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```
```// path.rs      2D vector paths.
//
// Copyright (c) 2017-2020  Douglas P Lau
//
use crate::geom::Pt;

/// Fill-rule for filling paths.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum FillRule {
/// All points within bounds are filled
NonZero,
/// Alternate filling with path outline
EvenOdd,
}

/// Path operation.
#[derive(Clone, Copy, Debug, PartialEq)]
pub enum PathOp {
/// Close the path
Close(),
/// Move to a point
Move(Pt),
/// Straight line to end point
Line(Pt),
/// Quadratic bézier curve (control point and end point)
/// Cubic bézier curve (two control points and end point)
Cubic(Pt, Pt, Pt),
/// Set pen width (for stroking)
PenWidth(f32),
}

/// Path builder.
///
/// # Example
/// ```
/// use footile::Path2D;
///
/// let path = Path2D::default()
///     .move_to(10.0, 10.0)
///     .line_to(90.0, 90.0)
///     .finish();
/// ```
pub struct Path2D {
/// Vec of path operations
ops: Vec<PathOp>,
/// Absolute vs relative coordinates
absolute: bool,
/// Current pen position
pen: Pt,
}

impl Default for Path2D {
fn default() -> Path2D {
let ops = Vec::with_capacity(32);
Path2D {
ops,
absolute: false,
pen: Pt::default(),
}
}
}

impl Path2D {
/// Use absolute coordinates for subsequent operations.
pub fn absolute(mut self) -> Self {
self.absolute = true;
self
}

/// Use relative coordinates for subsequent operations.
///
/// This is the default setting.
pub fn relative(mut self) -> Self {
self.absolute = false;
self
}

/// Get absolute point.
fn pt(&self, x: f32, y: f32) -> Pt {
if self.absolute {
Pt(x, y)
} else {
Pt(self.pen.x() + x, self.pen.y() + y)
}
}

/// Close current sub-path and move pen to origin.
pub fn close(mut self) -> Self {
self.ops.push(PathOp::Close());
self.pen = Pt::default();
self
}

/// Move the pen to a point.
///
/// * `x` X-position of point.
/// * `y` Y-position of point.
pub fn move_to(mut self, x: f32, y: f32) -> Self {
let pb = self.pt(x, y);
self.ops.push(PathOp::Move(pb));
self.pen = pb;
self
}

/// Add a line from pen to a point.
///
/// * `x` X-position of end point.
/// * `y` Y-position of end point.
pub fn line_to(mut self, x: f32, y: f32) -> Self {
let pb = self.pt(x, y);
self.ops.push(PathOp::Line(pb));
self.pen = pb;
self
}

///
/// The points are:
///
/// * Current pen position: P<sub>a</sub>
/// * Control point: P<sub>b</sub> (`bx` / `by`)
/// * Spline end point: P<sub>c</sub> (`cx` / `cy`)
pub fn quad_to(mut self, bx: f32, by: f32, cx: f32, cy: f32) -> Self {
let pb = self.pt(bx, by);
let pc = self.pt(cx, cy);
self.pen = pc;
self
}

/// Add a cubic bézier spline.
///
/// The points are:
///
/// * Current pen position: P<sub>a</sub>
/// * First control point: P<sub>b</sub> (`bx` / `by`)
/// * Second control point: P<sub>c</sub> (`cx` / `cy`)
/// * Spline end point: P<sub>d</sub> (`dx` / `dy`)
pub fn cubic_to(
mut self,
bx: f32,
by: f32,
cx: f32,
cy: f32,
dx: f32,
dy: f32,
) -> Self {
let pb = self.pt(bx, by);
let pc = self.pt(cx, cy);
let pd = self.pt(dx, dy);
self.ops.push(PathOp::Cubic(pb, pc, pd));
self.pen = pd;
self
}

/// Set pen stroke width.
///
/// All subsequent path points will be affected, until the stroke width
/// is changed again.
///
/// * `width` Pen stroke width.
pub fn pen_width(mut self, width: f32) -> Self {
self.ops.push(PathOp::PenWidth(width));
self
}

/// Finish path with specified operations.
pub fn finish(self) -> Vec<PathOp> {
self.ops
}
}
```