Python bindings configured correctly for PyPI releases (#54)

* Python bindings sep 2023 (#52)

* Added maturin-based Python binding, to be deployed to https://pypi.org/project/vtracer/

* Removed poetry mentions from pyproject.toml, added README_PY.md for use on PYPI

* ->   v0.6.1
-> moved Python bindings to bottom of converter.rs

* - README_PY.md needed to be inside the cmdapp directory to display on PyPi.irg
->  v0.6.3

* Move code around

* Edit Readme

* Edit RELEASES.md

* Feature guard

* Build wheels with the cmdapp/Cargo.toml rather than top-level Cargo.toml

* use cmdapp/Cargo.toml for all Maturin CI actions, which causes Github to build all platforms python wheels and submit a new release to PyPI

* Bump to 0.6.4 for new PyPI release with all platforms' wheels included

* PyPI didn't accept a 'linux_aarch64' wheel for a release. For the moment, remove the platform until I can convince the action to build 'manylinux_aarch64' or the like

* Version bump while I work out CI & PyPI release wrinkles

* Maturin authors say `compatibility = "linux"` in pyproject.toml is causing PyPI failure. Replacing with "manylinux2014"

* bump to v0.7.0 in preparation for release from original vtracer repo

---------

Co-authored-by: Chris Tsang <chris.2y3@outlook.com>

cmdapp/src/lib.rs

@@ -11,7 +11,11 @@
 mod config;
 mod converter;
 mod svg;
+#[cfg(feature = "python-binding")]
+mod python;
 
 pub use config::*;
 pub use converter::*;
-pub use svg::*;
+pub use svg::*;
+#[cfg(feature = "python-binding")]
+pub use python::*;

cmdapp/src/python.rs

@@ -0,0 +1,81 @@
+use pyo3::prelude::*;
+
+use visioncortex::{PathSimplifyMode};
+use super::converter::*;
+
+/// Python binding
+#[pyfunction]
+fn convert_image_to_svg_py( image_path: &str, 
+                            out_path: &str,   
+                            colormode: Option<&str>,       // "color" or "binary"
+                            hierarchical: Option<&str>,    // "stacked" or "cutout"
+                            mode: Option<&str>,            // "polygon", "spline", "none"
+                            filter_speckle: Option<usize>, // default: 4
+                            color_precision: Option<i32>,  // default: 6
+                            layer_difference: Option<i32>, // default: 16
+                            corner_threshold: Option<i32>, // default: 60   
+                            length_threshold: Option<f64>, // in [3.5, 10] default: 4.0
+                            max_iterations: Option<usize>, // default: 10
+                            splice_threshold: Option<i32>, // default: 45
+                            path_precision: Option<u32>    // default: 8
+                        ) -> PyResult<()> {
+    let input_path = PathBuf::from(image_path);
+    let output_path = PathBuf::from(out_path);
+
+    // TODO: enforce color mode with an enum so that we only 
+    // accept the strings 'color' or 'binary'
+    let color_mode = match colormode.unwrap_or("color") {
+        "color" => ColorMode::Color,
+        "binary" => ColorMode::Binary,
+        _ => ColorMode::Color,
+    };
+
+    let hierarchical = match hierarchical.unwrap_or("stacked") {
+        "stacked" => Hierarchical::Stacked,
+        "cutout" => Hierarchical::Cutout,
+        _ => Hierarchical::Stacked,
+    };
+    
+    let mode = match mode.unwrap_or("spline") {
+        "spline" => PathSimplifyMode::Spline,
+        "polygon" => PathSimplifyMode::Polygon,
+        "none" => PathSimplifyMode::None,
+        _ => PathSimplifyMode::Spline,
+    };
+
+    let filter_speckle =    filter_speckle.unwrap_or(4);
+    let color_precision =   color_precision.unwrap_or(6);
+    let layer_difference =  layer_difference.unwrap_or(16);
+    let corner_threshold =  corner_threshold.unwrap_or(60);
+    let length_threshold =  length_threshold.unwrap_or(4.0);
+    let splice_threshold =  splice_threshold.unwrap_or(45);
+    let max_iterations =    max_iterations.unwrap_or(10);
+
+    let config = Config {
+        input_path,
+        output_path,
+        color_mode,
+        hierarchical,
+        filter_speckle,
+        color_precision,
+        layer_difference,
+        mode,
+        corner_threshold,
+        length_threshold,
+        max_iterations,
+        splice_threshold,
+        path_precision,
+        ..Default::default()                
+    };
+
+
+    convert_image_to_svg(config).unwrap();
+    Ok(())
+}
+
+/// A Python module implemented in Rust.
+#[pymodule]
+fn vtracer(_py: Python, m: &PyModule) -> PyResult<()> {
+    m.add_function(wrap_pyfunction!(convert_image_to_svg_py, m)?)?;
+    Ok(())
+}