element.rs

   1use super::{
   2    display_map::{BlockContext, ToDisplayPoint},
   3    Anchor, DisplayPoint, Editor, EditorMode, EditorSettings, EditorSnapshot, EditorStyle, Input,
   4    Scroll, Select, SelectPhase, SoftWrap, ToPoint, MAX_LINE_LEN,
   5};
   6use clock::ReplicaId;
   7use collections::{BTreeMap, HashMap};
   8use gpui::{
   9    color::Color,
  10    elements::layout_highlighted_chunks,
  11    fonts::{HighlightStyle, Underline},
  12    geometry::{
  13        rect::RectF,
  14        vector::{vec2f, Vector2F},
  15        PathBuilder,
  16    },
  17    json::{self, ToJson},
  18    keymap::Keystroke,
  19    text_layout::{self, RunStyle, TextLayoutCache},
  20    AppContext, Axis, Border, Element, ElementBox, Event, EventContext, LayoutContext,
  21    MutableAppContext, PaintContext, Quad, Scene, SizeConstraint, ViewContext, WeakViewHandle,
  22};
  23use json::json;
  24use language::Bias;
  25use smallvec::SmallVec;
  26use std::{
  27    cmp::{self, Ordering},
  28    fmt::Write,
  29    ops::Range,
  30};
  31
  32pub struct EditorElement {
  33    view: WeakViewHandle<Editor>,
  34    settings: EditorSettings,
  35}
  36
  37impl EditorElement {
  38    pub fn new(view: WeakViewHandle<Editor>, settings: EditorSettings) -> Self {
  39        Self { view, settings }
  40    }
  41
  42    fn view<'a>(&self, cx: &'a AppContext) -> &'a Editor {
  43        self.view.upgrade(cx).unwrap().read(cx)
  44    }
  45
  46    fn update_view<F, T>(&self, cx: &mut MutableAppContext, f: F) -> T
  47    where
  48        F: FnOnce(&mut Editor, &mut ViewContext<Editor>) -> T,
  49    {
  50        self.view.upgrade(cx).unwrap().update(cx, f)
  51    }
  52
  53    fn snapshot(&self, cx: &mut MutableAppContext) -> EditorSnapshot {
  54        self.update_view(cx, |view, cx| view.snapshot(cx))
  55    }
  56
  57    fn mouse_down(
  58        &self,
  59        position: Vector2F,
  60        alt: bool,
  61        shift: bool,
  62        mut click_count: usize,
  63        layout: &mut LayoutState,
  64        paint: &mut PaintState,
  65        cx: &mut EventContext,
  66    ) -> bool {
  67        if paint.gutter_bounds.contains_point(position) {
  68            click_count = 3; // Simulate triple-click when clicking the gutter to select lines
  69        } else if !paint.text_bounds.contains_point(position) {
  70            return false;
  71        }
  72
  73        let snapshot = self.snapshot(cx.app);
  74        let (position, overshoot) = paint.point_for_position(&snapshot, layout, position);
  75
  76        if shift && alt {
  77            cx.dispatch_action(Select(SelectPhase::BeginColumnar {
  78                position,
  79                overshoot,
  80            }));
  81        } else if shift {
  82            cx.dispatch_action(Select(SelectPhase::Extend {
  83                position,
  84                click_count,
  85            }));
  86        } else {
  87            cx.dispatch_action(Select(SelectPhase::Begin {
  88                position,
  89                add: alt,
  90                click_count,
  91            }));
  92        }
  93
  94        true
  95    }
  96
  97    fn mouse_up(&self, _position: Vector2F, cx: &mut EventContext) -> bool {
  98        if self.view(cx.app.as_ref()).is_selecting() {
  99            cx.dispatch_action(Select(SelectPhase::End));
 100            true
 101        } else {
 102            false
 103        }
 104    }
 105
 106    fn mouse_dragged(
 107        &self,
 108        position: Vector2F,
 109        layout: &mut LayoutState,
 110        paint: &mut PaintState,
 111        cx: &mut EventContext,
 112    ) -> bool {
 113        let view = self.view(cx.app.as_ref());
 114
 115        if view.is_selecting() {
 116            let rect = paint.text_bounds;
 117            let mut scroll_delta = Vector2F::zero();
 118
 119            let vertical_margin = layout.line_height.min(rect.height() / 3.0);
 120            let top = rect.origin_y() + vertical_margin;
 121            let bottom = rect.lower_left().y() - vertical_margin;
 122            if position.y() < top {
 123                scroll_delta.set_y(-scale_vertical_mouse_autoscroll_delta(top - position.y()))
 124            }
 125            if position.y() > bottom {
 126                scroll_delta.set_y(scale_vertical_mouse_autoscroll_delta(position.y() - bottom))
 127            }
 128
 129            let horizontal_margin = layout.line_height.min(rect.width() / 3.0);
 130            let left = rect.origin_x() + horizontal_margin;
 131            let right = rect.upper_right().x() - horizontal_margin;
 132            if position.x() < left {
 133                scroll_delta.set_x(-scale_horizontal_mouse_autoscroll_delta(
 134                    left - position.x(),
 135                ))
 136            }
 137            if position.x() > right {
 138                scroll_delta.set_x(scale_horizontal_mouse_autoscroll_delta(
 139                    position.x() - right,
 140                ))
 141            }
 142
 143            let snapshot = self.snapshot(cx.app);
 144            let (position, overshoot) = paint.point_for_position(&snapshot, layout, position);
 145
 146            cx.dispatch_action(Select(SelectPhase::Update {
 147                position,
 148                overshoot,
 149                scroll_position: (snapshot.scroll_position() + scroll_delta)
 150                    .clamp(Vector2F::zero(), layout.scroll_max),
 151            }));
 152            true
 153        } else {
 154            false
 155        }
 156    }
 157
 158    fn key_down(&self, chars: &str, keystroke: &Keystroke, cx: &mut EventContext) -> bool {
 159        let view = self.view.upgrade(cx.app).unwrap();
 160
 161        if view.is_focused(cx.app) {
 162            if chars.is_empty() {
 163                false
 164            } else {
 165                if chars.chars().any(|c| c.is_control()) || keystroke.cmd || keystroke.ctrl {
 166                    false
 167                } else {
 168                    cx.dispatch_action(Input(chars.to_string()));
