added saving of figures as a new function in evxcr.rs issue #552

Author: JaminMartin

plotters/src/evcxr.rs

@@ -2,6 +2,8 @@ use crate::coord::Shift;
 use crate::drawing::{DrawingArea, IntoDrawingArea};
 use plotters_backend::DrawingBackend;
 use plotters_svg::SVGBackend;
+use std::fs::File;
+use std::io::Write;
 
 #[cfg(feature = "evcxr_bitmap")]
 #[cfg_attr(doc_cfg, doc(cfg(feature = "evcxr_bitmap")))]
@@ -46,6 +48,25 @@ pub fn evcxr_figure<
     SVGWrapper(buffer, "".to_string())
 }
 
+// An evcxr figure that can save to the local file system and render in a notebook.
+
+pub fn evcxr_figure_with_saving<
+    Draw: FnOnce(DrawingArea<SVGBackend, Shift>) -> Result<(), Box<dyn std::error::Error>>,
+>(
+    filename: &str,
+    size: (u32, u32),
+    draw: Draw,
+) -> SVGWrapper {
+    let mut buffer = "".to_string();
+    let root = SVGBackend::with_string(&mut buffer, size).into_drawing_area();
+    draw(root).expect("Drawing failure");
+
+    let mut file = File::create(filename).expect("Unable to create file");
+    file.write_all(buffer.as_bytes())
+        .expect("Unable to write data");
+
+    SVGWrapper(buffer, "".to_string())
+}
 /// Start drawing an evcxr figure
 #[cfg(feature = "evcxr_bitmap")]
 #[cfg_attr(doc_cfg, doc(cfg(feature = "evcxr_bitmap")))]