element.rs

  1use super::{DisplayPoint, Editor, EditorMode, Insert, Scroll, Select, SelectPhase, Snapshot};
  2use crate::{theme::EditorStyle, time::ReplicaId};
  3use gpui::{
  4    color::Color,
  5    geometry::{
  6        rect::RectF,
  7        vector::{vec2f, Vector2F},
  8        PathBuilder,
  9    },
 10    json::{self, ToJson},
 11    text_layout::{self, TextLayoutCache},
 12    AppContext, Axis, Border, Element, Event, EventContext, FontCache, LayoutContext,
 13    MutableAppContext, PaintContext, Quad, Scene, SizeConstraint, ViewContext, WeakViewHandle,
 14};
 15use json::json;
 16use smallvec::SmallVec;
 17use std::{
 18    cmp::{self, Ordering},
 19    collections::{BTreeMap, HashMap},
 20    ops::Range,
 21};
 22
 23pub struct EditorElement {
 24    view: WeakViewHandle<Editor>,
 25    style: EditorStyle,
 26}
 27
 28impl EditorElement {
 29    pub fn new(view: WeakViewHandle<Editor>, style: EditorStyle) -> Self {
 30        Self { view, style }
 31    }
 32
 33    fn view<'a>(&self, cx: &'a AppContext) -> &'a Editor {
 34        self.view.upgrade(cx).unwrap().read(cx)
 35    }
 36
 37    fn update_view<F, T>(&self, cx: &mut MutableAppContext, f: F) -> T
 38    where
 39        F: FnOnce(&mut Editor, &mut ViewContext<Editor>) -> T,
 40    {
 41        self.view.upgrade(cx).unwrap().update(cx, f)
 42    }
 43
 44    fn snapshot(&self, cx: &mut MutableAppContext) -> Snapshot {
 45        self.update_view(cx, |view, cx| view.snapshot(cx))
 46    }
 47
 48    fn mouse_down(
 49        &self,
 50        position: Vector2F,
 51        cmd: bool,
 52        layout: &mut LayoutState,
 53        paint: &mut PaintState,
 54        cx: &mut EventContext,
 55    ) -> bool {
 56        if paint.text_bounds.contains_point(position) {
 57            let snapshot = self.snapshot(cx.app);
 58            let position = paint.point_for_position(&snapshot, layout, position);
 59            cx.dispatch_action(Select(SelectPhase::Begin { position, add: cmd }));
 60            true
 61        } else {
 62            false
 63        }
 64    }
 65
 66    fn mouse_up(&self, _position: Vector2F, cx: &mut EventContext) -> bool {
 67        if self.view(cx.app.as_ref()).is_selecting() {
 68            cx.dispatch_action(Select(SelectPhase::End));
 69            true
 70        } else {
 71            false
 72        }
 73    }
 74
 75    fn mouse_dragged(
 76        &self,
 77        position: Vector2F,
 78        layout: &mut LayoutState,
 79        paint: &mut PaintState,
 80        cx: &mut EventContext,
 81    ) -> bool {
 82        let view = self.view(cx.app.as_ref());
 83
 84        if view.is_selecting() {
 85            let rect = paint.text_bounds;
 86            let mut scroll_delta = Vector2F::zero();
 87
 88            let vertical_margin = layout.line_height.min(rect.height() / 3.0);
 89            let top = rect.origin_y() + vertical_margin;
 90            let bottom = rect.lower_left().y() - vertical_margin;
 91            if position.y() < top {
 92                scroll_delta.set_y(-scale_vertical_mouse_autoscroll_delta(top - position.y()))
 93            }
 94            if position.y() > bottom {
 95                scroll_delta.set_y(scale_vertical_mouse_autoscroll_delta(position.y() - bottom))
 96            }
 97
 98            let horizontal_margin = layout.line_height.min(rect.width() / 3.0);
 99            let left = rect.origin_x() + horizontal_margin;
100            let right = rect.upper_right().x() - horizontal_margin;
101            if position.x() < left {
102                scroll_delta.set_x(-scale_horizontal_mouse_autoscroll_delta(
103                    left - position.x(),
104                ))
105            }
106            if position.x() > right {
107                scroll_delta.set_x(scale_horizontal_mouse_autoscroll_delta(
108                    position.x() - right,
109                ))
110            }
111
112            let font_cache = cx.font_cache.clone();
113            let text_layout_cache = cx.text_layout_cache.clone();
114            let snapshot = self.snapshot(cx.app);
115            let position = paint.point_for_position(&snapshot, layout, position);
116
117            cx.dispatch_action(Select(SelectPhase::Update {
118                position,
119                scroll_position: (snapshot.scroll_position() + scroll_delta).clamp(
120                    Vector2F::zero(),
121                    layout.scroll_max(&font_cache, &text_layout_cache),
122                ),
123            }));
124            true
125        } else {
126            false
127        }
128    }
129
130    fn key_down(&self, chars: &str, cx: &mut EventContext) -> bool {
131        let view = self.view.upgrade(cx.app).unwrap();
132
133        if view.is_focused(cx.app) {
134            if chars.is_empty() {
135                false
136            } else {
137                if chars.chars().any(|c| c.is_control()) {
138                    false
139                } else {
140                    cx.dispatch_action(Insert(chars.to_string()));