 169                    true
 170                }
 171            }
 172        } else {
 173            false
 174        }
 175    }
 176
 177    fn scroll(
 178        &self,
 179        position: Vector2F,
 180        mut delta: Vector2F,
 181        precise: bool,
 182        layout: &mut LayoutState,
 183        paint: &mut PaintState,
 184        cx: &mut EventContext,
 185    ) -> bool {
 186        if !paint.bounds.contains_point(position) {
 187            return false;
 188        }
 189
 190        let snapshot = self.snapshot(cx.app);
 191        let max_glyph_width = layout.em_width;
 192        if !precise {
 193            delta *= vec2f(max_glyph_width, layout.line_height);
 194        }
 195
 196        let scroll_position = snapshot.scroll_position();
 197        let x = (scroll_position.x() * max_glyph_width - delta.x()) / max_glyph_width;
 198        let y = (scroll_position.y() * layout.line_height - delta.y()) / layout.line_height;
 199        let scroll_position = vec2f(x, y).clamp(Vector2F::zero(), layout.scroll_max);
 200
 201        cx.dispatch_action(Scroll(scroll_position));
 202
 203        true
 204    }
 205
 206    fn paint_background(
 207        &self,
 208        gutter_bounds: RectF,
 209        text_bounds: RectF,
 210        layout: &LayoutState,
 211        cx: &mut PaintContext,
 212    ) {
 213        let bounds = gutter_bounds.union_rect(text_bounds);
 214        let scroll_top = layout.snapshot.scroll_position().y() * layout.line_height;
 215        let editor = self.view(cx.app);
 216        let style = &self.settings.style;
 217        cx.scene.push_quad(Quad {
 218            bounds: gutter_bounds,
 219            background: Some(style.gutter_background),
 220            border: Border::new(0., Color::transparent_black()),
 221            corner_radius: 0.,
 222        });
 223        cx.scene.push_quad(Quad {
 224            bounds: text_bounds,
 225            background: Some(style.background),
 226            border: Border::new(0., Color::transparent_black()),
 227            corner_radius: 0.,
 228        });
 229
 230        if let EditorMode::Full = editor.mode {
 231            let mut active_rows = layout.active_rows.iter().peekable();
 232            while let Some((start_row, contains_non_empty_selection)) = active_rows.next() {
 233                let mut end_row = *start_row;
 234                while active_rows.peek().map_or(false, |r| {
 235                    *r.0 == end_row + 1 && r.1 == contains_non_empty_selection
 236                }) {
 237                    active_rows.next().unwrap();
 238                    end_row += 1;
 239                }
 240
 241                if !contains_non_empty_selection {
 242                    let origin = vec2f(
 243                        bounds.origin_x(),
 244                        bounds.origin_y() + (layout.line_height * *start_row as f32) - scroll_top,
 245                    );
 246                    let size = vec2f(
 247                        bounds.width(),
 248                        layout.line_height * (end_row - start_row + 1) as f32,
 249                    );
 250                    cx.scene.push_quad(Quad {
 251                        bounds: RectF::new(origin, size),
 252                        background: Some(style.active_line_background),
 253                        border: Border::default(),
 254                        corner_radius: 0.,
 255                    });
 256                }
 257            }
 258
 259            if let Some(highlighted_rows) = &layout.highlighted_rows {
 260                let origin = vec2f(
 261                    bounds.origin_x(),
 262                    bounds.origin_y() + (layout.line_height * highlighted_rows.start as f32)
 263                        - scroll_top,
 264                );
 265                let size = vec2f(
 266                    bounds.width(),
 267                    layout.line_height * highlighted_rows.len() as f32,
 268                );
 269                cx.scene.push_quad(Quad {
 270                    bounds: RectF::new(origin, size),
 271                    background: Some(style.highlighted_line_background),
 272                    border: Border::default(),
 273                    corner_radius: 0.,
 274                });
 275            }
 276        }
 277    }
 278
 279    fn paint_gutter(
 280        &mut self,
 281        bounds: RectF,
 282        visible_bounds: RectF,
 283        layout: &LayoutState,
 284        cx: &mut PaintContext,
 285    ) {
 286        let scroll_top = layout.snapshot.scroll_position().y() * layout.line_height;
 287        for (ix, line) in layout.line_number_layouts.iter().enumerate() {
 288            if let Some(line) = line {
 289                let line_origin = bounds.origin()
 290                    + vec2f(
 291                        bounds.width() - line.width() - layout.gutter_padding,
 292                        ix as f32 * layout.line_height - (scroll_top % layout.line_height),
 293                    );
 294                line.paint(line_origin, visible_bounds, layout.line_height, cx);
 295            }
 296        }
 297    }
 298
 299    fn paint_text(
 300        &mut self,
 301        bounds: RectF,
 302        visible_bounds: RectF,
 303        layout: &LayoutState,
 304        cx: &mut PaintContext,
 305    ) {
 306        let view = self.view(cx.app);
 307        let style = &self.settings.style;
 308        let local_replica_id = view.replica_id(cx);
 309        let scroll_position = layout.snapshot.scroll_position();
 310        let start_row = scroll_position.y() as u32;
 311        let scroll_top = scroll_position.y() * layout.line_height;
 312        let end_row = ((scroll_top + bounds.height()) / layout.line_height).ceil() as u32 + 1; // Add 1 to ensure selections bleed off screen
 313        let max_glyph_width = layout.em_width;
 314        let scroll_left = scroll_position.x() * max_glyph_width;
 315
 316        cx.scene.push_layer(Some(bounds));
 317
 318        // Draw selections
 319        let corner_radius = 2.5;
