finalizing work on text rotation.

time_util.go

@@ -0,0 +1,20 @@
+package chart
+
+import "time"
+
+var (
+	// Time contains time utility functions.
+	Time = timeUtil{}
+)
+
+type timeUtil struct{}
+
+// TimeToFloat64 returns a float64 representation of a time.
+func (tu timeUtil) ToFloat64(t time.Time) float64 {
+	return float64(t.UnixNano())
+}
+
+// Float64ToTime returns a time from a float64.
+func (tu timeUtil) FromFloat64(tf float64) time.Time {
+	return time.Unix(0, int64(tf))
+}