From 81cb07d653f397d31c063ff3688c5e682f1d6d82 Mon Sep 17 00:00:00 2001
From: Klaus Weidner <klausw@google.com>
Date: Thu, 1 Mar 2012 10:57:01 -0800
Subject: [PATCH] Fix highlighting for zoomed graphs

The code wasn't correctly applying the left boundary offset when converting a row index in the pruned data to/from a row index for the full data set.

Add a getLeftBoundary_ helper method and replace the existing loops that attempted to find the first defined record. Not sure why it saves multiple boundaryIds anyway, the code assumes it can just use the first one.

Also fix an apparently-invalid usage in getSelection().
---
 dygraph.js | 57 +++++++++++++++++++++++++++++----------------------------
 1 file changed, 29 insertions(+), 28 deletions(-)

diff --git a/dygraph.js b/dygraph.js
index 40f1d11..01b10a3 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -1509,7 +1509,7 @@ Dygraph.prototype.eventToDomCoords = function(event) {
  * @private
  */
 Dygraph.prototype.findClosestRow = function(domX) {
-  var minDistX = null;
+  var minDistX = Infinity;
   var idx = -1;
   var points = this.layout_.points;
   var l = points.length;
@@ -1517,7 +1517,7 @@ Dygraph.prototype.findClosestRow = function(domX) {
     var point = points[i];
     if (!Dygraph.isValidPoint(point)) continue;
     var dist = Math.abs(point.canvasx - domX);
-    if (minDistX === null || dist < minDistX) {
+    if (dist < minDistX) {
       minDistX = dist;
       idx = i;
     }
@@ -1538,7 +1538,7 @@ Dygraph.prototype.findClosestRow = function(domX) {
  * @private
  */
 Dygraph.prototype.findClosestPoint = function(domX, domY) {
-  var minDist = null;
+  var minDist = Infinity;
   var idx = -1;
   var points = this.layout_.points;
   var dist, dx, dy, point, closestPoint, closestSeries;
@@ -1551,7 +1551,7 @@ Dygraph.prototype.findClosestPoint = function(domX, domY) {
       dx = point.canvasx - domX;
       dy = point.canvasy - domY;
       dist = dx * dx + dy * dy;
-      if (minDist === null || dist < minDist) {
+      if (dist < minDist) {
         minDist = dist;
         closestPoint = point;
         closestSeries = setIdx;
@@ -1561,7 +1561,7 @@ Dygraph.prototype.findClosestPoint = function(domX, domY) {
   }
   var name = this.layout_.setNames[closestSeries];
   return {
-    row: idx,
+    row: idx + this.getLeftBoundary_(),
     seriesName: name,
     point: closestPoint
   };
@@ -1581,18 +1581,20 @@ Dygraph.prototype.findClosestPoint = function(domX, domY) {
  */
 Dygraph.prototype.findStackedPoint = function(domX, domY) {
   var row = this.findClosestRow(domX);
+  var boundary = this.getLeftBoundary_();
+  var rowIdx = row - boundary;
   var points = this.layout_.points;
   var closestPoint, closestSeries;
   for (var setIdx = 0; setIdx < this.layout_.datasets.length; ++setIdx) {
     var first = this.layout_.setPointsOffsets[setIdx];
     var len = this.layout_.setPointsLengths[setIdx];
-    if (row >= len) continue;
-    var p1 = points[first + row];
+    if (rowIdx >= len) continue;
+    var p1 = points[first + rowIdx];
     if (!Dygraph.isValidPoint(p1)) continue;
     var py = p1.canvasy;
-    if (domX > p1.canvasx && row + 1 < len) {
+    if (domX > p1.canvasx && rowIdx + 1 < len) {
       // interpolate series Y value using next point
-      var p2 = points[first + row + 1];
+      var p2 = points[first + rowIdx + 1];
       if (Dygraph.isValidPoint(p2)) {
         var dx = p2.canvasx - p1.canvasx;
         if (dx > 0) {
@@ -1600,9 +1602,9 @@ Dygraph.prototype.findStackedPoint = function(domX, domY) {
           py += r * (p2.canvasy - p1.canvasy);
         }
       }
-    } else if (domX < p1.canvasx && row > 0) {
+    } else if (domX < p1.canvasx && rowIdx > 0) {
       // interpolate series Y value using previous point
-      var p0 = points[first + row - 1];
+      var p0 = points[first + rowIdx - 1];
       if (Dygraph.isValidPoint(p0)) {
         var dx = p1.canvasx - p0.canvasx;
         if (dx > 0) {
@@ -1663,6 +1665,18 @@ Dygraph.prototype.mouseMove_ = function(event) {
 };
 
 /**
+ * Fetch left offset from first defined boundaryIds record (see bug #236).
+ */
+Dygraph.prototype.getLeftBoundary_ = function() {
+  for (var i = 0; i < this.boundaryIds_.length; i++) {
+    if (this.boundaryIds_[i] !== undefined) {
+      return this.boundaryIds_[i][0];
+    }
+  }
+  return 0;
+};
+
+/**
  * Transforms layout_.points index into data row number.
  * @param int layout_.points index
  * @return int row number, or -1 if none could be found.
@@ -1671,19 +1685,11 @@ Dygraph.prototype.mouseMove_ = function(event) {
 Dygraph.prototype.idxToRow_ = function(idx) {
   if (idx < 0) return -1;
 
-  // make sure that you get the boundaryIds record which is also defined (see bug #236)
-  var boundaryIdx = -1;
-  for (var i = 0; i < this.boundaryIds_.length; i++) {
-    if (this.boundaryIds_[i] !== undefined) {
-      boundaryIdx = i;
-      break;
-    }
-  }
-  if (boundaryIdx < 0) return -1;
+  var boundary = this.getLeftBoundary_();
   for (var setIdx = 0; setIdx < this.layout_.datasets.length; ++setIdx) {
     var set = this.layout_.datasets[setIdx];
     if (idx < set.length) {
-      return this.boundaryIds_[boundaryIdx][0] + idx;
+      return boundary + idx;
     }
     idx -= set.length;
   }
@@ -1977,12 +1983,7 @@ Dygraph.prototype.setSelection = function(row, opt_seriesName) {
   var pos = 0;
 
   if (row !== false) {
-    for (var i = 0; i < this.boundaryIds_.length; i++) {
-      if (this.boundaryIds_[i] !== undefined) {
-        row -= this.boundaryIds_[i][0];
-        break;
-      }
-    }
+    row -= this.getLeftBoundary_();
   }
 
   var changed = false;
@@ -2070,7 +2071,7 @@ Dygraph.prototype.getSelection = function() {
 
   for (var row=0; row<this.layout_.points.length; row++ ) {
     if (this.layout_.points[row].x == this.selPoints_[0].x) {
-      return row + this.boundaryIds_[0][0];
+      return row + this.getLeftBoundary_();
     }
   }
   return -1;
-- 
2.7.4