141                    true
142                }
143            }
144        } else {
145            false
146        }
147    }
148
149    fn scroll(
150        &self,
151        position: Vector2F,
152        mut delta: Vector2F,
153        precise: bool,
154        layout: &mut LayoutState,
155        paint: &mut PaintState,
156        cx: &mut EventContext,
157    ) -> bool {
158        if !paint.bounds.contains_point(position) {
159            return false;
160        }
161
162        let snapshot = self.snapshot(cx.app);
163        let font_cache = &cx.font_cache;
164        let layout_cache = &cx.text_layout_cache;
165        let max_glyph_width = layout.em_width;
166        if !precise {
167            delta *= vec2f(max_glyph_width, layout.line_height);
168        }
169
170        let scroll_position = snapshot.scroll_position();
171        let x = (scroll_position.x() * max_glyph_width - delta.x()) / max_glyph_width;
172        let y = (scroll_position.y() * layout.line_height - delta.y()) / layout.line_height;
173        let scroll_position = vec2f(x, y).clamp(
174            Vector2F::zero(),
175            layout.scroll_max(font_cache, layout_cache),
176        );
177
178        cx.dispatch_action(Scroll(scroll_position));
179
180        true
181    }
182
183    fn paint_background(
184        &self,
185        gutter_bounds: RectF,
186        text_bounds: RectF,
187        layout: &LayoutState,
188        cx: &mut PaintContext,
189    ) {
190        let bounds = gutter_bounds.union_rect(text_bounds);
191        let scroll_top = layout.snapshot.scroll_position().y() * layout.line_height;
192        let editor = self.view(cx.app);
193        cx.scene.push_quad(Quad {
194            bounds: gutter_bounds,
195            background: Some(self.style.gutter_background),
196            border: Border::new(0., Color::transparent_black()),
197            corner_radius: 0.,
198        });
199        cx.scene.push_quad(Quad {
200            bounds: text_bounds,
201            background: Some(self.style.background),
202            border: Border::new(0., Color::transparent_black()),
203            corner_radius: 0.,
204        });
205
206        if let EditorMode::Full = editor.mode {
207            let mut active_rows = layout.active_rows.iter().peekable();
208            while let Some((start_row, contains_non_empty_selection)) = active_rows.next() {
209                let mut end_row = *start_row;
210                while active_rows.peek().map_or(false, |r| {
211                    *r.0 == end_row + 1 && r.1 == contains_non_empty_selection
212                }) {
213                    active_rows.next().unwrap();
214                    end_row += 1;
215                }
216
217                if !contains_non_empty_selection {
218                    let origin = vec2f(
219                        bounds.origin_x(),
220                        bounds.origin_y() + (layout.line_height * *start_row as f32) - scroll_top,
221                    );
222                    let size = vec2f(
223                        bounds.width(),
224                        layout.line_height * (end_row - start_row + 1) as f32,
225                    );
226                    cx.scene.push_quad(Quad {
227                        bounds: RectF::new(origin, size),
228                        background: Some(self.style.active_line_background),
229                        border: Border::default(),
230                        corner_radius: 0.,
231                    });
232                }
233            }
234        }
235    }
236
237    fn paint_gutter(
238        &mut self,
239        bounds: RectF,
240        visible_bounds: RectF,
241        layout: &LayoutState,
242        cx: &mut PaintContext,
243    ) {
244        let scroll_top = layout.snapshot.scroll_position().y() * layout.line_height;
245        for (ix, line) in layout.line_number_layouts.iter().enumerate() {
246            if let Some(line) = line {
247                let line_origin = bounds.origin()
248                    + vec2f(
249                        bounds.width() - line.width() - layout.gutter_padding,
250                        ix as f32 * layout.line_height - (scroll_top % layout.line_height),
251                    );
252                line.paint(line_origin, visible_bounds, layout.line_height, cx);
253            }
254        }
255    }
256
257    fn paint_text(
258        &mut self,
259        bounds: RectF,
260        visible_bounds: RectF,
261        layout: &LayoutState,
262        cx: &mut PaintContext,
263    ) {
264        let view = self.view(cx.app);
265        let settings = self.view(cx.app).settings.borrow();
266        let theme = &settings.theme.editor;
267        let scroll_position = layout.snapshot.scroll_position();
268        let start_row = scroll_position.y() as u32;
269        let scroll_top = scroll_position.y() * layout.line_height;
270        let end_row = ((scroll_top + bounds.height()) / layout.line_height).ceil() as u32 + 1; // Add 1 to ensure selections bleed off screen
