From 12b879f424bcdd49822f33378c740063370bb4be Mon Sep 17 00:00:00 2001
From: Dan Vanderkam <danvdk@gmail.com>
Date: Sat, 16 Feb 2013 21:36:58 -0500
Subject: [PATCH] Fix issue 176, which involved duplicated x-values in stacked
 graphs

---
 auto_tests/tests/Util.js       | 16 ++++++++++++++++
 auto_tests/tests/error_bars.js | 22 ++++------------------
 auto_tests/tests/stacked.js    | 26 ++++++++++++++++++++++++++
 dygraph-canvas.js              | 10 +++++++++-
 dygraph.js                     | 11 +++++++----
 5 files changed, 62 insertions(+), 23 deletions(-)

diff --git a/auto_tests/tests/Util.js b/auto_tests/tests/Util.js
index 2b308b3..2d652ed 100644
--- a/auto_tests/tests/Util.js
+++ b/auto_tests/tests/Util.js
@@ -79,3 +79,19 @@ Util.makeNumbers = function(ary) {
   }
   return ret;
 };
+
+
+/**
+ * Sample a pixel from the canvas.
+ * Returns an [r, g, b, a] tuple where each values is in [0, 255].
+ */
+Util.samplePixel = function(canvas, x, y) {
+  var ctx = canvas.getContext("2d");  // bypasses Proxy if applied.
+
+  // TODO(danvk): Any performance issues with this?
+  var imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
+
+  var i = 4 * (x + imageData.width * y);
+  var d = imageData.data;
+  return [d[i], d[i+1], d[i+2], d[i+3]];
+};
diff --git a/auto_tests/tests/error_bars.js b/auto_tests/tests/error_bars.js
index 5144363..e57898b 100644
--- a/auto_tests/tests/error_bars.js
+++ b/auto_tests/tests/error_bars.js
@@ -124,22 +124,8 @@ errorBarsTestCase.prototype.testErrorBarsCorrectColors = function() {
   // 249-299: empty (white)
   // TODO(danvk): test the edges of these regions.
 
-  var ctx = g.hidden_.getContext("2d");  // bypass Proxy
-  var imageData = ctx.getImageData(0, 0, 400, 300);
-
-  assertEquals(400, imageData.width);
-  assertEquals(300, imageData.height);
-
-  // returns an (r, g, b, alpha) tuple for the pixel.
-  // values are in [0, 255].
-  var getPixel = function(imageData, x, y) {
-    var i = 4 * (x + imageData.width * y);
-    var d = imageData.data;
-    return [d[i], d[i+1], d[i+2], d[i+3]];
-  };
-
-  assertEquals([0, 0, 255, 38], getPixel(imageData, 200, 75));
-  assertEquals([0, 0, 255, 38], getPixel(imageData, 200, 125));
-  assertEquals([0, 255, 0, 38], getPixel(imageData, 200, 175));
-  assertEquals([0, 255, 0, 38], getPixel(imageData, 200, 225));
+  assertEquals([0, 0, 255, 38], Util.samplePixel(g.hidden_, 200, 75));
+  assertEquals([0, 0, 255, 38], Util.samplePixel(g.hidden_, 200, 125));
+  assertEquals([0, 255, 0, 38], Util.samplePixel(g.hidden_, 200, 175));
+  assertEquals([0, 255, 0, 38], Util.samplePixel(g.hidden_, 200, 225));
 }
diff --git a/auto_tests/tests/stacked.js b/auto_tests/tests/stacked.js
index 706f56f..de41733 100644
--- a/auto_tests/tests/stacked.js
+++ b/auto_tests/tests/stacked.js
@@ -94,3 +94,29 @@ stackedTestCase.prototype.testSelectionValues = function() {
   g.setSelection(0, 'Y2');
   assertEquals("0: Y1: 1 Y2: 1", Util.getLegend());
 };
+
+// Regression test for http://code.google.com/p/dygraphs/issues/detail?id=176
+stackedTestCase.prototype.testDuplicatedXValue = function() {
+  var opts = {
+    stackedGraph: true,
+    fillAlpha: 0.15,
+    colors: ['#00ff00'],
+    width: 400,
+    height: 300
+  };
+  var data = "X,Y1\n" +
+      "0,1\n" +
+      "1,1\n" +
+      "2,1\n" +
+      "2,1\n" +  // duplicate x-value!
+      "3,1\n"
+  ;
+
+  var graph = document.getElementById("graph");
+  g = new Dygraph(graph, data, opts);
+
+  assert(g.yAxisRange()[1] < 2);
+
+  assertEquals([0, 255, 0, 38], Util.samplePixel(g.hidden_, 200, 250));
+  assertEquals([0, 255, 0, 38], Util.samplePixel(g.hidden_, 317, 250));
+}
diff --git a/dygraph-canvas.js b/dygraph-canvas.js
index b647b7a..99ad493 100644
--- a/dygraph-canvas.js
+++ b/dygraph-canvas.js
@@ -731,13 +731,21 @@ DygraphCanvasRenderer._fillPlotter = function(e) {
         'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
     ctx.fillStyle = err_color;
     ctx.beginPath();
-    while(iter.hasNext) {
+    var last_x, is_first = true;
+    while (iter.hasNext) {
       var point = iter.next();
       if (!Dygraph.isOK(point.y)) {
         prevX = NaN;
         continue;
       }
       if (stackedGraph) {
+        if (!is_first && last_x == point.xval) {
+          continue;
+        } else {
+          is_first = false;
+          last_x = point.xval;
+        }
+
         currBaseline = baseline[point.canvasx];
         var lastY;
         if (currBaseline === undefined) {
diff --git a/dygraph.js b/dygraph.js
index ceaac17..1d247ac 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -2279,9 +2279,8 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
                      series[j][1][2]];
       }
     } else if (this.attr_("stackedGraph")) {
-      var l = series.length;
-      var actual_y;
-      for (j = 0; j < l; j++) {
+      var actual_y, last_x;
+      for (j = 0; j < series.length; j++) {
         // If one data set has a NaN, let all subsequent stacked
         // sets inherit the NaN -- only start at 0 for the first set.
         var x = series[j][0];
@@ -2295,7 +2294,11 @@ Dygraph.prototype.gatherDatasets_ = function(rolledSeries, dateWindow) {
           continue;
         }
 
-        cumulative_y[x] += actual_y;
+        if (j === 0 || last_x != x) {
+          cumulative_y[x] += actual_y;
+          // If an x-value is repeated, we ignore the duplicates.
+        }
+        last_x = x;
 
         series[j] = [x, cumulative_y[x]];
 
-- 
2.7.4