Perf profiling and some low hanging perf improvements in text rendering

Cargo.lock

@@ -1934,6 +1934,22 @@ dependencies = [
  "tracing-subscriber",
 ]
 
+[[package]]
+name = "ruin_perf"
+version = "0.1.0"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
+[[package]]
+name = "ruin_perf_scenarios"
+version = "0.1.0"
+dependencies = [
+ "ruin_perf",
+ "ruin_ui",
+]
+
 [[package]]
 name = "ruin_reactivity"
 version = "0.1.0"

Cargo.toml

@@ -1,3 +1,18 @@
 [workspace]
 resolver = "3"
 members = ["lib/*", "examples/*"]
+default-members = [
+    "lib/reactivity",
+    "lib/reactivity_parsing",
+    "lib/ruin_app",
+    "lib/ruin_app_proc_macros",
+    "lib/runtime",
+    "lib/runtime_proc_macros",
+    "lib/perf",
+    "lib/ui",
+    "lib/ui_platform_macos",
+    "lib/ui_platform_wayland",
+    "lib/ui_renderer_wgpu",
+    "examples/calculator",
+    "examples/perf_scenarios",
+]

docs/performance-profiling.md

@@ -0,0 +1,94 @@
+# Performance profiling workflow
+
+RUIN performance investigations should start with reproducible reports before
+deep profiler sessions. The first-pass tooling is intentionally headless and
+focused on high-signal app-build, layout, text, scene, and cache counters.
+
+## Run a scenario
+
+Use the `ruin_perf_scenarios` package in release mode:
+
+```bash
+cargo run -p ruin_perf_scenarios --release -- \
+  --scenario large-scroll-list \
+  --frames 300 \
+  --output target/ruin-perf/large-scroll-list.json
+```
+
+List available scenarios:
+
+```bash
+cargo run -p ruin_perf_scenarios -- --list
+```
+
+Current scenarios:
+
+| Scenario | What it stresses |
+| --- | --- |
+| `counter` | tiny reactive-style app tree rebuild and layout baseline |
+| `large-scroll-list` | scroll culling, text cache reuse, layout cache behavior |
+| `calculator` | realistic small app tree with display, button grid, and history |
+| `resize-configure` | repeated viewport-size changes and layout reflow |
+| `large-text-body` | huge wrapped text body, text layout cache behavior, scroll clipping |
+
+The large text scenario accepts a body-size option:
+
+```bash
+cargo run -p ruin_perf_scenarios --release -- \
+  --scenario large-text-body \
+  --frames 100 \
+  --text-kb 1024
+```
+
+Each run writes JSON under `target/ruin-perf/` by default and prints a compact
+summary table to stdout.
+
+## Interpreting the report
+
+Start with the timing rows:
+
+- `app_build`: time spent building the deterministic app tree for the frame.
+- `layout_total`: full layout snapshot time.
+- `layout_intrinsic`: intrinsic measurement work inside layout.
+- `text_prepare` / `text_cache_miss`: text shaping/cache miss work.
+
+Then inspect counters:
+
+- High `layout_cache_misses` with low `layout_cache_hits` means the tree or
+  layout constraints are changing in a way that defeats caching.
+- High `viewport_culled` with low `scene_items` is expected for large scroll
+  lists and means scene culling is working.
+- High `text_cache_misses` or `text_cache_miss` time usually means text content,
+  bounds, style, or cache keys are changing too much.
+- Large `scene_items` or `text_glyphs` for tiny workloads suggests excessive UI
+  tree expansion or missing culling.
+
+## Investigation loop
+
+1. Reproduce the suspected degenerate workload with the closest scenario.
+2. Run it in release mode and keep the JSON report.
+3. Compare the stdout summary with a known-good run or a smaller frame count.
+4. If one phase dominates, use an OS profiler on that scenario:
+   - macOS: Instruments Time Profiler / Allocations / Metal System Trace.
+   - Linux: `perf`, `samply`, `heaptrack`, or RenderDoc as appropriate.
+5. After identifying a concrete hot path, add or update a narrow Criterion
+   benchmark before optimizing it.
+
+## Validation
+
+The scenario runner is part of the default workspace. The usual repository
+validation should keep it healthy:
+
+```bash
+cargo test
+cargo clippy --all-targets -- -D warnings
+cargo clippy --release --all-targets -- -D warnings
+```
+
+## Current limitations
+
+This first pass does not automate GUI input, GPU frame capture, or platform
+presentation traces. Renderer frame counters are exposed for platform-backed
+runs, but the headless scenario reports focus on app/layout/text degeneracy
+first. Platform-backed resize/presentation report generation should be added
+after these reports are useful enough to guide concrete optimization work.

examples/calculator/src/main.rs

@@ -177,7 +177,7 @@ mod tests {
 
         assert_eq!(state.expression.get(), "4");
         assert_eq!(state.result.get(), "");
-        assert_eq!(state.is_error.get(), false);
+        assert!(!state.is_error.get());
         assert_eq!(state.history.get().len(), 1);
         assert_eq!(state.history.get()[0].expression, "2+2");
         assert_eq!(state.history.get()[0].result, "4");

examples/calculator/src/state.rs

@@ -43,10 +43,10 @@ pub struct CalcState {
 impl CalcState {
     pub fn new() -> Self {
         Self {
-            expression: use_signal(|| String::new()),
-            result: use_signal(|| String::new()),
+            expression: use_signal(String::new),
+            result: use_signal(String::new),
             is_error: use_signal(|| false),
-            history: use_signal(|| Vec::new()),
+            history: use_signal(Vec::new),
             mode: use_signal(|| CalcMode::Basic),
             fresh: use_signal(|| false),
             history_scroll: use_signal(|| 10_000.0_f32),

examples/perf_scenarios/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "ruin_perf_scenarios"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+ruin_perf = { path = "../../lib/perf" }
+ruin_ui = { path = "../../lib/ui" }

