fix generate-combined
[dygraphs.git] / dygraph-canvas.js
index 1947ccd..0d0f895 100644 (file)
-// Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
-// All Rights Reserved.
+/**
+ * @license
+ * Copyright 2006 Dan Vanderkam (danvdk@gmail.com)
+ * MIT-licensed (http://opensource.org/licenses/MIT)
+ */
 
 /**
- * @fileoverview Based on PlotKit, but modified to meet the needs of dygraphs.
+ * @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
+ * needs of dygraphs.
+ *
  * In particular, support for:
- * - grid overlays 
+ * - grid overlays
  * - error bars
  * - dygraphs attribute system
  */
 
 /**
- * Creates a new DygraphLayout object.
- * @param {Object} options Options for PlotKit.Layout
- * @return {Object} The DygraphLayout object
- */
-DygraphLayout = function(dygraph, options) {
-  this.dygraph_ = dygraph;
-  this.options = {};  // TODO(danvk): remove, use attr_ instead.
-  Dygraph.update(this.options, options ? options : {});
-  this.datasets = new Array();
-  this.annotations = new Array()
-};
-
-DygraphLayout.prototype.attr_ = function(name) {
-  return this.dygraph_.attr_(name);
-};
-
-DygraphLayout.prototype.addDataset = function(setname, set_xy) {
-  this.datasets[setname] = set_xy;
-};
-
-// TODO(danvk): CONTRACT remove
-DygraphLayout.prototype.setAnnotations = function(ann) {
-  // The Dygraph object's annotations aren't parsed. We parse them here and
-  // save a copy.
-  var parse = this.attr_('xValueParser');
-  for (var i = 0; i < ann.length; i++) {
-    var a = {};
-    if (!ann[i].x) {
-      this.dygraph_.error("Annotations must have an 'x' property");
-      return;
-    }
-    if (ann[i].icon &&
-        !(ann[i].hasOwnProperty('iconWidth') &&
-          ann[i].hasOwnProperty('iconHeight'))) {
-      this.dygraph_.error("Must set iconWidth and iconHeight when setting " +
-                          "annotation.icon property");
-      return;
-    }
-    Dygraph.update(a, ann[i]);
-    a.xval = parse(a.x);
-    this.annotations.push(a);
-  }
-};
-
-DygraphLayout.prototype.evaluate = function() {
-  this._evaluateLimits();
-  this._evaluateLineCharts();
-  this._evaluateLineTicks();
-  this._evaluateAnnotations();
-};
-
-DygraphLayout.prototype._evaluateLimits = function() {
-  this.minxval = this.maxxval = null;
-  if (this.options.dateWindow) {
-    this.minxval = this.options.dateWindow[0];
-    this.maxxval = this.options.dateWindow[1];
-  } else {
-    for (var name in this.datasets) {
-      if (!this.datasets.hasOwnProperty(name)) continue;
-      var series = this.datasets[name];
-      var x1 = series[0][0];
-      if (!this.minxval || x1 < this.minxval) this.minxval = x1;
-
-      var x2 = series[series.length - 1][0];
-      if (!this.maxxval || x2 > this.maxxval) this.maxxval = x2;
-    }
-  }
-  this.xrange = this.maxxval - this.minxval;
-  this.xscale = (this.xrange != 0 ? 1/this.xrange : 1.0);
-
-  this.minyval = this.options.yAxis[0];
-  this.maxyval = this.options.yAxis[1];
-  this.yrange = this.maxyval - this.minyval;
-  this.yscale = (this.yrange != 0 ? 1/this.yrange : 1.0);
-};
-
-DygraphLayout.prototype._evaluateLineCharts = function() {
-  // add all the rects
-  this.points = new Array();
-  for (var setName in this.datasets) {
-    if (!this.datasets.hasOwnProperty(setName)) continue;
-
-    var dataset = this.datasets[setName];
-    for (var j = 0; j < dataset.length; j++) {
-      var item = dataset[j];
-      var point = {
-        // TODO(danvk): here
-        x: ((parseFloat(item[0]) - this.minxval) * this.xscale),
-        y: 1.0 - ((parseFloat(item[1]) - this.minyval) * this.yscale),
-        xval: parseFloat(item[0]),
-        yval: parseFloat(item[1]),
-        name: setName
-      };
-
-      // limit the x, y values so they do not overdraw
-      if (point.y <= 0.0) {
-        point.y = 0.0;
-      }
-      if (point.y >= 1.0) {
-        point.y = 1.0;
-      }
-      this.points.push(point);
-    }
-  }
-};
-
-DygraphLayout.prototype._evaluateLineTicks = function() {
-  this.xticks = new Array();
-  for (var i = 0; i < this.options.xTicks.length; i++) {
-    var tick = this.options.xTicks[i];
-    var label = tick.label;
-    var pos = this.xscale * (tick.v - this.minxval);
-    if ((pos >= 0.0) && (pos <= 1.0)) {
-      this.xticks.push([pos, label]);
-    }
-  }
-
-  this.yticks = new Array();
-  for (var i = 0; i < this.options.yTicks.length; i++) {
-    var tick = this.options.yTicks[i];
-    var label = tick.label;
-    var pos = 1.0 - (this.yscale * (tick.v - this.minyval));
-    if ((pos >= 0.0) && (pos <= 1.0)) {
-      this.yticks.push([pos, label]);
-    }
-  }
-};
-
-
-/**
- * Behaves the same way as PlotKit.Layout, but also copies the errors
- * @private
- */
-DygraphLayout.prototype.evaluateWithError = function() {
-  this.evaluate();
-  if (!this.options.errorBars) return;
-
-  // Copy over the error terms
-  var i = 0; // index in this.points
-  for (var setName in this.datasets) {
-    if (!this.datasets.hasOwnProperty(setName)) continue;
-    var j = 0;
-    var dataset = this.datasets[setName];
-    for (var j = 0; j < dataset.length; j++, i++) {
-      var item = dataset[j];
-      var xv = parseFloat(item[0]);
-      var yv = parseFloat(item[1]);
-
-      if (xv == this.points[i].xval &&
-          yv == this.points[i].yval) {
-        this.points[i].errorMinus = parseFloat(item[2]);
-        this.points[i].errorPlus = parseFloat(item[3]);
-      }
-    }
-  }
-};
-
-DygraphLayout.prototype._evaluateAnnotations = function() {
-  // Add the annotations to the point to which they belong.
-  // Make a map from (setName, xval) to annotation for quick lookups.
-  var annotations = {};
-  for (var i = 0; i < this.annotations.length; i++) {
-    var a = this.annotations[i];
-    annotations[a.xval + "," + a.series] = a;
-  }
-
-  this.annotated_points = [];
-  for (var i = 0; i < this.points.length; i++) {
-    var p = this.points[i];
-    var k = p.xval + "," + p.name;
-    if (k in annotations) {
-      p.annotation = annotations[k];
-      this.annotated_points.push(p);
-    }
-  }
-};
-
-/**
- * Convenience function to remove all the data sets from a graph
+ * The DygraphCanvasRenderer class does the actual rendering of the chart onto
+ * a canvas. It's based on PlotKit.CanvasRenderer.
+ * @param {Object} element The canvas to attach to
+ * @param {Object} elementContext The 2d context of the canvas (injected so it
+ * can be mocked for testing.)
+ * @param {Layout} layout The DygraphLayout object for this graph.
+ * @constructor
  */
-DygraphLayout.prototype.removeAllDatasets = function() {
-  delete this.datasets;
-  this.datasets = new Array();
-};
 