 320        let mut cursors = SmallVec::<[Cursor; 32]>::new();
 321
 322        let content_origin = bounds.origin() + layout.text_offset;
 323
 324        for (replica_id, selections) in &layout.selections {
 325            let style = style.replica_selection_style(*replica_id);
 326
 327            for selection in selections {
 328                if selection.start != selection.end {
 329                    let row_range = if selection.end.column() == 0 {
 330                        cmp::max(selection.start.row(), start_row)
 331                            ..cmp::min(selection.end.row(), end_row)
 332                    } else {
 333                        cmp::max(selection.start.row(), start_row)
 334                            ..cmp::min(selection.end.row() + 1, end_row)
 335                    };
 336
 337                    let selection = Selection {
 338                        color: style.selection,
 339                        line_height: layout.line_height,
 340                        start_y: content_origin.y() + row_range.start as f32 * layout.line_height
 341                            - scroll_top,
 342                        lines: row_range
 343                            .into_iter()
 344                            .map(|row| {
 345                                let line_layout = &layout.line_layouts[(row - start_row) as usize];
 346                                SelectionLine {
 347                                    start_x: if row == selection.start.row() {
 348                                        content_origin.x()
 349                                            + line_layout
 350                                                .x_for_index(selection.start.column() as usize)
 351                                            - scroll_left
 352                                    } else {
 353                                        content_origin.x() - scroll_left
 354                                    },
 355                                    end_x: if row == selection.end.row() {
 356                                        content_origin.x()
 357                                            + line_layout
 358                                                .x_for_index(selection.end.column() as usize)
 359                                            - scroll_left
 360                                    } else {
 361                                        content_origin.x()
 362                                            + line_layout.width()
 363                                            + corner_radius * 2.0
 364                                            - scroll_left
 365                                    },
 366                                }
 367                            })
 368                            .collect(),
 369                    };
 370
 371                    selection.paint(bounds, cx.scene);
 372                }
 373
 374                if view.show_local_cursors() || *replica_id != local_replica_id {
 375                    let cursor_position = selection.head();
 376                    if (start_row..end_row).contains(&cursor_position.row()) {
 377                        let cursor_row_layout =
 378                            &layout.line_layouts[(cursor_position.row() - start_row) as usize];
 379                        let x = cursor_row_layout.x_for_index(cursor_position.column() as usize)
 380                            - scroll_left;
 381                        let y = cursor_position.row() as f32 * layout.line_height - scroll_top;
 382                        cursors.push(Cursor {
 383                            color: style.cursor,
 384                            origin: content_origin + vec2f(x, y),
 385                            line_height: layout.line_height,
 386                        });
 387                    }
 388                }
 389            }
 390        }
 391
 392        if let Some(visible_text_bounds) = bounds.intersection(visible_bounds) {
 393            // Draw glyphs
 394            for (ix, line) in layout.line_layouts.iter().enumerate() {
 395                let row = start_row + ix as u32;
 396                line.paint(
 397                    content_origin
 398                        + vec2f(-scroll_left, row as f32 * layout.line_height - scroll_top),
 399                    visible_text_bounds,
 400                    layout.line_height,
 401                    cx,
 402                );
 403            }
 404        }
 405
 406        cx.scene.push_layer(Some(bounds));
 407        for cursor in cursors {
 408            cursor.paint(cx);
 409        }
 410        cx.scene.pop_layer();
 411
 412        cx.scene.pop_layer();
 413    }
 414
 415    fn paint_blocks(
 416        &mut self,
 417        bounds: RectF,
 418        visible_bounds: RectF,
 419        layout: &mut LayoutState,
 420        cx: &mut PaintContext,
 421    ) {
 422        let scroll_position = layout.snapshot.scroll_position();
 423        let scroll_left = scroll_position.x() * layout.em_width;
 424        let scroll_top = scroll_position.y() * layout.line_height;
 425
 426        for (row, element) in &mut layout.blocks {
 427            let origin = bounds.origin()
 428                + vec2f(-scroll_left, *row as f32 * layout.line_height - scroll_top);
 429            element.paint(origin, visible_bounds, cx);
 430        }
 431    }
 432
 433    fn max_line_number_width(&self, snapshot: &EditorSnapshot, cx: &LayoutContext) -> f32 {
 434        let digit_count = (snapshot.max_buffer_row() as f32).log10().floor() as usize + 1;
 435        let style = &self.settings.style;
 436
 437        cx.text_layout_cache
 438            .layout_str(
 439                "1".repeat(digit_count).as_str(),
 440                style.text.font_size,
 441                &[(
 442                    digit_count,
 443                    RunStyle {
 444                        font_id: style.text.font_id,
 445                        color: Color::black(),
 446                        underline: None,
 447                    },
 448                )],
