Add method to read SVG from file

src/lib.rs

@@ -1,6 +1,31 @@
-use pyo3::exceptions::PyValueError;
+use pyo3::exceptions::{PyFileNotFoundError, PyValueError};
 use pyo3::prelude::*;
 use std::error::Error;
+use std::fs::File;
+use std::io::ErrorKind;
+
+#[pyfunction]
+fn filter_file(py: Python, path: String) -> PyResult<String> {
+    let file = match File::open(&path) {
+        Err(e) if e.kind() == ErrorKind::NotFound => {
+            return Err(PyFileNotFoundError::new_err(format!(
+                "{}: {}",
+                e.to_string(),
+                &path
+            )))
+        }
+        Err(e) => return Err(PyValueError::new_err(e.to_string())),
+        Ok(f) => f,
+    };
+    let f = svg_hush::Filter::new();
+    let mut out = Vec::new();
+    let result = py.allow_threads(|| f.filter(file, &mut out));
+
+    match result {
+        Ok(()) => Ok(String::from_utf8_lossy(&out).to_string()),
+        Err(e) => Err(PyValueError::new_err(e.source().unwrap().to_string())),
+    }
+}
 
 #[pyfunction]
 fn filter(py: Python, input: String) -> PyResult<String> {
@@ -18,5 +43,6 @@ fn filter(py: Python, input: String) -> PyResult<String> {
 #[pymodule]
 fn svg_hush(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(filter, m)?)?;
+    m.add_function(wrap_pyfunction!(filter_file, m)?)?;
     Ok(())
 }