very basic rendering support

src/time.rs

@@ -1,6 +1,7 @@
 use anyhow::bail;
 use std::{
 	fmt::{self, Display, Write as _},
+	ops::{Add, Sub},
 	str::FromStr
 };
 
@@ -82,6 +83,35 @@ pub struct Time {
 	pub micros: u32
 }
 
+impl Add for Time {
+	type Output = Self;
+
+	fn add(self, rhs: Self) -> Self {
+		let mut seconds = self.seconds + rhs.seconds;
+		let mut micros = self.micros + rhs.micros;
+		if micros >= 1_000_000 {
+			seconds += 1;
+			micros -= 1_000_000;
+		}
+		Self { seconds, micros }
+	}
+}
+
+impl Sub for Time {
+	type Output = Self;
+
+	fn sub(mut self, rhs: Self) -> Self {
+		if rhs.micros > self.micros {
+			self.seconds -= 1;
+			self.micros += 1_000_000;
+		}
+		Self {
+			seconds: self.seconds - rhs.seconds,
+			micros: self.micros - rhs.micros
+		}
+	}
+}
+
 impl FromStr for Time {
 	type Err = anyhow::Error;