 449            )
 450            .width()
 451    }
 452
 453    fn layout_line_numbers(
 454        &self,
 455        rows: Range<u32>,
 456        active_rows: &BTreeMap<u32, bool>,
 457        snapshot: &EditorSnapshot,
 458        cx: &LayoutContext,
 459    ) -> Vec<Option<text_layout::Line>> {
 460        let style = &self.settings.style;
 461        let include_line_numbers = snapshot.mode == EditorMode::Full;
 462        let mut line_number_layouts = Vec::with_capacity(rows.len());
 463        let mut line_number = String::new();
 464        for (ix, row) in snapshot
 465            .buffer_rows(rows.start)
 466            .take((rows.end - rows.start) as usize)
 467            .enumerate()
 468        {
 469            let display_row = rows.start + ix as u32;
 470            let color = if active_rows.contains_key(&display_row) {
 471                style.line_number_active
 472            } else {
 473                style.line_number
 474            };
 475            if let Some(buffer_row) = row {
 476                if include_line_numbers {
 477                    line_number.clear();
 478                    write!(&mut line_number, "{}", buffer_row + 1).unwrap();
 479                    line_number_layouts.push(Some(cx.text_layout_cache.layout_str(
 480                        &line_number,
 481                        style.text.font_size,
 482                        &[(
 483                            line_number.len(),
 484                            RunStyle {
 485                                font_id: style.text.font_id,
 486                                color,
 487                                underline: None,
 488                            },
 489                        )],
 490                    )));
 491                }
 492            } else {
 493                line_number_layouts.push(None);
 494            }
 495        }
 496
 497        line_number_layouts
 498    }
 499
 500    fn layout_lines(
 501        &mut self,
 502        mut rows: Range<u32>,
 503        snapshot: &mut EditorSnapshot,
 504        cx: &LayoutContext,
 505    ) -> Vec<text_layout::Line> {
 506        rows.end = cmp::min(rows.end, snapshot.max_point().row() + 1);
 507        if rows.start >= rows.end {
 508            return Vec::new();
 509        }
 510
 511        // When the editor is empty and unfocused, then show the placeholder.
 512        if snapshot.is_empty() && !snapshot.is_focused() {
 513            let placeholder_style = self.settings.style.placeholder_text();
 514            let placeholder_text = snapshot.placeholder_text();
 515            let placeholder_lines = placeholder_text
 516                .as_ref()
 517                .map_or("", AsRef::as_ref)
 518                .split('\n')
 519                .skip(rows.start as usize)
 520                .take(rows.len());
 521            return placeholder_lines
 522                .map(|line| {
 523                    cx.text_layout_cache.layout_str(
 524                        line,
 525                        placeholder_style.font_size,
 526                        &[(
 527                            line.len(),
 528                            RunStyle {
 529                                font_id: placeholder_style.font_id,
 530                                color: placeholder_style.color,
 531                                underline: None,
 532                            },
 533                        )],
 534                    )
 535                })
 536                .collect();
 537        } else {
 538            let style = &self.settings.style;
 539            let chunks = snapshot
 540                .chunks(rows.clone(), Some(&style.syntax))
 541                .map(|chunk| {
 542                    let highlight = if let Some(severity) = chunk.diagnostic {
 543                        let diagnostic_style = super::diagnostic_style(severity, true, style);
 544                        let underline = Some(Underline {
 545                            color: diagnostic_style.message.text.color,
 546                            thickness: 1.0.into(),
 547                            squiggly: true,
 548                        });
 549                        if let Some(mut highlight) = chunk.highlight_style {
 550                            highlight.underline = underline;
 551                            Some(highlight)
 552                        } else {
 553                            Some(HighlightStyle {
 554                                underline,
 555                                color: style.text.color,
 556                                font_properties: style.text.font_properties,
 557                            })
 558                        }
 559                    } else {
 560                        chunk.highlight_style
 561                    };
 562                    (chunk.text, highlight)
 563                });
 564            layout_highlighted_chunks(
 565                chunks,
 566                &style.text,
 567                &cx.text_layout_cache,
 568                &cx.font_cache,
 569                MAX_LINE_LEN,
 570                rows.len() as usize,
 571            )
 572        }
 573    }
 574
 575    fn layout_blocks(
 576        &mut self,
 577        rows: Range<u32>,
 578        snapshot: &EditorSnapshot,
 579        width: f32,
 580        gutter_padding: f32,
 581        gutter_width: f32,
 582        em_width: f32,
 583        text_x: f32,
 584        line_height: f32,
 585        style: &EditorStyle,
 586        line_layouts: &[text_layout::Line],
 587        cx: &mut LayoutContext,
 588    ) -> Vec<(u32, ElementBox)> {
 589        snapshot
 590            .blocks_in_range(rows.clone())
 591            .map(|(start_row, block)| {
 592                let anchor_row = block
 593                    .position()
 594                    .to_point(&snapshot.buffer_snapshot)
 595                    .to_display_point(snapshot)
 596                    .row();
 597
 598                let anchor_x = text_x
 599                    + if rows.contains(&anchor_row) {
