Make FFI optional (#34)

.github/workflows/rust.yml

@@ -79,7 +79,7 @@ jobs:
         with:
           use-cross: ${{ matrix.use-cross }}
           command: build
-          args: --release --target=${{ matrix.target }} --features headers
+          args: --release --target=${{ matrix.target }} --features headers,ffi
       - name: Gather Assets
         run: |
           src=$(pwd)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "polylabel"
-version = "2.5.0"
+version = "3.0.0"
 authors = ["Stephan Hügel <urschrei@gmail.com>"]
 description = "A Rust implementation of the Polylabel algorithm for finding optimum polygon label positions."
 readme = "README.md"
@@ -10,7 +10,7 @@ license = "MIT"
 edition = "2021"
 
 [dependencies]
-libc = "0.2.149"
+libc = {version = "0.2.149", default-features=false, optional = true}
 geo = "0.26.0"
 num-traits = "0.2.8"
 thiserror = "1.0.4"
@@ -23,6 +23,7 @@ criterion = "0.4.0"
 
 [features]
 headers = ["cbindgen"]
+ffi = ["libc"]
 
 [lib]
 name = "polylabel"
@@ -39,3 +40,6 @@ lto = true
 name = "benchmark"
 harness = false
 
+[package.metadata.docs.rs]
+# Features to pass to Cargo (default: [])
+features = ["ffi"]

README.md

@@ -36,6 +36,7 @@ A command-line tool is available: `cargo install polylabel_cmd`. This enables th
 https://docs.rs/polylabel
 
 ## FFI
+### Enable the Cargo `ffi` and `headers` features to enable this functionality
 Call `polylabel_ffi` with the following three mandatory arguments:
 - [`Array`](https://docs.rs/polylabel/1.0.3/polylabel/struct.Array.html) (a struct with two fields):
     - `data`: a void pointer to an array of two-element `c_double` arrays, each of which represents a point on the exterior Polygon shell)
@@ -49,7 +50,7 @@ The function returns a [struct](https://docs.rs/polylabel/1.0.3/polylabel/struct
 - `x_pos`
 - `y_pos`
 
-A Python example is available in [`ffi.py`](ffi.py)
+Headers are provided in the `include` directory. A Python example is available in [`ffi.py`](ffi.py)
 
 An auto-generated header file is available at [`include/header.h`](include/header.h)
 

include/header.h

@@ -1,4 +1,4 @@
-/* Generated with cbindgen:0.22.0 */
+/* Generated with cbindgen:0.24.5 */
 
 /* Warning, this file is autogenerated by cbindgen. Don't modify this manually. */
 
@@ -40,11 +40,11 @@ typedef struct WrapperArray {
  *
  * Accepts three arguments:
  *
- * - an exterior ring [`Array`](struct.Array.html)
- * - zero or more interior rings [`WrapperArray`](struct.WrapperArray.html)
+ * - an exterior ring representing a Polygon shell or closed LineString
+ * - zero or more interior rings representing Polygon holes
  * - a tolerance `c_double`.
  * If an error occurs while attempting to calculate the label position, the resulting point coordinates
- * will be NaN, NaN.
+ * will be `NaN, NaN`.
  */
 struct Position polylabel_ffi(struct Array outer,
                               struct WrapperArray inners,

src/ffi.rs

@@ -56,11 +56,11 @@ fn reconstitute2(arr: WrapperArray) -> Vec<Vec<[f64; 2]>> {
 ///
 /// Accepts three arguments:
 ///
-/// - an exterior ring [`Array`](struct.Array.html)
-/// - zero or more interior rings [`WrapperArray`](struct.WrapperArray.html)
+/// - an exterior ring representing a Polygon shell or closed LineString
+/// - zero or more interior rings representing Polygon holes
 /// - a tolerance `c_double`.
 /// If an error occurs while attempting to calculate the label position, the resulting point coordinates
-/// will be NaN, NaN.
+/// will be `NaN, NaN`.
 #[no_mangle]
 pub extern "C" fn polylabel_ffi(
     outer: Array,

src/lib.rs

@@ -4,6 +4,8 @@
 )]
 //! This crate provides a Rust implementation of the [Polylabel](https://github.com/mapbox/polylabel) algorithm
 //! for finding the optimum position of a polygon label.
+//!
+//! ffi bindings are provided: enable the `ffi` and `headers` features when building the crate.
 use geo::{prelude::*, Coord, Rect};
 use geo::{GeoFloat, Point, Polygon};
 use num_traits::FromPrimitive;
@@ -16,8 +18,10 @@ pub mod errors;
 use errors::PolylabelError;
 
 #[cfg(not(target_arch = "wasm32"))]
+#[cfg(feature = "ffi")]
 mod ffi;
 #[cfg(not(target_arch = "wasm32"))]
+#[cfg(feature = "ffi")]
 pub use crate::ffi::{polylabel_ffi, Array, Position, WrapperArray};
 
 /// Represention of a Quadtree node's cells. A node contains four Qcells.