742 lines · 24.2 KB · Rust
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use crate::{FontId, FontRun, Pixels, PlatformTextSystem, SharedString, TextRun, px};use collections::HashMap;use std::{iter, sync::Arc}; /// The GPUI line wrapper, used to wrap lines of text to a given width.pub struct LineWrapper {    platform_text_system: Arc<dyn PlatformTextSystem>,    pub(crate) font_id: FontId,    pub(crate) font_size: Pixels,    cached_ascii_char_widths: [Option<Pixels>; 128],    cached_other_char_widths: HashMap<char, Pixels>,} impl LineWrapper {    /// The maximum indent that can be applied to a line.    pub const MAX_INDENT: u32 = 256;     pub(crate) fn new(        font_id: FontId,        font_size: Pixels,        text_system: Arc<dyn PlatformTextSystem>,    ) -> Self {        Self {            platform_text_system: text_system,            font_id,            font_size,            cached_ascii_char_widths: [None; 128],            cached_other_char_widths: HashMap::default(),        }    }     /// Wrap a line of text to the given width with this wrapper's font and font size.    pub fn wrap_line<'a>(        &'a mut self,        fragments: &'a [LineFragment],        wrap_width: Pixels,    ) -> impl Iterator<Item = Boundary> + 'a {        let mut width = px(0.);        let mut first_non_whitespace_ix = None;        let mut indent = None;        let mut last_candidate_ix = 0;        let mut last_candidate_width = px(0.);        let mut last_wrap_ix = 0;        let mut prev_c = '\0';        let mut index = 0;        let mut candidates = fragments            .into_iter()            .flat_map(move |fragment| fragment.wrap_boundary_candidates())            .peekable();        iter::from_fn(move || {            for candidate in candidates.by_ref() {                let ix = index;                index += candidate.len_utf8();                let mut new_prev_c = prev_c;                let item_width = match candidate {                    WrapBoundaryCandidate::Char { character: c } => {                        if c == '\n' {                            continue;                        }                         if Self::is_word_char(c) {                            if prev_c == ' ' && c != ' ' && first_non_whitespace_ix.is_some() {                                last_candidate_ix = ix;                                last_candidate_width = width;                            }                        } else {                            // CJK may not be space separated, e.g.: `Hello world你好世界`                            if c != ' ' && first_non_whitespace_ix.is_some() {                                last_candidate_ix = ix;                                last_candidate_width = width;                            }                        }                         if c != ' ' && first_non_whitespace_ix.is_none() {                            first_non_whitespace_ix = Some(ix);                        }                         new_prev_c = c;                         self.width_for_char(c)                    }                    WrapBoundaryCandidate::Element {                        width: element_width,                        ..                    } => {                        if prev_c == ' ' && first_non_whitespace_ix.is_some() {                            last_candidate_ix = ix;                            last_candidate_width = width;                        }                         if first_non_whitespace_ix.is_none() {                            first_non_whitespace_ix = Some(ix);                        }                         element_width                    }                };                 width += item_width;                if width > wrap_width && ix > last_wrap_ix {                    if let (None, Some(first_non_whitespace_ix)) = (indent, first_non_whitespace_ix)                    {                        indent = Some(                            Self::MAX_INDENT.min((first_non_whitespace_ix - last_wrap_ix) as u32),                        );                    }                     if last_candidate_ix > 0 {                        last_wrap_ix = last_candidate_ix;                        width -= last_candidate_width;                        last_candidate_ix = 0;                    } else {                        last_wrap_ix = ix;                        width = item_width;                    }                     if let Some(indent) = indent {                        width += self.width_for_char(' ') * indent as f32;                    }                     return Some(Boundary::new(last_wrap_ix, indent.unwrap_or(0)));                }                 prev_c = new_prev_c;            }             None        })    }     /// Truncate a line of text to the given width with this wrapper's font and font size.    pub fn truncate_line(        &mut self,        line: SharedString,        truncate_width: Pixels,        truncation_suffix: &str,        runs: &mut Vec<TextRun>,    ) -> SharedString {        let mut width = px(0.);        let mut suffix_width = truncation_suffix            .chars()            .map(|c| self.width_for_char(c))            .fold(px(0.0), |a, x| a + x);        let mut char_indices = line.char_indices();        let mut truncate_ix = 0;        for (ix, c) in char_indices {            if width + suffix_width < truncate_width {                truncate_ix = ix;            }             let char_width = self.width_for_char(c);            width += char_width;             if width.floor() > truncate_width {                let result =                    SharedString::from(format!