-/**
- * Change the values of various layout options
- * @param {Object} new_options an associative array of new properties
- */
-DygraphLayout.prototype.updateOptions = function(new_options) {
-  Dygraph.update(this.options, new_options ? new_options : {});
-};
+/*jshint globalstrict: true */
+/*global Dygraph:false,RGBColor:false */
+"use strict";
 
-// Subclass PlotKit.CanvasRenderer to add:
-// 1. X/Y grid overlay
-// 2. Ability to draw error bars (if required)
 
 /**
- * Sets some PlotKit.CanvasRenderer options
- * @param {Object} element The canvas to attach to
- * @param {Layout} layout The DygraphLayout object for this graph.
- * @param {Object} options Options to pass on to CanvasRenderer
+ * @constructor
+ *
+ * This gets called when there are "new points" to chart. This is generally the
+ * case when the underlying data being charted has changed. It is _not_ called
+ * in the common case that the user has zoomed or is panning the view.
+ *
+ * The chart canvas has already been created by the Dygraph object. The
+ * renderer simply gets a drawing context.
+ *
+ * @param {Dyraph} dygraph The chart to which this renderer belongs.
+ * @param {Canvas} element The &lt;canvas&gt; DOM element on which to draw.
+ * @param {CanvasRenderingContext2D} elementContext The drawing context.
+ * @param {DygraphLayout} layout The chart's DygraphLayout object.
+ *
+ * TODO(danvk): remove the elementContext property.
  */
-DygraphCanvasRenderer = function(dygraph, element, layout, options) {
-  // TODO(danvk): remove options, just use dygraph.attr_.
+var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
   this.dygraph_ = dygraph;
 
-  // default options
-  this.options = {
-    "strokeWidth": 0.5,
-    "drawXAxis": true,
-    "drawYAxis": true,
-    "axisLineColor": "black",
-    "axisLineWidth": 0.5,
-    "axisTickSize": 3,
-    "axisLabelColor": "black",
-    "axisLabelFont": "Arial",
-    "axisLabelFontSize": 9,
-    "axisLabelWidth": 50,
-    "drawYGrid": true,
-    "drawXGrid": true,
-    "gridLineColor": "rgb(128,128,128)",
-    "fillAlpha": 0.15,
-    "underlayCallback": null
-  };
-  Dygraph.update(this.options, options);
-
   this.layout = layout;
   this.element = element;
+  this.elementContext = elementContext;
   this.container = this.element.parentNode;
 
   this.height = this.element.height;
@@ -249,23 +62,43 @@ DygraphCanvasRenderer = function(dygraph, element, layout, options) {
       throw "Canvas is not supported.";
 
   // internal state
-  this.xlabels = new Array();
-  this.ylabels = new Array();
-  this.annotations = new Array();
-
-  this.area = {
-    x: this.options.yAxisLabelWidth + 2 * this.options.axisTickSize,
-    y: 0
-  };
-  this.area.w = this.width - this.area.x - this.options.rightGap;
-  this.area.h = this.height - this.options.axisLabelFontSize -
-                2 * this.options.axisTickSize;
-
+  this.area = layout.getPlotArea();
   this.container.style.position = "relative";
   this.container.style.width = this.width + "px";
+
+  // Set up a clipping area for the canvas (and the interaction canvas).
+  // This ensures that we don't overdraw.
+  if (this.dygraph_.isUsingExcanvas_) {
+    this._createIEClipArea();
+  } else {
+    // on Android 3 and 4, setting a clipping area on a canvas prevents it from
+    // displaying anything.
+    if (!Dygraph.isAndroid()) {
+      var ctx = this.dygraph_.canvas_ctx_;
+      ctx.beginPath();
+      ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
+      ctx.clip();
+
+      ctx = this.dygraph_.hidden_ctx_;
+      ctx.beginPath();
+      ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
+      ctx.clip();
+    }
+  }
+};
+
+DygraphCanvasRenderer.prototype.attr_ = function(x) {
+  return this.dygraph_.attr_(x);
 };
 