 600                        line_layouts[(anchor_row - rows.start) as usize]
 601                            .x_for_index(block.column() as usize)
 602                    } else {
 603                        layout_line(anchor_row, snapshot, style, cx.text_layout_cache)
 604                            .x_for_index(block.column() as usize)
 605                    };
 606
 607                let mut element = block.render(&BlockContext {
 608                    cx,
 609                    anchor_x,
 610                    gutter_padding,
 611                    line_height,
 612                    scroll_x: snapshot.scroll_position.x(),
 613                    gutter_width,
 614                    em_width,
 615                });
 616                element.layout(
 617                    SizeConstraint {
 618                        min: Vector2F::zero(),
 619                        max: vec2f(width, block.height() as f32 * line_height),
 620                    },
 621                    cx,
 622                );
 623                (start_row, element)
 624            })
 625            .collect()
 626    }
 627}
 628
 629impl Element for EditorElement {
 630    type LayoutState = Option<LayoutState>;
 631    type PaintState = Option<PaintState>;
 632
 633    fn layout(
 634        &mut self,
 635        constraint: SizeConstraint,
 636        cx: &mut LayoutContext,
 637    ) -> (Vector2F, Self::LayoutState) {
 638        let mut size = constraint.max;
 639        if size.x().is_infinite() {
 640            unimplemented!("we don't yet handle an infinite width constraint on buffer elements");
 641        }
 642
 643        let snapshot = self.snapshot(cx.app);
 644        let style = self.settings.style.clone();
 645        let line_height = style.text.line_height(cx.font_cache);
 646
 647        let gutter_padding;
 648        let gutter_width;
 649        if snapshot.mode == EditorMode::Full {
 650            gutter_padding = style.text.em_width(cx.font_cache) * style.gutter_padding_factor;
 651            gutter_width = self.max_line_number_width(&snapshot, cx) + gutter_padding * 2.0;
 652        } else {
 653            gutter_padding = 0.0;
 654            gutter_width = 0.0
 655        };
 656
 657        let text_width = size.x() - gutter_width;
 658        let text_offset = vec2f(-style.text.descent(cx.font_cache), 0.);
 659        let em_width = style.text.em_width(cx.font_cache);
 660        let em_advance = style.text.em_advance(cx.font_cache);
 661        let overscroll = vec2f(em_width, 0.);
 662        let wrap_width = match self.settings.soft_wrap {
 663            SoftWrap::None => None,
 664            SoftWrap::EditorWidth => Some(text_width - text_offset.x() - overscroll.x() - em_width),
 665            SoftWrap::Column(column) => Some(column as f32 * em_advance),
 666        };
 667        let snapshot = self.update_view(cx.app, |view, cx| {
 668            if view.set_wrap_width(wrap_width, cx) {
 669                view.snapshot(cx)
 670            } else {
 671                snapshot
 672            }
 673        });
 674
 675        let scroll_height = (snapshot.max_point().row() + 1) as f32 * line_height;
 676        if let EditorMode::AutoHeight { max_lines } = snapshot.mode {
 677            size.set_y(
 678                scroll_height
 679                    .min(constraint.max_along(Axis::Vertical))
 680                    .max(constraint.min_along(Axis::Vertical))
 681                    .min(line_height * max_lines as f32),
 682            )
 683        } else if size.y().is_infinite() {
 684            size.set_y(scroll_height);
 685        }
 686        let gutter_size = vec2f(gutter_width, size.y());
 687        let text_size = vec2f(text_width, size.y());
 688
 689        let (autoscroll_horizontally, mut snapshot) = self.update_view(cx.app, |view, cx| {
 690            let autoscroll_horizontally = view.autoscroll_vertically(size.y(), line_height, cx);
 691            let snapshot = view.snapshot(cx);
 692            (autoscroll_horizontally, snapshot)
 693        });
 694
 695        let scroll_position = snapshot.scroll_position();
 696        let start_row = scroll_position.y() as u32;
 697        let scroll_top = scroll_position.y() * line_height;
 698        let end_row = ((scroll_top + size.y()) / line_height).ceil() as u32 + 1; // Add 1 to ensure selections bleed off screen
 699
 700        let start_anchor = if start_row == 0 {
 701            Anchor::min()
 702        } else {
 703            snapshot
 704                .buffer_snapshot
 705                .anchor_before(DisplayPoint::new(start_row, 0).to_offset(&snapshot, Bias::Left))
 706        };
 707        let end_anchor = if end_row > snapshot.max_point().row() {
 708            Anchor::max()
 709        } else {
 710            snapshot
 711                .buffer_snapshot
 712                .anchor_before(DisplayPoint::new(end_row, 0).to_offset(&snapshot, Bias::Right))
 713        };
 714
 715        let mut selections = HashMap::default();
 716        let mut active_rows = BTreeMap::new();
 717        let mut highlighted_rows = None;
 718        self.update_view(cx.app, |view, cx| {
 719            highlighted_rows = view.highlighted_rows();
 720            let display_map = view.display_map.update(cx, |map, cx| map.snapshot(cx));
 721
 722            let local_selections = view
 723                .local_selections_in_range(start_anchor.clone()..end_anchor.clone(), &display_map);
 724            for selection in &local_selections {
 725                let is_empty = selection.start == selection.end;
 726                let selection_start = snapshot.prev_line_boundary(selection.start).1;
 727                let selection_end = snapshot.next_line_boundary(selection.end).1;
 728                for row in cmp::max(selection_start.row(), start_row)
 729                    ..=cmp::min(selection_end.row(), end_row)
 730                {
 731                    let contains_non_empty_selection = active_rows.entry(row).or_insert(!is_empty);
 732                    *contains_non_empty_selection |= !is_empty;
