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,
  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, FontCache, 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 font_cache = cx.font_cache.clone();
 144            let text_layout_cache = cx.text_layout_cache.clone();
 145            let snapshot = self.snapshot(cx.app);
 146            let (position, overshoot) = paint.point_for_position(&snapshot, layout, position);
 147
 148            cx.dispatch_action(Select(SelectPhase::Update {
 149                position,
 150                overshoot,
 151                scroll_position: (snapshot.scroll_position() + scroll_delta).clamp(
 152                    Vector2F::zero(),
 153                    layout.scroll_max(&font_cache, &text_layout_cache),
 154                ),
 155            }));
 156            true
 157        } else {
 158            false
 159        }
 160    }
 161
 162    fn key_down(&self, chars: &str, keystroke: &Keystroke, cx: &mut EventContext) -> bool {
 163        let view = self.view.upgrade(cx.app).unwrap();
 164
 165        if view.is_focused(cx.app) {
 166            if chars.is_empty() {
 167                false
 168            } else {
 169                if chars.chars().any(|c| c.is_control()) || keystroke.cmd || keystroke.ctrl {
 170                    false
 171                } else {
 172                    cx.dispatch_action(Input(chars.to_string()));
 173                    true
 174                }
 175            }
 176        } else {
 177            false
 178        }
 179    }
 180
 181    fn scroll(
 182        &self,
 183        position: Vector2F,
 184        mut delta: Vector2F,
 185        precise: bool,
 186        layout: &mut LayoutState,
 187        paint: &mut PaintState,
 188        cx: &mut EventContext,
 189    ) -> bool {
 190        if !paint.bounds.contains_point(position) {
 191            return false;
 192        }
 193
 194        let snapshot = self.snapshot(cx.app);
 195        let font_cache = &cx.font_cache;
 196        let layout_cache = &cx.text_layout_cache;
 197        let max_glyph_width = layout.em_width;
 198        if !precise {
 199            delta *= vec2f(max_glyph_width, layout.line_height);
 200        }
 201
 202        let scroll_position = snapshot.scroll_position();
 203        let x = (scroll_position.x() * max_glyph_width - delta.x()) / max_glyph_width;
 204        let y = (scroll_position.y() * layout.line_height - delta.y()) / layout.line_height;
 205        let scroll_position = vec2f(x, y).clamp(
 206            Vector2F::zero(),
 207            layout.scroll_max(font_cache, layout_cache),
 208        );
 209
 210        cx.dispatch_action(Scroll(scroll_position));
 211
 212        true
 213    }
 214
 215    fn paint_background(
 216        &self,
 217        gutter_bounds: RectF,
 218        text_bounds: RectF,
 219        layout: &LayoutState,
 220        cx: &mut PaintContext,
 221    ) {
 222        let bounds = gutter_bounds.union_rect(text_bounds);
 223        let scroll_top = layout.snapshot.scroll_position().y() * layout.line_height;
 224        let editor = self.view(cx.app);
 225        let style = &self.settings.style;
 226        cx.scene.push_quad(Quad {
 227            bounds: gutter_bounds,
 228            background: Some(style.gutter_background),
 229            border: Border::new(0., Color::transparent_black()),
 230            corner_radius: 0.,
 231        });
 232        cx.scene.push_quad(Quad {
 233            bounds: text_bounds,
 234            background: Some(style.background),
 235            border: Border::new(0., Color::transparent_black()),
 236            corner_radius: 0.,
 237        });
 238
 239        if let EditorMode::Full = editor.mode {
 240            let mut active_rows = layout.active_rows.iter().peekable();
 241            while let Some((start_row, contains_non_empty_selection)) = active_rows.next() {
 242                let mut end_row = *start_row;
 243                while active_rows.peek().map_or(false, |r| {
 244                    *r.0 == end_row + 1 && r.1 == contains_non_empty_selection
 245                }) {
 246                    active_rows.next().unwrap();
 247                    end_row += 1;
 248                }
 249
 250                if !contains_non_empty_selection {
 251                    let origin = vec2f(
 252                        bounds.origin_x(),
 253                        bounds.origin_y() + (layout.line_height * *start_row as f32) - scroll_top,
 254                    );
 255                    let size = vec2f(
 256                        bounds.width(),
 257                        layout.line_height * (end_row - start_row + 1) as f32,
 258                    );
 259                    cx.scene.push_quad(Quad {
 260                        bounds: RectF::new(origin, size),
 261                        background: Some(style.active_line_background),
 262                        border: Border::default(),
 263                        corner_radius: 0.,
 264                    });
 265                }
 266            }
 267
 268            if let Some(highlighted_rows) = &layout.highlighted_rows {
 269                let origin = vec2f(
 270                    bounds.origin_x(),
 271                    bounds.origin_y() + (layout.line_height * highlighted_rows.start as f32)
 272                        - scroll_top,
