libcosmic/examples/text/src/font/shape.rs

#[cfg(feature = "ab_glyph")]
use ab_glyph::Font;
use core::marker::PhantomData;

use super::{FontLayoutGlyph, FontLayoutLine, FontLineIndex};

pub struct FontShapeGlyph<'a> {
    pub start: usize,
    pub end: usize,
    pub x_advance: f32,
    pub y_advance: f32,
    pub x_offset: f32,
    pub y_offset: f32,
    #[cfg(feature = "ab_glyph")]
    pub font: &'a ab_glyph::FontRef<'a>,
    #[cfg(feature = "ab_glyph")]
    pub inner: ab_glyph::GlyphId,
    #[cfg(feature = "rusttype")]
    pub inner: rusttype::Glyph<'a>,
    #[cfg(feature = "swash")]
    pub font: &'a swash::FontRef<'a>,
    #[cfg(feature = "swash")]
    pub inner: swash::GlyphId,
}

impl<'a> FontShapeGlyph<'a> {
    fn layout(&self, font_size: i32, x: f32, y: f32) -> FontLayoutGlyph<'a, ()> {
        let x_offset = font_size as f32 * self.x_offset;
        let y_offset = font_size as f32 * self.y_offset;
        let x_advance = font_size as f32 * self.x_advance;

        #[cfg(feature = "ab_glyph")]
        let inner = self.font.outline_glyph(
            self.inner.with_scale_and_position(
                font_size as f32,
                ab_glyph::point(
                    x + x_offset,
                    y - y_offset,
                )
            )
        );

        #[cfg(feature = "rusttype")]
        let inner = self.inner.clone()
            .scaled(rusttype::Scale::uniform(font_size as f32))
            .positioned(rusttype::point(
                x + x_offset,
                y - y_offset,
            ));

        #[cfg(feature = "swash")]
        let inner = {
            use swash::scale::{Render, ScaleContext, Source, StrikeWith};
            use swash::zeno::{Format, Vector};

            //TODO: store somewhere else
            static mut CONTEXT: Option<ScaleContext> = None;

            unsafe {
                if CONTEXT.is_none() {
                    CONTEXT = Some(ScaleContext::new());
                }
            }

            // Build the scaler
            let mut scaler = unsafe { CONTEXT.as_mut().unwrap() }
                .builder(*self.font)
                .size(font_size as f32)
                .hint(true)
                .build();

            // Compute the fractional offset-- you'll likely want to quantize this
            // in a real renderer
            let offset = Vector::new((x + x_offset).fract(), (y - y_offset).fract());

            // Select our source order
            let image_opt = Render::new(&[
                // Color outline with the first palette
                Source::ColorOutline(0),
                // Color bitmap with best fit selection mode
                Source::ColorBitmap(StrikeWith::BestFit),
                // Standard scalable outline
                Source::Outline,
            ])
                // Select a subpixel format
                .format(Format::Alpha)
                // Apply the fractional offset
                .offset(offset)
                // Render the image
                .render(&mut scaler, self.inner);
            ((x + x_offset).trunc() as i32, (y - y_offset).trunc() as i32, image_opt)
        };

        FontLayoutGlyph {
            start: self.start,
            end: self.end,
            x: x,
            w: x_advance,
            inner,
            phantom: PhantomData,
        }
    }
}

pub struct FontShapeWord<'a> {
    pub rtl: bool,
    pub glyphs: Vec<FontShapeGlyph<'a>>,
}

pub struct FontShapeSpan<'a> {
    pub rtl: bool,
    pub words: Vec<FontShapeWord<'a>>,
}

pub struct FontShapeLine<'a> {
    pub line_i: FontLineIndex,
    pub rtl: bool,
    pub spans: Vec<FontShapeSpan<'a>>,
}

impl<'a> FontShapeLine<'a> {

    fn layout_ltr(&self, font_size: i32, line_width: i32, layout_lines: &mut Vec<FontLayoutLine<'a>>, mut layout_i: usize) {
        let mut push_line = true;
        let mut glyphs = Vec::new();

        let mut x = 0.0;
        let mut y = 0.0;
        for span in self.spans.iter() {
            for word in span.words.iter() {
                let mut word_size = 0.0;
                for glyph in word.glyphs.iter() {
                    word_size += font_size as f32 * glyph.x_advance;
                }

                //TODO: make wrapping optional
                if x + word_size > line_width as f32 && ! glyphs.is_empty() {
                    let mut glyphs_swap = Vec::new();
                    std::mem::swap(&mut glyphs, &mut glyphs_swap);
                    layout_lines.insert(layout_i, FontLayoutLine {
                        line_i: self.line_i,
                        glyphs: glyphs_swap
                    });
                    layout_i += 1;

                    x = 0.0;
                    y = 0.0;
                }

                for glyph in word.glyphs.iter() {
                    let x_advance = font_size as f32 * glyph.x_advance;
                    let y_advance = font_size as f32 * glyph.y_advance;

                    glyphs.push(glyph.layout(font_size, x, y));
                    push_line = true;

                    x += x_advance;
                    y += y_advance;
                }
            }
        }

        if push_line {
            layout_lines.insert(layout_i, FontLayoutLine {
                line_i: self.line_i,
                glyphs
            });
        }
    }

    fn layout_rtl(&self, font_size: i32, line_width: i32, layout_lines: &mut Vec<FontLayoutLine<'a>>, mut layout_i: usize) {
        let mut push_line = true;
        let mut glyphs = Vec::new();

        let mut x = line_width as f32;
        let mut y = 0.0;
        for span in self.spans.iter() {
            for word in span.words.iter() {
                let mut word_size = 0.0;
                for glyph in word.glyphs.iter() {
                    word_size += font_size as f32 * glyph.x_advance;
                }

                //TODO: make wrapping optional
                if x - word_size < 0.0 && ! glyphs.is_empty() {
                    let mut glyphs_swap = Vec::new();
                    std::mem::swap(&mut glyphs, &mut glyphs_swap);
                    layout_lines.insert(layout_i, FontLayoutLine {
                        line_i: self.line_i,
                        glyphs: glyphs_swap
                    });
                    layout_i += 1;

                    x = line_width as f32;
                    y = 0.0;
                }

                for glyph in word.glyphs.iter().rev() {
                    let x_advance = font_size as f32 * glyph.x_advance;
                    let y_advance = font_size as f32 * glyph.y_advance;

                    x -= x_advance;

                    glyphs.push(glyph.layout(font_size, x, y));
                    push_line = true;

                    y += y_advance;
                }
            }
        }

        if push_line {
            layout_lines.insert(layout_i, FontLayoutLine {
                line_i: self.line_i,
                glyphs
            });
        }

    }

    pub fn layout(&self, font_size: i32, line_width: i32, layout_lines: &mut Vec<FontLayoutLine<'a>>, layout_i: usize) {
        if self.rtl {
            self.layout_rtl(font_size, line_width, layout_lines, layout_i);
        } else {
            self.layout_ltr(font_size, line_width, layout_lines, layout_i);
        }
    }
}