 733                }
 734            }
 735            selections.insert(
 736                view.replica_id(cx),
 737                local_selections
 738                    .into_iter()
 739                    .map(|selection| crate::Selection {
 740                        id: selection.id,
 741                        goal: selection.goal,
 742                        reversed: selection.reversed,
 743                        start: selection.start.to_display_point(&display_map),
 744                        end: selection.end.to_display_point(&display_map),
 745                    })
 746                    .collect(),
 747            );
 748
 749            for (replica_id, selection) in display_map
 750                .buffer_snapshot
 751                .remote_selections_in_range(&(start_anchor..end_anchor))
 752            {
 753                selections
 754                    .entry(replica_id)
 755                    .or_insert(Vec::new())
 756                    .push(crate::Selection {
 757                        id: selection.id,
 758                        goal: selection.goal,
 759                        reversed: selection.reversed,
 760                        start: selection.start.to_display_point(&display_map),
 761                        end: selection.end.to_display_point(&display_map),
 762                    });
 763            }
 764        });
 765
 766        let line_number_layouts =
 767            self.layout_line_numbers(start_row..end_row, &active_rows, &snapshot, cx);
 768
 769        let mut max_visible_line_width = 0.0;
 770        let line_layouts = self.layout_lines(start_row..end_row, &mut snapshot, cx);
 771        for line in &line_layouts {
 772            if line.width() > max_visible_line_width {
 773                max_visible_line_width = line.width();
 774            }
 775        }
 776
 777        let style = self.settings.style.clone();
 778        let longest_line_width = layout_line(
 779            snapshot.longest_row(),
 780            &snapshot,
 781            &style,
 782            cx.text_layout_cache,
 783        )
 784        .width();
 785        let scroll_width = longest_line_width.max(max_visible_line_width) + overscroll.x();
 786        let em_width = style.text.em_width(cx.font_cache);
 787        let max_row = snapshot.max_point().row();
 788        let scroll_max = vec2f(
 789            ((scroll_width - text_size.x()) / em_width).max(0.0),
 790            max_row.saturating_sub(1) as f32,
 791        );
 792
 793        self.update_view(cx.app, |view, cx| {
 794            let clamped = view.clamp_scroll_left(scroll_max.x());
 795            let autoscrolled;
 796            if autoscroll_horizontally {
 797                autoscrolled = view.autoscroll_horizontally(
 798                    start_row,
 799                    text_size.x(),
 800                    scroll_width,
 801                    em_width,
 802                    &line_layouts,
 803                    cx,
 804                );
 805            } else {
 806                autoscrolled = false;
 807            }
 808
 809            if clamped || autoscrolled {
 810                snapshot = view.snapshot(cx);
 811            }
 812        });
 813
 814        let blocks = self.layout_blocks(
 815            start_row..end_row,
 816            &snapshot,
 817            size.x().max(scroll_width + gutter_width),
 818            gutter_padding,
 819            gutter_width,
 820            em_width,
 821            gutter_width + text_offset.x(),
 822            line_height,
 823            &style,
 824            &line_layouts,
 825            cx,
 826        );
 827
 828        (
 829            size,
 830            Some(LayoutState {
 831                size,
 832                scroll_max,
 833                gutter_size,
 834                gutter_padding,
 835                text_size,
 836                text_offset,
 837                snapshot,
 838                active_rows,
 839                highlighted_rows,
 840                line_layouts,
 841                line_number_layouts,
 842                blocks,
 843                line_height,
 844                em_width,
 845                em_advance,
 846                selections,
 847            }),
 848        )
 849    }
 850
 851    fn paint(
 852        &mut self,
 853        bounds: RectF,
 854        visible_bounds: RectF,
 855        layout: &mut Self::LayoutState,
 856        cx: &mut PaintContext,
 857    ) -> Self::PaintState {
 858        if let Some(layout) = layout {
 859            cx.scene.push_layer(Some(bounds));
 860
 861            let gutter_bounds = RectF::new(bounds.origin(), layout.gutter_size);
 862            let text_bounds = RectF::new(
 863                bounds.origin() + vec2f(layout.gutter_size.x(), 0.0),
 864                layout.text_size,
 865            );
 866
 867            self.paint_background(gutter_bounds, text_bounds, layout, cx);
 868            if layout.gutter_size.x() > 0. {
 869                self.paint_gutter(gutter_bounds, visible_bounds, layout, cx);
 870            }
 871            self.paint_text(text_bounds, visible_bounds, layout, cx);
 872            self.paint_blocks(bounds, visible_bounds, layout, cx);
 873
 874            cx.scene.pop_layer();
 875
 876            Some(PaintState {
 877                bounds,
 878                gutter_bounds,
 879                text_bounds,
 880            })
 881        } else {
 882            None
 883        }
 884    }
 885
 886    fn dispatch_event(
 887        &mut self,
 888        event: &Event,
 889        _: RectF,
 890        layout: &mut Self::LayoutState,
 891        paint: &mut Self::PaintState,
 892        cx: &mut EventContext,
 893    ) -> bool {
 894        if let (Some(layout), Some(paint)) = (layout, paint) {
 895            match event {
 896                Event::LeftMouseDown {
 897                    position,
 898                    alt,
 899                    shift,
 900                    click_count,
 901                    ..
