/**
* @fileoverview Based on PlotKit, but modified to meet the needs of dygraphs.
* In particular, support for:
- * - grid overlays
+ * - grid overlays
* - error bars
* - dygraphs attribute system
*/
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) {
this.datasets[setname] = set_xy;
};
+DygraphLayout.prototype.setAnnotations = function(ann) {
+ // The Dygraph object's annotations aren't parsed. We parse them here and
+ // save a copy.
+ this.annotations = [];
+ var parse = this.attr_('xValueParser');
+ for (var i = 0; i < ann.length; i++) {
+ var a = {};
+ if (!ann[i].xval && !ann[i].x) {
+ this.dygraph_.error("Annotations must have an 'x' property");
+ return;
+ }
+ if (ann[i].icon &&
+ !(ann[i].hasOwnProperty('width') &&
+ ann[i].hasOwnProperty('height'))) {
+ this.dygraph_.error("Must set width and height when setting " +
+ "annotation.icon property");
+ return;
+ }
+ Dygraph.update(a, ann[i]);
+ if (!a.xval) 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() {
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;
+ if (series.length > 1) {
+ 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);
+ for (var i = 0; i < this.options.yAxes.length; i++) {
+ var axis = this.options.yAxes[i];
+ axis.minyval = axis.computedValueRange[0];
+ axis.maxyval = axis.computedValueRange[1];
+ axis.yrange = axis.maxyval - axis.minyval;
+ axis.yscale = (axis.yrange != 0 ? 1.0 / axis.yrange : 1.0);
+ }
};
DygraphLayout.prototype._evaluateLineCharts = function() {
if (!this.datasets.hasOwnProperty(setName)) continue;
var dataset = this.datasets[setName];
+ var axis = this.options.yAxes[this.options.seriesToAxisMap[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),
+ y: 1.0 - ((parseFloat(item[1]) - axis.minyval) * axis.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);
}
}
}
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]);
+ for (var i = 0; i < this.options.yAxes.length; i++ ) {
+ var axis = this.options.yAxes[i];
+ for (var j = 0; j < axis.ticks.length; j++) {
+ var tick = axis.ticks[j];
+ var label = tick.label;
+ var pos = 1.0 - (axis.yscale * (tick.v - axis.minyval));
+ if ((pos >= 0.0) && (pos <= 1.0)) {
+ this.yticks.push([i, pos, label]);
+ }
}
}
};
}
};
+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
*/
Dygraph.update(this.options, new_options ? new_options : {});
};
+/**
+ * Return a copy of the point at the indicated index, with its yval unstacked.
+ * @param int index of point in layout_.points
+ */
+DygraphLayout.prototype.unstackPointAtIndex = function(idx) {
+ var point = this.points[idx];
+
+ // Clone the point since we modify it
+ var unstackedPoint = {};
+ for (var i in point) {
+ unstackedPoint[i] = point[i];
+ }
+
+ if (!this.attr_("stackedGraph")) {
+ return unstackedPoint;
+ }
+
+ // The unstacked yval is equal to the current yval minus the yval of the
+ // next point at the same xval.
+ for (var i = idx+1; i < this.points.length; i++) {
+ if (this.points[i].xval == point.xval) {
+ unstackedPoint.yval -= this.points[i].yval;
+ break;
+ }
+ }
+
+ return unstackedPoint;
+}
+
// Subclass PlotKit.CanvasRenderer to add:
// 1. X/Y grid overlay
// 2. Ability to draw error bars (if required)
// internal state
this.xlabels = new Array();
this.ylabels = new Array();
+ this.annotations = new Array();
+ // TODO(danvk): consider all axes in this computation.
this.area = {
+ // TODO(danvk): per-axis setting.
x: this.options.yAxisLabelWidth + 2 * this.options.axisTickSize,
y: 0
};
this.area.h = this.height - this.options.axisLabelFontSize -
2 * this.options.axisTickSize;
+ // Shrink the drawing area to accomodate additional y-axes.
+ if (this.dygraph_.numAxes() == 2) {
+ // TODO(danvk): per-axis setting.
+ this.area.w -= (this.options.yAxisLabelWidth + 2 * this.options.axisTickSize);
+ } else if (this.dygraph_.numAxes() > 2) {
+ this.dygraph_.error("Only two y-axes are supported at this time. (Trying " +
+ "to use " + this.dygraph_.numAxes() + ")");
+ }
+
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.