+/**
+ * Clears out all chart content and DOM elements.
+ * This is called immediately before render() on every frame, including
+ * during zooms and pans.
+ * @private
+ */
 DygraphCanvasRenderer.prototype.clear = function() {
+  var context;
   if (this.isIE) {
     // VML takes a while to start up, so we just poll every this.IEDelay
     try {
@@ -273,45 +106,33 @@ DygraphCanvasRenderer.prototype.clear = function() {
         this.clearDelay.cancel();
         this.clearDelay = null;
       }
-      var context = this.element.getContext("2d");
+      context = this.elementContext;
     }
     catch (e) {
       // TODO(danvk): this is broken, since MochiKit.Async is gone.
-      this.clearDelay = MochiKit.Async.wait(this.IEDelay);
-      this.clearDelay.addCallback(bind(this.clear, this));
+      // this.clearDelay = MochiKit.Async.wait(this.IEDelay);
+      // this.clearDelay.addCallback(bind(this.clear, this));
       return;
     }
   }
 
-  var context = this.element.getContext("2d");
+  context = this.elementContext;
   context.clearRect(0, 0, this.width, this.height);
-
-  for (var i = 0; i < this.xlabels.length; i++) {
-    var el = this.xlabels[i];
-    el.parentNode.removeChild(el);
-  }
-  for (var i = 0; i < this.ylabels.length; i++) {
-    var el = this.ylabels[i];
-    el.parentNode.removeChild(el);
-  }
-  for (var i = 0; i < this.annotations.length; i++) {
-    var el = this.annotations[i];
-    el.parentNode.removeChild(el);
-  }
-  this.xlabels = new Array();
-  this.ylabels = new Array();
-  this.annotations = new Array();
 };
 
-
+/**
+ * Checks whether the browser supports the &lt;canvas&gt; tag.
+ * @private
+ */
 DygraphCanvasRenderer.isSupported = function(canvasName) {
   var canvas = null;
   try {
-    if (typeof(canvasName) == 'undefined' || canvasName == null)
+    if (typeof(canvasName) == 'undefined' || canvasName === null) {
       canvas = document.createElement("canvas");
-    else
+    } else {
       canvas = canvasName;
-    var context = canvas.getContext("2d");
+    }
+    canvas.getContext("2d");
   }
   catch (e) {
     var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
@@ -324,472 +145,472 @@ DygraphCanvasRenderer.isSupported = function(canvasName) {
 };
 
 /**
- * Draw an X/Y grid on top of the existing plot
+ * This method is responsible for drawing everything on the chart, including
+ * lines, error bars, fills and axes.
+ * It is called immediately after clear() on every frame, including during pans
+ * and zooms.
+ * @private
  */
 DygraphCanvasRenderer.prototype.render = function() {
-  // Draw the new X/Y grid
-  var ctx = this.element.getContext("2d");
+  this._renderLineChart();
+};
 
-  if (this.options.underlayCallback) {
-    this.options.underlayCallback(ctx, this.area, this.layout, this.dygraph_);
+DygraphCanvasRenderer.prototype._createIEClipArea = function() {
+  var className = 'dygraph-clip-div';
+  var graphDiv = this.dygraph_.graphDiv;
+
+  // Remove old clip divs.
+  for (var i = graphDiv.childNodes.length-1; i >= 0; i--) {
+    if (graphDiv.childNodes[i].className == className) {
+      graphDiv.removeChild(graphDiv.childNodes[i]);
+    }
   }
 
-  if (this.options.drawYGrid) {
-    var ticks = this.layout.yticks;
-    ctx.save();
-    ctx.strokeStyle = this.options.gridLineColor;
-    ctx.lineWidth = this.options.axisLineWidth;
-    for (var i = 0; i < ticks.length; i++) {
-      var x = this.area.x;
-      var y = this.area.y + ticks[i][0] * this.area.h;
-      ctx.beginPath();
-      ctx.moveTo(x, y);
-      ctx.lineTo(x + this.area.w, y);
-      ctx.closePath();
-      ctx.stroke();
+  // Determine background color to give clip divs.
+  var backgroundColor = document.bgColor;
+  var element = this.dygraph_.graphDiv;
+  while (element != document) {
+    var bgcolor = element.currentStyle.backgroundColor;
+    if (bgcolor && bgcolor != 'transparent') {
+      backgroundColor = bgcolor;
+      break;
     }
+    element = element.parentNode;
   }
 
-  if (this.options.drawXGrid) {
-    var ticks = this.layout.xticks;
-    ctx.save();
-    ctx.strokeStyle = this.options.gridLineColor;
-    ctx.lineWidth = this.options.axisLineWidth;
-    for (var i=0; i<ticks.length; i++) {
-      var x = this.area.x + ticks[i][0] * this.area.w;
-      var y = this.area.y + this.area.h;
-      ctx.beginPath();
-      ctx.moveTo(x, y);
-      ctx.lineTo(x, this.area.y);
-      ctx.closePath();
-      ctx.stroke();
+  function createClipDiv(area) {
+    if (area.w === 0 || area.h === 0) {
+      return;
     }
+    var elem = document.createElement('div');
+    elem.className = className;
+    elem.style.backgroundColor = backgroundColor;
+    elem.style.position = 'absolute';
+    elem.style.left = area.x + 'px';
+    elem.style.top = area.y + 'px';
+    elem.style.width = area.w + 'px';
+    elem.style.height = area.h + 'px';
+    graphDiv.appendChild(elem);
   }
 