 273                );
 274                let size = vec2f(
 275                    bounds.width(),
 276                    layout.line_height * highlighted_rows.len() as f32,
 277                );
 278                cx.scene.push_quad(Quad {
 279                    bounds: RectF::new(origin, size),
 280                    background: Some(style.highlighted_line_background),
 281                    border: Border::default(),
 282                    corner_radius: 0.,
 283                });
 284            }
 285        }
 286    }
 287
 288    fn paint_gutter(
 289        &mut self,
 290        bounds: RectF,
 291        visible_bounds: RectF,
 292        layout: &LayoutState,
 293        cx: &mut PaintContext,
 294    ) {
 295        let scroll_top = layout.snapshot.scroll_position().y() * layout.line_height;
 296        for (ix, line) in layout.line_number_layouts.iter().enumerate() {
 297            if let Some(line) = line {
 298                let line_origin = bounds.origin()
 299                    + vec2f(
 300                        bounds.width() - line.width() - layout.gutter_padding,
 301                        ix as f32 * layout.line_height - (scroll_top % layout.line_height),
 302                    );
 303                line.paint(line_origin, visible_bounds, layout.line_height, cx);
 304            }
 305        }
 306    }
 307
 308    fn paint_text(
 309        &mut self,
 310        bounds: RectF,
 311        visible_bounds: RectF,
 312        layout: &LayoutState,
 313        cx: &mut PaintContext,
 314    ) {
 315        let view = self.view(cx.app);
 316        let style = &self.settings.style;
 317        let local_replica_id = view.replica_id(cx);
 318        let scroll_position = layout.snapshot.scroll_position();
 319        let start_row = scroll_position.y() as u32;
 320        let scroll_top = scroll_position.y() * layout.line_height;
 321        let end_row = ((scroll_top + bounds.height()) / layout.line_height).ceil() as u32 + 1; // Add 1 to ensure selections bleed off screen
 322        let max_glyph_width = layout.em_width;
 323        let scroll_left = scroll_position.x() * max_glyph_width;
 324
 325        cx.scene.push_layer(Some(bounds));
 326
 327        // Draw selections
 328        let corner_radius = 2.5;
 329        let mut cursors = SmallVec::<[Cursor; 32]>::new();
 330
 331        let content_origin = bounds.origin() + layout.text_offset;
 332
 333        for (replica_id, selections) in &layout.selections {
 334            let style = style.replica_selection_style(*replica_id);
 335
 336            for selection in selections {
 337                if selection.start != selection.end {
 338                    let row_range = if selection.end.column() == 0 {
 339                        cmp::max(selection.start.row(), start_row)
 340                            ..cmp::min(selection.end.row(), end_row)
 341                    } else {
 342                        cmp::max(selection.start.row(), start_row)
 343                            ..cmp::min(selection.end.row() + 1, end_row)
 344                    };
 345
 346                    let selection = Selection {
 347                        color: style.selection,
 348                        line_height: layout.line_height,
 349                        start_y: content_origin.y() + row_range.start as f32 * layout.line_height
 350                            - scroll_top,
 351                        lines: row_range
 352                            .into_iter()
 353                            .map(|row| {
 354                                let line_layout = &layout.line_layouts[(row - start_row) as usize];
 355                                SelectionLine {
 356                                    start_x: if row == selection.start.row() {
 357                                        content_origin.x()
 358                                            + line_layout
 359                                                .x_for_index(selection.start.column() as usize)
 360                                            - scroll_left
 361                                    } else {
 362                                        content_origin.x() - scroll_left
 363                                    },
 364                                    end_x: if row == selection.end.row() {
 365                                        content_origin.x()
 366                                            + line_layout
 367                                                .x_for_index(selection.end.column() as usize)
 368                                            - scroll_left
 369                                    } else {
 370                                        content_origin.x()
 371                                            + line_layout.width()
 372                                            + corner_radius * 2.0
 373                                            - scroll_left
 374                                    },
 375                                }
 376                            })
 377                            .collect(),
 378                    };
 379
 380                    selection.paint(bounds, cx.scene);
 381                }
 382
 383                if view.show_local_cursors() || *replica_id != local_replica_id {
 384                    let cursor_position = selection.head();