examples/perf_scenarios/src/main.rs

@@ -0,0 +1,366 @@
+use std::env;
+use std::io;
+use std::path::PathBuf;
+use std::time::Instant;
+
+use ruin_perf::{PerfReportBuilder, RunMetadata};
+use ruin_ui::{
+    AlignItems, Color, Edges, Element, FlexDirection, LayoutCache, LayoutFrameStats,
+    ScrollbarStyle, TextStyle, TextSystem, UiSize, layout_snapshot_with_cache_and_stats,
+};
+
+const DEFAULT_FRAMES: u64 = 300;
+
+#[derive(Clone, Debug)]
+struct Config {
+    scenario: Scenario,
+    frames: u64,
+    output: Option<PathBuf>,
+    text_kb: usize,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+enum Scenario {
+    Counter,
+    LargeScrollList,
+    Calculator,
+    ResizeConfigure,
+    LargeTextBody,
+}
+
+impl Scenario {
+    const ALL: &'static [Self] = &[
+        Self::Counter,
+        Self::LargeScrollList,
+        Self::Calculator,
+        Self::ResizeConfigure,
+        Self::LargeTextBody,
+    ];
+
+    const fn name(self) -> &'static str {
+        match self {
+            Self::Counter => "counter",
+            Self::LargeScrollList => "large-scroll-list",
+            Self::Calculator => "calculator",
+            Self::ResizeConfigure => "resize-configure",
+            Self::LargeTextBody => "large-text-body",
+        }
+    }
+
+    fn parse(value: &str) -> Option<Self> {
+        Self::ALL
+            .iter()
+            .copied()
+            .find(|scenario| scenario.name() == value)
+    }
+}
+
+fn main() -> io::Result<()> {
+    let config = Config::parse(env::args().skip(1))?;
+    let report = run_scenario(&config);
+    let output = config
+        .output
+        .clone()
+        .unwrap_or_else(|| report.default_output_path());
+    report.write_json(&output)?;
+    report.print_summary();
+    println!();
+    println!("wrote {}", output.display());
+    Ok(())
+}
+
+impl Config {
+    fn parse(mut args: impl Iterator<Item = String>) -> io::Result<Self> {
+        let mut scenario = Scenario::LargeScrollList;
+        let mut frames = DEFAULT_FRAMES;
+        let mut output = None;
+        let mut text_kb = 256usize;
+
+        while let Some(arg) = args.next() {
+            match arg.as_str() {
+                "--scenario" => {
+                    let value = args.next().ok_or_else(|| {
+                        io::Error::new(io::ErrorKind::InvalidInput, "--scenario needs a value")
+                    })?;
+                    scenario = Scenario::parse(&value).ok_or_else(|| {
+                        io::Error::new(
+                            io::ErrorKind::InvalidInput,
+                            format!("unknown scenario '{value}'"),
+                        )
+                    })?;
+                }
+                "--frames" => {
+                    let value = args.next().ok_or_else(|| {
+                        io::Error::new(io::ErrorKind::InvalidInput, "--frames needs a value")
+                    })?;
+                    frames = value.parse::<u64>().map_err(|error| {
+                        io::Error::new(
+                            io::ErrorKind::InvalidInput,
+                            format!("invalid frame count '{value}': {error}"),
+                        )
+                    })?;
+                }
+                "--output" => {
+                    let value = args.next().ok_or_else(|| {
+                        io::Error::new(io::ErrorKind::InvalidInput, "--output needs a value")
+                    })?;
+                    output = Some(PathBuf::from(value));
+                }
+                "--text-kb" => {
+                    let value = args.next().ok_or_else(|| {
+                        io::Error::new(io::ErrorKind::InvalidInput, "--text-kb needs a value")
+                    })?;
+                    text_kb = value.parse::<usize>().map_err(|error| {
+                        io::Error::new(
+                            io::ErrorKind::InvalidInput,
+                            format!("invalid text size '{value}': {error}"),
+                        )
+                    })?;
+                }
+                "--list" => {
+                    for scenario in Scenario::ALL {
+                        println!("{}", scenario.name());
+                    }
+                    std::process::exit(0);
+                }
+                "--help" | "-h" => {
+                    print_help();
+                    std::process::exit(0);
+                }
+                other => {
+                    return Err(io::Error::new(
+                        io::ErrorKind::InvalidInput,
+                        format!("unknown argument '{other}'"),
+                    ));
+                }
+            }
+        }
+
+        Ok(Self {
+            scenario,
+            frames,
+            output,
+            text_kb,
+        })
+    }
+}
+
+fn print_help() {
+    println!(
+        "ruin_perf_scenarios --scenario <name> [--frames <n>] [--output <path>] [--text-kb <n>]"
+    );
+    println!();
+    println!("scenarios:");
+    for scenario in Scenario::ALL {
+        println!("  {}", scenario.name());
+    }
+}
+
+fn run_scenario(config: &Config) -> ruin_perf::PerfReport {
+    let mut report =
+        PerfReportBuilder::new(RunMetadata::new(config.scenario.name(), config.frames));
+    let mut text_system = TextSystem::new();
+    let mut layout_cache = LayoutCache::new();
+
+    report.note("headless layout/app-build scenario; renderer/platform timings are not included");
+    if config.scenario == Scenario::LargeTextBody {
+        report.set_counter("text_body_kb", config.text_kb as f64);
+    }
+
+    for frame in 0..config.frames {
+        let build_started = Instant::now();
+        let (tree, viewport) = match config.scenario {
+            Scenario::Counter => counter_tree(frame),
+            Scenario::LargeScrollList => large_scroll_list_tree(frame),
+            Scenario::Calculator => calculator_tree(frame),
+            Scenario::ResizeConfigure => resize_configure_tree(frame),
+            Scenario::LargeTextBody => large_text_body_tree(frame, config.text_kb),
+        };
+        let build_ms = build_started.elapsed().as_secs_f64() * 1_000.0;
+        let (_snapshot, stats) = layout_snapshot_with_cache_and_stats(
+            frame + 1,
+            viewport,
+            &tree,
+            &mut text_system,
+            &mut layout_cache,
+        );
+
+        report.record_ms("app_build", build_ms);
+        record_layout_stats(&mut report, stats);
+    }
+
+    report.finish()
+}
+
+fn record_layout_stats(report: &mut PerfReportBuilder, stats: LayoutFrameStats) {
+    report.record_ms("layout_total", stats.total_ms);
+    report.record_ms("layout_intrinsic", stats.intrinsic_ms);
+    report.record_ms("text_prepare", stats.text_prepare_ms);
+    report.record_ms("text_cache_miss", stats.text_miss_ms);
+    report.record("layout_nodes", "count", stats.nodes as f64);
+    report.record("scene_items", "count", stats.scene_items as f64);
+    report.record("text_glyphs", "count", stats.text_output_glyphs as f64);
+    report.add_counter("layout_cache_hits", stats.layout_cache_hits as f64);
+    report.add_counter("layout_cache_misses", stats.layout_cache_misses as f64);
+    report.add_counter("intrinsic_cache_hits", stats.intrinsic_cache_hits as f64);
+    report.add_counter("viewport_culled", stats.viewport_culled as f64);
+    report.add_counter("text_cache_hits", stats.text_cache_hits as f64);
+    report.add_counter("text_cache_misses", stats.text_cache_misses as f64);
+    report.add_counter("text_requests", stats.text_requests as f64);
+}
+
+fn text_style(size: f32) -> TextStyle {
+    TextStyle::new(size, Color::rgb(0x20, 0x20, 0x20))
+}
+
+fn counter_tree(frame: u64) -> (Element, UiSize) {
+    let count = frame as i64;
+    let root = Element::column()
+        .gap(12.0)
+        .padding(Edges::all(24.0))
+        .align_items(AlignItems::Center)
+        .child(Element::text("Counter", text_style(28.0)))
+        .child(Element::text(format!("count = {count}"), text_style(18.0)))
+        .child(Element::text(
+            format!("double = {}", count * 2),
+            text_style(18.0),
+        ))
+        .child(button_row(["-1", "Reset", "+1"]));
+    (root, UiSize::new(480.0, 320.0))
+}
+
+fn large_scroll_list_tree(frame: u64) -> (Element, UiSize) {
+    let item_count = 1_000usize;
+    let item_height = 28.0;
+    let viewport = UiSize::new(480.0, 640.0);
+    let max_offset = (item_count as f32 * item_height - viewport.height).max(0.0);
+    let offset = ((frame as f32 * 19.0) % max_offset.max(1.0)).round();
+    let mut list = Element::column().gap(0.0);
+    for index in 0..item_count {
+        list = list.child(Element::new().height(item_height).child(Element::text(
+            format!("list item {index:04}"),
+            text_style(14.0),
+        )));
+    }
+    let root = Element::new().child(
+        Element::scroll_box(offset)
+            .width(viewport.width)
+            .height(viewport.height)
+            .scrollbar_style(ScrollbarStyle::default())
+            .child(list),
+    );
+    (root, viewport)
+}
+
+fn calculator_tree(frame: u64) -> (Element, UiSize) {
+    let expression = match frame % 6 {
+        0 => "2",
+        1 => "2+",
+        2 => "2+2",
+        3 => "4",
+        4 => "4*8",
+        _ => "32",
+    };
+    let history_len = (frame as usize / 12).min(40);
+    let mut history = Element::column().gap(4.0);
+    for index in 0..history_len {
+        history = history.child(Element::text(
+            format!("{} + {} = {}", index, index + 1, index * 2 + 1),
+            text_style(12.0),
+        ));
+    }
+
+    let root = Element::column()
+        .gap(10.0)
+        .padding(Edges::all(20.0))
+        .child(Element::text("Calculator", text_style(28.0)))
+        .child(display_panel(expression))
+        .child(button_grid())
+        .child(Element::scroll_box(10_000.0).height(180.0).child(history));
+    (root, UiSize::new(420.0, 720.0))
+}
+
+fn resize_configure_tree(frame: u64) -> (Element, UiSize) {
+    let width = 360.0 + (frame % 90) as f32 * 4.0;
+    let height = 280.0 + (frame % 60) as f32 * 3.0;
+    let mut content = Element::column().gap(8.0).padding(Edges::all(16.0));
+    for index in 0..40 {
+        content = content.child(Element::text(
+            format!("resize row {index:02}: {width:.0} x {height:.0}"),
+            text_style(14.0),
+        ));
+    }
+    (content, UiSize::new(width, height))
+}
+
+fn large_text_body_tree(frame: u64, text_kb: usize) -> (Element, UiSize) {
+    let viewport = UiSize::new(720.0, 720.0);
+    let text_width = 680.0;
+    let line_height = 18.0;
+    let text = large_text_body(text_kb);
+    let estimated_line_count = (text.len() as f32 / 72.0).ceil();
+    let estimated_height = (estimated_line_count * line_height).max(viewport.height);
+    let max_offset = (estimated_height - viewport.height).max(0.0);
+    let offset = ((frame as f32 * 127.0) % max_offset.max(1.0)).round();
+    let style = text_style(14.0)
+        .with_line_height(line_height)
+        .with_bounds(UiSize::new(text_width, estimated_height));
+
+    let root = Element::new().child(
+        Element::scroll_box(offset)
+            .width(viewport.width)
+            .height(viewport.height)
+            .child(
+                Element::new()
+                    .width(text_width)
+                    .child(Element::paragraph(text, style)),
+            ),
+    );
+    (root, viewport)
+}
+
+fn large_text_body(text_kb: usize) -> String {
+    let target_bytes = text_kb.saturating_mul(1024).max(1);
+    let paragraph = "RUIN large text profiling paragraph: the quick brown fox jumps over the lazy dog. This line is intentionally ordinary prose with enough words to exercise wrapping, glyph collection, hit-test geometry, and cache behavior.\n";
+    let mut text = String::with_capacity(target_bytes + paragraph.len());
+    while text.len() < target_bytes {
+        text.push_str(paragraph);
+    }
+    text.truncate(target_bytes);
+    text
+}
+
+fn display_panel(expression: &str) -> Element {
+    Element::new()
+        .padding(Edges::all(12.0))
+        .border(1.0, Color::rgb(0x80, 0x80, 0x80))
+        .child(Element::text(expression, text_style(24.0)))
+}
+
+fn button_grid() -> Element {
+    let rows = [
+        ["7", "8", "9", "/"],
+        ["4", "5", "6", "*"],
+        ["1", "2", "3", "-"],
+        ["0", ".", "=", "+"],
+    ];
+    let mut grid = Element::column().gap(6.0);
+    for row in rows {
+        grid = grid.child(button_row(row));
+    }
+    grid
+}
+
+fn button_row<const N: usize>(labels: [&str; N]) -> Element {
+    let mut row = Element::new().direction(FlexDirection::Row).gap(6.0);
+    for label in labels {
+        row = row.child(
+            Element::new()
+                .width(76.0)
+                .height(36.0)
+                .border(1.0, Color::rgb(0x90, 0x90, 0x90))
+                .child(Element::text(label, text_style(16.0))),
+        );
+    }
+    row
+}