-  // Do the ordinary rendering, as before
-  this._renderLineChart();
-  this._renderAxis();
-  this._renderAnnotations();
+  var plotArea = this.area;
+  // Left side
+  createClipDiv({
+    x:0, y:0,
+    w:plotArea.x,
+    h:this.height
+  });
+
+  // Top
+  createClipDiv({
+    x: plotArea.x, y: 0,
+    w: this.width - plotArea.x,
+    h: plotArea.y
+  });
+
+  // Right side
+  createClipDiv({
+    x: plotArea.x + plotArea.w, y: 0,
+    w: this.width-plotArea.x - plotArea.w,
+    h: this.height
+  });
+
+  // Bottom
+  createClipDiv({
+    x: plotArea.x,
+    y: plotArea.y + plotArea.h,
+    w: this.width - plotArea.x,
+    h: this.height - plotArea.h - plotArea.y
+  });
 };
 
 
-DygraphCanvasRenderer.prototype._renderAxis = function() {
-  if (!this.options.drawXAxis && !this.options.drawYAxis)
-    return;
-
-  var context = this.element.getContext("2d");
-
-  var labelStyle = {
-    "position": "absolute",
-    "fontSize": this.options.axisLabelFontSize + "px",
-    "zIndex": 10,
-    "color": this.options.axisLabelColor,
-    "width": this.options.axisLabelWidth + "px",
-    "overflow": "hidden"
-  };
-  var makeDiv = function(txt) {
-    var div = document.createElement("div");
-    for (var name in labelStyle) {
-      if (labelStyle.hasOwnProperty(name)) {
-        div.style[name] = labelStyle[name];
-      }
-    }
-    div.appendChild(document.createTextNode(txt));
-    return div;
-  };
-
-  // axis lines
-  context.save();
-  context.strokeStyle = this.options.axisLineColor;
-  context.lineWidth = this.options.axisLineWidth;
-
-  if (this.options.drawYAxis) {
-    if (this.layout.yticks && this.layout.yticks.length > 0) {
-      for (var i = 0; i < this.layout.yticks.length; i++) {
-        var tick = this.layout.yticks[i];
-        if (typeof(tick) == "function") return;
-        var x = this.area.x;
-        var y = this.area.y + tick[0] * this.area.h;
-        context.beginPath();
-        context.moveTo(x, y);
-        context.lineTo(x - this.options.axisTickSize, y);
-        context.closePath();
-        context.stroke();
-
-        var label = makeDiv(tick[1]);
-        var top = (y - this.options.axisLabelFontSize / 2);
-        if (top < 0) top = 0;
-
-        if (top + this.options.axisLabelFontSize + 3 > this.height) {
-          label.style.bottom = "0px";
-        } else {
-          label.style.top = top + "px";
-        }
-        label.style.left = "0px";
-        label.style.textAlign = "right";
-        label.style.width = this.options.yAxisLabelWidth + "px";
-        this.container.appendChild(label);
-        this.ylabels.push(label);
-      }
+/**
+ * Returns a predicate to be used with an iterator, which will
+ * iterate over points appropriately, depending on whether
+ * connectSeparatedPoints is true. When it's false, the predicate will
+ * skip over points with missing yVals.
+ */
+DygraphCanvasRenderer._getIteratorPredicate = function(connectSeparatedPoints) {
+  return connectSeparatedPoints
+      ? DygraphCanvasRenderer._predicateThatSkipsEmptyPoints
+      : null;
+}
 
-      // The lowest tick on the y-axis often overlaps with the leftmost
-      // tick on the x-axis. Shift the bottom tick up a little bit to
-      // compensate if necessary.
-      var bottomTick = this.ylabels[0];
-      var fontSize = this.options.axisLabelFontSize;
-      var bottom = parseInt(bottomTick.style.top) + fontSize;
-      if (bottom > this.height - fontSize) {
-        bottomTick.style.top = (parseInt(bottomTick.style.top) -
-            fontSize / 2) + "px";
-      }
-    }
+DygraphCanvasRenderer._predicateThatSkipsEmptyPoints =
+  function(array, idx) { return array[idx].yval !== null; }
 
-    context.beginPath();
-    context.moveTo(this.area.x, this.area.y);
-    context.lineTo(this.area.x, this.area.y + this.area.h);
-    context.closePath();
-    context.stroke();
+/**
+ *
+ * @private
+ */
+DygraphCanvasRenderer.prototype._drawStyledLine = function(
+    ctx, i, setName, color, strokeWidth, strokePattern, drawPoints,
+    drawPointCallback, pointSize) {
+  // TODO(konigsberg): Compute attributes outside this method call.
+  var stepPlot = this.attr_("stepPlot");
+  var firstIndexInSet = this.layout.setPointsOffsets[i];
+  var setLength = this.layout.setPointsLengths[i];
+  var points = this.layout.points;
+  if (!Dygraph.isArrayLike(strokePattern)) {
+    strokePattern = null;
   }
+  var drawGapPoints = this.dygraph_.attr_('drawGapEdgePoints', setName);
 
-  if (this.options.drawXAxis) {
-    if (this.layout.xticks) {
-      for (var i = 0; i < this.layout.xticks.length; i++) {
-        var tick = this.layout.xticks[i];
-        if (typeof(dataset) == "function") return;
-
-        var x = this.area.x + tick[0] * this.area.w;
-        var y = this.area.y + this.area.h;
-        context.beginPath();
-        context.moveTo(x, y);
-        context.lineTo(x, y + this.options.axisTickSize);
-        context.closePath();
-        context.stroke();
-
-        var label = makeDiv(tick[1]);
-        label.style.textAlign = "center";
-        label.style.bottom = "0px";
-
-        var left = (x - this.options.axisLabelWidth/2);
-        if (left + this.options.axisLabelWidth > this.width) {
-          left = this.width - this.options.xAxisLabelWidth;
-          label.style.textAlign = "right";
-        }
-        if (left < 0) {
-          left = 0;
-          label.style.textAlign = "left";
-        }
+  var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
+      DygraphCanvasRenderer._getIteratorPredicate(
+          this.attr_("connectSeparatedPoints")));
 
