From: Sebastian Harl <sh@tokkee.org>
Date: Fri, 21 Nov 2014 20:36:21 +0000 (+0100)
Subject: graph: Use a date string for x-axis tick markers.
X-Git-Url: https://git.tokkee.org/?p=sysdb%2Fwebui.git;a=commitdiff_plain;h=9b31c619cc89f45286357eb6791005bc1d7621ae

graph: Use a date string for x-axis tick markers.

This is a very basic implementation which is not well suited for all time
ranges but it's good enough to get started.
---

diff --git a/server/graph.go b/server/graph.go
index 054fe8e..11b55b8 100644
--- a/server/graph.go
+++ b/server/graph.go
@@ -70,6 +70,7 @@ func (s *Server) graph(w http.ResponseWriter, req request) {
 		return
 	}
 	p.Add(plotter.NewGrid())
+	p.X.Tick.Marker = dateTicks
 
 	var i int
 	for name, data := range ts.Data {
@@ -102,4 +103,18 @@ func (s *Server) graph(w http.ResponseWriter, req request) {
 	io.Copy(w, &buf)
 }
 
+func dateTicks(min, max float64) []plot.Tick {
+	// TODO: this is surely not the best we can do
+	// but it'll distribute ticks evenly.
+	ticks := plot.DefaultTicks(min, max)
+	for i, t := range ticks {
+		if t.Label == "" {
+			// Skip minor ticks.
+			continue
+		}
+		ticks[i].Label = time.Unix(0, int64(t.Value)).Format(time.RFC822)
+	}
+	return ticks
+}
+
 // vim: set tw=78 sw=4 sw=4 noexpandtab :