 902                } => self.mouse_down(*position, *alt, *shift, *click_count, layout, paint, cx),
 903                Event::LeftMouseUp { position } => self.mouse_up(*position, cx),
 904                Event::LeftMouseDragged { position } => {
 905                    self.mouse_dragged(*position, layout, paint, cx)
 906                }
 907                Event::ScrollWheel {
 908                    position,
 909                    delta,
 910                    precise,
 911                } => self.scroll(*position, *delta, *precise, layout, paint, cx),
 912                Event::KeyDown {
 913                    chars, keystroke, ..
 914                } => self.key_down(chars, keystroke, cx),
 915                _ => false,
 916            }
 917        } else {
 918            false
 919        }
 920    }
 921
 922    fn debug(
 923        &self,
 924        bounds: RectF,
 925        _: &Self::LayoutState,
 926        _: &Self::PaintState,
 927        _: &gpui::DebugContext,
 928    ) -> json::Value {
 929        json!({
 930            "type": "BufferElement",
 931            "bounds": bounds.to_json()
 932        })
 933    }
 934}
 935
 936pub struct LayoutState {
 937    size: Vector2F,
 938    scroll_max: Vector2F,
 939    gutter_size: Vector2F,
 940    gutter_padding: f32,
 941    text_size: Vector2F,
 942    snapshot: EditorSnapshot,
 943    active_rows: BTreeMap<u32, bool>,
 944    highlighted_rows: Option<Range<u32>>,
 945    line_layouts: Vec<text_layout::Line>,
 946    line_number_layouts: Vec<Option<text_layout::Line>>,
 947    blocks: Vec<(u32, ElementBox)>,
 948    line_height: f32,
 949    em_width: f32,
 950    em_advance: f32,
 951    selections: HashMap<ReplicaId, Vec<text::Selection<DisplayPoint>>>,
 952    text_offset: Vector2F,
 953}
 954
 955fn layout_line(
 956    row: u32,
 957    snapshot: &EditorSnapshot,
 958    style: &EditorStyle,
 959    layout_cache: &TextLayoutCache,
 960) -> text_layout::Line {
 961    let mut line = snapshot.line(row);
 962
 963    if line.len() > MAX_LINE_LEN {
 964        let mut len = MAX_LINE_LEN;
 965        while !line.is_char_boundary(len) {
 966            len -= 1;
 967        }
 968        line.truncate(len);
 969    }
 970
 971    layout_cache.layout_str(
 972        &line,
 973        style.text.font_size,
 974        &[(
 975            snapshot.line_len(row) as usize,
 976            RunStyle {
 977                font_id: style.text.font_id,
 978                color: Color::black(),
 979                underline: None,
 980            },
 981        )],
 982    )
 983}
 984
 985pub struct PaintState {
 986    bounds: RectF,
 987    gutter_bounds: RectF,
 988    text_bounds: RectF,
 989}
 990
 991impl PaintState {
 992    fn point_for_position(
 993        &self,
 994        snapshot: &EditorSnapshot,
 995        layout: &LayoutState,
 996        position: Vector2F,
 997    ) -> (DisplayPoint, u32) {
 998        let scroll_position = snapshot.scroll_position();
 999        let position = position - self.text_bounds.origin();
1000        let y = position.y().max(0.0).min(layout.size.y());
1001        let row = ((y / layout.line_height) + scroll_position.y()) as u32;
1002        let row = cmp::min(row, snapshot.max_point().row());
1003        let line = &layout.line_layouts[(row - scroll_position.y() as u32) as usize];
1004        let x = position.x() + (scroll_position.x() * layout.em_width);
1005
1006        let column = if x >= 0.0 {
1007            line.index_for_x(x)
1008                .map(|ix| ix as u32)
1009                .unwrap_or_else(|| snapshot.line_len(row))
1010        } else {
1011            0
1012        };
1013        let overshoot = (0f32.max(x - line.width()) / layout.em_advance) as u32;
1014
1015        (DisplayPoint::new(row, column), overshoot)
1016    }
1017}
1018
1019struct Cursor {
1020    origin: Vector2F,
1021    line_height: f32,
1022    color: Color,
1023}
1024
1025impl Cursor {
1026    fn paint(&self, cx: &mut PaintContext) {
1027        cx.scene.push_quad(Quad {
1028            bounds: RectF::new(self.origin, vec2f(2.0, self.line_height)),
1029            background: Some(self.color),
1030            border: Border::new(0., Color::black()),
1031            corner_radius: 0.,
1032        });
1033    }
1034}
1035
1036#[derive(Debug)]
1037struct Selection {
1038    start_y: f32,
1039    line_height: f32,
1040    lines: Vec<SelectionLine>,
1041    color: Color,
1042}
1043
1044#[derive(Debug)]
1045struct SelectionLine {
1046    start_x: f32,
1047    end_x: f32,
1048}
1049
1050impl Selection {
1051    fn paint(&self, bounds: RectF, scene: &mut Scene) {
1052        if self.lines.len() >= 2 && self.lines[0].start_x > self.lines[1].end_x {
1053            self.paint_lines(self.start_y, &self.lines[0..1], bounds, scene);
1054            self.paint_lines(
1055                self.start_y + self.line_height,
1056                &self.lines[1..],
1057                bounds,
1058                scene,
1059            );
1060        } else {
1061            self.paint_lines(self.start_y, &self.lines, bounds, scene);
1062        }
1063    }
1064
1065    fn paint_lines(&self, start_y: f32, lines: &[SelectionLine], bounds: RectF, scene: &mut Scene) {
1066        if lines.is_empty() {
1067            return;
1068        }
1069
1070        let mut path = PathBuilder::new();
1071        let corner_radius = 0.15 * self.line_height;
1072        let first_line = lines.first().unwrap();
1073        let last_line = lines.last().unwrap();
1074
1075        let first_top_left = vec2f(first_line.start_x, start_y);
1076        let first_top_right = vec2f(first_line.end_x, start_y);
1077
1078        let curve_height = vec2f(0., corner_radius);
1079        let curve_width = |start_x: f32, end_x: f32| {
1080            let max = (end_x - start_x) / 2.;
1081            let width = if max < corner_radius {
1082                max
1083            } else {
1084                corner_radius
1085            };
1086
1087            vec2f(width, 0.)
