aboutsummaryrefslogtreecommitdiff
path: root/helix-term/src/ui/document.rs
blob: d417626491c9c926b741d396d730584fe9d74d2d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
use std::cmp::min;

use helix_core::doc_formatter::{DocumentFormatter, GraphemeSource, TextFormat};
use helix_core::graphemes::Grapheme;
use helix_core::str_utils::char_to_byte_idx;
use helix_core::syntax::Highlight;
use helix_core::syntax::HighlightEvent;
use helix_core::text_annotations::TextAnnotations;
use helix_core::{visual_offset_from_block, Position, RopeSlice};
use helix_view::editor::{WhitespaceConfig, WhitespaceRenderValue};
use helix_view::graphics::Rect;
use helix_view::theme::Style;
use helix_view::view::ViewPosition;
use helix_view::Document;
use helix_view::Theme;
use tui::buffer::Buffer as Surface;

pub trait LineDecoration {
    fn render_background(&mut self, _renderer: &mut TextRenderer, _pos: LinePos) {}
    fn render_foreground(
        &mut self,
        _renderer: &mut TextRenderer,
        _pos: LinePos,
        _end_char_idx: usize,
    ) {
    }
}

impl<F: FnMut(&mut TextRenderer, LinePos)> LineDecoration for F {
    fn render_background(&mut self, renderer: &mut TextRenderer, pos: LinePos) {
        self(renderer, pos)
    }
}

/// A wrapper around a HighlightIterator
/// that merges the layered highlights to create the final text style
/// and yields the active text style and the char_idx where the active
/// style will have to be recomputed.
struct StyleIter<'a, H: Iterator<Item = HighlightEvent>> {
    text_style: Style,
    active_highlights: Vec<Highlight>,
    highlight_iter: H,
    theme: &'a Theme,
}

impl<H: Iterator<Item = HighlightEvent>> Iterator for StyleIter<'_, H> {
    type Item = (Style, usize);
    fn next(&mut self) -> Option<(Style, usize)> {
        while let Some(event) = self.highlight_iter.next() {
            match event {
                HighlightEvent::HighlightStart(highlights) => {
                    self.active_highlights.push(highlights)
                }
                HighlightEvent::HighlightEnd => {
                    self.active_highlights.pop();
                }
                HighlightEvent::Source { start, end } => {
                    if start == end {
                        continue;
                    }
                    let style = self
                        .active_highlights
                        .iter()
                        .fold(self.text_style, |acc, span| {
                            acc.patch(self.theme.highlight(span.0))
                        });
                    return Some((style, end));
                }
            }
        }
        None
    }
}

#[derive(Debug, PartialEq, Eq, Copy, Clone)]
pub struct LinePos {
    /// Indicates whether the given visual line
    /// is the first visual line of the given document line
    pub first_visual_line: bool,
    /// The line index of the document line that contains the given visual line
    pub doc_line: usize,
    /// Vertical offset from the top of the inner view area
    pub visual_line: u16,
    /// The first char index of this visual line.
    /// Note that if the visual line is entirely filled by
    /// a very long inline virtual text then this index will point
    /// at the next (non-virtual) char after this visual line
    pub start_char_idx: usize,
}

pub type TranslatedPosition<'a> = (usize, Box<dyn FnMut(&mut TextRenderer, Position) + 'a>);

#[allow(clippy::too_many_arguments)]
pub fn render_document(
    surface: &mut Surface,
    viewport: Rect,
    doc: &Document,
    offset: ViewPosition,
    doc_annotations: &TextAnnotations,
    highlight_iter: impl Iterator<Item = HighlightEvent>,
    theme: &Theme,
    line_decoration: &mut [Box<dyn LineDecoration + '_>],
    translated_positions: &mut [TranslatedPosition],
) {
    let mut renderer = TextRenderer::new(surface, doc, theme, offset.horizontal_offset, viewport);
    render_text(
        &mut renderer,
        doc.text().slice(..),
        offset,
        &doc.text_format(viewport.width, Some(theme)),
        doc_annotations,
        highlight_iter,
        theme,
        line_decoration,
        translated_positions,
    )
}

fn translate_positions(
    char_pos: usize,
    first_visisble_char_idx: usize,
    translated_positions: &mut [TranslatedPosition],
    text_fmt: &TextFormat,
    renderer: &mut TextRenderer,
    pos: Position,
) {
    // check if any positions translated on the fly (like cursor) has been reached
    for (char_idx, callback) in &mut *translated_positions {
        if *char_idx < char_pos && *char_idx >= first_visisble_char_idx {
            // by replacing the char_index with usize::MAX large number we ensure
            // that the same position is only translated once
            // text will never reach usize::MAX as rust memory allocations are limited
            // to isize::MAX
            *char_idx = usize::MAX;

            if text_fmt.soft_wrap {
                callback(renderer, pos)
            } else if pos.col >= renderer.col_offset
                && pos.col - renderer.col_offset < renderer.viewport.width as usize
            {
                callback(
                    renderer,
                    Position {
                        row: pos.row,
                        col: pos.col - renderer.col_offset,
                    },
                )
            }
        }
    }
}

