,
+    text::benches,
     constraints::benches,
 );

ratatui/benches/main/text.rs

@@ -0,0 +1,63 @@
+use criterion::{BatchSize, Bencher, Criterion, criterion_group};
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use ratatui::style::Stylize;
+use ratatui::text::{Line, Text};
+use ratatui::widgets::Widget;
+
+/// Benchmark for rendering a text.
+fn text(c: &mut Criterion) {
+    let mut group = c.benchmark_group("text");
+    for (width, height) in [
+        (200, 50),     // 1080p fullscreen area with medium font.
+        (1, u16::MAX), // Heavily vertically skewed area.
+        (u16::MAX, 1), // Heavily horizontally skewed area.
+        (4096, 4096),  // Max sized area for benchmarking (~sqrt(u16::MAX) * 16, ~768 MB buffer).
+    ] {
+        let buffer_size = Rect::new(0, 0, width, height);
+
+        // Generates sample text content scaled to the given rendering area.
+        // The number of repeated text blocks is roughly proportional to the area size.
+        //  - Small areas produce a few lines (at least 5 x 1 lines).
+        //  - Large areas produce many lines (up to ~5 x 1000 lines).
+        let make_text = |height: u16| {
+            let repeat = (height as usize / 5).clamp(1, 1000);
+            Text::from(
+                (0..repeat)
+                    .flat_map(|_| {
+                        vec![
+                            Line::from("The quick brown fox jumps over the lazy dog. Pack my box with five dozen liquor jugs."),
+                            Line::from("🦀 Rustaceans unite! 東京・İstanbul・Sydney・San Francisco・Warsaw 🌏 RustConf連携中！").bold(),
+                            Line::from("naïve cafés ☕ serve résumé-ready developers 👩‍💻🧑🏾‍💻 testing text rendering engines.").green(),
+                            Line::from("ゼロ幅スペース\u{200B}、結合絵文字👨‍👩‍👧‍👦、全角文字ＡＢＣ、半角abcが混在。").blue(),
+                            Line::from("Emoji test: 🙂😇🤖👩🏻‍🎨🧑‍🚀 — wrapped in a buffer for layout & clipping check.").italic(),
+                        ]
+                    })
+                    .collect::<Vec<_>>(),
+            )
+        };
+
+        group.bench_with_input(
+            format!("render/{width}x{height}"),
+            &make_text(height),
+            |b, text| render(b, text, buffer_size),
+        );
+    }
+    group.finish();
+}
+
+/// Renders the text into a buffer of the given `size`
+fn render(bencher: &mut Bencher, text: &Text, size: Rect) {
+    let mut buffer = Buffer::empty(size);
+    // We use `iter_batched` to clone the value in the setup function.
+    // See https://github.com/ratatui/ratatui/pull/377.
+    bencher.iter_batched(
+        || text.to_owned(),
+        |bench_text| {
+            bench_text.render(buffer.area, &mut buffer);
+        },
+        BatchSize::SmallInput,
+    );
+}
+
+criterion_group!(benches, text);