lib/perf/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "ruin_perf"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"

lib/perf/src/lib.rs

@@ -0,0 +1,226 @@
+use std::cmp::Ordering;
+use std::collections::BTreeMap;
+use std::fs;
+use std::io;
+use std::path::{Path, PathBuf};
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct RunMetadata {
+    pub scenario: String,
+    pub frames: u64,
+    pub profile: String,
+    pub target_os: String,
+    pub target_arch: String,
+    pub started_unix_ms: u128,
+}
+
+impl RunMetadata {
+    pub fn new(scenario: impl Into<String>, frames: u64) -> Self {
+        Self {
+            scenario: scenario.into(),
+            frames,
+            profile: if cfg!(debug_assertions) {
+                "debug".into()
+            } else {
+                "release".into()
+            },
+            target_os: std::env::consts::OS.into(),
+            target_arch: std::env::consts::ARCH.into(),
+            started_unix_ms: SystemTime::now()
+                .duration_since(UNIX_EPOCH)
+                .unwrap_or(Duration::ZERO)
+                .as_millis(),
+        }
+    }
+}
+
+#[derive(Clone, Debug, Default, Serialize, Deserialize)]
+pub struct SampleSeries {
+    pub name: String,
+    pub unit: String,
+    pub samples: Vec<f64>,
+}
+
+impl SampleSeries {
+    pub fn new(name: impl Into<String>, unit: impl Into<String>) -> Self {
+        Self {
+            name: name.into(),
+            unit: unit.into(),
+            samples: Vec::new(),
+        }
+    }
+
+    pub fn push(&mut self, sample: f64) {
+        if sample.is_finite() {
+            self.samples.push(sample);
+        }
+    }
+
+    pub fn summary(&self) -> SampleSummary {
+        SampleSummary::from_samples(&self.name, &self.unit, &self.samples)
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct SampleSummary {
+    pub name: String,
+    pub unit: String,
+    pub count: usize,
+    pub avg: f64,
+    pub p50: f64,
+    pub p95: f64,
+    pub max: f64,
+}
+
+impl SampleSummary {
+    fn from_samples(name: &str, unit: &str, samples: &[f64]) -> Self {
+        if samples.is_empty() {
+            return Self {
+                name: name.into(),
+                unit: unit.into(),
+                count: 0,
+                avg: 0.0,
+                p50: 0.0,
+                p95: 0.0,
+                max: 0.0,
+            };
+        }
+
+        let mut sorted = samples.to_vec();
+        sorted.sort_by(|a, b| a.partial_cmp(b).unwrap_or(Ordering::Equal));
+        let sum = sorted.iter().sum::<f64>();
+        Self {
+            name: name.into(),
+            unit: unit.into(),
+            count: sorted.len(),
+            avg: sum / sorted.len() as f64,
+            p50: percentile(&sorted, 0.50),
+            p95: percentile(&sorted, 0.95),
+            max: *sorted.last().unwrap_or(&0.0),
+        }
+    }
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct PerfReport {
+    pub metadata: RunMetadata,
+    pub summaries: Vec<SampleSummary>,
+    pub counters: BTreeMap<String, f64>,
+    pub notes: Vec<String>,
+}
+
+#[derive(Clone, Debug)]
+pub struct PerfReportBuilder {
+    metadata: RunMetadata,
+    series: BTreeMap<String, SampleSeries>,
+    counters: BTreeMap<String, f64>,
+    notes: Vec<String>,
+}
+
+impl PerfReportBuilder {
+    pub fn new(metadata: RunMetadata) -> Self {
+        Self {
+            metadata,
+            series: BTreeMap::new(),
+            counters: BTreeMap::new(),
+            notes: Vec::new(),
+        }
+    }
+
+    pub fn record_ms(&mut self, name: impl Into<String>, value: f64) {
+        self.record(name, "ms", value);
+    }
+
+    pub fn record(&mut self, name: impl Into<String>, unit: impl Into<String>, value: f64) {
+        let name = name.into();
+        let unit = unit.into();
+        self.series
+            .entry(name.clone())
+            .or_insert_with(|| SampleSeries::new(name, unit))
+            .push(value);
+    }
+
+    pub fn add_counter(&mut self, name: impl Into<String>, value: impl Into<f64>) {
+        *self.counters.entry(name.into()).or_insert(0.0) += value.into();
+    }
+
+    pub fn set_counter(&mut self, name: impl Into<String>, value: impl Into<f64>) {
+        self.counters.insert(name.into(), value.into());
+    }
+
+    pub fn note(&mut self, note: impl Into<String>) {
+        self.notes.push(note.into());
+    }
+
+    pub fn finish(self) -> PerfReport {
+        PerfReport {
+            metadata: self.metadata,
+            summaries: self.series.values().map(SampleSeries::summary).collect(),
+            counters: self.counters,
+            notes: self.notes,
+        }
+    }
+}
+
+impl PerfReport {
+    pub fn write_json(&self, path: impl AsRef<Path>) -> io::Result<()> {
+        let path = path.as_ref();
+        if let Some(parent) = path.parent() {
+            fs::create_dir_all(parent)?;
+        }
+        let json = serde_json::to_string_pretty(self).map_err(io::Error::other)?;
+        fs::write(path, json)?;
+        Ok(())
+    }
+
+    pub fn default_output_path(&self) -> PathBuf {
+        PathBuf::from("target")
+            .join("ruin-perf")
+            .join(format!("{}.json", self.metadata.scenario))
+    }
+
+    pub fn print_summary(&self) {
+        println!(
+            "scenario={} frames={} profile={} target={}/{}",
+            self.metadata.scenario,
+            self.metadata.frames,
+            self.metadata.profile,
+            self.metadata.target_os,
+            self.metadata.target_arch
+        );
+        println!(
+            "{:<32} {:>8} {:>10} {:>10} {:>10} {:>10}",
+            "metric", "count", "avg", "p50", "p95", "max"
+        );
+        for summary in &self.summaries {
+            println!(
+                "{:<32} {:>8} {:>10.3} {:>10.3} {:>10.3} {:>10.3} {}",
+                summary.name,
+                summary.count,
+                summary.avg,
+                summary.p50,
+                summary.p95,
+                summary.max,
+                summary.unit
+            );
+        }
+        if !self.counters.is_empty() {
+            println!();
+            println!("{:<32} {:>12}", "counter", "value");
+            for (name, value) in &self.counters {
+                println!("{name:<32} {value:>12.3}");
+            }
+        }
+    }
+}
+
+fn percentile(sorted: &[f64], percentile: f64) -> f64 {
+    if sorted.is_empty() {
+        return 0.0;
+    }
+    let index = ((sorted.len() - 1) as f64 * percentile).round() as usize;
+    sorted[index.min(sorted.len() - 1)]
+}

lib/reactivity_parsing/examples/json_reactive_parser.rs

@@ -66,6 +66,13 @@ struct JsonParser {
     next_id: u64,
 }
 
+struct ReuseContext<'a, 'count> {
+    old_text: &'a str,
+    new_text: &'a str,
+    delta: &'a EditDelta,
+    reused: &'count mut usize,
+}
+
 struct Cursor<'a> {
     text: &'a str,
     offset: usize,
@@ -114,7 +121,7 @@ async fn main() {
     let parse_state = cell_in(&reactor, initial_snapshot);
     let last_delta = cell_in(&reactor, None::<EditDelta>);
 