 385                    if (start_row..end_row).contains(&cursor_position.row()) {
 386                        let cursor_row_layout =
 387                            &layout.line_layouts[(cursor_position.row() - start_row) as usize];
 388                        let x = cursor_row_layout.x_for_index(cursor_position.column() as usize)
 389                            - scroll_left;
 390                        let y = cursor_position.row() as f32 * layout.line_height - scroll_top;
 391                        cursors.push(Cursor {
 392                            color: style.cursor,
 393                            origin: content_origin + vec2f(x, y),
 394                            line_height: layout.line_height,
 395                        });
 396                    }
 397                }
 398            }
 399        }
 400
 401        if let Some(visible_text_bounds) = bounds.intersection(visible_bounds) {
 402            // Draw glyphs
 403            for (ix, line) in layout.line_layouts.iter().enumerate() {
 404                let row = start_row + ix as u32;
 405                line.paint(
 406                    content_origin
 407                        + vec2f(-scroll_left, row as f32 * layout.line_height - scroll_top),
 408                    visible_text_bounds,
 409                    layout.line_height,
 410                    cx,
 411                );
 412            }
 413        }
 414
 415        cx.scene.push_layer(Some(bounds));
 416        for cursor in cursors {
 417            cursor.paint(cx);
 418        }
 419        cx.scene.pop_layer();
 420
 421        cx.scene.pop_layer();
 422    }
 423
 424    fn paint_blocks(
 425        &mut self,
 426        bounds: RectF,
 427        visible_bounds: RectF,
 428        layout: &mut LayoutState,
 429        cx: &mut PaintContext,
 430    ) {
 431        let scroll_position = layout.snapshot.scroll_position();
 432        let scroll_left = scroll_position.x() * layout.em_width;
 433        let scroll_top = scroll_position.y() * layout.line_height;
 434
 435        for (row, element) in &mut layout.blocks {
 436            let origin = bounds.origin()
 437                + vec2f(-scroll_left, *row as f32 * layout.line_height - scroll_top);
 438            element.paint(origin, visible_bounds, cx);
 439        }
 440    }
 441
 442    fn max_line_number_width(&self, snapshot: &EditorSnapshot, cx: &LayoutContext) -> f32 {
 443        let digit_count = (snapshot.max_buffer_row() as f32).log10().floor() as usize + 1;
 444        let style = &self.settings.style;
 445
 446        cx.text_layout_cache
 447            .layout_str(
 448                "1".repeat(digit_count).as_str(),
 449                style.text.font_size,
 450                &[(
 451                    digit_count,
 452                    RunStyle {
 453                        font_id: style.text.font_id,
 454                        color: Color::black(),
 455                        underline: None,
 456                    },
 457                )],
 458            )
 459            .width()
 460    }
 461
 462    fn layout_rows(
 463        &self,
 464        rows: Range<u32>,
 465        active_rows: &BTreeMap<u32, bool>,
 466        snapshot: &EditorSnapshot,
 467        cx: &LayoutContext,
 468    ) -> Vec<Option<text_layout::Line>> {
 469        let style = &self.settings.style;
 470        let include_line_numbers = snapshot.mode == EditorMode::Full;
 471        let mut line_number_layouts = Vec::with_capacity(rows.len());
 472        let mut line_number = String::new();
 473        for (ix, row) in snapshot
 474            .buffer_rows(rows.start)
 475            .take((rows.end - rows.start) as usize)
 476            .enumerate()
 477        {
 478            let display_row = rows.start + ix as u32;
 479            let color = if active_rows.contains_key(&display_row) {
 480                style.line_number_active
 481            } else {
 482                style.line_number
 483            };
 484            if let Some(buffer_row) = row {
 485                if include_line_numbers {
 486                    line_number.clear();
 487                    write!(&mut line_number, "{}", buffer_row + 1).unwrap();
 488                    line_number_layouts.push(Some(cx.text_layout_cache.layout_str(
 489                        &line_number,
 490                        style.text.font_size,
 491                        &[(
 492                            line_number.len(),
 493                            RunStyle {
 494                                font_id: style.text.font_id,
 495                                color,
 496                                underline: None,
 497                            },
 498                        )],
 499                    )));
 500                }
 501            } else {
 502                line_number_layouts.push(None);
 503            }
 504        }
 505
 506        line_number_layouts
 507    }
 508
 509    fn layout_lines(
 510        &mut self,
 511        mut rows: Range<u32>,
 512        snapshot: &mut EditorSnapshot,
 513        cx: &LayoutContext,
 514    ) -> Vec<text_layout::Line> {
 515        rows.end = cmp::min(rows.end, snapshot.max_point().row() + 1);
 516        if rows.start >= rows.end {
 517            return Vec::new();
 518        }
 519
 520        // When the editor is empty and unfocused, then show the placeholder.