271        let max_glyph_width = layout.em_width;
272        let scroll_left = scroll_position.x() * max_glyph_width;
273
274        cx.scene.push_layer(Some(bounds));
275
276        // Draw selections
277        let corner_radius = 2.5;
278        let mut cursors = SmallVec::<[Cursor; 32]>::new();
279
280        let content_origin = bounds.origin() + layout.text_offset;
281
282        for (replica_id, selections) in &layout.selections {
283            let style_ix = *replica_id as usize % (theme.guest_selections.len() + 1);
284            let style = if style_ix == 0 {
285                &theme.selection
286            } else {
287                &theme.guest_selections[style_ix - 1]
288            };
289
290            for selection in selections {
291                if selection.start != selection.end {
292                    let range_start = cmp::min(selection.start, selection.end);
293                    let range_end = cmp::max(selection.start, selection.end);
294                    let row_range = if range_end.column() == 0 {
295                        cmp::max(range_start.row(), start_row)..cmp::min(range_end.row(), end_row)
296                    } else {
297                        cmp::max(range_start.row(), start_row)
298                            ..cmp::min(range_end.row() + 1, end_row)
299                    };
300
301                    let selection = Selection {
302                        color: style.selection,
303                        line_height: layout.line_height,
304                        start_y: content_origin.y() + row_range.start as f32 * layout.line_height
305                            - scroll_top,
306                        lines: row_range
307                            .into_iter()
308                            .map(|row| {
309                                let line_layout = &layout.line_layouts[(row - start_row) as usize];
310                                SelectionLine {
311                                    start_x: if row == range_start.row() {
312                                        content_origin.x()
313                                            + line_layout.x_for_index(range_start.column() as usize)
314                                            - scroll_left
315                                    } else {
316                                        content_origin.x() - scroll_left
317                                    },
318                                    end_x: if row == range_end.row() {
319                                        content_origin.x()
320                                            + line_layout.x_for_index(range_end.column() as usize)
321                                            - scroll_left
322                                    } else {
323                                        content_origin.x()
324                                            + line_layout.width()
325                                            + corner_radius * 2.0
326                                            - scroll_left
327                                    },
328                                }
329                            })
330                            .collect(),
331                    };
332
333                    selection.paint(bounds, cx.scene);
334                }
335
336                if view.cursors_visible() {
337                    let cursor_position = selection.end;
338                    if (start_row..end_row).contains(&cursor_position.row()) {
339                        let cursor_row_layout =
340                            &layout.line_layouts[(selection.end.row() - start_row) as usize];
341                        let x = cursor_row_layout.x_for_index(selection.end.column() as usize)
342                            - scroll_left;
343                        let y = selection.end.row() as f32 * layout.line_height - scroll_top;
344                        cursors.push(Cursor {
345                            color: style.cursor,
346                            origin: content_origin + vec2f(x, y),
347                            line_height: layout.line_height,
348                        });
349                    }
350                }
351            }
352        }
353
354        if let Some(visible_text_bounds) = bounds.intersection(visible_bounds) {
355            // Draw glyphs
356            for (ix, line) in layout.line_layouts.iter().enumerate() {
357                let row = start_row + ix as u32;
358                line.paint(
359                    content_origin
360                        + vec2f(-scroll_left, row as f32 * layout.line_height - scroll_top),
361                    visible_text_bounds,
362                    layout.line_height,
363                    cx,
364                );
365            }
366        }
367
368        cx.scene.push_layer(Some(bounds));
369        for cursor in cursors {
370            cursor.paint(cx);
371        }
372        cx.scene.pop_layer();
373
374        cx.scene.pop_layer();
375    }
376}
377
378impl Element for EditorElement {
379    type LayoutState = Option<LayoutState>;
