Support for no-alloc

Cargo.toml

@@ -15,11 +15,13 @@ categories = ["graphics"]
 features = ["mint", "schemars", "serde"]
 
 [features]
-default = ["std"]
-std = []
+default = ["std", "alloc"]
+std = ["alloc"]
+alloc = ["serde/alloc", "smallvec"]
 
-[dependencies]
-smallvec = "1.10"
+[dependencies.smallvec]
+version = "1.10"
+optional = true
 
 [dependencies.arrayvec]
 version = "0.7.1"
@@ -41,7 +43,7 @@ optional = true
 version = "1.0.105"
 optional = true
 default-features = false
-features = ["alloc", "derive"]
+features = ["derive"]
 
 # This is used for research but not really needed; maybe refactor.
 [dev-dependencies]

src/bezpath.rs

@@ -9,6 +9,7 @@ use core::iter::{Extend, FromIterator};
 use core::mem;
 use core::ops::{Mul, Range};
 
+#[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 
 use arrayvec::ArrayVec;
@@ -103,6 +104,7 @@ use crate::common::FloatFuncs;
 #[derive(Clone, Default, Debug, PartialEq)]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg(feature = "alloc")]
 pub struct BezPath(Vec<PathEl>);
 
 /// The element of a Bézier path.
@@ -173,6 +175,7 @@ pub struct MinDistance {
     pub t2: f64,
 }
 
+#[cfg(feature = "alloc")]
 impl BezPath {
     /// Create a new path.
     pub fn new() -> BezPath {
@@ -488,6 +491,7 @@ impl BezPath {
 /// Helper for reversing a subpath.
 ///
 /// The `els` parameter must not contain any `MoveTo` or `ClosePath` elements.
+#[cfg(feature = "alloc")]
 fn reverse_subpath(start_pt: Point, els: &[PathEl], reversed: &mut BezPath) {
     let end_pt = els.last().and_then(|el| el.end_point()).unwrap_or(start_pt);
     reversed.push(PathEl::MoveTo(end_pt));
@@ -506,6 +510,7 @@ fn reverse_subpath(start_pt: Point, els: &[PathEl], reversed: &mut BezPath) {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl FromIterator<PathEl> for BezPath {
     fn from_iter<T: IntoIterator<Item = PathEl>>(iter: T) -> Self {
         let el_vec: Vec<_> = iter.into_iter().collect();
@@ -517,6 +522,7 @@ impl FromIterator<PathEl> for BezPath {
 ///
 /// Note: the semantics are slightly different from simply iterating over the
 /// slice, as it returns `PathEl` items, rather than references.
+#[cfg(feature = "alloc")]
 impl<'a> IntoIterator for &'a BezPath {
     type Item = PathEl;
     type IntoIter = core::iter::Cloned<core::slice::Iter<'a, PathEl>>;
@@ -526,6 +532,7 @@ impl<'a> IntoIterator for &'a BezPath {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl IntoIterator for BezPath {
     type Item = PathEl;
     type IntoIter = alloc::vec::IntoIter<PathEl>;
@@ -535,6 +542,7 @@ impl IntoIterator for BezPath {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl Extend<PathEl> for BezPath {
     fn extend<I: IntoIterator<Item = PathEl>>(&mut self, iter: I) {
         self.0.extend(iter);
@@ -549,6 +557,7 @@ const TO_QUAD_TOL: f64 = 0.1;
 /// See [`BezPath::flatten`] for more discussion.
 /// This signature is a bit more general, allowing flattening of `&[PathEl]` slices
 /// and other iterators yielding `PathEl`.
+#[cfg(feature = "alloc")]
 pub fn flatten(
     path: impl IntoIterator<Item = PathEl>,
     tolerance: f64,
@@ -662,6 +671,7 @@ impl Mul<PathSeg> for Affine {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl Mul<BezPath> for Affine {
     type Output = BezPath;
 
@@ -670,6 +680,7 @@ impl Mul<BezPath> for Affine {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl<'a> Mul<&'a BezPath> for Affine {
     type Output = BezPath;
 