-        label.style.left = left + "px";
-        label.style.width = this.options.xAxisLabelWidth + "px";
-        this.container.appendChild(label);
-        this.xlabels.push(label);
-      }
-    }
+  var stroking = strokePattern && (strokePattern.length >= 2);
 
-    context.beginPath();
-    context.moveTo(this.area.x, this.area.y + this.area.h);
-    context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
-    context.closePath();
-    context.stroke();
+  ctx.save();
+  if (stroking) {
+    ctx.installPattern(strokePattern);
   }
 
-  context.restore();
-};
-
+  var pointsOnLine = this._drawSeries(ctx, iter, strokeWidth, pointSize, drawPoints, drawGapPoints, stepPlot, color);
+  this._drawPointsOnLine(ctx, pointsOnLine, drawPointCallback, setName, color, pointSize);
 
-DygraphCanvasRenderer.prototype._renderAnnotations = function() {
-  var annotationStyle = {
-    "position": "absolute",
-    "fontSize": this.options.axisLabelFontSize + "px",
-    "zIndex": 10,
-    "overflow": "hidden",
-  };
-
-  var bindEvt = function(eventName, classEventName, p, self) {
-    return function(e) {
-      var a = p.annotation;
-      if (a.hasOwnProperty(eventName)) {
-        a[eventName](a, p, self.dygraph_, e);
-      } else if (self.dygraph_.attr_(classEventName)) {
-        self.dygraph_.attr_(classEventName)(a, p, self.dygraph_,e );
-      }
-    };
+  if (stroking) {
+    ctx.uninstallPattern();
   }
 
-  // Get a list of point with annotations.
-  var points = this.layout.annotated_points;
-  for (var i = 0; i < points.length; i++) {
-    var p = points[i];
-    var a = p.annotation;
-    var tick_height = 6;
-    if (a.hasOwnProperty("tickHeight")) {
-      tick_height = a.tickHeight;
-    }
+  ctx.restore();
+};
 
-    var div = document.createElement("div");
-    for (var name in annotationStyle) {
-      if (annotationStyle.hasOwnProperty(name)) {
-        div.style[name] = annotationStyle[name];
+DygraphCanvasRenderer.prototype._drawPointsOnLine = function(ctx, pointsOnLine, drawPointCallback, setName, color, pointSize) {
+  for (var idx = 0; idx < pointsOnLine.length; idx++) {
+    var cb = pointsOnLine[idx];
+    ctx.save();
+    drawPointCallback(
+        this.dygraph_, setName, ctx, cb[0], cb[1], color, pointSize);
+    ctx.restore();
+  }
+}
+
+DygraphCanvasRenderer.prototype._drawSeries = function(
+    ctx, iter, strokeWidth, pointSize, drawPoints, drawGapPoints,
+    stepPlot, color) {
+
+  var prevCanvasX = null;
+  var prevCanvasY = null;
+  var nextCanvasY = null;
+  var isIsolated; // true if this point is isolated (no line segments)
+  var point; // the point being processed in the while loop
+  var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
+  var first = true; // the first cycle through the while loop
+
+  ctx.beginPath();
+  ctx.strokeStyle = color;
+  ctx.lineWidth = strokeWidth;
+
+  while (iter.hasNext) {
+    point = iter.next();
+    if (point.canvasy === null || point.canvasy != point.canvasy) {
+      if (stepPlot && prevCanvasX !== null) {
+        // Draw a horizontal line to the start of the missing data
+        ctx.moveTo(prevX, prevY);
+        ctx.lineTo(point.canvasx, prevY);
       }
+      prevCanvasX = prevCanvasY = null;
+    } else {
+      nextCanvasY = iter.hasNext ? iter.peek.canvasy : null;
+      // TODO: we calculate isNullOrNaN for this point, and the next, and then,
+      // when we iterate, test for isNullOrNaN again. Why bother?
+      var isNextCanvasYNullOrNaN = nextCanvasY === null || nextCanvasY != nextCanvasY;
+      isIsolated = (!prevCanvasX && isNextCanvasYNullOrNaN);
+      if (drawGapPoints) {
+        // Also consider a point to be "isolated" if it's adjacent to a
+        // null point, excluding the graph edges.
+        if ((!first && !prevCanvasX) ||
+            (iter.hasNext && isNextCanvasYNullOrNaN)) {
+          isIsolated = true;
+        }
+      }
+      if (prevCanvasX !== null) {
+        if (strokeWidth) {
+          if (stepPlot) {
+            ctx.moveTo(prevCanvasX, prevCanvasY);
+            ctx.lineTo(point.canvasx, prevCanvasY);
+            prevCanvasX = point.canvasx;
+          }
+          ctx.moveTo(prevCanvasX, prevCanvasY);
+          ctx.lineTo(point.canvasx, point.canvasy);
+        }
+      }
+      if (drawPoints || isIsolated) {
+        pointsOnLine.push([point.canvasx, point.canvasy]);
+      }
+      prevCanvasX = point.canvasx;
+      prevCanvasY = point.canvasy;
     }
-    if (!a.hasOwnProperty('icon')) {
-      div.className = "dygraphDefaultAnnotation";
-    }
-    if (a.hasOwnProperty('cssClass')) {
-      div.className += " " + a.cssClass;
-    }
-
-    var width = a.hasOwnProperty('height') ? a.height : 20;
-    var height = a.hasOwnProperty('width') ? a.width : 16;
-    if (a.hasOwnProperty('icon')) {
-      var img = document.createElement("img");
-      img.src = a.icon;
-      img.width = width = a.iconWidth;
-      img.height = height = a.iconHeight;
-      div.appendChild(img);
-    } else if (p.annotation.hasOwnProperty('shortText')) {
-      div.appendChild(document.createTextNode(p.annotation.shortText));
-    }
-    div.style.left = (p.canvasx - width / 2) + "px";
-    div.style.top = (p.canvasy - height - tick_height) + "px";
-    div.style.width = width + "px";
-    div.style.height = height + "px";
-    div.title = p.annotation.text;
-    div.style.color = this.colors[p.name];
-    div.style.borderColor = this.colors[p.name];
-
-    Dygraph.addEvent(div, 'click',
-        bindEvt('clickHandler', 'annotationClickHandler', p, this));
-    Dygraph.addEvent(div, 'mouseover',
-        bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
-    Dygraph.addEvent(div, 'mouseout',
-        bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
-    Dygraph.addEvent(div, 'dblclick',
-        bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
-
-    this.container.appendChild(div);
-    this.annotations.push(div);
-
-    var ctx = this.element.getContext("2d");
-    ctx.strokeStyle = this.colors[p.name];
-    ctx.beginPath();
-    ctx.moveTo(p.canvasx, p.canvasy);
-    ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
-    ctx.closePath();
-    ctx.stroke();
+    first = false;
   }
+  ctx.stroke();
+  return pointsOnLine;
 };
 