380    type PaintState = Option<PaintState>;
381
382    fn layout(
383        &mut self,
384        constraint: SizeConstraint,
385        cx: &mut LayoutContext,
386    ) -> (Vector2F, Self::LayoutState) {
387        let mut size = constraint.max;
388        if size.x().is_infinite() {
389            unimplemented!("we don't yet handle an infinite width constraint on buffer elements");
390        }
391
392        let font_cache = &cx.font_cache;
393        let layout_cache = &cx.text_layout_cache;
394        let snapshot = self.snapshot(cx.app);
395        let line_height = snapshot.line_height(font_cache);
396
397        let gutter_padding;
398        let gutter_width;
399        if snapshot.mode == EditorMode::Full {
400            gutter_padding = snapshot.em_width(cx.font_cache);
401            match snapshot.max_line_number_width(cx.font_cache, cx.text_layout_cache) {
402                Err(error) => {
403                    log::error!("error computing max line number width: {}", error);
404                    return (size, None);
405                }
406                Ok(width) => gutter_width = width + gutter_padding * 2.0,
407            }
408        } else {
409            gutter_padding = 0.0;
410            gutter_width = 0.0
411        };
412
413        let text_width = size.x() - gutter_width;
414        let text_offset = vec2f(-snapshot.font_descent(cx.font_cache), 0.);
415        let em_width = snapshot.em_width(font_cache);
416        let overscroll = vec2f(em_width, 0.);
417        let wrap_width = text_width - text_offset.x() - overscroll.x() - em_width;
418        let snapshot = self.update_view(cx.app, |view, cx| {
419            if view.set_wrap_width(wrap_width, cx) {
420                view.snapshot(cx)
421            } else {
422                snapshot
423            }
424        });
425
426        let scroll_height = (snapshot.max_point().row() + 1) as f32 * line_height;
427        if let EditorMode::AutoHeight { max_lines } = snapshot.mode {
428            size.set_y(
429                scroll_height
430                    .min(constraint.max_along(Axis::Vertical))
431                    .max(constraint.min_along(Axis::Vertical))
432                    .min(line_height * max_lines as f32),
433            )
434        } else if size.y().is_infinite() {
435            size.set_y(scroll_height);
436        }
437        let gutter_size = vec2f(gutter_width, size.y());
438        let text_size = vec2f(text_width, size.y());
439
440        let (autoscroll_horizontally, mut snapshot) = self.update_view(cx.app, |view, cx| {
441            let autoscroll_horizontally = view.autoscroll_vertically(size.y(), line_height, cx);
442            let snapshot = view.snapshot(cx);
443            (autoscroll_horizontally, snapshot)
444        });
445
446        let scroll_position = snapshot.scroll_position();
447        let start_row = scroll_position.y() as u32;
448        let scroll_top = scroll_position.y() * line_height;
449        let end_row = ((scroll_top + size.y()) / line_height).ceil() as u32 + 1; // Add 1 to ensure selections bleed off screen
450
451        let mut selections = HashMap::new();
452        let mut active_rows = BTreeMap::new();
453        self.update_view(cx.app, |view, cx| {
454            for selection_set_id in view.active_selection_sets(cx).collect::<Vec<_>>() {
455                let mut set = Vec::new();
456                for selection in view.selections_in_range(
457                    selection_set_id,
458                    DisplayPoint::new(start_row, 0)..DisplayPoint::new(end_row, 0),
459                    cx,
460                ) {
461                    set.push(selection.clone());
462                    if selection_set_id == view.selection_set_id {
463                        let is_empty = selection.start == selection.end;
464                        let mut selection_start;
465                        let mut selection_end;
466                        if selection.start < selection.end {
467                            selection_start = selection.start;
468                            selection_end = selection.end;
469                        } else {
470                            selection_start = selection.end;
471                            selection_end = selection.start;
472                        };
473                        selection_start = snapshot.prev_row_boundary(selection_start).0;
474                        selection_end = snapshot.next_row_boundary(selection_end).0;
475                        for row in cmp::max(selection_start.row(), start_row)
476                            ..=cmp::min(selection_end.row(), end_row)
477                        {
478                            let contains_non_empty_selection =
479                                active_rows.entry(row).or_insert(!is_empty);
480                            *contains_non_empty_selection |= !is_empty;
481                        }
482                    }
483                }
484
485                selections.insert(selection_set_id.replica_id, set);