 521        if snapshot.is_empty() && !snapshot.is_focused() {
 522            let placeholder_style = self.settings.style.placeholder_text();
 523            let placeholder_text = snapshot.placeholder_text();
 524            let placeholder_lines = placeholder_text
 525                .as_ref()
 526                .map_or("", AsRef::as_ref)
 527                .split('\n')
 528                .skip(rows.start as usize)
 529                .take(rows.len());
 530            return placeholder_lines
 531                .map(|line| {
 532                    cx.text_layout_cache.layout_str(
 533                        line,
 534                        placeholder_style.font_size,
 535                        &[(
 536                            line.len(),
 537                            RunStyle {
 538                                font_id: placeholder_style.font_id,
 539                                color: placeholder_style.color,
 540                                underline: None,
 541                            },
 542                        )],
 543                    )
 544                })
 545                .collect();
 546        } else {
 547            let style = &self.settings.style;
 548            let chunks = snapshot
 549                .chunks(rows.clone(), Some(&style.syntax))
 550                .map(|chunk| {
 551                    let highlight = if let Some(severity) = chunk.diagnostic {
 552                        let underline = Some(
 553                            super::diagnostic_style(severity, true, style)
 554                                .message
 555                                .text
 556                                .color,
 557                        );
 558                        if let Some(mut highlight) = chunk.highlight_style {
 559                            highlight.underline = underline;
 560                            Some(highlight)
 561                        } else {
 562                            Some(HighlightStyle {
 563                                underline,
 564                                color: style.text.color,
 565                                font_properties: style.text.font_properties,
 566                            })
 567                        }
 568                    } else {
 569                        chunk.highlight_style
 570                    };
 571                    (chunk.text, highlight)
 572                });
 573            layout_highlighted_chunks(
 574                chunks,
 575                &style.text,
 576                &cx.text_layout_cache,
 577                &cx.font_cache,
 578                MAX_LINE_LEN,
 579                rows.len() as usize,
 580            )
 581        }
 582    }
 583
 584    fn layout_blocks(
 585        &mut self,
 586        rows: Range<u32>,
 587        snapshot: &EditorSnapshot,
 588        width: f32,
 589        line_number_x: f32,
 590        text_x: f32,
 591        line_height: f32,
 592        style: &EditorStyle,
 593        line_layouts: &[text_layout::Line],
 594        cx: &mut LayoutContext,
 595    ) -> Vec<(u32, ElementBox)> {
 596        snapshot
 597            .blocks_in_range(rows.clone())
 598            .map(|(start_row, block)| {
 599                let anchor_row = block
 600                    .position()
 601                    .to_point(&snapshot.buffer_snapshot)
 602                    .to_display_point(snapshot)
 603                    .row();
 604
 605                let anchor_x = text_x
 606                    + if rows.contains(&anchor_row) {
 607                        line_layouts[(anchor_row - rows.start) as usize]
 608                            .x_for_index(block.column() as usize)
 609                    } else {
 610                        layout_line(anchor_row, snapshot, style, cx.text_layout_cache)
 611                            .x_for_index(block.column() as usize)
 612                    };
 613
 614                let mut element = block.render(&BlockContext {
 615                    cx,
 616                    anchor_x,
 617                    line_number_x,
 618                });
 619                element.layout(
 620                    SizeConstraint {
 621                        min: Vector2F::zero(),
 622                        max: vec2f(width, block.height() as f32 * line_height),
 623                    },
 624                    cx,
 625                );
 626                (start_row, element)
 627            })
 628            .collect()
 629    }
 630}
 631
 632impl Element for EditorElement {
 633    type LayoutState = Option<LayoutState>;
 634    type PaintState = Option<PaintState>;
 635
 636    fn layout(
 637        &mut self,
 638        constraint: SizeConstraint,
 639        cx: &mut LayoutContext,
 640    ) -> (Vector2F, Self::LayoutState) {
 641        let mut size = constraint.max;
 642        if size.x().is_infinite() {
 643            unimplemented!("we don't yet handle an infinite width constraint on buffer elements");
 644        }
 645
 646        let snapshot = self.snapshot(cx.app);
 647        let style = self.settings.style.clone();
 648        let line_height = style.text.line_height(cx.font_cache);
 649
 650        let gutter_padding;
 651        let gutter_width;
 652        if snapshot.mode == EditorMode::Full {
 653            gutter_padding = style.text.em_width(cx.font_cache);
 654            gutter_width = self.max_line_number_width(&snapshot, cx) + gutter_padding * 2.0;
 655        } else {
