perf: add backend diff comparison benchmark for crossterm

ratatui/benches/main.rs

@@ -2,6 +2,7 @@ pub mod main {
     pub mod barchart;
     pub mod block;
     pub mod buffer;
+    pub mod crossterm;
     pub mod line;
     pub mod list;
     pub mod paragraph;
@@ -15,6 +16,7 @@ criterion::criterion_main!(
     barchart::benches,
     block::benches,
     buffer::benches,
+    crossterm::benches,
     line::benches,
     list::benches,
     paragraph::benches,

ratatui/benches/main/crossterm.rs

@@ -0,0 +1,72 @@
+use criterion::{criterion_group, BenchmarkId, Criterion};
+use crossterm::{
+    execute,
+    terminal::{EnterAlternateScreen, LeaveAlternateScreen},
+};
+use rand::Rng;
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use ratatui::style::{Color, Style};
+use ratatui::{backend::Backend, buffer::Cell};
+use ratatui_crossterm::CrosstermBackend;
+use std::io::stdout;
+
+criterion_group!(benches, draw_random_buffer);
+
+fn draw_random_buffer(criterion: &mut Criterion) {
+    let mut group = criterion.benchmark_group("crossterm");
+    group.sample_size(10);
+    let mut backend = CrosstermBackend::new(stdout());
+
+    let size = backend.size().unwrap();
+    let area = Rect::new(0, 0, size.width, size.height);
+    let Rect { width, height, .. } = area;
+
+    backend.hide_cursor().unwrap();
+    for churn in [0.0, 0.1, 0.5, 1.0] {
+        // draw a buffer where a certain percentage of cells have changed, using the diff
+        let with_diff = format!("draw_random_buffer_{width}x{height}_with_diff");
+        group.bench_function(BenchmarkId::new(with_diff, churn), |bencher| {
+            let empty = Buffer::empty(area);
+            let buffer = generate_random_buffer(area, churn);
+            execute!(stdout(), EnterAlternateScreen).unwrap();
+            bencher.iter(|| backend.draw(empty.diff(&buffer).into_iter()).unwrap());
+            execute!(stdout(), LeaveAlternateScreen).unwrap();
+        });
+
+        // draw a buffer where every cell has changed
+        let without_diff = format!("draw_random_buffer_{width}x{height}_without_diff");
+        group.bench_function(BenchmarkId::new(without_diff, churn), |bencher| {
+            let mut cell = Cell::new(".");
+            cell.set_fg(Color::Red).set_bg(Color::White);
+            let filled = Buffer::filled(area, cell);
+            let buffer = generate_random_buffer(area, churn);
+            let diff = filled.diff(&buffer);
+            execute!(stdout(), EnterAlternateScreen).unwrap();
+            bencher.iter(|| backend.draw(diff.clone().into_iter()).unwrap());
+            execute!(stdout(), LeaveAlternateScreen).unwrap();
+        });
+    }
+    group.finish();
+    backend.show_cursor().unwrap();
+}
+
+fn generate_random_buffer(area: Rect, churn: f64) -> Buffer {
+    let mut buffer = Buffer::empty(area);
+    let mut rng = rand::thread_rng();
+    for y in 0..area.height {
+        if rng.gen::<f64>() > churn {
+            continue;
+        }
+        for x in 0..area.width {
+            let symbol = (rng.gen::<u8>() % 26 + b'A') as char;
+            let fg = Color::Indexed(rng.gen_range(0..16));
+            let bg = Color::Indexed(rng.gen_range(0..16));
+            let style = Style::default().fg(fg).bg(bg);
+            if let Some(cell) = buffer.cell_mut((x, y)) {
+                cell.set_symbol(&symbol.to_string()).set_style(style);
+            }
+        }
+    }
+    buffer
+}