i_slint_core/textlayout/
glyphclusters.rs

1// Copyright © SixtyFPS GmbH <info@slint.dev>
2// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
3
4use core::{marker::PhantomData, ops::Range};
5
6use euclid::num::Zero;
7
8use super::ShapeBuffer;
9
10#[derive(Clone)]
11pub struct GlyphCluster<Length: Clone> {
12    pub byte_range: Range<usize>,
13    pub glyph_range: Range<usize>,
14    pub width: Length,
15    pub is_whitespace: bool,
16    pub is_line_or_paragraph_separator: bool,
17}
18
19#[derive(Clone)]
20pub struct GlyphClusterIterator<'a, Length> {
21    text: &'a str,
22    shaped_text: &'a ShapeBuffer<Length>,
23    current_run: usize,
24    // absolute byte offset in the entire text
25    byte_offset: usize,
26    glyph_index: usize,
27    marker: PhantomData<Length>,
28}
29
30impl<'a, Length> GlyphClusterIterator<'a, Length> {
31    pub fn new(text: &'a str, shaped_text: &'a ShapeBuffer<Length>) -> Self {
32        Self {
33            text,
34            shaped_text,
35            current_run: 0,
36            byte_offset: 0,
37            glyph_index: 0,
38            marker: Default::default(),
39        }
40    }
41}
42
43impl<Length: Copy + Clone + Zero + core::ops::AddAssign> Iterator
44    for GlyphClusterIterator<'_, Length>
45{
46    type Item = GlyphCluster<Length>;
47
48    fn next(&mut self) -> Option<Self::Item> {
49        if self.current_run >= self.shaped_text.text_runs.len() {
50            return None;
51        }
52
53        let current_run =
54            if self.byte_offset < self.shaped_text.text_runs[self.current_run].byte_range.end {
55                &self.shaped_text.text_runs[self.current_run]
56            } else {
57                self.current_run += 1;
58                self.shaped_text.text_runs.get(self.current_run)?
59            };
60
61        let mut cluster_width: Length = Length::zero();
62
63        let cluster_start = self.glyph_index;
64
65        let mut cluster_byte_offset;
66        loop {
67            let glyph = &self.shaped_text.glyphs[self.glyph_index];
68            // Rustybuzz uses a relative byte offset as cluster index
69            cluster_byte_offset = current_run.byte_range.start + glyph.text_byte_offset;
70            if cluster_byte_offset != self.byte_offset {
71                break;
72            }
73            cluster_width += glyph.advance;
74
75            self.glyph_index += 1;
76
77            if self.glyph_index >= current_run.glyph_range.end {
78                cluster_byte_offset = current_run.byte_range.end;
79                break;
80            }
81        }
82        let byte_range = self.byte_offset..cluster_byte_offset;
83        let (is_whitespace, is_line_or_paragraph_separator) = self.text[self.byte_offset..]
84            .chars()
85            .next()
86            .map(|ch| {
87                let is_line_or_paragraph_separator =
88                    ch == '\n' || ch == '\u{2028}' || ch == '\u{2029}';
89                (ch.is_whitespace(), is_line_or_paragraph_separator)
90            })
91            .unwrap_or_default();
92        self.byte_offset = cluster_byte_offset;
93
94        Some(GlyphCluster {
95            byte_range,
96            glyph_range: Range { start: cluster_start, end: self.glyph_index },
97            width: cluster_width,
98            is_whitespace,
99            is_line_or_paragraph_separator,
100        })
101    }
102}
i_slint_core/textlayout/glyphclusters.rs

i_slint_core/textlayout/
glyphclusters.rs