+DygraphCanvasRenderer.prototype._drawLine = function(ctx, i) {
+  var setNames = this.layout.setNames;
+  var setName = setNames[i];
+
+  var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
+  var borderWidth = this.dygraph_.attr_("strokeBorderWidth", setName);
+  var drawPointCallback = this.dygraph_.attr_("drawPointCallback", setName) ||
+      Dygraph.Circles.DEFAULT;
+
+  if (borderWidth && strokeWidth) {
+    this._drawStyledLine(ctx, i, setName,
+        this.dygraph_.attr_("strokeBorderColor", setName),
+        strokeWidth + 2 * borderWidth,
+        this.dygraph_.attr_("strokePattern", setName),
+        this.dygraph_.attr_("drawPoints", setName),
+        drawPointCallback,
+        this.dygraph_.attr_("pointSize", setName));
+  }
+
+  this._drawStyledLine(ctx, i, setName,
+      this.colors[setName],
+      strokeWidth,
+      this.dygraph_.attr_("strokePattern", setName),
+      this.dygraph_.attr_("drawPoints", setName),
+      drawPointCallback,
+      this.dygraph_.attr_("pointSize", setName));
+};
 
 /**
- * Overrides the CanvasRenderer method to draw error bars
+ * Actually draw the lines chart, including error bars.
+ * @private
  */
 DygraphCanvasRenderer.prototype._renderLineChart = function() {
-  var context = this.element.getContext("2d");
-  var colorCount = this.options.colorScheme.length;
-  var colorScheme = this.options.colorScheme;
-  var fillAlpha = this.options.fillAlpha;
-  var errorBars = this.layout.options.errorBars;
-  var fillGraph = this.layout.options.fillGraph;
-  var stackedGraph = this.layout.options.stackedGraph;
-  var stepPlot = this.layout.options.stepPlot;
-
-  var setNames = [];
-  for (var name in this.layout.datasets) {
-    if (this.layout.datasets.hasOwnProperty(name)) {
-      setNames.push(name);
-    }
-  }
+  var ctx = this.elementContext;
+  var errorBars = this.attr_("errorBars") || this.attr_("customBars");
+  var fillGraph = this.attr_("fillGraph");
+  var i;
+
+  var setNames = this.layout.setNames;
   var setCount = setNames.length;
 
-  this.colors = {}
-  for (var i = 0; i < setCount; i++) {
-    this.colors[setNames[i]] = colorScheme[i % colorCount];
-  }
+  this.colors = this.dygraph_.colorsMap_;
 
   // Update Points
   // TODO(danvk): here
-  for (var i = 0; i < this.layout.points.length; i++) {
-    var point = this.layout.points[i];
+  //
+  // TODO(bhs): this loop is a hot-spot for high-point-count charts. These
+  // transformations can be pushed into the canvas via linear transformation
+  // matrices.
+  var points = this.layout.points;
+  for (i = points.length; i--;) {
+    var point = points[i];
     point.canvasx = this.area.w * point.x + this.area.x;
     point.canvasy = this.area.h * point.y + this.area.y;
   }
 
-  // create paths
-  var isOK = function(x) { return x && !isNaN(x); };
-
-  var ctx = context;
+  // Draw any "fills", i.e. error bars or the filled area under a series.
+  // These must all be drawn before any lines, so that the main lines of a
+  // series are drawn on top.
   if (errorBars) {
     if (fillGraph) {
       this.dygraph_.warn("Can't use fillGraph option with error bars");
     }
 