@@ -704,6 +715,7 @@ impl Mul<PathSeg> for TranslateScale {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl Mul<BezPath> for TranslateScale {
     type Output = BezPath;
 
@@ -712,6 +724,7 @@ impl Mul<BezPath> for TranslateScale {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl<'a> Mul<&'a BezPath> for TranslateScale {
     type Output = BezPath;
 
@@ -1277,6 +1290,7 @@ impl From<QuadBez> for PathSeg {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl Shape for BezPath {
     type PathElementsIter<'iter> = core::iter::Copied<core::slice::Iter<'iter, PathEl>>;
 
@@ -1366,6 +1380,7 @@ impl<'a> Shape for &'a [PathEl] {
         self.iter().copied()
     }
 
+    #[cfg(feature = "alloc")]
     fn to_path(&self, _tolerance: f64) -> BezPath {
         BezPath::from_vec(self.to_vec())
     }
@@ -1406,6 +1421,7 @@ impl<const N: usize> Shape for [PathEl; N] {
         self.iter().copied()
     }
 
+    #[cfg(feature = "alloc")]
     fn to_path(&self, _tolerance: f64) -> BezPath {
         BezPath::from_vec(self.to_vec())
     }

src/cubicbez.rs

@@ -3,12 +3,17 @@
 
 //! Cubic Bézier segments.
 
+#[cfg(feature = "alloc")]
 use alloc::vec;
+#[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 use core::ops::{Mul, Range};
 
+#[cfg(feature = "alloc")]
+use crate::QuadSpline;
+
 use crate::MAX_EXTREMA;
-use crate::{Line, QuadSpline, Vec2};
+use crate::{Line, Vec2};
 use arrayvec::ArrayVec;
 
 use crate::common::{
@@ -100,11 +105,13 @@ impl CubicBez {
     ///
     /// Returns `None` if no suitable approximation is found within the given
     /// tolerance.
+    #[cfg(feature = "alloc")]
     pub fn approx_spline(&self, accuracy: f64) -> Option<QuadSpline> {
         (1..=MAX_SPLINE_SPLIT).find_map(|n| self.approx_spline_n(n, accuracy))
     }
 
     // Approximate a cubic curve with a quadratic spline of `n` curves
+    #[cfg(feature = "alloc")]
     fn approx_spline_n(&self, n: usize, accuracy: f64) -> Option<QuadSpline> {
         if n == 1 {
             return self
@@ -687,7 +694,7 @@ impl ParamCurveExtrema for CubicBez {
         let d2 = self.p3 - self.p2;
         one_coord(&mut result, d0.x, d1.x, d2.x);
         one_coord(&mut result, d0.y, d1.y, d2.y);
-        result.sort_by(|a, b| a.partial_cmp(b).unwrap());
+        result.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap());
         result
     }
 }
@@ -734,6 +741,7 @@ impl Iterator for ToQuads {
 /// Ensures that the resulting splines have the same number of control points.
 ///
 /// Rust port of cu2qu [cubic_approx_quadratic](https://github.com/fonttools/fonttools/blob/3b9a73ff8379ab49d3ce35aaaaf04b3a7d9d1655/Lib/fontTools/cu2qu/cu2qu.py#L322)
+#[cfg(feature = "alloc")]
 pub fn cubics_to_quadratic_splines(curves: &[CubicBez], accuracy: f64) -> Option<Vec<QuadSpline>> {
     let mut result = Vec::new();
     let mut split_order = 0;

src/lib.rs

@@ -61,8 +61,11 @@
 //! math functionality. The `std` feature is enabled by default, but can be
 //! disabled, as long as the `libm` feature is enabled. This is useful for
 //! `no_std` environments. However, note that the `libm` crate is not as
-//! efficient as the standard library, and that this crate still uses the
-//! `alloc` crate regardless.
+//! efficient as the standard library.
+//!
+//! The `alloc` feature (which is enabled by default) may be turned off to
+//! disable all allocations. This removes support for [`BezPath`] and all
+//! features (including curve fitting and offsets) that depend on it.
 //!
 //! [`Piet`]: https://docs.rs/piet
 //! [`Druid`]: https://docs.rs/druid
@@ -78,10 +81,12 @@
     clippy::bool_to_int_with_if
 )]
 #![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
+#![cfg_attr(not(feature = "alloc"), allow(dead_code, unused_imports))]
 