486            }
487        });
488
489        let line_number_layouts = if snapshot.mode == EditorMode::Full {
490            let settings = self
491                .view
492                .upgrade(cx.app)
493                .unwrap()
494                .read(cx.app)
495                .settings
496                .borrow();
497            match snapshot.layout_line_numbers(
498                start_row..end_row,
499                &active_rows,
500                cx.font_cache,
501                cx.text_layout_cache,
502                &settings.theme,
503            ) {
504                Err(error) => {
505                    log::error!("error laying out line numbers: {}", error);
506                    return (size, None);
507                }
508                Ok(layouts) => layouts,
509            }
510        } else {
511            Vec::new()
512        };
513
514        let mut max_visible_line_width = 0.0;
515        let line_layouts = match snapshot.layout_lines(
516            start_row..end_row,
517            &self.style,
518            font_cache,
519            layout_cache,
520        ) {
521            Err(error) => {
522                log::error!("error laying out lines: {}", error);
523                return (size, None);
524            }
525            Ok(layouts) => {
526                for line in &layouts {
527                    if line.width() > max_visible_line_width {
528                        max_visible_line_width = line.width();
529                    }
530                }
531
532                layouts
533            }
534        };
535
536        let mut layout = LayoutState {
537            size,
538            gutter_size,
539            gutter_padding,
540            text_size,
541            overscroll,
542            text_offset,
543            snapshot,
544            active_rows,
545            line_layouts,
546            line_number_layouts,
547            line_height,
548            em_width,
549            selections,
550            max_visible_line_width,
551        };
552
553        self.update_view(cx.app, |view, cx| {
554            let clamped = view.clamp_scroll_left(layout.scroll_max(font_cache, layout_cache).x());
555            let autoscrolled;
556            if autoscroll_horizontally {
557                autoscrolled = view.autoscroll_horizontally(
558                    start_row,
559                    layout.text_size.x(),
560                    layout.scroll_width(font_cache, layout_cache),
561                    layout.snapshot.em_width(font_cache),
562                    &layout.line_layouts,
563                    cx,
564                );
565            } else {
566                autoscrolled = false;
567            }
568
569            if clamped || autoscrolled {
570                layout.snapshot = view.snapshot(cx);
571            }
572        });
573
574        (size, Some(layout))
575    }
576
577    fn paint(
578        &mut self,
579        bounds: RectF,
580        visible_bounds: RectF,
581        layout: &mut Self::LayoutState,
582        cx: &mut PaintContext,
583    ) -> Self::PaintState {
584        if let Some(layout) = layout {
585            cx.scene.push_layer(Some(bounds));
586
587            let gutter_bounds = RectF::new(bounds.origin(), layout.gutter_size);
588            let text_bounds = RectF::new(
589                bounds.origin() + vec2f(layout.gutter_size.x(), 0.0),
590                layout.text_size,
591            );
592
593            self.paint_background(gutter_bounds, text_bounds, layout, cx);
594            if layout.gutter_size.x() > 0. {
595                self.paint_gutter(gutter_bounds, visible_bounds, layout, cx);
596            }
597            self.paint_text(text_bounds, visible_bounds, layout, cx);
598
599            cx.scene.pop_layer();
600
601            Some(PaintState {
602                bounds,
603                text_bounds,
604            })
605        } else {
606            None
607        }
608    }
609
610    fn dispatch_event(
611        &mut self,
612        event: &Event,
613        _: RectF,
614        layout: &mut Self::LayoutState,
615        paint: &mut Self::PaintState,
616        cx: &mut EventContext,
617    ) -> bool {
618        if let (Some(layout), Some(paint)) = (layout, paint) {
619            match event {
620                Event::LeftMouseDown { position, cmd } => {
621                    self.mouse_down(*position, *cmd, layout, paint, cx)
622                }
623                Event::LeftMouseUp { position } => self.mouse_up(*position, cx),
624                Event::LeftMouseDragged { position } => {
625                    self.mouse_dragged(*position, layout, paint, cx)
626                }
627                Event::ScrollWheel {
628                    position,
629                    delta,
630                    precise,
631                } => self.scroll(*position, *delta, *precise, layout, paint, cx),
632                Event::KeyDown { chars, .. } => self.key_down(chars, cx),
633                _ => false,