1088        };
1089
1090        let top_curve_width = curve_width(first_line.start_x, first_line.end_x);
1091        path.reset(first_top_right - top_curve_width);
1092        path.curve_to(first_top_right + curve_height, first_top_right);
1093
1094        let mut iter = lines.iter().enumerate().peekable();
1095        while let Some((ix, line)) = iter.next() {
1096            let bottom_right = vec2f(line.end_x, start_y + (ix + 1) as f32 * self.line_height);
1097
1098            if let Some((_, next_line)) = iter.peek() {
1099                let next_top_right = vec2f(next_line.end_x, bottom_right.y());
1100
1101                match next_top_right.x().partial_cmp(&bottom_right.x()).unwrap() {
1102                    Ordering::Equal => {
1103                        path.line_to(bottom_right);
1104                    }
1105                    Ordering::Less => {
1106                        let curve_width = curve_width(next_top_right.x(), bottom_right.x());
1107                        path.line_to(bottom_right - curve_height);
1108                        path.curve_to(bottom_right - curve_width, bottom_right);
1109                        path.line_to(next_top_right + curve_width);
1110                        path.curve_to(next_top_right + curve_height, next_top_right);
1111                    }
1112                    Ordering::Greater => {
1113                        let curve_width = curve_width(bottom_right.x(), next_top_right.x());
1114                        path.line_to(bottom_right - curve_height);
1115                        path.curve_to(bottom_right + curve_width, bottom_right);
1116                        path.line_to(next_top_right - curve_width);
1117                        path.curve_to(next_top_right + curve_height, next_top_right);
1118                    }
1119                }
1120            } else {
1121                let curve_width = curve_width(line.start_x, line.end_x);
1122                path.line_to(bottom_right - curve_height);
1123                path.curve_to(bottom_right - curve_width, bottom_right);
1124
1125                let bottom_left = vec2f(line.start_x, bottom_right.y());
1126                path.line_to(bottom_left + curve_width);
1127                path.curve_to(bottom_left - curve_height, bottom_left);
1128            }
1129        }
1130
1131        if first_line.start_x > last_line.start_x {
1132            let curve_width = curve_width(last_line.start_x, first_line.start_x);
1133            let second_top_left = vec2f(last_line.start_x, start_y + self.line_height);
1134            path.line_to(second_top_left + curve_height);
1135            path.curve_to(second_top_left + curve_width, second_top_left);
1136            let first_bottom_left = vec2f(first_line.start_x, second_top_left.y());
1137            path.line_to(first_bottom_left - curve_width);
1138            path.curve_to(first_bottom_left - curve_height, first_bottom_left);
1139        }
1140
1141        path.line_to(first_top_left + curve_height);
1142        path.curve_to(first_top_left + top_curve_width, first_top_left);
1143        path.line_to(first_top_right - top_curve_width);
1144
1145        scene.push_path(path.build(self.color, Some(bounds)));
1146    }
1147}
1148
1149fn scale_vertical_mouse_autoscroll_delta(delta: f32) -> f32 {
1150    delta.powf(1.5) / 100.0
1151}
1152
1153fn scale_horizontal_mouse_autoscroll_delta(delta: f32) -> f32 {
1154    delta.powf(1.2) / 300.0
1155}
1156
1157#[cfg(test)]
1158mod tests {
1159    use super::*;
1160    use crate::{Editor, EditorSettings, MultiBuffer};
1161    use std::sync::Arc;
1162    use util::test::sample_text;
1163
1164    #[gpui::test]
1165    fn test_layout_line_numbers(cx: &mut gpui::MutableAppContext) {
1166        let settings = EditorSettings::test(cx);
1167        let buffer = MultiBuffer::build_simple(&sample_text(6, 6, 'a'), cx);
1168        let (window_id, editor) = cx.add_window(Default::default(), |cx| {
1169            Editor::for_buffer(
1170                buffer,
1171                {
1172                    let settings = settings.clone();
1173                    Arc::new(move |_| settings.clone())
1174                },
1175                cx,
1176            )
1177        });
1178        let element = EditorElement::new(editor.downgrade(), settings);
1179
1180        let layouts = editor.update(cx, |editor, cx| {
1181            let snapshot = editor.snapshot(cx);
1182            let mut presenter = cx.build_presenter(window_id, 30.);
1183            let mut layout_cx = presenter.build_layout_context(false, cx);
1184            element.layout_line_numbers(0..6, &Default::default(), &snapshot, &mut layout_cx)
1185        });
1186        assert_eq!(layouts.len(), 6);
1187    }
1188}