X-Git-Url: https://adrianiainlam.tk/git/?a=blobdiff_plain;f=dygraph-tickers.js;h=4909909ae681befb9ded8056c7c78fc6d62a3ee4;hb=5ca15c05928cb263d9f43c8ce2fb3fb67f124ad4;hp=0e18394da0519253a801d0fd012ebcdc1c88f503;hpb=2fd143d3e284124506b00e4afa9e29f9de636543;p=dygraphs.git

diff --git a/dygraph-tickers.js b/dygraph-tickers.js
index 0e18394..4909909 100644
--- a/dygraph-tickers.js
+++ b/dygraph-tickers.js
@@ -348,21 +348,25 @@ Dygraph.getDateAxis = function(start_time, end_time, granularity, opts, dg) {
     // for this granularity.
     var g = spacing / 1000;
     var d = new Date(start_time);
-    d.setMilliseconds(0);
+    Dygraph.setDateSameTZ(d, {ms: 0});
+
     var x;
     if (g <= 60) {  // seconds
-      x = d.getSeconds(); d.setSeconds(x - x % g);
+      x = d.getSeconds();
+      Dygraph.setDateSameTZ(d, {s: x - x % g});
     } else {
-      d.setSeconds(0);
+      Dygraph.setDateSameTZ(d, {s: 0});
       g /= 60;
       if (g <= 60) {  // minutes
-        x = d.getMinutes(); d.setMinutes(x - x % g);
+        x = d.getMinutes();
+        Dygraph.setDateSameTZ(d, {m: x - x % g});
       } else {
-        d.setMinutes(0);
+        Dygraph.setDateSameTZ(d, {m: 0});
         g /= 60;
 
         if (g <= 24) {  // days
-          x = d.getHours(); d.setHours(x - x % g);
+          x = d.getHours();
+          d.setHours(x - x % g);
         } else {
           d.setHours(0);
           g /= 24;
@@ -375,9 +379,38 @@ Dygraph.getDateAxis = function(start_time, end_time, granularity, opts, dg) {
     }
     start_time = d.getTime();
 
+    // For spacings coarser than two-hourly, we want to ignore daylight
+    // savings transitions to get consistent ticks. For finer-grained ticks,
+    // it's essential to show the DST transition in all its messiness.
+    var start_offset_min = new Date(start_time).getTimezoneOffset();
+    var check_dst = (spacing >= Dygraph.SHORT_SPACINGS[Dygraph.TWO_HOURLY]);
+
     for (t = start_time; t <= end_time; t += spacing) {
+      var d = new Date(t);
+
+      // This ensures that we stay on the same hourly "rhythm" across
+      // daylight savings transitions. Without this, the ticks could get off
+      // by an hour. See tests/daylight-savings.html or issue 147.
+      if (check_dst && d.getTimezoneOffset() != start_offset_min) {
+        var delta_min = d.getTimezoneOffset() - start_offset_min;
+        t += delta_min * 60 * 1000;
+        d = new Date(t);
+        start_offset_min = d.getTimezoneOffset();
+
+        // Check whether we've backed into the previous timezone again.
+        // This can happen during a "spring forward" transition. In this case,
+        // it's best to skip this tick altogether (we may be shooting for a
+        // non-existent time like the 2AM that's skipped) and go to the next
+        // one.
+        if (new Date(t + spacing).getTimezoneOffset() != start_offset_min) {
+          t += spacing;
+          d = new Date(t);
+          start_offset_min = d.getTimezoneOffset();
+        }
+      }
+
       ticks.push({ v:t,
-                   label: formatter(new Date(t), granularity, opts, dg)
+                   label: formatter(d, granularity, opts, dg)
                  });
     }
   } else {
@@ -426,11 +459,13 @@ Dygraph.getDateAxis = function(start_time, end_time, granularity, opts, dg) {
 
 // These are set here so that this file can be included after dygraph.js
 // or independently.
-Dygraph.DEFAULT_ATTRS = Dygraph.DEFAULT_ATTRS || {};
-Dygraph.DEFAULT_ATTRS['axes'] = Dygraph.DEFAULT_ATTRS['axes'] || {};
-Dygraph.DEFAULT_ATTRS['axes']['x'] = Dygraph.DEFAULT_ATTRS['axes']['x'] || {};
-Dygraph.DEFAULT_ATTRS['axes']['y'] = Dygraph.DEFAULT_ATTRS['axes']['y'] || {};
-Dygraph.DEFAULT_ATTRS['axes']['y2'] = Dygraph.DEFAULT_ATTRS['axes']['y2'] || {};
-Dygraph.DEFAULT_ATTRS['axes']['x']['ticker'] = Dygraph.dateTicker;
-Dygraph.DEFAULT_ATTRS['axes']['y']['ticker'] = Dygraph.numericTicks;
-Dygraph.DEFAULT_ATTRS['axes']['y2']['ticker'] = Dygraph.numericTicks;
+if (Dygraph &&
+    Dygraph.DEFAULT_ATTRS &&
+    Dygraph.DEFAULT_ATTRS['axes'] &&
+    Dygraph.DEFAULT_ATTRS['axes']['x'] &&
+    Dygraph.DEFAULT_ATTRS['axes']['y'] &&
+    Dygraph.DEFAULT_ATTRS['axes']['y2']) {
+  Dygraph.DEFAULT_ATTRS['axes']['x']['ticker'] = Dygraph.dateTicker;
+  Dygraph.DEFAULT_ATTRS['axes']['y']['ticker'] = Dygraph.numericTicks;
+  Dygraph.DEFAULT_ATTRS['axes']['y2']['ticker'] = Dygraph.numericTicks;
+}