From 5d13ef68a27544eff72ea3a2ef3aabdc4c4fd740 Mon Sep 17 00:00:00 2001
From: Neal Nelson <neal@makalumedia.com>
Date: Thu, 17 Jun 2010 16:22:29 +0200
Subject: [PATCH] Fix problems with multiple null values in a row for stepped
 graphs.

---
 dygraph-canvas.js | 2 +-
 tests/steps.html  | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/dygraph-canvas.js b/dygraph-canvas.js
index 3988b19..d5c812e 100644
--- a/dygraph-canvas.js
+++ b/dygraph-canvas.js
@@ -616,7 +616,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
       var point = points[j];
       if (point.name == setName) {
         if (!isOK(point.canvasy)) {
-          if (stepPlot) {
+          if (stepPlot && prevX != null) {
             // Draw a horizontal line to the start of the missing data
             ctx.beginPath();
             ctx.strokeStyle = color;
diff --git a/tests/steps.html b/tests/steps.html
index 81dfbd0..8d77989 100644
--- a/tests/steps.html
+++ b/tests/steps.html
@@ -99,7 +99,7 @@
       "2009/12/01,10,10\n" +
       "2009/12/02,15,11\n" +
       "2009/12/03,,12\n" +
-      "2009/12/04,20,13\n" +
+      "2009/12/04,,13\n" +
       "2009/12/05,15,\n" +
       "2009/12/06,18,15\n" +
       "2009/12/07,12,16\n",
@@ -118,7 +118,7 @@
         [ new Date("2009/12/01"), 10, 10],
         [ new Date("2009/12/02"), 15, 11],
         [ new Date("2009/12/03"), null, 12],
-        [ new Date("2009/12/04"), 20, 13],
+        [ new Date("2009/12/04"), null, 13],
         [ new Date("2009/12/05"), 15, null],
         [ new Date("2009/12/06"), 18, 15],
         [ new Date("2009/12/07"), 12, 16]
-- 
2.7.4