 #[cfg(not(any(feature = "std", feature = "libm")))]
 compile_error!("kurbo requires either the `std` or `libm` feature");
 
+#[cfg(feature = "alloc")]
 extern crate alloc;
 
 mod affine;
@@ -91,21 +96,26 @@ mod circle;
 pub mod common;
 mod cubicbez;
 mod ellipse;
+#[cfg(feature = "alloc")]
 mod fit;
 mod insets;
 mod line;
 mod mindist;
+#[cfg(feature = "alloc")]
 pub mod offset;
 mod param_curve;
 mod point;
 mod quadbez;
+#[cfg(feature = "alloc")]
 mod quadspline;
 mod rect;
 mod rounded_rect;
 mod rounded_rect_radii;
 mod shape;
+#[cfg(feature = "alloc")]
 pub mod simplify;
 mod size;
+#[cfg(feature = "alloc")]
 mod stroke;
 #[cfg(feature = "std")]
 mod svg;
@@ -118,18 +128,21 @@ pub use crate::bezpath::*;
 pub use crate::circle::*;
 pub use crate::cubicbez::*;
 pub use crate::ellipse::*;
+#[cfg(feature = "alloc")]
 pub use crate::fit::*;
 pub use crate::insets::*;
 pub use crate::line::*;
 pub use crate::param_curve::*;
 pub use crate::point::*;
 pub use crate::quadbez::*;
+#[cfg(feature = "alloc")]
 pub use crate::quadspline::*;
 pub use crate::rect::*;
 pub use crate::rounded_rect::*;
 pub use crate::rounded_rect_radii::*;
 pub use crate::shape::*;
 pub use crate::size::*;
+#[cfg(feature = "alloc")]
 pub use crate::stroke::*;
 #[cfg(feature = "std")]
 pub use crate::svg::*;

src/shape.rs

@@ -3,7 +3,10 @@
 
 //! A generic trait for shapes.
 
-use crate::{segments, BezPath, Circle, Line, PathEl, Point, Rect, RoundedRect, Segments};
+use crate::{segments, Circle, Line, PathEl, Point, Rect, RoundedRect, Segments};
+
+#[cfg(feature = "alloc")]
+use crate::BezPath;
 
 /// A generic trait for open and closed shapes.
 ///
@@ -64,12 +67,14 @@ pub trait Shape: Sized {
     /// The `tolerance` parameter is the same as for [`path_elements`].
     ///
     /// [`path_elements`]: Shape::path_elements
+    #[cfg(feature = "alloc")]
     fn to_path(&self, tolerance: f64) -> BezPath {
         self.path_elements(tolerance).collect()
     }
 
     #[deprecated(since = "0.7.0", note = "Use path_elements instead")]
     #[doc(hidden)]
+    #[cfg(feature = "alloc")]
     fn to_bez_path(&self, tolerance: f64) -> Self::PathElementsIter<'_> {
         self.path_elements(tolerance)
     }
@@ -81,12 +86,14 @@ pub trait Shape: Sized {
     /// The `tolerance` parameter is the same as for [`path_elements()`].
     ///
     /// [`path_elements()`]: Shape::path_elements
+    #[cfg(feature = "alloc")]
     fn into_path(self, tolerance: f64) -> BezPath {
         self.to_path(tolerance)
     }
 
     #[deprecated(since = "0.7.0", note = "Use into_path instead")]
     #[doc(hidden)]
+    #[cfg(feature = "alloc")]
     fn into_bez_path(self, tolerance: f64) -> BezPath {
         self.into_path(tolerance)
     }
@@ -181,6 +188,7 @@ impl<'a, T: Shape> Shape for &'a T {
         (*self).path_elements(tolerance)
     }
 
+    #[cfg(feature = "alloc")]
     fn to_path(&self, tolerance: f64) -> BezPath {
         (*self).to_path(tolerance)
     }