-    let _parser_subscription = {
+    {
         let rope = rope.clone();
         let parser = Rc::clone(&parser);
         let parse_state = parse_state.clone();
@@ -283,15 +290,18 @@ impl JsonParser {
         let mut root_anchor = previous.root_anchor;
         root_anchor.map_through(delta);
         let mut reused = 0usize;
+        let mut reuse = ReuseContext {
+            old_text: &previous.text,
+            new_text: &text,
+            delta,
+            reused: &mut reused,
+        };
         let root = self.reuse_node(
             &parsed,
             Some(&previous.root),
             previous.root_anchor.byte,
             root_anchor.byte,
-            &previous.text,
-            &text,
-            delta,
-            &mut reused,
+            &mut reuse,
         );
         Ok(ParseSnapshot {
             text,
@@ -322,21 +332,18 @@ impl JsonParser {
         old: Option<&AstNode>,
         old_parent_start: usize,
         new_parent_start: usize,
-        old_text: &str,
-        new_text: &str,
-        delta: &EditDelta,
-        reused: &mut usize,
+        reuse: &mut ReuseContext<'_, '_>,
     ) -> AstNode {
         let parsed_local = localize(parsed.range, new_parent_start);
         if let Some(old) = old
             && old.kind == parsed.kind
-            && map_range(absolute_range(old, old_parent_start), delta) == parsed.range
-            && old_text.get(
+            && map_range(absolute_range(old, old_parent_start), reuse.delta) == parsed.range
+            && reuse.old_text.get(
                 absolute_range(old, old_parent_start).start
                     ..absolute_range(old, old_parent_start).end,
-            ) == new_text.get(parsed.range.start..parsed.range.end)
+            ) == reuse.new_text.get(parsed.range.start..parsed.range.end)
         {
-            *reused += count_nodes(old);
+            *reuse.reused += count_nodes(old);
             return AstNode {
                 id: old.id,
                 kind: old.kind,
@@ -359,10 +366,7 @@ impl JsonParser {
                     previous_child,
                     next_old_parent_start,
                     parsed.range.start,
-                    old_text,
-                    new_text,
-                    delta,
-                    reused,
+                    reuse,
                 )
             })
             .collect();

lib/reactivity_parsing/src/parse.rs

@@ -38,6 +38,8 @@ pub struct ParseError {
     pub message: String,
 }
 
+pub type ParserResult<C, T, D> = Result<ParseResult<C, T, D>, ParseError>;
+
 impl ParseError {
     pub fn new(message: impl Into<String>) -> Self {
         Self {
@@ -66,7 +68,7 @@ pub trait IncrementalParser {
         cursor: RopeCursor,
         fragments: &[SyntaxFragment<Self::Checkpoint, Self::Tree, Self::Diagnostic>],
         invalidation: ParseInvalidation<Self::Checkpoint>,
-    ) -> Result<ParseResult<Self::Checkpoint, Self::Tree, Self::Diagnostic>, ParseError>;
+    ) -> ParserResult<Self::Checkpoint, Self::Tree, Self::Diagnostic>;
 }
 
 #[cfg(test)]

lib/reactivity_parsing/src/rope.rs

@@ -1,6 +1,7 @@
 use std::cell::{Cell, RefCell};
 use std::cmp::min;
 use std::collections::BTreeSet;
+use std::fmt;
 use std::rc::Rc;
 
 use ruin_reactivity::{Event, Reactor, Source, event_in, source_in};
@@ -139,10 +140,6 @@ impl ReactiveRope {
         self.len_bytes() == 0
     }
 
-    pub fn to_string(&self) -> String {
-        self.slice(TextRange::new(0, self.len_bytes()))
-    }
-
     pub fn point_at(&self, offset: usize) -> TextPoint {
         self.inner.structure.observe();
         let offset = offset.min(self.len_bytes());
@@ -416,6 +413,12 @@ impl ReactiveRope {
     }
 }
 
+impl fmt::Display for ReactiveRope {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(&self.slice(TextRange::new(0, self.len_bytes())))
+    }
+}
+
 impl RopeChunk {
     pub fn text(&self) -> &str {
         &self.text

lib/reactivity_parsing/src/tokentree.rs

@@ -323,6 +323,13 @@ pub struct TokenTreeParser {
     next_id: u64,
 }
 
+struct ReuseContext<'a, 'count> {
+    old_text: &'a str,
+    new_text: &'a str,
+    delta: &'a EditDelta,
+    reused_nodes: &'count mut usize,
+}
+
 impl TokenTreeParser {
     pub fn new() -> Self {
         Self::default()
@@ -358,15 +365,18 @@ impl TokenTreeParser {
         let mut root_anchor = previous.root_anchor;
         root_anchor.map_through(delta);
         let mut reused_nodes = 0usize;
+        let mut reuse = ReuseContext {
+            old_text: &previous.text,
+            new_text: &text,
+            delta,
+            reused_nodes: &mut reused_nodes,
+        };
         let root = self.reuse_node(
             &raw.root,
             Some(&previous.root),
             previous.root_anchor.byte,
             root_anchor.byte,
-            &previous.text,
-            &text,
-            delta,
-            &mut reused_nodes,
+            &mut reuse,
         );
         let total_nodes = count_nodes(&root);
 
@@ -403,16 +413,20 @@ impl TokenTreeParser {
         old: Option<&TokenTreeNode>,
         old_parent_start: usize,
         new_parent_start: usize,
-        old_text: &str,
-        new_text: &str,
-        delta: &EditDelta,
-        reused_nodes: &mut usize,
+        reuse: &mut ReuseContext<'_, '_>,
     ) -> TokenTreeNode {
         let parsed_local = localize(parsed.range, new_parent_start);
-        if let Some(old) = old
-            .filter(|old| can_reuse_node(old, old_parent_start, parsed, old_text, new_text, delta))
-        {
-            *reused_nodes += count_nodes(old);
+        if let Some(old) = old.filter(|old| {
+            can_reuse_node(
+                old,
+                old_parent_start,
+                parsed,
+                reuse.old_text,
+                reuse.new_text,
+                reuse.delta,
+            )
+        }) {
+            *reuse.reused_nodes += count_nodes(old);
             return TokenTreeNode {
                 id: old.id,
                 local_range: parsed_local,
@@ -432,9 +446,8 @@ impl TokenTreeParser {
                         .children
                         .get(index)
                         .filter(|candidate| !used[index] && can_descend_into_node(candidate, child))
-                        .map(|candidate| {
+                        .inspect(|_| {
                             used[index] = true;
-                            candidate
                         })
                         .or_else(|| {
                             old.children.iter().enumerate().find_map(
@@ -455,10 +468,7 @@ impl TokenTreeParser {
                         candidate,
                         absolute_range(old, old_parent_start).start,
                         parsed.range.start,
-                        old_text,
-                        new_text,
-                        delta,
-                        reused_nodes,
+                        reuse,
                     )
                 })
                 .collect()
@@ -467,16 +477,7 @@ impl TokenTreeParser {
                 .children
                 .iter()
                 .map(|child| {
-                    self.reuse_node(
-                        child,
-                        None,
-                        old_parent_start,
-                        parsed.range.start,
-                        old_text,
-                        new_text,
-                        delta,
-                        reused_nodes,
-                    )
+                    self.reuse_node(child, None, old_parent_start, parsed.range.start, reuse)
                 })
                 .collect()
         };
@@ -545,13 +546,13 @@ impl<'a> Cursor<'a> {
                 break;
             }
 
-            if let Some(close) = terminator {
-                if self.peek_char() == Some(close) {
+            if let Some(close) = terminator
+                && self.peek_char() == Some(close)
+            {
                 self.bump_char();
                 terminated = true;
                 break;
             }
-            }
 
             let Some(ch) = self.peek_char() else {
                 break;
@@ -1376,7 +1377,7 @@ mod tests {
             .collect()
     }
 
-    fn find_list_child<'a>(node: &'a TokenTreeNode, delimiter: DelimiterKind) -> &'a TokenTreeNode {
+    fn find_list_child(node: &TokenTreeNode, delimiter: DelimiterKind) -> &TokenTreeNode {
         node.children
             .iter()
             .find(|child| {

lib/ruin_app/src/input.rs

@@ -201,7 +201,7 @@ pub(crate) fn sync_primary_selection(
     #[cfg(not(target_os = "linux"))]
     {
         let _ = (window, interaction_tree, selection);
-        return Ok(());
+        Ok(())
     }
 
     #[cfg(target_os = "linux")]

lib/ui/src/layout.rs

@@ -36,6 +36,35 @@ pub struct LayoutSnapshot {
     pub root_min_size: UiSize,
 }
 
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+pub struct LayoutFrameStats {
+    pub total_ms: f64,
+    pub nodes: usize,
+    pub text_nodes: usize,
+    pub container_nodes: usize,
+    pub background_quads: usize,
+    pub intrinsic_calls: usize,
+    pub intrinsic_size_calls: usize,
+    pub intrinsic_text_calls: usize,
+    pub intrinsic_container_calls: usize,
+    pub intrinsic_ms: f64,
+    pub text_prepare_calls: usize,
+    pub text_prepare_ms: f64,
+    pub viewport_culled: usize,
+    pub layout_cache_hits: usize,
+    pub layout_cache_misses: usize,
+    pub intrinsic_cache_hits: usize,
+    pub text_requests: u32,
+    pub text_cache_hits: u32,
+    pub text_cache_misses: u32,
+    pub text_output_glyphs: u32,
+    pub text_family_resolve_ms: f64,
+    pub text_buffer_build_ms: f64,
+    pub text_glyph_collect_ms: f64,
+    pub text_miss_ms: f64,
+    pub scene_items: usize,
+}
+
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub struct LayoutPath(Vec<u32>);
 