+ var ctx = this.dygraph_.canvas_.getContext("2d");
+ ctx.beginPath();
+ ctx.rect(this.area.x, this.area.y, this.area.w, this.area.h);
+ ctx.clip();
+
+ ctx = this.dygraph_.hidden_.getContext("2d");
+ 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);
};
DygraphCanvasRenderer.prototype.clear = function() {
for (var i = 0; i < this.xlabels.length; i++) {
var el = this.xlabels[i];
- el.parentNode.removeChild(el);
+ if (el.parentNode) el.parentNode.removeChild(el);
}
for (var i = 0; i < this.ylabels.length; i++) {
var el = this.ylabels[i];
- el.parentNode.removeChild(el);
+ if (el.parentNode) el.parentNode.removeChild(el);
+ }
+ for (var i = 0; i < this.annotations.length; i++) {
+ var el = this.annotations[i];
+ if (el.parentNode) el.parentNode.removeChild(el);
}
this.xlabels = new Array();
this.ylabels = new Array();
+ this.annotations = new Array();
};
* Draw an X/Y grid on top of the existing plot
*/
DygraphCanvasRenderer.prototype.render = function() {
- // Draw the new X/Y grid
+ // Draw the new X/Y grid. Lines appear crisper when pixels are rounded to
+ // half-integers. This prevents them from drawing in two rows/cols.
var ctx = this.element.getContext("2d");
+ function halfUp(x){return Math.round(x)+0.5};
+ function halfDown(y){return Math.round(y)-0.5};
if (this.options.underlayCallback) {
- this.options.underlayCallback(ctx, this.area, this.layout);
+ this.options.underlayCallback(ctx, this.area, this.layout, this.dygraph_);
}
if (this.options.drawYGrid) {
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;
+ // TODO(danvk): allow secondary axes to draw a grid, too.
+ if (ticks[i][0] != 0) continue;
+ var x = halfUp(this.area.x);
+ var y = halfDown(this.area.y + ticks[i][1] * this.area.h);
ctx.beginPath();
ctx.moveTo(x, y);
ctx.lineTo(x + this.area.w, y);
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;
+ var x = halfUp(this.area.x + ticks[i][0] * this.area.w);
+ var y = halfDown(this.area.y + this.area.h);
ctx.beginPath();
ctx.moveTo(x, y);
ctx.lineTo(x, this.area.y);
// Do the ordinary rendering, as before
this._renderLineChart();
this._renderAxis();
+ this._renderAnnotations();
};
if (!this.options.drawXAxis && !this.options.drawYAxis)
return;
+ // Round pixels to half-integer boundaries for crisper drawing.
+ function halfUp(x){return Math.round(x)+0.5};
+ function halfDown(y){return Math.round(y)-0.5};
+
var context = this.element.getContext("2d");
var labelStyle = {
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;
+ var sgn = 1;
+ if (tick[0] == 1) { // right-side y-axis
+ x = this.area.x + this.area.w;
+ sgn = -1;
+ }
+ var y = this.area.y + tick[1] * this.area.h;
context.beginPath();
- context.moveTo(x, y);
- context.lineTo(x - this.options.axisTickSize, y);
+ context.moveTo(halfUp(x), halfDown(y));
+ context.lineTo(halfUp(x - sgn * this.options.axisTickSize), halfDown(y));
context.closePath();
context.stroke();
- var label = makeDiv(tick[1]);
+ var label = makeDiv(tick[2]);
var top = (y - this.options.axisLabelFontSize / 2);
if (top < 0) top = 0;
} else {
label.style.top = top + "px";
}
- label.style.left = "0px";
- label.style.textAlign = "right";
+ if (tick[0] == 0) {
+ label.style.left = "0px";
+ label.style.textAlign = "right";
+ } else if (tick[0] == 1) {
+ label.style.left = (this.area.x + this.area.w +
+ this.options.axisTickSize) + "px";
+ label.style.textAlign = "left";
+ }
label.style.width = this.options.yAxisLabelWidth + "px";
this.container.appendChild(label);
this.ylabels.push(label);
}
}
+ // draw a vertical line on the left to separate the chart from the labels.
context.beginPath();
- context.moveTo(this.area.x, this.area.y);
- context.lineTo(this.area.x, this.area.y + this.area.h);
+ context.moveTo(halfUp(this.area.x), halfDown(this.area.y));
+ context.lineTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
context.closePath();
context.stroke();
+
+ // if there's a secondary y-axis, draw a vertical line for that, too.
