Make all measurements in inches by default

src/lib.rs

@@ -1,4 +1,5 @@
 use std::fmt::Display;
+use std::fmt::{Formatter, Error};
 use std::io::Write;
 
 /// An SVG document
@@ -7,6 +8,18 @@ pub struct SVG {
     size: (f64, f64),
 }
 
+#[derive(Copy, Clone)]
+pub struct Inches { amt: f64 }
+
+impl Display for Inches {
+    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
+        self.amt.fmt(f)?;
+        write!(f, "in")
+    }
+}
+
+fn inches(amt: f64) -> Inches { Inches { amt } }
+
 fn xml_tag(w: &mut Vec<u8>, name: &str, attrs: &[(&str, &dyn Display)]) {
     write!(w, "<{}", name);
     for (k, v) in attrs {
@@ -24,7 +37,7 @@ fn xml_open(w: &mut Vec<u8>, name: &str, attrs: &[(&str, &dyn Display)]) {
 }
 
 fn xml_close(w: &mut Vec<u8>, name: &str) {
-    write!(w, "<{}/>", name);
+    write!(w, "</{}>", name);
 }
 
 /// Create a new empty SVG document of the specified width and height
@@ -52,13 +65,15 @@ impl SVG {
     pub fn to_bytes(self) -> Vec<u8> {
         let mut buf = Vec::new();
         let (w, h) = self.size;
-        writeln!(buf, "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>");
+        writeln!(buf, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
         xml_open(
             &mut buf, "svg",
             &[("xmlns", &"http://www.w3.org/2000/svg"),
               ("version", &"1.1"),
-              ("width", &w),
-              ("height", &h),
+              ("width", &inches(w)),
+              ("height", &inches(h)),
+              ("viewBox", &format!("0 0 {} {}", w, h)),
+              ("stroke-width", &"0.0001in"),
             ],
         );
         for elem in self.stuff {
@@ -105,7 +120,7 @@ impl AsSVG for Line {
                 buf, "circle",
                 &[("cx", &x),
                   ("cy", &y),
-                  ("r", &"0.5"),
+                  ("r", &"0.01in"),
                   ("fill", &"black"),
                 ],
             );
@@ -150,7 +165,7 @@ impl Line {
     }
 
     /// Draw a line segment from this point to another point
-    pub fn draw_to(mut self, x: f64, y: f64) -> Line {
+    pub fn to(mut self, x: f64, y: f64) -> Line {
         self.points.push((x, y));
         self
     }