634            }
635        } else {
636            false
637        }
638    }
639
640    fn debug(
641        &self,
642        bounds: RectF,
643        _: &Self::LayoutState,
644        _: &Self::PaintState,
645        _: &gpui::DebugContext,
646    ) -> json::Value {
647        json!({
648            "type": "BufferElement",
649            "bounds": bounds.to_json()
650        })
651    }
652}
653
654pub struct LayoutState {
655    size: Vector2F,
656    gutter_size: Vector2F,
657    gutter_padding: f32,
658    text_size: Vector2F,
659    snapshot: Snapshot,
660    active_rows: BTreeMap<u32, bool>,
661    line_layouts: Vec<text_layout::Line>,
662    line_number_layouts: Vec<Option<text_layout::Line>>,
663    line_height: f32,
664    em_width: f32,
665    selections: HashMap<ReplicaId, Vec<Range<DisplayPoint>>>,
666    overscroll: Vector2F,
667    text_offset: Vector2F,
668    max_visible_line_width: f32,
669}
670
671impl LayoutState {
672    fn scroll_width(&self, font_cache: &FontCache, layout_cache: &TextLayoutCache) -> f32 {
673        let row = self.snapshot.longest_row();
674        let longest_line_width = self
675            .snapshot
676            .layout_line(row, font_cache, layout_cache)
677            .unwrap()
678            .width();
679        longest_line_width.max(self.max_visible_line_width) + self.overscroll.x()
680    }
681
682    fn scroll_max(&self, font_cache: &FontCache, layout_cache: &TextLayoutCache) -> Vector2F {
683        let text_width = self.text_size.x();
684        let scroll_width = self.scroll_width(font_cache, layout_cache);
685        let em_width = self.snapshot.em_width(font_cache);
686        let max_row = self.snapshot.max_point().row();
687
688        vec2f(
689            ((scroll_width - text_width) / em_width).max(0.0),
690            max_row.saturating_sub(1) as f32,
691        )
692    }
693}
694
695pub struct PaintState {
696    bounds: RectF,
697    text_bounds: RectF,
698}
699
700impl PaintState {
701    fn point_for_position(
702        &self,
703        snapshot: &Snapshot,
704        layout: &LayoutState,
705        position: Vector2F,
706    ) -> DisplayPoint {
707        let scroll_position = snapshot.scroll_position();
708        let position = position - self.text_bounds.origin();
709        let y = position.y().max(0.0).min(layout.size.y());
710        let row = ((y / layout.line_height) + scroll_position.y()) as u32;
711        let row = cmp::min(row, snapshot.max_point().row());
712        let line = &layout.line_layouts[(row - scroll_position.y() as u32) as usize];
713        let x = position.x() + (scroll_position.x() * layout.em_width);
714
715        let column = if x >= 0.0 {
716            line.index_for_x(x)
717                .map(|ix| ix as u32)
718                .unwrap_or(snapshot.line_len(row))
719        } else {
720            0
721        };
722
723        DisplayPoint::new(row, column)
724    }
725}
726
727struct Cursor {
728    origin: Vector2F,
729    line_height: f32,
730    color: Color,
731}
732
733impl Cursor {
734    fn paint(&self, cx: &mut PaintContext) {
735        cx.scene.push_quad(Quad {
736            bounds: RectF::new(self.origin, vec2f(2.0, self.line_height)),
737            background: Some(self.color),
738            border: Border::new(0., Color::black()),
739            corner_radius: 0.,
740        });
741    }
742}
743
744#[derive(Debug)]
745struct Selection {
746    start_y: f32,
747    line_height: f32,
748    lines: Vec<SelectionLine>,
749    color: Color,
750}
751
752#[derive(Debug)]
753struct SelectionLine {
754    start_x: f32,
755    end_x: f32,
756}
757
758impl Selection {
759    fn paint(&self, bounds: RectF, scene: &mut Scene) {
760        if self.lines.len() >= 2 && self.lines[0].start_x > self.lines[1].end_x {
761            self.paint_lines(self.start_y, &self.lines[0..1], bounds, scene);
762            self.paint_lines(
763                self.start_y + self.line_height,
764                &self.lines[1..],
765                bounds,
766                scene,
767            );
768        } else {
769            self.paint_lines(self.start_y, &self.lines, bounds, scene);
770        }
771    }
772
773    fn paint_lines(&self, start_y: f32, lines: &[SelectionLine], bounds: RectF, scene: &mut Scene) {
774        if lines.is_empty() {
775            return;
776        }
777
778        let mut path = PathBuilder::new();
779        let corner_radius = 0.15 * self.line_height;
780        let first_line = lines.first().unwrap();
781        let last_line = lines.last().unwrap();
782
783        let first_top_left = vec2f(first_line.start_x, start_y);
784        let first_top_right = vec2f(first_line.end_x, start_y);
785
786        let curve_height = vec2f(0., corner_radius);
787        let curve_width = |start_x: f32, end_x: f32| {
788            let max = (end_x - start_x) / 2.;
789            let width = if max < corner_radius {
790                max
791            } else {
792                corner_radius
793            };
794
795            vec2f(width, 0.)
