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//! Path data.
use super::command::{Command, PointsCommands, Verb};
use super::geometry::{Point, Transform};
use super::path_builder::PathBuilder;
use super::segment::segments;
use super::svg_parser::SvgCommands;
#[cfg(feature = "eval")]
use super::stroke::stroke_into;
#[cfg(feature = "eval")]
use super::style::*;
#[cfg(feature = "eval")]
use super::geometry::{Bounds, BoundsBuilder};
#[cfg(feature = "eval")]
use super::path_builder::TransformSink;
use crate::lib::Vec;
/// Trait for types that represent path data.
///
/// A primary design goal for this crate is to be agnostic with regard to
/// storage of path data. This trait provides the abstraction to make that
/// possible.
///
/// All path data is consumed internally as an iterator over path
/// [commands](enum.Command.html) and as such, this trait is similar to
/// the IntoIterator trait, but restricted to iterators of commands and
/// without consuming itself.
///
/// Implementations of this trait are provided for SVG path data (in the form
/// of strings), slices/vectors of commands, and the common point and
/// verb list structure (as the tuple `(&[Point], &[Verb])`).
///
/// As such, these paths are all equivalent:
///
/// ```rust
/// use zeno::{Command, PathData, Point, Verb};
///
/// // SVG path data
/// let path1 = "M1,2 L3,4";
///
/// // Slice of commands
/// let path2 = &[
/// Command::MoveTo(Point::new(1.0, 2.0)),
/// Command::LineTo(Point::new(3.0, 4.0)),
/// ][..];
///
/// // Tuple of slices to points and verbs
/// let path3 = (
/// &[Point::new(1.0, 2.0), Point::new(3.0, 4.0)][..],
/// &[Verb::MoveTo, Verb::LineTo][..],
/// );
///
/// assert!(path1.commands().eq(path2.commands()));
/// assert!(path2.commands().eq(path3.commands()));
/// ```
///
/// Implementing PathData is similar to implementing IntoIterator:
///
/// ```rust
/// use zeno::{Command, PathData};
///
/// pub struct MyPath {
/// data: Vec<Command>
/// }
///
/// impl<'a> PathData for &'a MyPath {
/// // Copied here because PathData expects Commands by value
/// type Commands = std::iter::Copied<std::slice::Iter<'a, Command>>;
///
/// fn commands(&self) -> Self::Commands {
/// self.data.iter().copied()
/// }
/// }
/// ```
///
/// The provided copy_into() method evaluates the command iterator and
/// submits the commands to a sink. You should also implement this if you
/// have a more direct method of dispatching to a sink as rasterizer
/// performance can be sensitive to latencies here.
pub trait PathData {
/// Command iterator.
type Commands: Iterator<Item = Command> + Clone;
/// Returns an iterator over the commands described by the path data.
fn commands(&self) -> Self::Commands;
/// Copies the path data into the specified sink.
fn copy_to(&self, sink: &mut impl PathBuilder) {
for cmd in self.commands() {
use Command::*;
match cmd {
MoveTo(p) => sink.move_to(p),
LineTo(p) => sink.line_to(p),
QuadTo(c, p) => sink.quad_to(c, p),
CurveTo(c1, c2, p) => sink.curve_to(c1, c2, p),
Close => sink.close(),
};
}
}
}
/// Computes the total length of the path.
pub fn length(data: impl PathData, transform: Option<Transform>) -> f32 {
let data = data.commands();
let mut length = 0.;
if let Some(transform) = transform {
for s in segments(data.map(|cmd| cmd.transform(&transform)), false) {
length += s.length();
}
} else {
for s in segments(data, false) {
length += s.length();
}
}
length
}
/// Computes the bounding box of the path.
#[cfg(feature = "eval")]
pub fn bounds<'a>(
data: impl PathData,
style: impl Into<Style<'a>>,
transform: Option<Transform>,
) -> Bounds {
let style = style.into();
let mut bounds = BoundsBuilder::new();
apply(data, style, transform, &mut bounds);
bounds.build()
}
/// Applies the style and transform to the path and emits the result to the
/// specified sink.
#[cfg(feature = "eval")]
pub fn apply<'a>(
data: impl PathData,
style: impl Into<Style<'a>>,
transform: Option<Transform>,
sink: &mut impl PathBuilder,
) -> Fill {
let style = style.into();
match style {
Style::Fill(fill) => {
if let Some(transform) = transform {
let mut transform_sink = TransformSink { sink, transform };
data.copy_to(&mut transform_sink);
fill
} else {
data.copy_to(sink);
fill
}
}
Style::Stroke(stroke) => {
if let Some(transform) = transform {
if stroke.scale {
let mut transform_sink = TransformSink { sink, transform };
stroke_into(data.commands(), &stroke, &mut transform_sink);
} else {
stroke_into(
data.commands().map(|cmd| cmd.transform(&transform)),
&stroke,
sink,
);
}
} else {
stroke_into(data.commands(), &stroke, sink);
}
Fill::NonZero
}
}
}
impl<T> PathData for &'_ T
where
T: PathData,
{
type Commands = T::Commands;
fn commands(&self) -> Self::Commands {
T::commands(*self)
}
#[inline(always)]
fn copy_to(&self, sink: &mut impl PathBuilder) {
T::copy_to(*self, sink)
}
}
impl<'a> PathData for &'a str {
type Commands = SvgCommands<'a>;
fn commands(&self) -> Self::Commands {
SvgCommands::new(self)
}
}
impl<'a> PathData for (&'a [Point], &'a [Verb]) {
type Commands = PointsCommands<'a>;
fn commands(&self) -> Self::Commands {
PointsCommands::new(self.0, self.1)
}
#[inline(always)]
fn copy_to(&self, sink: &mut impl PathBuilder) {
self.commands().copy_to(sink);
}
}
impl<'a> PathData for &'a [Command] {
type Commands = core::iter::Copied<core::slice::Iter<'a, Command>>;
fn commands(&self) -> Self::Commands {
self.iter().copied()
}
}
impl<'a> PathData for &'a Vec<Command> {
type Commands = core::iter::Copied<core::slice::Iter<'a, Command>>;
fn commands(&self) -> Self::Commands {
self.iter().copied()
}
}