@@ -194,6 +223,16 @@ pub fn layout_snapshot_with_cache(
     text_system: &mut TextSystem,
     layout_cache: &mut LayoutCache,
 ) -> LayoutSnapshot {
+    layout_snapshot_with_cache_and_stats(version, logical_size, root, text_system, layout_cache).0
+}
+
+pub fn layout_snapshot_with_cache_and_stats(
+    version: u64,
+    logical_size: UiSize,
+    root: &Element,
+    text_system: &mut TextSystem,
+    layout_cache: &mut LayoutCache,
+) -> (LayoutSnapshot, LayoutFrameStats) {
     let layout_started = Instant::now();
     let perf_enabled = tracing::enabled!(target: "ruin_ui::layout_perf", tracing::Level::DEBUG);
     let mut perf_stats = LayoutPerfStats::new(perf_enabled);
@@ -215,48 +254,78 @@ pub fn layout_snapshot_with_cache(
         None,
     );
     let text_stats = text_system.take_frame_stats();
+    let stats = LayoutFrameStats {
+        total_ms: layout_started.elapsed().as_secs_f64() * 1_000.0,
+        nodes: perf_stats.nodes,
+        text_nodes: perf_stats.text_nodes,
+        container_nodes: perf_stats.container_nodes,
+        background_quads: perf_stats.background_quads,
+        intrinsic_calls: perf_stats.intrinsic_calls,
+        intrinsic_size_calls: perf_stats.intrinsic_size_calls,
+        intrinsic_text_calls: perf_stats.intrinsic_text_calls,
+        intrinsic_container_calls: perf_stats.intrinsic_container_calls,
+        intrinsic_ms: perf_stats.intrinsic_ms,
+        text_prepare_calls: perf_stats.text_prepare_calls,
+        text_prepare_ms: perf_stats.text_prepare_ms,
+        viewport_culled: perf_stats.viewport_culled,
+        layout_cache_hits: perf_stats.layout_cache_hits,
+        layout_cache_misses: perf_stats.layout_cache_misses,
+        intrinsic_cache_hits: perf_stats.intrinsic_cache_hits,
+        text_requests: text_stats.requests,
+        text_cache_hits: text_stats.cache_hits,
+        text_cache_misses: text_stats.cache_misses,
+        text_output_glyphs: text_stats.output_glyphs,
+        text_family_resolve_ms: text_stats.family_resolve_ms,
+        text_buffer_build_ms: text_stats.buffer_build_ms,
+        text_glyph_collect_ms: text_stats.glyph_collect_ms,
+        text_miss_ms: text_stats.miss_ms,
+        scene_items: scene.items.len(),
+    };
     if perf_stats.enabled {
         tracing::debug!(
             target: "ruin_ui::layout_perf",
             scene_version = version,
             width = logical_size.width,
             height = logical_size.height,
-            total_ms = layout_started.elapsed().as_secs_f64() * 1_000.0,
-            nodes = perf_stats.nodes,
-            text_nodes = perf_stats.text_nodes,
-            container_nodes = perf_stats.container_nodes,
-            background_quads = perf_stats.background_quads,
-            intrinsic_calls = perf_stats.intrinsic_calls,
-            intrinsic_size_calls = perf_stats.intrinsic_size_calls,
-            intrinsic_text_calls = perf_stats.intrinsic_text_calls,
-            intrinsic_container_calls = perf_stats.intrinsic_container_calls,
-            intrinsic_ms = perf_stats.intrinsic_ms,
-            text_prepare_calls = perf_stats.text_prepare_calls,
-            text_prepare_ms = perf_stats.text_prepare_ms,
-            viewport_culled = perf_stats.viewport_culled,
-            layout_cache_hits = perf_stats.layout_cache_hits,
-            layout_cache_misses = perf_stats.layout_cache_misses,
-            intrinsic_cache_hits = perf_stats.intrinsic_cache_hits,
-            text_requests = text_stats.requests,
-            text_cache_hits = text_stats.cache_hits,
-            text_cache_misses = text_stats.cache_misses,
-            text_output_glyphs = text_stats.output_glyphs,
-            text_family_resolve_ms = text_stats.family_resolve_ms,
-            text_buffer_build_ms = text_stats.buffer_build_ms,
-            text_glyph_collect_ms = text_stats.glyph_collect_ms,
-            text_miss_ms = text_stats.miss_ms,
-            scene_items = scene.items.len(),
+            total_ms = stats.total_ms,
+            nodes = stats.nodes,
+            text_nodes = stats.text_nodes,
+            container_nodes = stats.container_nodes,
+            background_quads = stats.background_quads,
+            intrinsic_calls = stats.intrinsic_calls,
+            intrinsic_size_calls = stats.intrinsic_size_calls,
+            intrinsic_text_calls = stats.intrinsic_text_calls,
+            intrinsic_container_calls = stats.intrinsic_container_calls,
+            intrinsic_ms = stats.intrinsic_ms,
+            text_prepare_calls = stats.text_prepare_calls,
+            text_prepare_ms = stats.text_prepare_ms,
+            viewport_culled = stats.viewport_culled,
+            layout_cache_hits = stats.layout_cache_hits,
+            layout_cache_misses = stats.layout_cache_misses,
+            intrinsic_cache_hits = stats.intrinsic_cache_hits,
+            text_requests = stats.text_requests,
+            text_cache_hits = stats.text_cache_hits,
+            text_cache_misses = stats.text_cache_misses,
+            text_output_glyphs = stats.text_output_glyphs,
+            text_family_resolve_ms = stats.text_family_resolve_ms,
+            text_buffer_build_ms = stats.text_buffer_build_ms,
+            text_glyph_collect_ms = stats.text_glyph_collect_ms,
+            text_miss_ms = stats.text_miss_ms,
+            scene_items = stats.scene_items,
             "layout snapshot perf"
         );
     }
     let root_min_size = element_min_size(root);
+    (
         LayoutSnapshot {
             scene,
             interaction_tree: InteractionTree {
                 root: interaction_root,
             },
             root_min_size,
-    }
+        },
+        stats,
+    )
 }
 
 #[allow(clippy::too_many_arguments)]
@@ -2903,7 +2972,7 @@ mod tests {
                 .items
                 .iter()
                 .filter_map(|item| match item {
-                    DisplayItem::Text(text) => Some(text.text.as_str()),
+                    DisplayItem::Text(text) => Some(text.text.as_ref()),
                     _ => None,
                 })
                 .collect()

lib/ui/src/lib.rs

@@ -31,8 +31,9 @@ pub use interaction::{
 };
 pub use keyboard::{KeyboardEvent, KeyboardEventKind, KeyboardKey, KeyboardModifiers};
 pub use layout::{
-    HitTarget, InteractionTree, LayoutCache, LayoutNode, LayoutPath, LayoutSnapshot, ScrollMetrics,
-    TextHitTarget, element_min_size, layout_snapshot, layout_snapshot_with_cache,
+    HitTarget, InteractionTree, LayoutCache, LayoutFrameStats, LayoutNode, LayoutPath,
+    LayoutSnapshot, ScrollMetrics, TextHitTarget, element_min_size, layout_snapshot,
+    layout_snapshot_with_cache, layout_snapshot_with_cache_and_stats,
     layout_snapshot_with_text_system,
 };
 pub use layout::{layout_scene, layout_scene_with_text_system};

lib/ui/src/scene.rs

@@ -189,7 +189,7 @@ pub struct PreparedTextLine {
 #[derive(Clone, Debug, PartialEq)]
 pub struct PreparedText {
     pub element_id: Option<ElementId>,
-    pub text: String,
+    pub text: Arc<str>,
     pub origin: Point,
     pub bounds: Option<UiSize>,
     pub font_size: f32,
@@ -206,6 +206,8 @@ pub struct PreparedText {
 /// Add `origin` to convert to absolute window coords.
 #[derive(Clone, Debug, PartialEq)]
 pub struct TextLayoutData {
+    pub text: Arc<str>,
+    pub cache_key: u64,
     pub lines: Vec<PreparedTextLine>,
     pub glyphs: Vec<GlyphInstance>,
     /// Measured (unclamped) size of the laid-out text.
@@ -225,7 +227,6 @@ impl PreparedText {
     #[allow(clippy::too_many_arguments)]
     pub(crate) fn from_layout(
         element_id: Option<ElementId>,
-        text: String,
         origin: Point,
         bounds: Option<UiSize>,
         font_size: f32,
@@ -237,7 +238,7 @@ impl PreparedText {
     ) -> Self {
         Self {
             element_id,
-            text,
+            text: layout.text.clone(),
             origin,
             bounds,
             font_size,
@@ -256,6 +257,10 @@ impl PreparedText {
         Arc::as_ptr(&self.layout)
     }
 
