[OSM-dev] Too many decimal places in permalinks

[Robert (Jamie) Munro]

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I noticed the other day that the permalinks on the view tab of
www.openstreetmap.org have way more decimal places than is useful.

Below is a little (untested) patch to site.js that should make the links
much shorter. It rounds the numbers to the (current zoom level)/3
decimal places, which at zoom level 2 (the worst case) is accurate to
less than 3 pixels - zoom level 2 is:
 (1024 pixels wide)/(360 degrees)= 2.8 pixels/degree.

Robert (Jamie) Munro

- --- site.js.orig	2007-10-16 14:32:15.000000000 +0000
+++ site.js	2007-10-16 14:36:11.000000000 +0000
@@ -4,8 +4,9 @@
   node = document.getElementById("viewanchor");
   if (node) {
     var args = getArgs(node.href);
- -    args["lat"] = lat;
- -    args["lon"] = lon;
+    var decimals = Math.pow(10,Math.floor(zoom/3));
+    args["lat"] = Math.round(lat*decimals)/decimals;
+    args["lon"] = Math.round(lon*decimals)/decimals;
     args["zoom"] = zoom;
     args["layers"] = layers;
     node.href = setArgs(node.href, args);
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