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#[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.
///
/// See [`OutlinedGlyph::px_bounds`].
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 eliminate 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 outline.
/// The returned rect is exactly large enough to [`Self::draw`] into.
///
/// The rect holds bounding coordinates in the same coordinate space as the [`Glyph::position`].
///
/// Note: These bounds depend on the glyph outline. That outline is *not* necessarily bound
/// by the layout/`glyph_bounds()` bounds.
/// * The min.x bound may be greater or smaller than the [`Glyph::position`] x.
/// E.g. if a glyph at position x=0 has an outline going off to the left a bit, min.x will be negative.
/// * The max.x bound may be greater/smaller than the `position.x + h_advance`.
/// * The min.y bound may be greater/smaller than the `position.y - ascent`.
/// * The max.y bound may be greater/smaller than the `position.y - descent`.
///
/// Pixel bounds coordinates should not be used for layout logic.
#[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 indicating how much the glyph covered that pixel.
///
/// A coverage value of `0.0` means the pixel is totally uncovered by the glyph.
/// A value of `1.0` or greater means fully covered.
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
}
}