("{}{}", &line[..truncate_ix], truncation_suffix));                update_runs_after_truncation(&result, truncation_suffix, runs);                 return result;            }        }         line    }     pub(crate) fn is_word_char(c: char) -> bool {        // ASCII alphanumeric characters, for English, numbers: `Hello123`, etc.        c.is_ascii_alphanumeric() ||        // Latin script in Unicode for French, German, Spanish, etc.        // Latin-1 Supplement        // https://en.wikipedia.org/wiki/Latin-1_Supplement        matches!(c, '\u{00C0}'..='\u{00FF}') ||        // Latin Extended-A        // https://en.wikipedia.org/wiki/Latin_Extended-A        matches!(c, '\u{0100}'..='\u{017F}') ||        // Latin Extended-B        // https://en.wikipedia.org/wiki/Latin_Extended-B        matches!(c, '\u{0180}'..='\u{024F}') ||        // Cyrillic for Russian, Ukrainian, etc.        // https://en.wikipedia.org/wiki/Cyrillic_script_in_Unicode        matches!(c, '\u{0400}'..='\u{04FF}') ||        // Some other known special characters that should be treated as word characters,        // e.g. `a-b`, `var_name`, `I'm`, '@mention`, `#hashtag`, `100%`, `3.1415`, `2^3`, `a~b`, etc.        matches!(c, '-' | '_' | '.' | '\'' | '$' | '%' | '@' | '#' | '^' | '~' | ',') ||        // Characters that used in URL, e.g. `https://github.com/zed-industries/zed?a=1&b=2` for better wrapping a long URL.        matches!(c,  '/' | ':' | '?' | '&' | '=') ||        // `⋯` character is special used in Zed, to keep this at the end of the line.        matches!(c, '⋯')    }     #[inline(always)]    fn width_for_char(&mut self, c: char) -> Pixels {        if (c as u32) < 128 {            if let Some(cached_width) = self.cached_ascii_char_widths[c as usize] {                cached_width            } else {                let width = self.compute_width_for_char(c);                self.cached_ascii_char_widths[c as usize] = Some(width);                width            }        } else if let Some(cached_width) = self.cached_other_char_widths.get(&c) {            *cached_width        } else {            let width = self.compute_width_for_char(c);            self.cached_other_char_widths.insert(c, width);            width        }    }     fn compute_width_for_char(&self, c: char) -> Pixels {        let mut buffer = [0; 4];        let buffer = c.encode_utf8(&mut buffer);        self.platform_text_system            .layout_line(                buffer,                self.font_size,                &[FontRun {                    len: buffer.len(),                    font_id: self.font_id,                }],            )            .width    }} fn update_runs_after_truncation(result: &str, ellipsis: &str, runs: &mut Vec<TextRun>) {    let mut truncate_at = result.len() - ellipsis.len();    let mut run_end = None;    for (run_index, run) in runs.iter_mut().enumerate() {        if run.len <= truncate_at {            truncate_at -= run.len;        } else {            run.len = truncate_at + ellipsis.len();            run_end = Some(run_index + 1);            break;        }    }    if let Some(run_end) = run_end {        runs.truncate(run_end);    }} /// A fragment of a line that can be wrapped.pub enum LineFragment<'a> {    /// A text fragment consisting of characters.    Text {        /// The text content of the fragment.        text: &'a str,    },    /// A non-text element with a fixed width.    Element {        /// The width of the element in pixels.        width: Pixels,        /// The UTF-8 encoded length of the element.        len_utf8: usize,    },} impl<'a> LineFragment<'a> {    /// Creates a new text fragment from the given text.    pub fn text(text: &'a str) -> Self {        LineFragment::Text { text }    }     /// Creates a new non-text element with the given width and UTF-8 encoded length.    pub fn element(width: Pixels, len_utf8: usize) -> Self {        LineFragment::Element { width, len_utf8 }    }     fn wrap_boundary_candidates(&self) -> impl Iterator<Item = WrapBoundaryCandidate> {        let text = match self {            LineFragment::Text { text } => text,            LineFragment::Element { .. } => "\0",        };        text.chars().map(move |character| {            if let LineFragment::Element { width, len_utf8 } = self {                WrapBoundaryCandidate::Element {                    width: *width,                    len_utf8: *len_utf8,                }            } else {                WrapBoundaryCandidate::Char { character }            }        })    }} enum WrapBoundaryCandidate {    Char { character: char },    Element { width: Pixels, len_utf8: usize },} impl WrapBoundaryCandidate {    pub fn len_utf8(&self) -> usize {        match self {            WrapBoundaryCandidate::Char { character } => character.len_utf8(),            WrapBoundaryCandidate::Element { len_utf8: len, .. } => *len,        }    }} /// A boundary between two lines of text.