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

#[cfg(all(feature = "libm", not(feature = "std")))]
use crate::nostd_float::FloatExt;
use crate::{point, Glyph, Point, PxScaleFactor};
#[cfg(not(feature = "std"))]
use alloc::vec::Vec;

/// A "raw" collection of outline curves for a glyph, unscaled & unpositioned.
#[derive(Clone, Debug)]
pub struct Outline {
    /// Unscaled bounding box.
    pub bounds: Rect,
    /// Unscaled & unpositioned outline curves.
    pub curves: Vec<OutlineCurve>,
}

impl Outline {
    /// Convert unscaled bounds into pixel bounds at a given scale & position.
    pub fn px_bounds(&self, scale_factor: PxScaleFactor, position: Point) -> Rect {
        let Rect { min, max } = self.bounds;

        // Use subpixel fraction in floor/ceil rounding to elimate rounding error
        // from identical subpixel positions
        let (x_trunc, x_fract) = (position.x.trunc(), position.x.fract());
        let (y_trunc, y_fract) = (position.y.trunc(), position.y.fract());

        Rect {
            min: point(
                (min.x * scale_factor.horizontal + x_fract).floor() + x_trunc,
                (min.y * -scale_factor.vertical + y_fract).floor() + y_trunc,
            ),
            max: point(
                (max.x * scale_factor.horizontal + x_fract).ceil() + x_trunc,
                (max.y * -scale_factor.vertical + y_fract).ceil() + y_trunc,
            ),
        }
    }
}

/// A glyph that has been outlined at a scale & position.
#[derive(Clone, Debug)]
pub struct OutlinedGlyph {
    glyph: Glyph,
    // Pixel scale bounds.
    px_bounds: Rect,
    // Scale factor
    scale_factor: PxScaleFactor,
    // Raw outline
    outline: Outline,
}

impl OutlinedGlyph {
    /// Constructs an `OutlinedGlyph` from the source `Glyph`, pixel bounds
    /// & relatively positioned outline curves.
    #[inline]
    pub fn new(glyph: Glyph, outline: Outline, scale_factor: PxScaleFactor) -> Self {
        // work this out now as it'll usually be used more than once
        let px_bounds = outline.px_bounds(scale_factor, glyph.position);

        Self {
            glyph,
            px_bounds,
            scale_factor,
            outline,
        }
    }

    /// Glyph info.
    #[inline]
    pub fn glyph(&self) -> &Glyph {
        &self.glyph
    }

    #[deprecated = "Renamed to `px_bounds`"]
    #[doc(hidden)]
    pub fn bounds(&self) -> Rect {
        self.px_bounds()
    }

    /// Conservative whole number pixel bounding box for this glyph.
    #[inline]
    pub fn px_bounds(&self) -> Rect {
        self.px_bounds
    }

    /// Draw this glyph outline using a pixel & coverage handling function.
    ///
    /// The callback will be called for each `(x, y)` pixel coordinate inside the bounds
    /// with a coverage value in the range `[0.0, 1.0]` indicating how much the glyph covered
    /// that pixel.
    pub fn draw<O: FnMut(u32, u32, f32)>(&self, o: O) {
        use ab_glyph_rasterizer::Rasterizer;
        let h_factor = self.scale_factor.horizontal;
        let v_factor = -self.scale_factor.vertical;
        let offset = self.glyph.position - self.px_bounds.min;
        let (w, h) = (
            self.px_bounds.width() as usize,
            self.px_bounds.height() as usize,
        );

        let scale_up = |&Point { x, y }| point(x * h_factor, y * v_factor);

        self.outline
            .curves
            .iter()
            .fold(Rasterizer::new(w, h), |mut rasterizer, curve| match curve {
                OutlineCurve::Line(p0, p1) => {
                    // eprintln!("r.draw_line({:?}, {:?});",
                    //     scale_up(p0) + offset, scale_up(p1) + offset);
                    rasterizer.draw_line(scale_up(p0) + offset, scale_up(p1) + offset);
                    rasterizer
                }
                OutlineCurve::Quad(p0, p1, p2) => {
                    // eprintln!("r.draw_quad({:?}, {:?}, {:?});",
                    //     scale_up(p0) + offset, scale_up(p1) + offset, scale_up(p2) + offset);
                    rasterizer.draw_quad(
                        scale_up(p0) + offset,
                        scale_up(p1) + offset,
                        scale_up(p2) + offset,
                    );
                    rasterizer
                }
                OutlineCurve::Cubic(p0, p1, p2, p3) => {
                    // eprintln!("r.draw_cubic({:?}, {:?}, {:?}, {:?});",
                    //     scale_up(p0) + offset, scale_up(p1) + offset, scale_up(p2) + offset, scale_up(p3) + offset);
                    rasterizer.draw_cubic(
                        scale_up(p0) + offset,
                        scale_up(p1) + offset,
                        scale_up(p2) + offset,
                        scale_up(p3) + offset,
                    );
                    rasterizer
                }
            })
            .for_each_pixel_2d(o);
    }
}

impl AsRef<Glyph> for OutlinedGlyph {
    #[inline]
    fn as_ref(&self) -> &Glyph {
        self.glyph()
    }
}

/// Glyph outline primitives.
#[derive(Clone, Debug)]
pub enum OutlineCurve {
    /// Straight line from `.0` to `.1`.
    Line(Point, Point),
    /// Quadratic Bézier curve from `.0` to `.2` using `.1` as the control.
    Quad(Point, Point, Point),
    /// Cubic Bézier curve from `.0` to `.3` using `.1` as the control at the beginning of the
    /// curve and `.2` at the end of the curve.
    Cubic(Point, Point, Point, Point),
}

/// A rectangle, with top-left corner at `min`, and bottom-right corner at `max`.
#[derive(Copy, Clone, Debug, Default, PartialEq, PartialOrd)]
pub struct Rect {
    pub min: Point,
    pub max: Point,
}

impl Rect {
    #[inline]
    pub fn width(&self) -> f32 {
        self.max.x - self.min.x
    }

    #[inline]
    pub fn height(&self) -> f32 {
        self.max.y - self.min.y
    }
}