#[allow(clippy::too_many_arguments)]
pub fn render_text<'t>(
    renderer: &mut TextRenderer,
    text: RopeSlice<'t>,
    offset: ViewPosition,
    text_fmt: &TextFormat,
    text_annotations: &TextAnnotations,
    highlight_iter: impl Iterator<Item = HighlightEvent>,
    theme: &Theme,
    line_decorations: &mut [Box<dyn LineDecoration + '_>],
    translated_positions: &mut [TranslatedPosition],
) {
    let (
        Position {
            row: mut row_off, ..
        },
        mut char_pos,
    ) = visual_offset_from_block(
        text,
        offset.anchor,
        offset.anchor,
        text_fmt,
        text_annotations,
    );
    row_off += offset.vertical_offset;
    assert_eq!(0, offset.vertical_offset);

    let (mut formatter, mut first_visible_char_idx) =
        DocumentFormatter::new_at_prev_checkpoint(text, text_fmt, text_annotations, offset.anchor);
    let mut styles = StyleIter {
        text_style: renderer.text_style,
        active_highlights: Vec::with_capacity(64),
        highlight_iter,
        theme,
    };

    let mut last_line_pos = LinePos {
        first_visual_line: false,
        doc_line: usize::MAX,
        visual_line: u16::MAX,
        start_char_idx: usize::MAX,
    };
    let mut is_in_indent_area = true;
    let mut last_line_indent_level = 0;
    let mut style_span = styles
        .next()
        .unwrap_or_else(|| (Style::default(), usize::MAX));

    loop {
        // formattter.line_pos returns to line index of the next grapheme
        // so it must be called before formatter.next
        let doc_line = formatter.line_pos();
        let Some((grapheme, mut pos)) = formatter.next() else {
            let mut last_pos = formatter.visual_pos();
            if last_pos.row >= row_off {
                last_pos.col -= 1;
                last_pos.row -= row_off;
                // check if any positions translated on the fly (like cursor) are at the EOF
                translate_positions(
                    char_pos + 1,
                    first_visible_char_idx,
                    translated_positions,
                    text_fmt,
                    renderer,
                    last_pos,
                );
            }
            break;
        };

        // skip any graphemes on visual lines before the block start
        if pos.row < row_off {
            if char_pos >= style_span.1 {
                style_span = if let Some(style_span) = styles.next() {
                    style_span
                } else {
                    break;
                }
            }
            char_pos += grapheme.doc_chars();
            first_visible_char_idx = char_pos + 1;
            continue;
        }
        pos.row -= row_off;

        // if the end of the viewport is reached stop rendering
        if pos.row as u16 >= renderer.viewport.height {
            break;
        }

        // apply decorations before rendering a new line
        if pos.row as u16 != last_line_pos.visual_line {
            if pos.row > 0 {
                renderer.draw_indent_guides(last_line_indent_level, last_line_pos.visual_line);
                is_in_indent_area = true;
                for line_decoration in &mut *line_decorations {
                    line_decoration.render_foreground(renderer, last_line_pos, char_pos);
                }
            }
            last_line_pos = LinePos {
                first_visual_line: doc_line != last_line_pos.doc_line,
                doc_line,
                visual_line: pos.row as u16,
                start_char_idx: char_pos,
            };
            for line_decoration in &mut *line_decorations {
                line_decoration.render_background(renderer, last_line_pos);
            }
        }

        // aquire the correct grapheme style
        if char_pos >= style_span.1 {
            style_span = styles.next().unwrap_or((Style::default(), usize::MAX));
        }
        char_pos += grapheme.doc_chars();

        // check if any positions translated on the fly (like cursor) has been reached
        translate_positions(
            char_pos,
            first_visible_char_idx,
            translated_positions,
            text_fmt,
            renderer,
            pos,
        );

        let grapheme_style = if let GraphemeSource::VirtualText { highlight } = grapheme.source {
            let style = renderer.text_style;
            if let Some(highlight) = highlight {
                style.patch(theme.highlight(highlight.0))
            } else {
                style
            }
        } else {
            style_span.0
        };

        let virt = grapheme.is_virtual();
        renderer.draw_grapheme(
            grapheme.grapheme,
            grapheme_style,
            virt,
            &mut last_line_indent_level,
            &mut is_in_indent_area,
            pos,
        );
    }

    renderer.draw_indent_guides(last_line_indent_level, last_line_pos.visual_line);
    for line_decoration in &mut *line_decorations {
        line_decoration.render_foreground(renderer, last_line_pos, char_pos);
    }
}