+ if (this.dygraph_.numAxes() == 2) {
+ context.beginPath();
+ context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
+ context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
+ context.closePath();
+ context.stroke();
+ }
}
if (this.options.drawXAxis) {
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.moveTo(halfUp(x), halfDown(y));
+ context.lineTo(halfUp(x), halfDown(y + this.options.axisTickSize));
context.closePath();
context.stroke();
}
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.moveTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
+ context.lineTo(halfUp(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
context.closePath();
context.stroke();
}
};
+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 );
+ }
+ };
+ }
+
+ // 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];
+ if (p.canvasx < this.area.x || p.canvasx > this.area.x + this.area.w) {
+ continue;
+ }
+
+ var a = p.annotation;
+ var tick_height = 6;
+ if (a.hasOwnProperty("tickHeight")) {
+ tick_height = a.tickHeight;
+ }
+
+ var div = document.createElement("div");
+ for (var name in annotationStyle) {
+ if (annotationStyle.hasOwnProperty(name)) {
+ div.style[name] = annotationStyle[name];
+ }
+ }
+ if (!a.hasOwnProperty('icon')) {
+ div.className = "dygraphDefaultAnnotation";
+ }
+ if (a.hasOwnProperty('cssClass')) {
+ div.className += " " + a.cssClass;
+ }
+
+ var width = a.hasOwnProperty('width') ? a.width : 16;
+ var height = a.hasOwnProperty('height') ? a.height : 16;
+ if (a.hasOwnProperty('icon')) {
+ var img = document.createElement("img");
+ img.src = a.icon;
+ img.width = width;
+ img.height = height;
+ div.appendChild(img);
+ } else if (p.annotation.hasOwnProperty('shortText')) {
+ div.appendChild(document.createTextNode(p.annotation.shortText));
+ }
+ div.style.left = (p.canvasx - width / 2) + "px";
+ if (a.attachAtBottom) {
+ div.style.top = (this.area.h - height - tick_height) + "px";
+ } else {
+ 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];
+ a.div = div;
+
+ 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();
+ if (!a.attachAtBottom) {
+ ctx.moveTo(p.canvasx, p.canvasy);
+ ctx.lineTo(p.canvasx, p.canvasy - 2 - tick_height);
+ } else {
+ ctx.moveTo(p.canvasx, this.area.h);
+ ctx.lineTo(p.canvasx, this.area.h - 2 - tick_height);
+ }
+ ctx.closePath();
+ ctx.stroke();
+ }
+};
+
+
/**
* Overrides the CanvasRenderer method to draw error bars
*/
DygraphCanvasRenderer.prototype._renderLineChart = function() {
+ // TODO(danvk): use this.attr_ for many of these.
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 fillGraph = this.attr_("fillGraph");
+ var stackedGraph = this.layout.options.stackedGraph;
+ var stepPlot = this.layout.options.stepPlot;
var setNames = [];
for (var name in this.layout.datasets) {
for (var i = 0; i < setCount; i++) {
var setName = setNames[i];
+ var axis = this.layout.options.yAxes[
+ this.layout.options.seriesToAxisMap[setName]];
var color = this.colors[setName];
// setup graphics context
ctx.save();
- ctx.strokeStyle = color;
- ctx.lineWidth = this.options.strokeWidth;
var prevX = NaN;
+ var prevY = NaN;
var prevYs = [-1, -1];
- var count = 0;
- var yscale = this.layout.yscale;
+ 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 + ',' +
ctx.beginPath();
for (var j = 0; j < this.layout.points.length; j++) {
var point = this.layout.points[j];
- count++;
if (point.name == setName) {
if (!isOK(point.y)) {
prevX = NaN;
continue;
}
+
// TODO(danvk): here
- var newYs = [ point.y - point.errorPlus * yscale,
- point.y + point.errorMinus * yscale ];
+ if (stepPlot) {
+ var newYs = [ prevY - point.errorPlus * yscale,
+ prevY + point.errorMinus * yscale ];
+ prevY = point.y;
+ } else {
+ var newYs = [ point.y - point.errorPlus * yscale,
+ 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 (!isNaN(prevX)) {
- ctx.moveTo(prevX, prevYs[0]);
+ 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]);
- ctx.lineTo(prevX, prevYs[1]);
+ if (stepPlot) {
+ ctx.lineTo(prevX, newYs[1]);
+ } else {
+ ctx.lineTo(prevX, prevYs[1]);
+ }
ctx.closePath();
}
- prevYs[0] = newYs[0];
- prevYs[1] = newYs[1];
+ prevYs = newYs;
prevX = point.canvasx;
}
}
ctx.fill();
}
} else if (fillGraph) {
- // TODO(danvk): merge this code with the logic above; they're very similar.