#[derive(Copy, Clone, Debug, PartialEq, Eq)]pub struct Boundary {    /// The index of the last character in a line    pub ix: usize,    /// The indent of the next line.    pub next_indent: u32,} impl Boundary {    fn new(ix: usize, next_indent: u32) -> Self {        Self { ix, next_indent }    }} #[cfg(test)]mod tests {    use super::*;    use crate::{        Font, FontFeatures, FontStyle, FontWeight, Hsla, TestAppContext, TestDispatcher, font,    };    #[cfg(target_os = "macos")]    use crate::{TextRun, WindowTextSystem, WrapBoundary};    use rand::prelude::*;     fn build_wrapper() -> LineWrapper {        let dispatcher = TestDispatcher::new(StdRng::seed_from_u64(0));        let cx = TestAppContext::build(dispatcher, None);        let id = cx.text_system().font_id(&font("Zed Plex Mono")).unwrap();        LineWrapper::new(id, px(16.), cx.text_system().platform_text_system.clone())    }     fn generate_test_runs(input_run_len: &[usize]) -> Vec<TextRun> {        input_run_len            .iter()            .map(|run_len| TextRun {                len: *run_len,                font: Font {                    family: "Dummy".into(),                    features: FontFeatures::default(),                    fallbacks: None,                    weight: FontWeight::default(),                    style: FontStyle::Normal,                },                color: Hsla::default(),                background_color: None,                underline: None,                strikethrough: None,            })            .collect()    }     #[test]    fn test_wrap_line() {        let mut wrapper = build_wrapper();         assert_eq!(            wrapper                .wrap_line(&[LineFragment::text("aa bbb cccc ddddd eeee")], px(72.))                .collect::<Vec<_>>(),            &[                Boundary::new(7, 0),                Boundary::new(12, 0),                Boundary::new(18, 0)            ],        );        assert_eq!(            wrapper                .wrap_line(&[LineFragment::text("aaa aaaaaaaaaaaaaaaaaa")], px(72.0))                .collect::<Vec<_>>(),            &[                Boundary::new(4, 0),                Boundary::new(11, 0),                Boundary::new(18, 0)            ],        );        assert_eq!(            wrapper                .wrap_line(&[LineFragment::text("     aaaaaaa")], px(72.))                .collect::<Vec<_>>(),            &[                Boundary::new(7, 5),                Boundary::new(9, 5),                Boundary::new(11, 5),            ]        );        assert_eq!(            wrapper                .wrap_line(                    &[LineFragment::text("                            ")],                    px(72.)                )                .collect::<Vec<_>>(),            &[                Boundary::new(7, 0),                Boundary::new(14, 0),                Boundary::new(21, 0)            ]        );        assert_eq!(            wrapper                .wrap_line(&[LineFragment::text("          aaaaaaaaaaaaaa")], px(72.))                .collect::<Vec<_>>(),            &[                Boundary::new(7, 0),                Boundary::new(14, 3),                Boundary::new(18, 3),                Boundary::new(22, 3),            ]        );         // Test wrapping multiple text fragments        assert_eq!(            wrapper                .wrap_line(                    &[                        LineFragment::text("aa bbb "),                        LineFragment::text("cccc ddddd eeee")                    ],                    px(72.)                )                .collect::<Vec<_>>(),            &[                Boundary::new(7, 0),                Boundary::new(12, 0),                Boundary::new(18, 0)            ],        );         // Test wrapping with a mix of text and element fragments        assert_eq!(            wrapper                .wrap_line(                    &[                        LineFragment::text("aa "),                        LineFragment::element(px(20.), 1),                        LineFragment::text(" bbb "),                        LineFragment::element(px(30.), 1),                        LineFragment::text(" cccc")                    ],                    px(72.)                )                .collect::<Vec<_>>(),            &[                Boundary::new(5, 0),                Boundary::new(9, 0),                Boundary::new(11, 0)            ],        );         // Test with element at the beginning and text afterward        assert_eq!(            wrapper                .wrap_line(                    &[                        LineFragment::element(px(50.), 1),                        LineFragment::text(" aaaa bbbb cccc dddd")                    ],                    px(72.)                )                .collect::<Vec<_>>(),            &[                Boundary::new(2, 0),                Boundary::new(7, 0),                Boundary::new(12, 0),                Boundary::new(17, 0)            ],        );         // Test with a large element that forces wrapping by itself        assert_eq!(            wrapper                .wrap_line(                    &[                        LineFragment::text("short text "),                        LineFragment::element(px(100.), 1),                        LineFragment::text(" more text")                    ],                    px(72.)                )                .collect::<Vec<_>>(),            &[                Boundary::new(6, 0),                Boundary::new(11, 0),                Boundary::new(12, 0),                Boundary::new(18, 0)            ],        );    }     #[test]    fn test_truncate_line() {        let mut wrapper = build_wrapper();         fn perform_test(            wrapper: &mut LineWrapper,            text: &'static str,            result: &'static str,            ellipsis: &str,

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