fyrox-ui 1.0.1

// Copyright (c) 2019-present Dmitry Stepanov and Fyrox Engine contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

use std::ops::Range;

pub trait TextWrapper {
    fn push(&mut self, c: char, advance: f32);
    fn finish(&mut self);
}

pub trait LineSink {
    fn push_line(&mut self, range: Range<usize>, width: f32);
    fn max_width(&self) -> f32;
}

fn is_newline(c: char) -> bool {
    c == '\n' || c == '\r'
}

pub struct NoWrap<S> {
    sink: S,
    start: usize,
    position: usize,
    width: f32,
}

impl<S> NoWrap<S> {
    pub fn new(sink: S) -> Self {
        NoWrap {
            sink,
            start: 0,
            position: 0,
            width: 0.0,
        }
    }
}

impl<S: LineSink> TextWrapper for NoWrap<S> {
    fn push(&mut self, c: char, advance: f32) {
        if is_newline(c) {
            self.sink.push_line(self.start..self.position, self.width);
            self.start = self.position + 1; // Next like starts after the newline, so skip ahead by one.
            self.position += 1;
            self.width = 0.0;
        } else {
            self.position += 1;
            self.width += advance;
        }
    }
    fn finish(&mut self) {
        self.sink.push_line(self.start..self.position, self.width);
    }
}

pub struct LetterWrap<S> {
    sink: S,
    start: usize,
    position: usize,
    width: f32,
}

impl<S> LetterWrap<S> {
    pub fn new(sink: S) -> Self {
        LetterWrap {
            sink,
            start: 0,
            position: 0,
            width: 0.0,
        }
    }
}

impl<S: LineSink> TextWrapper for LetterWrap<S> {
    fn push(&mut self, c: char, advance: f32) {
        if self.position != self.start && self.width + advance > self.sink.max_width() {
            self.sink.push_line(self.start..self.position, self.width);
            self.start = self.position;
            self.width = 0.0;
        }
        self.position += 1;
        self.width += advance;
        if is_newline(c) {
            self.sink.push_line(self.start..self.position, self.width);
            self.start = self.position; // Next line starts after the newline
            self.width = 0.0;
        }
    }

    fn finish(&mut self) {
        if self.start != self.position {
            self.sink.push_line(self.start..self.position, self.width);
        }
    }
}

pub struct WordWrap<S> {
    sink: S,
    // Start of the current line
    start: usize,
    // Position of the next character
    position: usize,
    // Width of the current line
    width: f32,
    // Start of the current word
    word_start: usize,
    // Width of the current word
    word_width: f32,
}

impl<S> WordWrap<S> {
    pub fn new(sink: S) -> Self {
        WordWrap {
            sink,
            start: 0,
            position: 0,
            width: 0.0,
            word_start: 0,
            word_width: 0.0,
        }
    }
}

impl<S: LineSink> TextWrapper for WordWrap<S> {
    fn push(&mut self, c: char, advance: f32) {
        if self.position != self.start && self.width + advance > self.sink.max_width() {
            if self.start < self.word_start {
                self.sink
                    .push_line(self.start..self.word_start, self.width - self.word_width);
                // The current word becomes the current line.
                self.start = self.word_start;
                self.width = self.word_width;
            } else {
                // The current word started at or before the start of the current line,
                // so ignore the word and just wrap at the current position.
                self.sink.push_line(self.start..self.position, self.width);
                self.start = self.position;
                self.width = 0.0;
            }
        }
        self.position += 1;
        self.width += advance;
        if is_newline(c) {
            self.sink.push_line(self.start..self.position, self.width);
            self.start = self.position;
            self.width = 0.0;
            // newline is not part of a word, so move word_start ahead.
            self.word_start = self.position;
            self.word_width = 0.0;
        } else if c.is_whitespace() {
            // We are not in a word, so move word_start ahead.
            self.word_start = self.position;
            self.word_width = 0.0;
        } else {
            // We are in a word, so leave word_start alone and increase word_width.
            self.word_width += advance;
        }
    }

    fn finish(&mut self) {
        self.sink.push_line(self.start..self.position, self.width);
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    struct Sink(f32, Vec<(Range<usize>, f32)>);

    impl Sink {
        fn new(width: f32) -> Self {
            Self(width, Vec::default())
        }
        fn result(&self) -> &[(Range<usize>, f32)] {
            self.1.as_slice()
        }
    }

    impl LineSink for Sink {
        fn push_line(&mut self, range: Range<usize>, width: f32) {
            self.1.push((range, width));
        }

        fn max_width(&self) -> f32 {
            self.0
        }
    }

    fn wrap<W: TextWrapper>(wrap: &mut W, text: &str) {
        for c in text.chars() {
            wrap.push(c, 1.0);
        }
        wrap.finish();
    }

    #[test]
    fn one_line_no_wrap() {
        let mut w = NoWrap::new(Sink::new(10.0));
        wrap(&mut w, "One line");
        assert_eq!(w.sink.result(), &[(0..8, 8.0)]);
    }
    #[test]
    fn two_line_no_wrap() {
        let mut w = NoWrap::new(Sink::new(10.0));
        wrap(&mut w, "Two\nline");
        assert_eq!(w.sink.result(), &[(0..3, 3.0), (4..8, 4.0)]);
    }
    #[test]
    fn one_line_letter() {
        let mut w = LetterWrap::new(Sink::new(8.0));
        wrap(&mut w, "One line");
        assert_eq!(w.sink.result(), &[(0..8, 8.0)]);
    }
    #[test]
    fn two_line_letter() {
        let mut w = LetterWrap::new(Sink::new(8.0));
        wrap(&mut w, "Two line!");
        assert_eq!(w.sink.result(), &[(0..8, 8.0), (8..9, 1.0)]);
    }
    #[test]
    fn new_line_letter() {
        let mut w = LetterWrap::new(Sink::new(8.0));
        wrap(&mut w, "Two\nline");
        assert_eq!(w.sink.result(), &[(0..4, 4.0), (4..8, 4.0)]);
    }
    #[test]
    fn one_line_word() {
        let mut w = WordWrap::new(Sink::new(8.0));
        wrap(&mut w, "One line");
        assert_eq!(w.sink.result(), &[(0..8, 8.0)]);
    }
    #[test]
    fn two_line_word() {
        let mut w = WordWrap::new(Sink::new(8.0));
        wrap(&mut w, "Two line!");
        assert_eq!(w.sink.result(), &[(0..4, 4.0), (4..9, 5.0)]);
    }
    #[test]
    fn new_line_word() {
        let mut w = WordWrap::new(Sink::new(8.0));
        wrap(&mut w, "Two\nline");
        assert_eq!(w.sink.result(), &[(0..4, 4.0), (4..8, 4.0)]);
    }
}