+    pub fn layout_cache_key(&self) -> u64 {
+        self.layout.cache_key
+    }
+
     /// Create a monospace `PreparedText` without going through the text system.
     /// Used for testing and low-level terminal-style rendering.
     pub fn monospace(
@@ -265,7 +270,7 @@ impl PreparedText {
         advance: f32,
         color: Color,
     ) -> Self {
-        let text = text.into();
+        let text: Arc<str> = Arc::from(text.into());
         // Glyphs are stored in LOCAL (origin-relative) coordinates.
         let mut local_x = 0.0f32;
         let mut glyphs = Vec::with_capacity(text.chars().count());
@@ -293,7 +298,7 @@ impl PreparedText {
         let size = UiSize::new(local_x, font_size);
         Self {
             element_id: None,
-            text,
+            text: text.clone(),
             origin,
             bounds: None,
             font_size,
@@ -302,6 +307,8 @@ impl PreparedText {
             selectable: true,
             selection_style: TextSelectionStyle::DEFAULT,
             layout: Arc::new(TextLayoutData {
+                text: text.clone(),
+                cache_key: monospace_text_cache_key(&text, font_size, advance, color),
                 lines: vec![line],
                 glyphs,
                 size,
@@ -466,7 +473,10 @@ impl PreparedText {
         if range.is_empty() {
             return;
         }
-        for glyph in Arc::make_mut(&mut self.layout).glyphs.iter_mut() {
+        let layout = Arc::make_mut(&mut self.layout);
+        layout.cache_key =
+            selected_text_cache_key(layout.cache_key, range.start, range.end, selected_color);
+        for glyph in layout.glyphs.iter_mut() {
             if glyph.text_end > range.start && glyph.text_start < range.end {
                 glyph.color = selected_color;
             }
@@ -583,6 +593,28 @@ impl PreparedText {
     }
 }
 
+fn monospace_text_cache_key(text: &str, font_size: f32, advance: f32, color: Color) -> u64 {
+    use std::hash::{DefaultHasher, Hash, Hasher};
+
+    let mut hasher = DefaultHasher::new();
+    text.hash(&mut hasher);
+    font_size.to_bits().hash(&mut hasher);
+    advance.to_bits().hash(&mut hasher);
+    color.hash(&mut hasher);
+    hasher.finish()
+}
+
+fn selected_text_cache_key(base: u64, start: usize, end: usize, color: Color) -> u64 {
+    use std::hash::{DefaultHasher, Hash, Hasher};
+
+    let mut hasher = DefaultHasher::new();
+    base.hash(&mut hasher);
+    start.hash(&mut hasher);
+    end.hash(&mut hasher);
+    color.hash(&mut hasher);
+    hasher.finish()
+}
+
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 enum WordClass {
     Word,
@@ -886,6 +918,8 @@ mod tests {
         }
         let orig_size = text.layout.size;
         text.layout = Arc::new(TextLayoutData {
+            text: text.text.clone(),
+            cache_key: text.layout.cache_key,
             lines,
             glyphs,
             size: orig_size,

lib/ui/src/text.rs

@@ -269,7 +269,7 @@ pub struct TextSystem {
 }
 
 #[derive(Clone, Copy, Debug, Default)]
-pub(crate) struct TextFrameStats {
+pub struct TextFrameStats {
     pub requests: u32,
     pub cache_hits: u32,
     pub cache_misses: u32,
@@ -341,7 +341,6 @@ impl TextSystem {
         bounds: Option<UiSize>,
     ) -> PreparedText {
         let bounds = bounds.or(style.bounds);
-        let text = combined_text(spans);
         // Use the cached Arc directly — glyphs are in local (origin-0) coords.
         let layout_data = self.layout(
             spans,
@@ -352,7 +351,6 @@ impl TextSystem {
 
         PreparedText::from_layout(
             None,
-            text,
             origin,
             bounds,
             style.font_size,
@@ -476,7 +474,8 @@ impl TextSystem {
         }
         self.frame_stats.buffer_build_ms += buffer_build_started.elapsed().as_secs_f64() * 1_000.0;
 
-        let line_starts = line_start_offsets(&combined_text(spans));
+        let text = combined_text(spans);
+        let line_starts = line_start_offsets(&text);
         let mut measured_width: f32 = 0.0;
         let mut measured_height: f32 = 0.0;
         let mut lines = Vec::new();
@@ -527,6 +526,8 @@ impl TextSystem {
             glyph_collect_started.elapsed().as_secs_f64() * 1_000.0;
 
         let layout = Arc::new(TextLayoutData {
+            text: Arc::from(text),
+            cache_key,
             lines,
             glyphs,
             size: UiSize::new(measured_width.max(0.0), measured_height.max(0.0)),

lib/ui/src/tree.rs

@@ -244,6 +244,7 @@ enum ElementContent {
 pub(crate) struct TextNode {
     pub spans: Vec<TextSpan>,
     pub style: TextStyle,
+    content_hash: u64,
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -281,12 +282,14 @@ impl Element {
     }
 
     pub fn spans(spans: impl IntoIterator<Item = TextSpan>, style: TextStyle) -> Self {
+        let spans = spans.into_iter().collect::<Vec<_>>();
         Self {
             id: None,
             style: Style::default(),
             children: Vec::new(),
             content: ElementContent::Text(TextNode {
-                spans: spans.into_iter().collect(),
+                content_hash: text_node_content_hash(&spans, &style),
+                spans,
                 style,
             }),
         }
@@ -599,8 +602,7 @@ impl Hash for Style {
 
 impl Hash for TextNode {
     fn hash<H: Hasher>(&self, state: &mut H) {
-        self.spans.hash(state);
-        self.style.hash(state);
+        self.content_hash.hash(state);
     }
 }
 
@@ -611,6 +613,15 @@ impl Hash for ImageNode {
     }
 }
 
+fn text_node_content_hash(spans: &[TextSpan], style: &TextStyle) -> u64 {
+    use std::hash::DefaultHasher;
+
+    let mut hasher = DefaultHasher::new();
+    spans.hash(&mut hasher);
+    style.hash(&mut hasher);
+    hasher.finish()
+}
+
 impl Hash for ScrollBoxNode {
     fn hash<H: Hasher>(&self, state: &mut H) {
         self.offset_y.to_bits().hash(state);

lib/ui_platform_macos/Cargo.toml

@@ -4,6 +4,12 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+ruin_ui = { path = "../ui" }
+ruin_ui_renderer_wgpu = { path = "../ui_renderer_wgpu" }
+ruin_runtime = { package = "ruin-runtime", path = "../runtime" }
+tracing = "0.1"
+
+[target.'cfg(target_os = "macos")'.dependencies]
 libc = "0.2"
 objc2 = "0.6.4"
 objc2-core-foundation = "0.3.2"
@@ -11,7 +17,3 @@ objc2-foundation = "0.3.2"
 objc2-quartz-core = "0.3.2"
 raw-window-handle = "0.6"
 raw-window-metal = "1.1.0"
-ruin_ui = { path = "../ui" }
-ruin_ui_renderer_wgpu = { path = "../ui_renderer_wgpu" }
-ruin_runtime = { package = "ruin-runtime", path = "../runtime" }
-tracing = "0.1"

lib/ui_platform_macos/src/lib.rs

@@ -2,6 +2,8 @@
 //!
 //! Native backend implemented on top of Cocoa/AppKit runtime messaging.
 
+#![cfg(target_os = "macos")]
+
 use std::cell::{Cell, RefCell};
 use std::collections::BTreeMap;
 use std::ffi::{CStr, CString, c_void};
@@ -353,9 +355,7 @@ impl ResizePipeline {
     }
 
     fn note_presented_scene(&mut self, scene_viewport: UiSize) -> Option<WindowConfigured> {
-        let Some(presented_configuration) = self.active_resize else {
-            return None;
-        };
+        let presented_configuration = self.active_resize?;
         if presented_configuration.actual_inner_size != scene_viewport {
             return None;
         }
@@ -365,9 +365,7 @@ impl ResizePipeline {
             self.next_resize = None;
         }
 
-        let Some(next_resize) = self.next_resize.take() else {
-            return None;
-        };
+        let next_resize = self.next_resize.take()?;
         self.active_resize = Some(next_resize);
         Some(next_resize)
     }

lib/ui_platform_wayland/Cargo.toml

@@ -4,12 +4,14 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-libc = "0.2"
-raw-window-handle = "0.6"
 ruin_runtime = { package = "ruin-runtime", path = "../runtime" }
 ruin_ui = { path = "../ui" }
 ruin_ui_renderer_wgpu = { path = "../ui_renderer_wgpu" }
 tracing = "0.1"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+libc = "0.2"
+raw-window-handle = "0.6"
 wayland-backend = { version = "0.3", features = ["client_system"] }
 wayland-client = "0.31"
 wayland-protocols = { version = "0.32", features = ["client", "staging", "unstable"] }

lib/ui_platform_wayland/src/lib.rs

@@ -1,3 +1,5 @@
+#![cfg(target_os = "linux")]
+
 use std::cell::RefCell;
 use std::collections::BTreeMap;
 use std::error::Error;

lib/ui_renderer_wgpu/src/lib.rs

@@ -169,22 +169,12 @@ struct UploadedAtlasText {
 
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 struct TextTextureKey {
-    text: String,
+    layout_key: u64,
     bounds: Option<(i32, i32)>,
     clip: Option<(i32, i32, i32, i32)>,
     font_size_bits: u32,
     line_height_bits: u32,
     color: (u8, u8, u8, u8),
-    glyphs: Vec<TextTextureGlyph>,
-}
-
-#[derive(Clone, Debug, Eq, Hash, PartialEq)]
-struct TextTextureGlyph {
-    local_x_bits: u32,
-    local_y_bits: u32,
-    advance_bits: u32,
-    color: (u8, u8, u8, u8),
-    cache_key: Option<CacheKey>,
 }
 
 const VERTEX_ATTRIBUTES: [wgpu::VertexAttribute; 11] = [
@@ -315,6 +305,21 @@ pub enum RenderError {
     Validation,
 }
 