 656            gutter_padding = 0.0;
 657            gutter_width = 0.0
 658        };
 659
 660        let text_width = size.x() - gutter_width;
 661        let text_offset = vec2f(-style.text.descent(cx.font_cache), 0.);
 662        let em_width = style.text.em_width(cx.font_cache);
 663        let em_advance = style.text.em_advance(cx.font_cache);
 664        let overscroll = vec2f(em_width, 0.);
 665        let wrap_width = match self.settings.soft_wrap {
 666            SoftWrap::None => None,
 667            SoftWrap::EditorWidth => Some(text_width - text_offset.x() - overscroll.x() - em_width),
 668            SoftWrap::Column(column) => Some(column as f32 * em_advance),
 669        };
 670        let snapshot = self.update_view(cx.app, |view, cx| {
 671            if view.set_wrap_width(wrap_width, cx) {
 672                view.snapshot(cx)
 673            } else {
 674                snapshot
 675            }
 676        });
 677
 678        let scroll_height = (snapshot.max_point().row() + 1) as f32 * line_height;
 679        if let EditorMode::AutoHeight { max_lines } = snapshot.mode {
 680            size.set_y(
 681                scroll_height
 682                    .min(constraint.max_along(Axis::Vertical))
 683                    .max(constraint.min_along(Axis::Vertical))
 684                    .min(line_height * max_lines as f32),
 685            )
 686        } else if size.y().is_infinite() {
 687            size.set_y(scroll_height);
 688        }
 689        let gutter_size = vec2f(gutter_width, size.y());
 690        let text_size = vec2f(text_width, size.y());
 691
 692        let (autoscroll_horizontally, mut snapshot) = self.update_view(cx.app, |view, cx| {
 693            let autoscroll_horizontally = view.autoscroll_vertically(size.y(), line_height, cx);
 694            let snapshot = view.snapshot(cx);
 695            (autoscroll_horizontally, snapshot)
 696        });
 697
 698        let scroll_position = snapshot.scroll_position();
 699        let start_row = scroll_position.y() as u32;
 700        let scroll_top = scroll_position.y() * line_height;
 701        let end_row = ((scroll_top + size.y()) / line_height).ceil() as u32 + 1; // Add 1 to ensure selections bleed off screen
 702
 703        let start_anchor = if start_row == 0 {
 704            Anchor::min()
 705        } else {
 706            snapshot
 707                .buffer_snapshot
 708                .anchor_before(DisplayPoint::new(start_row, 0).to_offset(&snapshot, Bias::Left))
 709        };
 710        let end_anchor = if end_row > snapshot.max_point().row() {
 711            Anchor::max()
 712        } else {
 713            snapshot
 714                .buffer_snapshot
 715                .anchor_before(DisplayPoint::new(end_row, 0).to_offset(&snapshot, Bias::Right))
 716        };
 717
 718        let mut selections = HashMap::default();
 719        let mut active_rows = BTreeMap::new();
 720        let mut highlighted_rows = None;
 721        self.update_view(cx.app, |view, cx| {
 722            highlighted_rows = view.highlighted_rows();
 723            let display_map = view.display_map.update(cx, |map, cx| map.snapshot(cx));
 724
 725            let local_selections = view
 726                .local_selections_in_range(start_anchor.clone()..end_anchor.clone(), &display_map);
 727            for selection in &local_selections {
 728                let is_empty = selection.start == selection.end;
 729                let selection_start = snapshot.prev_line_boundary(selection.start).1;
 730                let selection_end = snapshot.next_line_boundary(selection.end).1;
 731                for row in cmp::max(selection_start.row(), start_row)
 732                    ..=cmp::min(selection_end.row(), end_row)
 733                {
 734                    let contains_non_empty_selection = active_rows.entry(row).or_insert(!is_empty);
 735                    *contains_non_empty_selection |= !is_empty;
 736                }
 737            }
 738            selections.insert(
 739                view.replica_id(cx),
 740                local_selections
 741                    .into_iter()
 742                    .map(|selection| crate::Selection {
 743                        id: selection.id,
 744                        goal: selection.goal,
 745                        reversed: selection.reversed,
 746                        start: selection.start.to_display_point(&display_map),
 747                        end: selection.end.to_display_point(&display_map),
 748                    })
 749                    .collect(),
 750            );
 751
 752            for (replica_id, selection) in display_map
 753                .buffer_snapshot
 754                .remote_selections_in_range(&(start_anchor..end_anchor))
 755            {
 756                selections
 757                    .entry(replica_id)
 758                    .or_insert(Vec::new())
 759                    .push(crate::Selection {
 760                        id: selection.id,
 761                        goal: selection.goal,
 762                        reversed: selection.reversed,
 763                        start: selection.start.to_display_point(&display_map),
 764                        end: selection.end.to_display_point(&display_map),
 765                    });
 766            }
 767        });
 768
 769        let line_number_layouts = self.layout_rows(start_row..end_row, &active_rows, &snapshot, cx);
 770
