Optimize editing long text by caching each paragraph

Cargo.lock

@@ -642,6 +642,17 @@ dependencies = [
  "piper",
 ]
 
+[[package]]
+name = "bstr"
+version = "1.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "531a9155a481e2ee699d4f98f43c0ca4ff8ee1bfd55c31e9e98fb29d2b176fe0"
+dependencies = [
+ "memchr",
+ "regex-automata",
+ "serde",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.16.0"
@@ -896,6 +907,18 @@ dependencies = [
  "env_logger",
 ]
 
+[[package]]
+name = "console"
+version = "0.15.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "054ccb5b10f9f2cbf51eb355ca1d05c2d279ce1804688d0db74b4733a5aeafd8"
+dependencies = [
+ "encode_unicode",
+ "libc",
+ "once_cell",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "core-foundation"
 version = "0.9.4"
@@ -1331,6 +1354,7 @@ dependencies = [
  "egui",
  "egui_extras",
  "egui_kittest",
+ "rand",
  "serde",
  "unicode_names2",
 ]
@@ -1420,6 +1444,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "encode_unicode"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34aa73646ffb006b8f5147f3dc182bd4bcb190227ce861fc4a4844bf8e3cb2c0"
+
 [[package]]
 name = "endi"
 version = "1.1.0"
@@ -1520,6 +1550,7 @@ dependencies = [
  "profiling",
  "rayon",
  "serde",
+ "similar-asserts",
 ]
 
 [[package]]
@@ -2389,7 +2420,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4979f22fdb869068da03c9f7528f8297c6fd2606bc3a4affe42e6a823fdb8da4"
 dependencies = [
  "cfg-if",
- "windows-targets 0.48.5",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -3669,6 +3700,26 @@ version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d66dc143e6b11c1eddc06d5c423cfc97062865baf299914ab64caa38182078fe"
 
+[[package]]
+name = "similar"
+version = "2.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbbb5d9659141646ae647b42fe094daf6c6192d1620870b449d9557f748b2daa"
+dependencies = [
+ "bstr",
+ "unicode-segmentation",
+]
+
+[[package]]
+name = "similar-asserts"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5b441962c817e33508847a22bd82f03a30cff43642dc2fae8b050566121eb9a"
+dependencies = [
+ "console",
+ "similar",
+]
+
 [[package]]
 name = "simplecss"
 version = "0.2.1"

Cargo.toml

@@ -96,6 +96,7 @@ puffin_http = "0.16"
 raw-window-handle = "0.6.0"
 ron = "0.8"
 serde = { version = "1", features = ["derive"] }
+similar-asserts = "1.4.2"
 thiserror = "1.0.37"
 type-map = "0.5.0"
 wasm-bindgen = "0.2"

crates/egui/src/text_selection/accesskit_text.rs

@@ -45,7 +45,7 @@ pub fn update_accesskit_for_text_widget(
             let row_id = parent_id.with(row_index);
             ctx.accesskit_node_builder(row_id, |builder| {
                 builder.set_role(accesskit::Role::TextRun);
-                let rect = global_from_galley * row.rect;
+                let rect = global_from_galley * row.rect();
                 builder.set_bounds(accesskit::Rect {
                     x0: rect.min.x.into(),
                     y0: rect.min.y.into(),
@@ -76,14 +76,14 @@ pub fn update_accesskit_for_text_widget(
                     let old_len = value.len();
                     value.push(glyph.chr);
                     character_lengths.push((value.len() - old_len) as _);
-                    character_positions.push(glyph.pos.x - row.rect.min.x);
+                    character_positions.push(glyph.pos.x - row.pos.x);
                     character_widths.push(glyph.advance_width);
                 }
 
                 if row.ends_with_newline {
                     value.push('\n');
                     character_lengths.push(1);
-                    character_positions.push(row.rect.max.x - row.rect.min.x);
+                    character_positions.push(row.size.x);
                     character_widths.push(0.0);
                 }
                 word_lengths.push((character_lengths.len() - last_word_start) as _);

crates/egui/src/text_selection/label_text_selection.rs

@@ -186,7 +186,10 @@ impl LabelSelectionState {
                                 if let epaint::Shape::Text(text_shape) = &mut shape.shape {
                                     let galley = Arc::make_mut(&mut text_shape.galley);
                                     for row_selection in row_selections {
-                                        if let Some(row) = galley.rows.get_mut(row_selection.row) {
+                                        if let Some(placed_row) =
+                                            galley.rows.get_mut(row_selection.row)
+                                        {
+                                            let row = Arc::make_mut(&mut placed_row.row);
                                             for vertex_index in row_selection.vertex_indices {
                                                 if let Some(vertex) = row
                                                     .visuals
@@ -701,8 +704,8 @@ fn selected_text(galley: &Galley, cursor_range: &CCursorRange) -> String {
 }
 
