From 56623f3b4aa7ba86b08c3710be9b219de9e99f9d Mon Sep 17 00:00:00 2001
From: Dan Vanderkam <danvdk@gmail.com>
Date: Fri, 19 Feb 2010 19:37:12 -0800
Subject: [PATCH] overdrawing with error bars

---
 dygraph-canvas.js | 12 ++++++------
 dygraph.js        | 18 +++++-------------
 2 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/dygraph-canvas.js b/dygraph-canvas.js
index fc47be5..979688d 100644
--- a/dygraph-canvas.js
+++ b/dygraph-canvas.js
@@ -488,7 +488,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
       ctx.save();
       ctx.strokeStyle = color;
       ctx.lineWidth = this.options.strokeWidth;
-      var prevX = -1;
+      var prevX = NaN;
       var prevYs = [-1, -1];
       var count = 0;
       var yscale = this.layout.yscale;
@@ -503,7 +503,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
         count++;
         if (point.name == setName) {
           if (!isOK(point.y)) {
-            prevX = -1;
+            prevX = NaN;
             continue;
           }
           // TODO(danvk): here
@@ -511,7 +511,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
                         point.y + point.errorMinus * yscale ];
           newYs[0] = this.area.h * newYs[0] + this.area.y;
           newYs[1] = this.area.h * newYs[1] + this.area.y;
-          if (prevX >= 0) {
+          if (!isNaN(prevX)) {
             ctx.moveTo(prevX, prevYs[0]);
             ctx.lineTo(point.canvasx, newYs[0]);
             ctx.lineTo(point.canvasx, newYs[1]);
@@ -537,7 +537,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
       ctx.save();
       ctx.strokeStyle = color;
       ctx.lineWidth = this.options.strokeWidth;
-      var prevX = -1;
+      var prevX = NaN;
       var prevYs = [-1, -1];
       var count = 0;
       var yscale = this.layout.yscale;
@@ -552,7 +552,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
         count++;
         if (point.name == setName) {
           if (!isOK(point.y)) {
-            prevX = -1;
+            prevX = NaN;
             continue;
           }
           var pX = 1.0 + this.layout.minyval * this.layout.yscale;
@@ -561,7 +561,7 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
           var newYs = [ point.y, pX ];
           newYs[0] = this.area.h * newYs[0] + this.area.y;
           newYs[1] = this.area.h * newYs[1] + this.area.y;
-          if (prevX >= 0) {
+          if (!isNaN(prevX)) {
             ctx.moveTo(prevX, prevYs[0]);
             ctx.lineTo(point.canvasx, newYs[0]);
             ctx.lineTo(point.canvasx, newYs[1]);
diff --git a/dygraph.js b/dygraph.js
index 6bacea2..c0f4ded 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -309,6 +309,7 @@ Dygraph.prototype.toDomCoords = function(x, y) {
   return ret;
 };
 
+// TODO(danvk): use these functions throughout dygraphs.
 /**
  * Convert from canvas/div coords to data coordinates.
  * Returns a two-element array: [X, Y]
@@ -850,19 +851,10 @@ Dygraph.prototype.drawZoomRect_ = function(startX, endX, prevEndX) {
  */
 Dygraph.prototype.doZoom_ = function(lowX, highX) {
   // Find the earliest and latest dates contained in this canvasx range.
-  var points = this.layout_.points;
-  var minDate = null;
-  var maxDate = null;
-  // Find the nearest [minDate, maxDate] that contains [lowX, highX]
-  for (var i = 0; i < points.length; i++) {
-    var cx = points[i].canvasx;
-    var x = points[i].xval;
-    if (cx < lowX  && (minDate == null || x > minDate)) minDate = x;
-    if (cx > highX && (maxDate == null || x < maxDate)) maxDate = x;
-  }
-  // Use the extremes if either is missing
-  if (minDate == null) minDate = points[0].xval;
-  if (maxDate == null) maxDate = points[points.length-1].xval;
+  var r = this.toDataCoords(lowX, null);
+  var minDate = r[0];
+  r = this.toDataCoords(highX, null);
+  var maxDate = r[0];
 
   this.dateWindow_ = [minDate, maxDate];
   this.drawGraph_(this.rawData_);
-- 
2.7.4