 771        let mut max_visible_line_width = 0.0;
 772        let line_layouts = self.layout_lines(start_row..end_row, &mut snapshot, cx);
 773        for line in &line_layouts {
 774            if line.width() > max_visible_line_width {
 775                max_visible_line_width = line.width();
 776            }
 777        }
 778
 779        let blocks = self.layout_blocks(
 780            start_row..end_row,
 781            &snapshot,
 782            size.x(),
 783            gutter_padding,
 784            gutter_width + text_offset.x(),
 785            line_height,
 786            &style,
 787            &line_layouts,
 788            cx,
 789        );
 790
 791        let mut layout = LayoutState {
 792            size,
 793            gutter_size,
 794            gutter_padding,
 795            text_size,
 796            overscroll,
 797            text_offset,
 798            snapshot,
 799            style: self.settings.style.clone(),
 800            active_rows,
 801            highlighted_rows,
 802            line_layouts,
 803            line_number_layouts,
 804            blocks,
 805            line_height,
 806            em_width,
 807            em_advance,
 808            selections,
 809            max_visible_line_width,
 810        };
 811
 812        let scroll_max = layout.scroll_max(cx.font_cache, cx.text_layout_cache).x();
 813        let scroll_width = layout.scroll_width(cx.text_layout_cache);
 814        let max_glyph_width = style.text.em_width(&cx.font_cache);
 815        self.update_view(cx.app, |view, cx| {
 816            let clamped = view.clamp_scroll_left(scroll_max);
 817            let autoscrolled;
 818            if autoscroll_horizontally {
 819                autoscrolled = view.autoscroll_horizontally(
 820                    start_row,
 821                    layout.text_size.x(),
 822                    scroll_width,
 823                    max_glyph_width,
 824                    &layout.line_layouts,
 825                    cx,
 826                );
 827            } else {
 828                autoscrolled = false;
 829            }
 830
 831            if clamped || autoscrolled {
 832                layout.snapshot = view.snapshot(cx);
 833            }
 834        });
 835
 836        (size, Some(layout))
 837    }
 838
 839    fn paint(
 840        &mut self,
 841        bounds: RectF,
 842        visible_bounds: RectF,
 843        layout: &mut Self::LayoutState,
 844        cx: &mut PaintContext,
 845    ) -> Self::PaintState {
 846        if let Some(layout) = layout {
 847            cx.scene.push_layer(Some(bounds));
 848
 849            let gutter_bounds = RectF::new(bounds.origin(), layout.gutter_size);
 850            let text_bounds = RectF::new(
 851                bounds.origin() + vec2f(layout.gutter_size.x(), 0.0),
 852                layout.text_size,
 853            );
 854
 855            self.paint_background(gutter_bounds, text_bounds, layout, cx);
 856            if layout.gutter_size.x() > 0. {
 857                self.paint_gutter(gutter_bounds, visible_bounds, layout, cx);
 858            }
 859            self.paint_text(text_bounds, visible_bounds, layout, cx);
 860            self.paint_blocks(bounds, visible_bounds, layout, cx);
 861
 862            cx.scene.pop_layer();
 863
 864            Some(PaintState {
 865                bounds,
 866                gutter_bounds,
 867                text_bounds,
 868            })
 869        } else {
 870            None
 871        }
 872    }
 873
 874    fn dispatch_event(
 875        &mut self,
 876        event: &Event,
 877        _: RectF,
 878        layout: &mut Self::LayoutState,
 879        paint: &mut Self::PaintState,
 880        cx: &mut EventContext,
 881    ) -> bool {
 882        if let (Some(layout), Some(paint)) = (layout, paint) {
 883            match event {
 884                Event::LeftMouseDown {
 885                    position,
 886                    alt,
 887                    shift,
 888                    click_count,
 889                    ..
 890                } => self.mouse_down(*position, *alt, *shift, *click_count, layout, paint, cx),
 891                Event::LeftMouseUp { position } => self.mouse_up(*position, cx),
 892                Event::LeftMouseDragged { position } => {
 893                    self.mouse_dragged(*position, layout, paint, cx)
 894                }
 895                Event::ScrollWheel {
 896                    position,
 897                    delta,
 898                    precise,
 899                } => self.scroll(*position, *delta, *precise, layout, paint, cx),
 900                Event::KeyDown {
 901                    chars, keystroke, ..
 902                } => self.key_down(chars, keystroke, cx),
 903                _ => false,
 904            }
 905        } else {
 906            false
 907        }
 908    }
 909
 910    fn debug(
 911        &self,
 912        bounds: RectF,
 913        _: &Self::LayoutState,
 914        _: &Self::PaintState,
 915        _: &gpui::DebugContext,
 916    ) -> json::Value {
 917        json!({
 918            "type": "BufferElement",
 919            "bounds": bounds.to_json()
 920        })
 921    }
 922}
 923
 924pub struct LayoutState {
 925    size: Vector2F,
 926    gutter_size: Vector2F,
 927    gutter_padding: f32,
 928    text_size: Vector2F,
 929    style: EditorStyle,
 930    snapshot: EditorSnapshot,
 931    active_rows: BTreeMap<u32, bool>,
 932    highlighted_rows: Option<Range<u32>>,