#[derive(Debug)]
pub struct TextRenderer<'a> {
    pub surface: &'a mut Surface,
    pub text_style: Style,
    pub whitespace_style: Style,
    pub indent_guide_char: String,
    pub indent_guide_style: Style,
    pub newline: String,
    pub nbsp: String,
    pub space: String,
    pub tab: String,
    pub virtual_tab: String,
    pub indent_width: u16,
    pub starting_indent: usize,
    pub draw_indent_guides: bool,
    pub col_offset: usize,
    pub viewport: Rect,
}

impl<'a> TextRenderer<'a> {
    pub fn new(
        surface: &'a mut Surface,
        doc: &Document,
        theme: &Theme,
        col_offset: usize,
        viewport: Rect,
    ) -> TextRenderer<'a> {
        let editor_config = doc.config.load();
        let WhitespaceConfig {
            render: ws_render,
            characters: ws_chars,
        } = &editor_config.whitespace;

        let tab_width = doc.tab_width();
        let tab = if ws_render.tab() == WhitespaceRenderValue::All {
            std::iter::once(ws_chars.tab)
                .chain(std::iter::repeat(ws_chars.tabpad).take(tab_width - 1))
                .collect()
        } else {
            " ".repeat(tab_width)
        };
        let virtual_tab = " ".repeat(tab_width);
        let newline = if ws_render.newline() == WhitespaceRenderValue::All {
            ws_chars.newline.into()
        } else {
            " ".to_owned()
        };

        let space = if ws_render.space() == WhitespaceRenderValue::All {
            ws_chars.space.into()
        } else {
            " ".to_owned()
        };
        let nbsp = if ws_render.nbsp() == WhitespaceRenderValue::All {
            ws_chars.nbsp.into()
        } else {
            " ".to_owned()
        };

        let text_style = theme.get("ui.text");

        let indent_width = doc.indent_style.indent_width(tab_width) as u16;

        TextRenderer {
            surface,
            indent_guide_char: editor_config.indent_guides.character.into(),
            newline,
            nbsp,
            space,
            tab,
            virtual_tab,
            whitespace_style: theme.get("ui.virtual.whitespace"),
            indent_width,
            starting_indent: col_offset / indent_width as usize
                + (col_offset % indent_width as usize != 0) as usize
                + editor_config.indent_guides.skip_levels as usize,
            indent_guide_style: text_style.patch(
                theme
                    .try_get("ui.virtual.indent-guide")
                    .unwrap_or_else(|| theme.get("ui.virtual.whitespace")),
            ),
            text_style,
            draw_indent_guides: editor_config.indent_guides.render,
            viewport,
            col_offset,
        }
    }

    /// Draws a single `grapheme` at the current render position with a specified `style`.
    pub fn draw_grapheme(
        &mut self,
        grapheme: Grapheme,
        mut style: Style,
        is_virtual: bool,
        last_indent_level: &mut usize,
        is_in_indent_area: &mut bool,
        position: Position,
    ) {
        let cut_off_start = self.col_offset.saturating_sub(position.col);
        let is_whitespace = grapheme.is_whitespace();

        // TODO is it correct to apply the whitspace style to all unicode white spaces?
        if is_whitespace {
            style = style.patch(self.whitespace_style);
        }

        let width = grapheme.width();
        let space = if is_virtual { " " } else { &self.space };
        let nbsp = if is_virtual { " " } else { &self.nbsp };
        let tab = if is_virtual {
            &self.virtual_tab
        } else {
            &self.tab
        };
        let grapheme = match grapheme {
            Grapheme::Tab { width } => {
                let grapheme_tab_width = char_to_byte_idx(tab, width);
                &tab[..grapheme_tab_width]
            }
            // TODO special rendering for other whitespaces?
            Grapheme::Other { ref g } if g == " " => space,
            Grapheme::Other { ref g } if g == "\u{00A0}" => nbsp,
            Grapheme::Other { ref g } => g,
            Grapheme::Newline => &self.newline,
        };

        let in_bounds = self.col_offset <= position.col
            && position.col < self.viewport.width as usize + self.col_offset;

        if in_bounds {
            self.surface.set_string(
                self.viewport.x + (position.col - self.col_offset) as u16,
                self.viewport.y + position.row as u16,
                grapheme,
                style,
            );
        } else if cut_off_start != 0 && cut_off_start < width {
            // partially on screen
            let rect = Rect::new(
                self.viewport.x,
                self.viewport.y + position.row as u16,
                (width - cut_off_start) as u16,
                1,
            );
            self.surface.set_style(rect, style);
        }

        if *is_in_indent_area && !is_whitespace {
            *last_indent_level = position.col;
            *is_in_indent_area = false;
        }
    }

    /// Overlay indentation guides ontop of a rendered line
    /// The indentation level is computed in `draw_lines`.
    /// Therefore this function must always be called afterwards.
    pub fn draw_indent_guides(&mut self, indent_level: usize, row: u16) {
        if !self.draw_indent_guides {
            return;
        }

        // Don't draw indent guides outside of view
        let end_indent = min(
            indent_level,
            // Add indent_width - 1 to round up, since the first visible
            // indent might be a bit after offset.col
            self.col_offset + self.viewport.width as usize + (self.indent_width as usize - 1),
        ) / self.indent_width as usize;

        for i in self.starting_indent..end_indent {
            let x = (self.viewport.x as usize + (i * self.indent_width as usize) - self.col_offset)
                as u16;
            let y = self.viewport.y + row;
            debug_assert!(self.surface.in_bounds(x, y));
            self.surface
                .set_string(x, y, &self.indent_guide_char, self.indent_guide_style);
        }
    }
}