-    for (var i = 0; i < setCount; i++) {
-      var setName = setNames[i];
-      var color = this.colors[setName];
-
-      // setup graphics context
-      ctx.save();
-      var prevX = NaN;
-      var prevY = NaN;
-      var prevYs = [-1, -1];
-      var yscale = this.layout.yscale;
-      // should be same color as the lines but only 15% opaque.
-      var rgb = new RGBColor(color);
-      var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
-                            fillAlpha + ')';
-      ctx.fillStyle = err_color;
-      ctx.beginPath();
-      for (var j = 0; j < this.layout.points.length; j++) {
-        var point = this.layout.points[j];
-        if (point.name == setName) {
-          if (!isOK(point.y)) {
-            prevX = NaN;
-            continue;
-          }
+    ctx.save();
+    this.drawErrorBars_(points);
+    ctx.restore();
+  } else if (fillGraph) {
+    ctx.save();
+    this.drawFillBars_(points);
+    ctx.restore();
+  }
+
+  // Drawing the lines.
+  for (i = 0; i < setCount; i += 1) {
+    this._drawLine(ctx, i);
+  }
+};
+
+/**
+ * Draws the shaded error bars/confidence intervals for each series.
+ * This happens before the center lines are drawn, since the center lines
+ * need to be drawn on top of the error bars for all series.
+ *
+ * @private
+ */
+DygraphCanvasRenderer.prototype.drawErrorBars_ = function(points) {
+  var ctx = this.elementContext;
+  var setNames = this.layout.setNames;
+  var setCount = setNames.length;
+  var fillAlpha = this.attr_('fillAlpha');
+  var stepPlot = this.attr_('stepPlot');
 
-          // TODO(danvk): here
+  var newYs;
+
+  for (var i = 0; i < setCount; i++) {
+    var setName = setNames[i];
+    var axis = this.dygraph_.axisPropertiesForSeries(setName);
+    var color = this.colors[setName];
+
+    var firstIndexInSet = this.layout.setPointsOffsets[i];
+    var setLength = this.layout.setPointsLengths[i];
+
+    var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
+        DygraphCanvasRenderer._getIteratorPredicate(
+            this.attr_("connectSeparatedPoints")));
+
+    // setup graphics context
+    var prevX = NaN;
+    var prevY = NaN;
+    var prevYs = [-1, -1];
+    var yscale = axis.yscale;
+    // should be same color as the lines but only 15% opaque.
+    var rgb = new RGBColor(color);
+    var err_color =
+        'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
+    ctx.fillStyle = err_color;
+    ctx.beginPath();
+    while (iter.hasNext) {
+      var point = iter.next();
+      if (point.name == setName) { // TODO(klausw): this is always true
+        if (!Dygraph.isOK(point.y)) {
+          prevX = NaN;
+          continue;
+        }
+
+        // TODO(danvk): here
+        if (stepPlot) {
+          newYs = [ point.y_bottom, point.y_top ];
+          prevY = point.y;
+        } else {
+          newYs = [ point.y_bottom, point.y_top ];
+        }
+        newYs[0] = this.area.h * newYs[0] + this.area.y;
+        newYs[1] = this.area.h * newYs[1] + this.area.y;
+        if (!isNaN(prevX)) {
           if (stepPlot) {
-            var newYs = [ prevY - point.errorPlus * yscale,
-                          prevY + point.errorMinus * yscale ];
-            prevY = point.y;
+            ctx.moveTo(prevX, newYs[0]);
           } else {
-            var newYs = [ point.y - point.errorPlus * yscale,
-                          point.y + point.errorMinus * yscale ];
+            ctx.moveTo(prevX, prevYs[0]);
           }
-          newYs[0] = this.area.h * newYs[0] + this.area.y;
-          newYs[1] = this.area.h * newYs[1] + this.area.y;
-          if (!isNaN(prevX)) {
-            if (stepPlot) {
-              ctx.moveTo(prevX, newYs[0]);
-            } else {
-              ctx.moveTo(prevX, prevYs[0]);
-            }
-            ctx.lineTo(point.canvasx, newYs[0]);
-            ctx.lineTo(point.canvasx, newYs[1]);
-            if (stepPlot) {
-              ctx.lineTo(prevX, newYs[1]);
-            } else {
-              ctx.lineTo(prevX, prevYs[1]);
-            }
-            ctx.closePath();
+          ctx.lineTo(point.canvasx, newYs[0]);
+          ctx.lineTo(point.canvasx, newYs[1]);
+          if (stepPlot) {
+            ctx.lineTo(prevX, newYs[1]);
+          } else {
+            ctx.lineTo(prevX, prevYs[1]);
           }
-          prevYs = newYs;
-          prevX = point.canvasx;
+          ctx.closePath();
         }
+        prevYs = newYs;
+        prevX = point.canvasx;
       }
-      ctx.fill();
     }
-  } else if (fillGraph) {
-    var axisY = 1.0 + this.layout.minyval * this.layout.yscale;
+    ctx.fill();
+  }
+};
+
+/**
+ * Draws the shaded regions when "fillGraph" is set. Not to be confused with
+ * error bars.
+ *
+ * @private
+ */
+DygraphCanvasRenderer.prototype.drawFillBars_ = function(points) {
+  var ctx = this.elementContext;
+  var setNames = this.layout.setNames;
+  var setCount = setNames.length;
+  var fillAlpha = this.attr_('fillAlpha');
+  var stepPlot = this.attr_('stepPlot');
+  var stackedGraph = this.attr_("stackedGraph");
+
+  var baseline = {};  // for stacked graphs: baseline for filling
+  var currBaseline;
+
+  // process sets in reverse order (needed for stacked graphs)
+  for (var i = setCount - 1; i >= 0; i--) {
+    var setName = setNames[i];
+    var color = this.colors[setName];
+    var axis = this.dygraph_.axisPropertiesForSeries(setName);
+    var axisY = 1.0 + axis.minyval * axis.yscale;
     if (axisY < 0.0) axisY = 0.0;
     else if (axisY > 1.0) axisY = 1.0;
     axisY = this.area.h * axisY + this.area.y;
+    var firstIndexInSet = this.layout.setPointsOffsets[i];
+    var setLength = this.layout.setPointsLengths[i];
 