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+pub struct RendererFrameStats {
+    pub scene_version: u64,
+    pub scene_items: usize,
+    pub quad_vertices: usize,
+    pub image_batches: usize,
+    pub atlas_text_vertices: u32,
+    pub fallback_text_batches: usize,
+    pub fallback_text_vertices: u32,
+    pub atlas_glyphs_total: u32,
+    pub atlas_glyphs_clip_culled: u32,
+    pub text_prepare_ms: f64,
+    pub render_ms: f64,
+}
+
 pub struct WgpuSceneRenderer {
     surface: wgpu::Surface<'static>,
     device: wgpu::Device,
@@ -334,6 +339,7 @@ pub struct WgpuSceneRenderer {
     glyph_atlas: GlyphAtlas,
     scale_factor: f32,
     base_color: Color,
+    last_frame_stats: RendererFrameStats,
 }
 
 const MAX_TEXT_CACHE_ENTRIES: usize = 64;
@@ -729,6 +735,7 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
             glyph_atlas,
             scale_factor: 1.0,
             base_color,
+            last_frame_stats: RendererFrameStats::default(),
         })
     }
 
@@ -758,6 +765,10 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
         );
     }
 
+    pub fn last_frame_stats(&self) -> RendererFrameStats {
+        self.last_frame_stats
+    }
+
     pub fn render(&mut self, scene: &SceneSnapshot) -> Result<(), RenderError> {
         self.render_with_logical_size(scene, scene.logical_size)
     }
@@ -885,19 +896,34 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
         }
         self.queue.submit([encoder.finish()]);
         frame.present();
-        trace!(
-            target: "ruin_ui_renderer_wgpu::perf",
-            scene_version = scene.version,
-            quad_vertices = vertices.len(),
-            image_batches = uploaded_images.len(),
-            atlas_text_vertices = uploaded_atlas_text
+        self.last_frame_stats = RendererFrameStats {
+            scene_version: scene.version,
+            scene_items: scene.items.len(),
+            quad_vertices: vertices.len(),
+            image_batches: uploaded_images.len(),
+            atlas_text_vertices: uploaded_atlas_text
                 .as_ref()
                 .map_or(0_u32, |text| text.vertex_count),
-            fallback_text_batches = uploaded_texts.len(),
-            atlas_glyphs_total = atlas_perf.glyphs_total,
-            atlas_glyphs_clip_culled = atlas_perf.glyphs_clip_culled,
-            text_prepare_ms = text_prepare_ms,
-            render_ms = render_start.elapsed().as_secs_f64() * 1_000.0,
+            fallback_text_batches: uploaded_texts.len(),
+            fallback_text_vertices: uploaded_texts.iter().map(|text| text.vertex_count).sum(),
+            atlas_glyphs_total: atlas_perf.glyphs_total,
+            atlas_glyphs_clip_culled: atlas_perf.glyphs_clip_culled,
+            text_prepare_ms,
+            render_ms: render_start.elapsed().as_secs_f64() * 1_000.0,
+        };
+        trace!(
+            target: "ruin_ui_renderer_wgpu::perf",
+            scene_version = self.last_frame_stats.scene_version,
+            scene_items = self.last_frame_stats.scene_items,
+            quad_vertices = self.last_frame_stats.quad_vertices,
+            image_batches = self.last_frame_stats.image_batches,
+            atlas_text_vertices = self.last_frame_stats.atlas_text_vertices,
+            fallback_text_batches = self.last_frame_stats.fallback_text_batches,
+            fallback_text_vertices = self.last_frame_stats.fallback_text_vertices,
+            atlas_glyphs_total = self.last_frame_stats.atlas_glyphs_total,
+            atlas_glyphs_clip_culled = self.last_frame_stats.atlas_glyphs_clip_culled,
+            text_prepare_ms = self.last_frame_stats.text_prepare_ms,
+            render_ms = self.last_frame_stats.render_ms,
             "rendered scene"
         );
         Ok(())
@@ -908,10 +934,8 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
         text: &PreparedText,
         raster_clip: Option<Rect>,
     ) -> Option<RasterizedText> {
-        if (self.scale_factor - 1.0).abs() <= f32::EPSILON
-            && text.glyphs.iter().all(|glyph| glyph.cache_key.is_some())
-        {
-            return self.rasterize_prepared_text(text, raster_clip);
+        if text.glyphs.iter().all(|glyph| glyph.cache_key.is_some()) {
+            return self.rasterize_prepared_text(text, raster_clip, self.scale_factor);
         }
 
         let clip = raster_clip.map(|clip| scale_rect_to_pixel_rect(clip, self.scale_factor));
@@ -953,16 +977,18 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
         &mut self,
         text: &PreparedText,
         raster_clip: Option<Rect>,
+        scale_factor: f32,
     ) -> Option<RasterizedText> {
-        let glyphs = self.collect_prepared_glyphs(text);
+        let clip = raster_clip.map(|clip| scale_rect_to_pixel_rect(clip, scale_factor));
+        let glyphs = self.collect_prepared_glyphs(text, raster_clip, clip, scale_factor);
         let clip = raster_clip
-            .map(rect_to_pixel_rect)
+            .map(|clip| scale_rect_to_pixel_rect(clip, scale_factor))
             .or_else(|| {
                 text.bounds.map(|bounds| PixelRect {
                     left: 0,
                     top: 0,
-                    right: bounds.width.ceil() as i32,
-                    bottom: bounds.height.ceil() as i32,
+                    right: (bounds.width * scale_factor).ceil() as i32,
+                    bottom: (bounds.height * scale_factor).ceil() as i32,
                 })
             })
             .or_else(|| glyph_union_prepared(&glyphs))?;
@@ -983,17 +1009,41 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
         }
 
         Some(RasterizedText {
-            origin_offset: Point::new(clip.left as f32, clip.top as f32),
-            draw_size: UiSize::new(clip.width() as f32, clip.height() as f32),
+            origin_offset: Point::new(
+                clip.left as f32 / scale_factor,
+                clip.top as f32 / scale_factor,
+            ),
+            draw_size: UiSize::new(
+                clip.width() as f32 / scale_factor,
+                clip.height() as f32 / scale_factor,
+            ),
             texture_size: UiSize::new(clip.width() as f32, clip.height() as f32),
             pixels,
         })
     }
 
-    fn collect_prepared_glyphs(&mut self, text: &PreparedText) -> Vec<PreparedGlyphBitmap> {
-        let mut glyphs = Vec::with_capacity(text.glyphs.len());
-        for glyph in &text.glyphs {
-            let Some(cache_key) = glyph.cache_key else {
+    fn collect_prepared_glyphs(
+        &mut self,
+        text: &PreparedText,
+        logical_clip: Option<Rect>,
+        pixel_clip: Option<PixelRect>,
+        scale_factor: f32,
+    ) -> Vec<PreparedGlyphBitmap> {
+        let absolute_clip = logical_clip.map(|clip| {
+            Rect::new(
+                text.origin.x + clip.origin.x,
+                text.origin.y + clip.origin.y,
+                clip.size.width,
+                clip.size.height,
+            )
+        });
+        let visible_glyphs = clip_visible_glyphs(text, absolute_clip);
+        let mut glyphs = Vec::with_capacity(visible_glyphs.len());
+        for glyph in visible_glyphs {
+            let Some(cache_key) = glyph
+                .cache_key
+                .map(|cache_key| scale_glyph_cache_key(cache_key, scale_factor))
+            else {
                 continue;
             };
             let Some(image) = self
@@ -1010,15 +1060,19 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
             }
 