 933    line_layouts: Vec<text_layout::Line>,
 934    line_number_layouts: Vec<Option<text_layout::Line>>,
 935    blocks: Vec<(u32, ElementBox)>,
 936    line_height: f32,
 937    em_width: f32,
 938    em_advance: f32,
 939    selections: HashMap<ReplicaId, Vec<text::Selection<DisplayPoint>>>,
 940    overscroll: Vector2F,
 941    text_offset: Vector2F,
 942    max_visible_line_width: f32,
 943}
 944
 945impl LayoutState {
 946    fn scroll_width(&self, layout_cache: &TextLayoutCache) -> f32 {
 947        let row = self.snapshot.longest_row();
 948        let longest_line_width =
 949            layout_line(row, &self.snapshot, &self.style, layout_cache).width();
 950        longest_line_width.max(self.max_visible_line_width) + self.overscroll.x()
 951    }
 952
 953    fn scroll_max(&self, font_cache: &FontCache, layout_cache: &TextLayoutCache) -> Vector2F {
 954        let text_width = self.text_size.x();
 955        let scroll_width = self.scroll_width(layout_cache);
 956        let em_width = self.style.text.em_width(font_cache);
 957        let max_row = self.snapshot.max_point().row();
 958
 959        vec2f(
 960            ((scroll_width - text_width) / em_width).max(0.0),
 961            max_row.saturating_sub(1) as f32,
 962        )
 963    }
 964}
 965
 966fn layout_line(
 967    row: u32,
 968    snapshot: &EditorSnapshot,
 969    style: &EditorStyle,
 970    layout_cache: &TextLayoutCache,
 971) -> text_layout::Line {
 972    let mut line = snapshot.line(row);
 973
 974    if line.len() > MAX_LINE_LEN {
 975        let mut len = MAX_LINE_LEN;
 976        while !line.is_char_boundary(len) {
 977            len -= 1;
 978        }
 979        line.truncate(len);
 980    }
 981
 982    layout_cache.layout_str(
 983        &line,
 984        style.text.font_size,
 985        &[(
 986            snapshot.line_len(row) as usize,
 987            RunStyle {
 988                font_id: style.text.font_id,
 989                color: Color::black(),
 990                underline: None,
 991            },
 992        )],
 993    )
 994}
 995
 996pub struct PaintState {
 997    bounds: RectF,
 998    gutter_bounds: RectF,
 999    text_bounds: RectF,
1000}
1001
1002impl PaintState {
1003    fn point_for_position(
1004        &self,
1005        snapshot: &EditorSnapshot,
1006        layout: &LayoutState,
1007        position: Vector2F,
1008    ) -> (DisplayPoint, u32) {
1009        let scroll_position = snapshot.scroll_position();
1010        let position = position - self.text_bounds.origin();
1011        let y = position.y().max(0.0).min(layout.size.y());
1012        let row = ((y / layout.line_height) + scroll_position.y()) as u32;
1013        let row = cmp::min(row, snapshot.max_point().row());
1014        let line = &layout.line_layouts[(row - scroll_position.y() as u32) as usize];
1015        let x = position.x() + (scroll_position.x() * layout.em_width);
1016
1017        let column = if x >= 0.0 {
1018            line.index_for_x(x)
1019                .map(|ix| ix as u32)
1020                .unwrap_or_else(|| snapshot.line_len(row))
1021        } else {
1022            0
1023        };
1024        let overshoot = (0f32.max(x - line.width()) / layout.em_advance) as u32;
1025
1026        (DisplayPoint::new(row, column), overshoot)
1027    }
1028}
1029
1030struct Cursor {
1031    origin: Vector2F,
1032    line_height: f32,
1033    color: Color,
1034}
1035
1036impl Cursor {
1037    fn paint(&self, cx: &mut PaintContext) {
1038        cx.scene.push_quad(Quad {
1039            bounds: RectF::new(self.origin, vec2f(2.0, self.line_height)),
1040            background: Some(self.color),
1041            border: Border::new(0., Color::black()),
1042            corner_radius: 0.,
1043        });
1044    }
1045}
1046
1047#[derive(Debug)]
1048struct Selection {
1049    start_y: f32,
1050    line_height: f32,
1051    lines: Vec<SelectionLine>,
1052    color: Color,
1053}
1054
1055#[derive(Debug)]
1056struct SelectionLine {
1057    start_x: f32,
1058    end_x: f32,
1059}
1060
1061impl Selection {
1062    fn paint(&self, bounds: RectF, scene: &mut Scene) {
1063        if self.lines.len() >= 2 && self.lines[0].start_x > self.lines[1].end_x {
1064            self.paint_lines(self.start_y, &self.lines[0..1], bounds, scene);
1065            self.paint_lines(
1066                self.start_y + self.line_height,
1067                &self.lines[1..],
1068                bounds,
1069                scene,
1070            );
1071        } else {
1072            self.paint_lines(self.start_y, &self.lines, bounds, scene);
1073        }
1074    }
1075
1076    fn paint_lines(&self, start_y: f32, lines: &[SelectionLine], bounds: RectF, scene: &mut Scene) {
1077        if lines.is_empty() {
1078            return;
1079        }
1080
1081        let mut path = PathBuilder::new();
1082        let corner_radius = 0.15 * self.line_height;
1083        let first_line = lines.first().unwrap();
1084        let last_line = lines.last().unwrap();
1085
1086        let first_top_left = vec2f(first_line.start_x, start_y);
1087        let first_top_right = vec2f(first_line.end_x, start_y);
1088
1089        let curve_height = vec2f(0., corner_radius);
1090        let curve_width = |start_x: f32, end_x: f32| {
1091            let max = (end_x - start_x) / 2.;
1092            let width = if max < corner_radius {
1093                max
1094            } else {
1095                corner_radius
1096            };
1097
1098            vec2f(width, 0.)