 fn estimate_row_height(galley: &Galley) -> f32 {
-    if let Some(row) = galley.rows.first() {
-        row.rect.height()
+    if let Some(placed_row) = galley.rows.first() {
+        placed_row.height()
     } else {
         galley.size().y
     }

crates/egui/src/text_selection/visuals.rs

@@ -31,11 +31,12 @@ pub fn paint_text_selection(
     let max = galley.layout_from_cursor(max);
 
     for ri in min.row..=max.row {
-        let row = &mut galley.rows[ri];
+        let row = Arc::make_mut(&mut galley.rows[ri].row);
+
         let left = if ri == min.row {
             row.x_offset(min.column)
         } else {
-            row.rect.left()
+            0.0
         };
         let right = if ri == max.row {
             row.x_offset(max.column)
@@ -45,10 +46,10 @@ pub fn paint_text_selection(
             } else {
                 0.0
             };
-            row.rect.right() + newline_size
+            row.size.x + newline_size
         };
 
-        let rect = Rect::from_min_max(pos2(left, row.min_y()), pos2(right, row.max_y()));
+        let rect = Rect::from_min_max(pos2(left, 0.0), pos2(right, row.size.y));
         let mesh = &mut row.visuals.mesh;
 
         // Time to insert the selection rectangle into the row mesh.

crates/egui/src/widget_text.rs

@@ -671,8 +671,8 @@ impl WidgetText {
             Self::RichText(text) => text.font_height(fonts, style),
             Self::LayoutJob(job) => job.font_height(fonts),
             Self::Galley(galley) => {
-                if let Some(row) = galley.rows.first() {
-                    row.height().round_ui()
+                if let Some(placed_row) = galley.rows.first() {
+                    placed_row.height().round_ui()
                 } else {
                     galley.size().y.round_ui()
                 }

crates/egui/src/widgets/label.rs

@@ -1,8 +1,8 @@
 use std::sync::Arc;
 
 use crate::{
-    epaint, pos2, text_selection, vec2, Align, Direction, FontSelection, Galley, Pos2, Response,
-    Sense, Stroke, TextWrapMode, Ui, Widget, WidgetInfo, WidgetText, WidgetType,
+    epaint, pos2, text_selection, Align, Direction, FontSelection, Galley, Pos2, Response, Sense,
+    Stroke, TextWrapMode, Ui, Widget, WidgetInfo, WidgetText, WidgetType,
 };
 
 use self::text_selection::LabelSelectionState;
@@ -216,10 +216,10 @@ impl Label {
             let pos = pos2(ui.max_rect().left(), ui.cursor().top());
             assert!(!galley.rows.is_empty(), "Galleys are never empty");
             // collect a response from many rows:
-            let rect = galley.rows[0].rect.translate(vec2(pos.x, pos.y));
+            let rect = galley.rows[0].rect().translate(pos.to_vec2());
             let mut response = ui.allocate_rect(rect, sense);
-            for row in galley.rows.iter().skip(1) {
-                let rect = row.rect.translate(vec2(pos.x, pos.y));
+            for placed_row in galley.rows.iter().skip(1) {
+                let rect = placed_row.rect().translate(pos.to_vec2());
                 response |= ui.allocate_rect(rect, sense);
             }
             (pos, galley, response)

crates/egui_demo_lib/Cargo.toml

@@ -58,6 +58,7 @@ serde = { workspace = true, optional = true }
 criterion.workspace = true
 egui_kittest = { workspace = true, features = ["wgpu", "snapshot"] }
 egui = { workspace = true, features = ["default_fonts"] }
+rand = "0.9"
 
 [[bench]]
 name = "benchmark"

crates/egui_demo_lib/benches/benchmark.rs

@@ -1,7 +1,10 @@
+use std::fmt::Write as _;
+
 use criterion::{criterion_group, criterion_main, Criterion};
 
 use egui::epaint::TextShape;
 use egui_demo_lib::LOREM_IPSUM_LONG;
+use rand::Rng as _;
 
 pub fn criterion_benchmark(c: &mut Criterion) {
     use egui::RawInput;
@@ -128,6 +131,30 @@ pub fn criterion_benchmark(c: &mut Criterion) {
             });
         });
 