- for (var i = 0; i < setCount; 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 setNameLast;
- if (i>0) setNameLast = setNames[i-1];
var color = this.colors[setName];
+ var axis = this.layout.options.yAxes[
+ this.layout.options.seriesToAxisMap[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;
// setup graphics context
ctx.save();
- ctx.strokeStyle = color;
- ctx.lineWidth = this.options.strokeWidth;
var prevX = NaN;
var prevYs = [-1, -1];
- var count = 0;
- var yscale = this.layout.yscale;
+ 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 + ',' +
ctx.beginPath();
for (var j = 0; j < this.layout.points.length; j++) {
var point = this.layout.points[j];
- count++;
if (point.name == setName) {
if (!isOK(point.y)) {
prevX = NaN;
continue;
}
- var pX = 1.0 + this.layout.minyval * this.layout.yscale;
- if (pX < 0.0) pX = 0.0;
- else if (pX > 1.0) pX = 1.0;
- 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;
+ var newYs;
+ if (stackedGraph) {
+ lastY = baseline[point.canvasx];
+ if (lastY === undefined) lastY = axisY;
+ baseline[point.canvasx] = point.canvasy;
+ newYs = [ point.canvasy, lastY ];
+ } else {
+ newYs = [ point.canvasy, axisY ];
+ }
if (!isNaN(prevX)) {
ctx.moveTo(prevX, prevYs[0]);
- ctx.lineTo(point.canvasx, newYs[0]);
+ if (stepPlot) {
+ ctx.lineTo(point.canvasx, prevYs[0]);
+ } else {
+ ctx.lineTo(point.canvasx, newYs[0]);
+ }
ctx.lineTo(point.canvasx, newYs[1]);
ctx.lineTo(prevX, prevYs[1]);
ctx.closePath();
}
- prevYs[0] = newYs[0];
- prevYs[1] = newYs[1];
+ prevYs = newYs;
prevX = point.canvasx;
}
}
for (var i = 0; i < setCount; i++) {
var setName = setNames[i];
var color = this.colors[setName];
+ var strokeWidth = this.dygraph_.attr_("strokeWidth", setName);
// setup graphics context
context.save();
var point = this.layout.points[0];
- var pointSize = this.dygraph_.attr_("pointSize");
+ var pointSize = this.dygraph_.attr_("pointSize", setName);
var prevX = null, prevY = null;
- var drawPoints = this.dygraph_.attr_("drawPoints");
+ var drawPoints = this.dygraph_.attr_("drawPoints", setName);
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)) {
+ if (stepPlot && prevX != null) {
+ // Draw a horizontal line to the start of the missing data
+ ctx.beginPath();
+ ctx.strokeStyle = color;
+ ctx.lineWidth = this.options.strokeWidth;
+ ctx.moveTo(prevX, prevY);
+ ctx.lineTo(point.canvasx, prevY);
+ ctx.stroke();
+ }
// this will make us move to the next point, not draw a line to it.
prevX = prevY = null;
} else {
prevX = point.canvasx;
prevY = point.canvasy;
} else {
- ctx.beginPath();
- ctx.strokeStyle = color;
- ctx.lineWidth = this.options.strokeWidth;
- ctx.moveTo(prevX, prevY);
- prevX = point.canvasx;
- prevY = point.canvasy;
- ctx.lineTo(prevX, prevY);
- ctx.stroke();
+ // TODO(danvk): figure out why this conditional is necessary.
+ if (strokeWidth) {
+ ctx.beginPath();
+ ctx.strokeStyle = color;
+ ctx.lineWidth = strokeWidth;
+ ctx.moveTo(prevX, prevY);
+ if (stepPlot) {
+ ctx.lineTo(point.canvasx, prevY);
+ }
+ prevX = point.canvasx;
+ prevY = point.canvasy;
+ ctx.lineTo(prevX, prevY);
+ ctx.stroke();
+ }
}
if (drawPoints || isIsolated) {