1099        };
1100
1101        let top_curve_width = curve_width(first_line.start_x, first_line.end_x);
1102        path.reset(first_top_right - top_curve_width);
1103        path.curve_to(first_top_right + curve_height, first_top_right);
1104
1105        let mut iter = lines.iter().enumerate().peekable();
1106        while let Some((ix, line)) = iter.next() {
1107            let bottom_right = vec2f(line.end_x, start_y + (ix + 1) as f32 * self.line_height);
1108
1109            if let Some((_, next_line)) = iter.peek() {
1110                let next_top_right = vec2f(next_line.end_x, bottom_right.y());
1111
1112                match next_top_right.x().partial_cmp(&bottom_right.x()).unwrap() {
1113                    Ordering::Equal => {
1114                        path.line_to(bottom_right);
1115                    }
1116                    Ordering::Less => {
1117                        let curve_width = curve_width(next_top_right.x(), bottom_right.x());
1118                        path.line_to(bottom_right - curve_height);
1119                        path.curve_to(bottom_right - curve_width, bottom_right);
1120                        path.line_to(next_top_right + curve_width);
1121                        path.curve_to(next_top_right + curve_height, next_top_right);
1122                    }
1123                    Ordering::Greater => {
1124                        let curve_width = curve_width(bottom_right.x(), next_top_right.x());
1125                        path.line_to(bottom_right - curve_height);
1126                        path.curve_to(bottom_right + curve_width, bottom_right);
1127                        path.line_to(next_top_right - curve_width);
1128                        path.curve_to(next_top_right + curve_height, next_top_right);
1129                    }
1130                }
1131            } else {
1132                let curve_width = curve_width(line.start_x, line.end_x);
1133                path.line_to(bottom_right - curve_height);
1134                path.curve_to(bottom_right - curve_width, bottom_right);
1135
1136                let bottom_left = vec2f(line.start_x, bottom_right.y());
1137                path.line_to(bottom_left + curve_width);
1138                path.curve_to(bottom_left - curve_height, bottom_left);
1139            }
1140        }
1141
1142        if first_line.start_x > last_line.start_x {
1143            let curve_width = curve_width(last_line.start_x, first_line.start_x);
1144            let second_top_left = vec2f(last_line.start_x, start_y + self.line_height);
1145            path.line_to(second_top_left + curve_height);
1146            path.curve_to(second_top_left + curve_width, second_top_left);
1147            let first_bottom_left = vec2f(first_line.start_x, second_top_left.y());
1148            path.line_to(first_bottom_left - curve_width);
1149            path.curve_to(first_bottom_left - curve_height, first_bottom_left);
1150        }
1151
1152        path.line_to(first_top_left + curve_height);
1153        path.curve_to(first_top_left + top_curve_width, first_top_left);
1154        path.line_to(first_top_right - top_curve_width);
1155
1156        scene.push_path(path.build(self.color, Some(bounds)));
1157    }
1158}
1159
1160fn scale_vertical_mouse_autoscroll_delta(delta: f32) -> f32 {
1161    delta.powf(1.5) / 100.0
1162}
1163
1164fn scale_horizontal_mouse_autoscroll_delta(delta: f32) -> f32 {
1165    delta.powf(1.2) / 300.0
1166}
1167
1168#[cfg(test)]
1169mod tests {
1170    use super::*;
1171    use crate::{Editor, EditorSettings, MultiBuffer};
1172    use std::sync::Arc;
1173    use util::test::sample_text;
1174
1175    #[gpui::test]
1176    fn test_layout_line_numbers(cx: &mut gpui::MutableAppContext) {
1177        let settings = EditorSettings::test(cx);
1178        let buffer = MultiBuffer::build_simple(&sample_text(6, 6, 'a'), cx);
1179        let (window_id, editor) = cx.add_window(Default::default(), |cx| {
1180            Editor::for_buffer(
1181                buffer,
1182                {
1183                    let settings = settings.clone();
1184                    Arc::new(move |_| settings.clone())
1185                },
1186                cx,
1187            )
1188        });
1189        let element = EditorElement::new(editor.downgrade(), settings);
1190
1191        let layouts = editor.update(cx, |editor, cx| {
1192            let snapshot = editor.snapshot(cx);
1193            let mut presenter = cx.build_presenter(window_id, 30.);
1194            let mut layout_cx = presenter.build_layout_context(false, cx);
1195            element.layout_rows(0..6, &Default::default(), &snapshot, &mut layout_cx)
1196        });
1197        assert_eq!(layouts.len(), 6);
1198    }
1199}