+        c.bench_function("text_layout_cached_many_lines_modified", |b| {
+            const NUM_LINES: usize = 2_000;
+
+            let mut string = String::new();
+            for _ in 0..NUM_LINES {
+                for i in 0..30_u8 {
+                    write!(string, "{i:02X} ").unwrap();
+                }
+                string.push('\n');
+            }
+
+            let mut rng = rand::rng();
+            b.iter(|| {
+                fonts.begin_pass(pixels_per_point, max_texture_side);
+
+                // Delete a random character, simulating a user making an edit in a long file:
+                let mut new_string = string.clone();
+                let idx = rng.random_range(0..string.len());
+                new_string.remove(idx);
+
+                fonts.layout(new_string, font_id.clone(), text_color, wrap_width);
+            });
+        });
+
         let galley = fonts.layout(LOREM_IPSUM_LONG.to_owned(), font_id, text_color, wrap_width);
         let font_image_size = fonts.font_image_size();
         let prepared_discs = fonts.texture_atlas().lock().prepared_discs();

crates/emath/src/pos2.rs

@@ -1,5 +1,7 @@
-use std::fmt;
-use std::ops::{Add, AddAssign, Sub, SubAssign};
+use std::{
+    fmt,
+    ops::{Add, AddAssign, MulAssign, Sub, SubAssign},
+};
 
 use crate::{lerp, Div, Mul, Vec2};
 
@@ -305,6 +307,14 @@ impl Mul<Pos2> for f32 {
     }
 }
 
+impl MulAssign<f32> for Pos2 {
+    #[inline(always)]
+    fn mul_assign(&mut self, rhs: f32) {
+        self.x *= rhs;
+        self.y *= rhs;
+    }
+}
+
 impl Div<f32> for Pos2 {
     type Output = Self;
 

crates/emath/src/rect.rs

@@ -710,7 +710,11 @@ impl Rect {
 
 impl fmt::Debug for Rect {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "[{:?} - {:?}]", self.min, self.max)
+        if let Some(precision) = f.precision() {
+            write!(f, "[{1:.0$?} - {2:.0$?}]", precision, self.min, self.max)
+        } else {
+            write!(f, "[{:?} - {:?}]", self.min, self.max)
+        }
     }
 }
 

crates/epaint/Cargo.toml

@@ -101,6 +101,7 @@ backtrace = { workspace = true, optional = true }
 
 [dev-dependencies]
 criterion.workspace = true
+similar-asserts.workspace = true
 
 
 [[bench]]

crates/epaint/src/shape_transform.rs

@@ -89,7 +89,8 @@ pub fn adjust_colors(
 
             if !galley.is_empty() {
                 let galley = Arc::make_mut(galley);
-                for row in &mut galley.rows {
+                for placed_row in &mut galley.rows {
+                    let row = Arc::make_mut(&mut placed_row.row);
                     for vertex in &mut row.visuals.mesh.vertices {
                         adjust_color(&mut vertex.color);
                     }

crates/epaint/src/shapes/shape.rs

@@ -456,39 +456,7 @@ impl Shape {
                 rect_shape.blur_width *= transform.scaling;
             }
             Self::Text(text_shape) => {
-                let TextShape {
-                    pos,
-                    galley,
-                    underline,
-                    fallback_color: _,
-                    override_text_color: _,
-                    opacity_factor: _,
-                    angle: _,
-                } = text_shape;
-
-                *pos = transform * *pos;
-                underline.width *= transform.scaling;
-
-                let Galley {
-                    job: _,
-                    rows,
-                    elided: _,
-                    rect,
-                    mesh_bounds,
-                    num_vertices: _,
-                    num_indices: _,
-                    pixels_per_point: _,
-                } = Arc::make_mut(galley);
-
-                for row in rows {
-                    row.visuals.mesh_bounds = transform.scaling * row.visuals.mesh_bounds;
-                    for v in &mut row.visuals.mesh.vertices {
-                        v.pos = Pos2::new(transform.scaling * v.pos.x, transform.scaling * v.pos.y);
-                    }
-                }
-
-                *mesh_bounds = transform.scaling * *mesh_bounds;
-                *rect = transform.scaling * *rect;
+                text_shape.transform(transform);
             }
             Self::Mesh(mesh) => {
                 Arc::make_mut(mesh).transform(transform);