-    var baseline = []  // for stacked graphs: baseline for filling
-
-    // process sets in reverse order (needed for stacked graphs)
-    for (var i = setCount - 1; i >= 0; i--) {
-      var setName = setNames[i];
-      var color = this.colors[setName];
-
-      // setup graphics context
-      ctx.save();
-      var prevX = NaN;
-      var prevYs = [-1, -1];
-      var yscale = this.layout.yscale;
-      // should be same color as the lines but only 15% opaque.
-      var rgb = new RGBColor(color);
-      var err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
-                            fillAlpha + ')';
-      ctx.fillStyle = err_color;
-      ctx.beginPath();
-      for (var j = 0; j < this.layout.points.length; j++) {
-        var point = this.layout.points[j];
-        if (point.name == setName) {
-          if (!isOK(point.y)) {
-            prevX = NaN;
-            continue;
-          }
-          var newYs;
-          if (stackedGraph) {
-            lastY = baseline[point.canvasx];
-            if (lastY === undefined) lastY = axisY;
-            baseline[point.canvasx] = point.canvasy;
-            newYs = [ point.canvasy, lastY ];
+    var iter = Dygraph.createIterator(points, firstIndexInSet, setLength,
+        DygraphCanvasRenderer._getIteratorPredicate(
+            this.attr_("connectSeparatedPoints")));
+
+    // setup graphics context
+    var prevX = NaN;
+    var prevYs = [-1, -1];
+    var newYs;
+    var yscale = axis.yscale;
+    // should be same color as the lines but only 15% opaque.
+    var rgb = new RGBColor(color);
+    var err_color =
+        'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' + fillAlpha + ')';
+    ctx.fillStyle = err_color;
+    ctx.beginPath();
+    while(iter.hasNext) {
+      var point = iter.next();
+      if (point.name == setName) { // TODO(klausw): this is always true
+        if (!Dygraph.isOK(point.y)) {
+          prevX = NaN;
+          continue;
+        }
+        if (stackedGraph) {
+          currBaseline = baseline[point.canvasx];
+          var lastY;
+          if (currBaseline === undefined) {
+            lastY = axisY;
           } else {
-            newYs = [ point.canvasy, axisY ];
-          }
-          if (!isNaN(prevX)) {
-            ctx.moveTo(prevX, prevYs[0]);
-            if (stepPlot) {
-              ctx.lineTo(point.canvasx, prevYs[0]);
+            if(stepPlot) {
+              lastY = currBaseline[0];
             } else {
-              ctx.lineTo(point.canvasx, newYs[0]);
+              lastY = currBaseline;
             }
-            ctx.lineTo(point.canvasx, newYs[1]);
-            ctx.lineTo(prevX, prevYs[1]);
-            ctx.closePath();
           }
-          prevYs = newYs;
-          prevX = point.canvasx;
-        }
-      }
-      ctx.fill();
-    }
-  }
+          newYs = [ point.canvasy, lastY ];
 
-  for (var i = 0; i < setCount; i++) {
-    var setName = setNames[i];
-    var color = this.colors[setName];
+          if(stepPlot) {
+            // Step plots must keep track of the top and bottom of
+            // the baseline at each point.
+            if(prevYs[0] === -1) {
+              baseline[point.canvasx] = [ point.canvasy, axisY ];
+            } else {
+              baseline[point.canvasx] = [ point.canvasy, prevYs[0] ];
+            }
+          } else {
+            baseline[point.canvasx] = point.canvasy;
+          }
 
-    // setup graphics context
-    context.save();
-    var point = this.layout.points[0];
-    var pointSize = this.dygraph_.attr_("pointSize");
-    var prevX = null, prevY = null;
-    var drawPoints = this.dygraph_.attr_("drawPoints");
-    var points = this.layout.points;
-    for (var j = 0; j < points.length; j++) {
-      var point = points[j];
-      if (point.name == setName) {
-        if (!isOK(point.canvasy)) {
-          // this will make us move to the next point, not draw a line to it.
-          prevX = prevY = null;
         } else {
-          // A point is "isolated" if it is non-null but both the previous
-          // and next points are null.
-          var isIsolated = (!prevX && (j == points.length - 1 ||
-                                       !isOK(points[j+1].canvasy)));
-
-          if (!prevX) {
-            prevX = point.canvasx;
-            prevY = point.canvasy;
-          } else {
-            ctx.beginPath();
-            ctx.strokeStyle = color;
-            ctx.lineWidth = this.options.strokeWidth;
-            ctx.moveTo(prevX, prevY);
-            if (stepPlot) {
-              ctx.lineTo(point.canvasx, prevY);
+          newYs = [ point.canvasy, axisY ];
+        }
+        if (!isNaN(prevX)) {
+          ctx.moveTo(prevX, prevYs[0]);
+
+          if (stepPlot) {
+            ctx.lineTo(point.canvasx, prevYs[0]);
+            if(currBaseline) {
+              // Draw to the bottom of the baseline
+              ctx.lineTo(point.canvasx, currBaseline[1]);
+            } else {
+              ctx.lineTo(point.canvasx, newYs[1]);
             }
-            prevX = point.canvasx;
-            prevY = point.canvasy;
-            ctx.lineTo(prevX, prevY);
-            ctx.stroke();
+          } else {
+            ctx.lineTo(point.canvasx, newYs[0]);
+            ctx.lineTo(point.canvasx, newYs[1]);
           }
 
-          if (drawPoints || isIsolated) {
-           ctx.beginPath();
-           ctx.fillStyle = color;
-           ctx.arc(point.canvasx, point.canvasy, pointSize,
-                   0, 2 * Math.PI, false);
-           ctx.fill();
-          }
+          ctx.lineTo(prevX, prevYs[1]);
+          ctx.closePath();
         }
+        prevYs = newYs;
+        prevX = point.canvasx;
       }
     }
+    ctx.fill();
   }
-
-  context.restore();
 };