796        };
797
798        let top_curve_width = curve_width(first_line.start_x, first_line.end_x);
799        path.reset(first_top_right - top_curve_width);
800        path.curve_to(first_top_right + curve_height, first_top_right);
801
802        let mut iter = lines.iter().enumerate().peekable();
803        while let Some((ix, line)) = iter.next() {
804            let bottom_right = vec2f(line.end_x, start_y + (ix + 1) as f32 * self.line_height);
805
806            if let Some((_, next_line)) = iter.peek() {
807                let next_top_right = vec2f(next_line.end_x, bottom_right.y());
808
809                match next_top_right.x().partial_cmp(&bottom_right.x()).unwrap() {
810                    Ordering::Equal => {
811                        path.line_to(bottom_right);
812                    }
813                    Ordering::Less => {
814                        let curve_width = curve_width(next_top_right.x(), bottom_right.x());
815                        path.line_to(bottom_right - curve_height);
816                        path.curve_to(bottom_right - curve_width, bottom_right);
817                        path.line_to(next_top_right + curve_width);
818                        path.curve_to(next_top_right + curve_height, next_top_right);
819                    }
820                    Ordering::Greater => {
821                        let curve_width = curve_width(bottom_right.x(), next_top_right.x());
822                        path.line_to(bottom_right - curve_height);
823                        path.curve_to(bottom_right + curve_width, bottom_right);
824                        path.line_to(next_top_right - curve_width);
825                        path.curve_to(next_top_right + curve_height, next_top_right);
826                    }
827                }
828            } else {
829                let curve_width = curve_width(line.start_x, line.end_x);
830                path.line_to(bottom_right - curve_height);
831                path.curve_to(bottom_right - curve_width, bottom_right);
832
833                let bottom_left = vec2f(line.start_x, bottom_right.y());
834                path.line_to(bottom_left + curve_width);
835                path.curve_to(bottom_left - curve_height, bottom_left);
836            }
837        }
838
839        if first_line.start_x > last_line.start_x {
840            let curve_width = curve_width(last_line.start_x, first_line.start_x);
841            let second_top_left = vec2f(last_line.start_x, start_y + self.line_height);
842            path.line_to(second_top_left + curve_height);
843            path.curve_to(second_top_left + curve_width, second_top_left);
844            let first_bottom_left = vec2f(first_line.start_x, second_top_left.y());
845            path.line_to(first_bottom_left - curve_width);
846            path.curve_to(first_bottom_left - curve_height, first_bottom_left);
847        }
848
849        path.line_to(first_top_left + curve_height);
850        path.curve_to(first_top_left + top_curve_width, first_top_left);
851        path.line_to(first_top_right - top_curve_width);
852
853        scene.push_path(path.build(self.color, Some(bounds)));
854    }
855}
856
857fn scale_vertical_mouse_autoscroll_delta(delta: f32) -> f32 {
858    delta.powf(1.5) / 100.0
859}
860
861fn scale_horizontal_mouse_autoscroll_delta(delta: f32) -> f32 {
862    delta.powf(1.2) / 300.0
863}