             // Glyph positions are LOCAL (origin-relative); no subtraction needed.
-            let local_x = glyph.position.x.round() as i32;
-            let local_y = glyph.position.y.round() as i32;
-            glyphs.push(PreparedGlyphBitmap {
-                rect: PixelRect {
+            let local_x = (glyph.position.x * scale_factor).round() as i32;
+            let local_y = (glyph.position.y * scale_factor).round() as i32;
+            let rect = PixelRect {
                 left: local_x + image.placement.left,
                 top: local_y - image.placement.top,
                 right: local_x + image.placement.left + width,
                 bottom: local_y - image.placement.top + height,
-                },
+            };
+            if pixel_clip.is_some_and(|clip| !pixel_rects_intersect(rect, clip)) {
+                continue;
+            }
+            glyphs.push(PreparedGlyphBitmap {
+                rect,
                 cache_key,
                 color: resolve_glyph_color(glyph.color, text.default_color),
             });
@@ -1046,6 +1100,13 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
 
         let mut glyphs = Vec::new();
         for run in buffer.layout_runs() {
+            if let Some(clip) = raster_clip {
+                let line_top = run.line_top.floor() as i32;
+                let line_bottom = (run.line_top + run.line_height).ceil() as i32;
+                if line_bottom < clip.top || line_top > clip.bottom {
+                    continue;
+                }
+            }
             for glyph in run.glyphs {
                 let physical = glyph.physical((0.0, run.line_y), 1.0);
                 let Some(image) = self
@@ -1163,10 +1224,12 @@ fn fs_main(input: VertexOut) -> @location(0) vec4<f32> {
                             glyph_rect,
                             atlas_glyph.atlas_rect,
                             clip_rect,
+                            GlyphVertexContext {
                                 logical_size,
-                            self.scale_factor,
-                            resolved_color,
-                            active_clip,
+                                scale_factor: self.scale_factor,
+                                color: resolved_color,
+                                clip: active_clip,
+                            },
                         );
                     }
                 }
@@ -1888,34 +1951,40 @@ fn build_textured_vertices(
     ])
 }
 
+#[allow(dead_code)]
+#[derive(Clone, Copy)]
+struct GlyphVertexContext {
+    logical_size: UiSize,
+    scale_factor: f32,
+    color: Color,
+    clip: ActiveClip,
+}
+
 #[allow(dead_code)]
 fn push_glyph_vertices(
     vertices: &mut Vec<TextVertex>,
     glyph_rect: PixelRect,
     atlas_rect: AtlasRect,
     clip_rect: Option<PixelRect>,
-    logical_size: UiSize,
-    scale_factor: f32,
-    color: Color,
-    clip: ActiveClip,
+    context: GlyphVertexContext,
 ) {
     let Some((dest_rect, uv_rect)) = clipped_glyph_quad(glyph_rect, atlas_rect, clip_rect) else {
         return;
     };
 
-    let scale_factor = scale_factor.max(1.0);
+    let scale_factor = context.scale_factor.max(1.0);
     let logical_left = dest_rect.left as f32 / scale_factor;
     let logical_top = dest_rect.top as f32 / scale_factor;
     let logical_right = dest_rect.right as f32 / scale_factor;
     let logical_bottom = dest_rect.bottom as f32 / scale_factor;
-    let left = to_ndc_x(logical_left, logical_size.width.max(1.0));
-    let right = to_ndc_x(logical_right, logical_size.width.max(1.0));
-    let top = to_ndc_y(logical_top, logical_size.height.max(1.0));
-    let bottom = to_ndc_y(logical_bottom, logical_size.height.max(1.0));
+    let left = to_ndc_x(logical_left, context.logical_size.width.max(1.0));
+    let right = to_ndc_x(logical_right, context.logical_size.width.max(1.0));
+    let top = to_ndc_y(logical_top, context.logical_size.height.max(1.0));
+    let bottom = to_ndc_y(logical_bottom, context.logical_size.height.max(1.0));
 
-    let color = color_to_f32(color);
-    let clip_rect = clip_rect_array(clip);
-    let (rounded_clip_rect, clip_params) = rounded_clip_arrays(clip);
+    let color = color_to_f32(context.color);
+    let clip_rect = clip_rect_array(context.clip);
+    let (rounded_clip_rect, clip_params) = rounded_clip_arrays(context.clip);
     vertices.extend_from_slice(&[
         TextVertex {
             position: [left, top],
@@ -2238,15 +2307,6 @@ fn expand_rect(rect: Rect, inset: f32) -> Rect {
     )
 }
 
-fn rect_to_pixel_rect(rect: Rect) -> PixelRect {
-    PixelRect {
-        left: rect.origin.x.floor() as i32,
-        top: rect.origin.y.floor() as i32,
-        right: (rect.origin.x + rect.size.width).ceil() as i32,
-        bottom: (rect.origin.y + rect.size.height).ceil() as i32,
-    }
-}
-
 fn scale_rect_to_pixel_rect(rect: Rect, scale: f32) -> PixelRect {
     PixelRect {
         left: (rect.origin.x * scale).floor() as i32,
@@ -2335,9 +2395,7 @@ fn text_raster_clip(
         let text_bounds = Rect::new(text.origin.x, text.origin.y, bounds.width, bounds.height);
         absolute_clip = intersect_rects(absolute_clip, Some(text_bounds));
     }
-    if absolute_clip.is_none() {
-        return None;
-    }
+    absolute_clip?;
 
     Some(absolute_clip.map(|rect| {
         Rect::new(
@@ -2458,7 +2516,7 @@ fn clip_visible_glyphs(text: &PreparedText, clip: Option<Rect>) -> &[GlyphInstan
     let local_bottom = local_top + clip.size.height;
 
     // First line whose bottom edge reaches or passes the clip top.
-    let start = lines.partition_point(|l| l.rect.origin.y + l.rect.size.height < local_top);
+    let start = lines.partition_point(|l| l.rect.origin.y + l.rect.size.height <= local_top);
     // First line whose top edge is strictly past the clip bottom.
     let end = lines.partition_point(|l| l.rect.origin.y <= local_bottom);
 
@@ -2477,7 +2535,7 @@ fn text_texture_key(
     scale_factor: f32,
 ) -> TextTextureKey {
     TextTextureKey {
-        text: text.text.clone(),
+        layout_key: text.layout_cache_key(),
         bounds: text.bounds.map(|bounds| {
             (
                 (bounds.width * scale_factor).ceil() as i32,
@@ -2494,18 +2552,6 @@ fn text_texture_key(
             text.default_color.b,
             text.default_color.a,
         ),
-        glyphs: text
-            .glyphs
-            .iter()
-            .map(|glyph| TextTextureGlyph {
-                // Glyph positions are already LOCAL; no subtraction needed.
-                local_x_bits: glyph.position.x.to_bits(),
-                local_y_bits: glyph.position.y.to_bits(),
-                advance_bits: glyph.advance.to_bits(),
-                color: (glyph.color.r, glyph.color.g, glyph.color.b, glyph.color.a),
-                cache_key: glyph.cache_key,
-            })
-            .collect(),
     }
 }
 
@@ -2524,12 +2570,15 @@ fn scale_glyph_cache_key(cache_key: CacheKey, scale_factor: f32) -> CacheKey {
 #[cfg(test)]
 mod tests {
     use super::{
-        ActiveClip, AtlasRect, PixelRect, blend_rgba, build_text_vertices, build_vertices,
-        clip_rect_array, push_clip_state, push_glyph_vertices, rounded_clip_arrays,
-        scale_glyph_cache_key, text_texture_key,
+        ActiveClip, AtlasRect, GlyphVertexContext, PixelRect, blend_rgba, build_text_vertices,
+        build_vertices, clip_rect_array, clip_visible_glyphs, push_clip_state, push_glyph_vertices,
+        rounded_clip_arrays, scale_glyph_cache_key, text_texture_key,
     };
     use cosmic_text::{CacheKey, CacheKeyFlags, SubpixelBin, fontdb};
-    use ruin_ui::{ClipRegion, Color, Point, PreparedText, Rect, SceneSnapshot, UiSize};
+    use ruin_ui::{
+        ClipRegion, Color, Point, PreparedText, Rect, SceneSnapshot, TextStyle, TextSystem,
+        TextWrap, UiSize,
+    };
 
     #[test]
     fn quad_scenes_expand_to_six_vertices_per_quad() {
@@ -2607,6 +2656,20 @@ mod tests {
         assert_ne!(first, different_pixel);
     }
 
+    #[test]
+    fn clip_visible_glyphs_returns_only_lines_intersecting_clip() {
+        let mut text_system = TextSystem::new();
+        let style = TextStyle::new(16.0, Color::rgb(0xEE, 0xEE, 0xEE))
+            .with_wrap(TextWrap::None)
+            .with_line_height(20.0);
+        let text = text_system.prepare("abcd\nefgh", Point::new(10.0, 20.0), &style);
+        let visible = clip_visible_glyphs(&text, Some(Rect::new(10.0, 40.0, 100.0, 20.0)));
+
+        assert_eq!(visible.len(), 4);
+        assert_eq!(visible[0].text_start, 5);
+        assert_eq!(visible[3].text_end, 9);
+    }
+
     #[test]
     fn scale_glyph_cache_key_scales_font_size_only() {
         let key = CacheKey {
@@ -2648,10 +2711,12 @@ mod tests {
                 height: 20,
             },
             None,
-            UiSize::new(100.0, 100.0),
-            2.0,
-            Color::rgb(0xFF, 0xFF, 0xFF),
-            ActiveClip::default(),
+            GlyphVertexContext {
+                logical_size: UiSize::new(100.0, 100.0),
+                scale_factor: 2.0,
+                color: Color::rgb(0xFF, 0xFF, 0xFF),
+                clip: ActiveClip::default(),
+            },
         );
 
         assert_eq!(vertices.len(), 6);