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dygraph-canvas.js
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dygraph-canvas.js
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/**
* @license
* Copyright 2006 Dan Vanderkam ([email protected])
* MIT-licensed (http://opensource.org/licenses/MIT)
*/
/**
* @fileoverview Based on PlotKit.CanvasRenderer, but modified to meet the
* needs of dygraphs.
*
* In particular, support for:
* - grid overlays
* - error bars
* - dygraphs attribute system
*/
/**
* 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
*/
/*jshint globalstrict: true */
/*global Dygraph:false,RGBColor:false */
"use strict";
var DygraphCanvasRenderer = function(dygraph, element, elementContext, layout) {
this.dygraph_ = dygraph;
this.layout = layout;
this.element = element;
this.elementContext = elementContext;
this.container = this.element.parentNode;
this.height = this.element.height;
this.width = this.element.width;
// --- check whether everything is ok before we return
if (!this.isIE && !(DygraphCanvasRenderer.isSupported(this.element)))
throw "Canvas is not supported.";
// internal state
this.xlabels = [];
this.ylabels = [];
this.annotations = [];
this.chartLabels = {};
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);
};
DygraphCanvasRenderer.prototype.clear = function() {
var context;
if (this.isIE) {
// VML takes a while to start up, so we just poll every this.IEDelay
try {
if (this.clearDelay) {
this.clearDelay.cancel();
this.clearDelay = null;
}
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));
return;
}
}
context = this.elementContext;
context.clearRect(0, 0, this.width, this.height);
function removeArray(ary) {
for (var i = 0; i < ary.length; i++) {
var el = ary[i];
if (el.parentNode) el.parentNode.removeChild(el);
}
}
removeArray(this.xlabels);
removeArray(this.ylabels);
removeArray(this.annotations);
for (var k in this.chartLabels) {
if (!this.chartLabels.hasOwnProperty(k)) continue;
var el = this.chartLabels[k];
if (el.parentNode) el.parentNode.removeChild(el);
}
this.xlabels = [];
this.ylabels = [];
this.annotations = [];
this.chartLabels = {};
};
DygraphCanvasRenderer.isSupported = function(canvasName) {
var canvas = null;
try {
if (typeof(canvasName) == 'undefined' || canvasName === null) {
canvas = document.createElement("canvas");
} else {
canvas = canvasName;
}
canvas.getContext("2d");
}
catch (e) {
var ie = navigator.appVersion.match(/MSIE (\d\.\d)/);
var opera = (navigator.userAgent.toLowerCase().indexOf("opera") != -1);
if ((!ie) || (ie[1] < 6) || (opera))
return false;
return true;
}
return true;
};
/**
* @param { [String] } colors Array of color strings. Should have one entry for
* each series to be rendered.
*/
DygraphCanvasRenderer.prototype.setColors = function(colors) {
this.colorScheme_ = colors;
};
/**
* Draw an X/Y grid on top of the existing plot
*/
DygraphCanvasRenderer.prototype.render = function() {
// 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.elementContext;
function halfUp(x) { return Math.round(x) + 0.5; }
function halfDown(y){ return Math.round(y) - 0.5; }
if (this.attr_('underlayCallback')) {
// NOTE: we pass the dygraph object to this callback twice to avoid breaking
// users who expect a deprecated form of this callback.
this.attr_('underlayCallback')(ctx, this.area, this.dygraph_, this.dygraph_);
}
var x, y, i, ticks;
if (this.attr_('drawYGrid')) {
ticks = this.layout.yticks;
// TODO(konigsberg): I don't think these calls to save() have a corresponding restore().
ctx.save();
ctx.strokeStyle = this.attr_('gridLineColor');
ctx.lineWidth = this.attr_('gridLineWidth');
for (i = 0; i < ticks.length; i++) {
// TODO(danvk): allow secondary axes to draw a grid, too.
if (ticks[i][0] !== 0) continue;
x = halfUp(this.area.x);
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.closePath();
ctx.stroke();
}
ctx.restore();
}
if (this.attr_('drawXGrid')) {
ticks = this.layout.xticks;
ctx.save();
ctx.strokeStyle = this.attr_('gridLineColor');
ctx.lineWidth = this.attr_('gridLineWidth');
for (i=0; i<ticks.length; i++) {
x = halfUp(this.area.x + ticks[i][0] * this.area.w);
y = halfDown(this.area.y + this.area.h);
ctx.beginPath();
ctx.moveTo(x, y);
ctx.lineTo(x, this.area.y);
ctx.closePath();
ctx.stroke();
}
ctx.restore();
}
// Do the ordinary rendering, as before
this._renderLineChart();
this._renderAxis();
this._renderChartLabels();
this._renderAnnotations();
};
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]);
}
}
// 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;
}
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);
}
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.attr_('drawXAxis') && !this.attr_('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.elementContext;
var label, x, y, tick, i;
var labelStyle = {
position: "absolute",
fontSize: this.attr_('axisLabelFontSize') + "px",
zIndex: 10,
color: this.attr_('axisLabelColor'),
width: this.attr_('axisLabelWidth') + "px",
// height: this.attr_('axisLabelFontSize') + 2 + "px",
lineHeight: "normal", // Something other than "normal" line-height screws up label positioning.
overflow: "hidden"
};
var makeDiv = function(txt, axis, prec_axis) {
var div = document.createElement("div");
for (var name in labelStyle) {
if (labelStyle.hasOwnProperty(name)) {
div.style[name] = labelStyle[name];
}
}
var inner_div = document.createElement("div");
inner_div.className = 'dygraph-axis-label' +
' dygraph-axis-label-' + axis +
(prec_axis ? ' dygraph-axis-label-' + prec_axis : '');
inner_div.innerHTML=txt;
div.appendChild(inner_div);
return div;
};
// axis lines
context.save();
context.strokeStyle = this.attr_('axisLineColor');
context.lineWidth = this.attr_('axisLineWidth');
if (this.attr_('drawYAxis')) {
if (this.layout.yticks && this.layout.yticks.length > 0) {
var num_axes = this.dygraph_.numAxes();
for (i = 0; i < this.layout.yticks.length; i++) {
tick = this.layout.yticks[i];
if (typeof(tick) == "function") return;
x = this.area.x;
var sgn = 1;
var prec_axis = 'y1';
if (tick[0] == 1) { // right-side y-axis
x = this.area.x + this.area.w;
sgn = -1;
prec_axis = 'y2';
}
y = this.area.y + tick[1] * this.area.h;
/* Tick marks are currently clipped, so don't bother drawing them.
context.beginPath();
context.moveTo(halfUp(x), halfDown(y));
context.lineTo(halfUp(x - sgn * this.attr_('axisTickSize')), halfDown(y));
context.closePath();
context.stroke();
*/
label = makeDiv(tick[2], 'y', num_axes == 2 ? prec_axis : null);
var top = (y - this.attr_('axisLabelFontSize') / 2);
if (top < 0) top = 0;
if (top + this.attr_('axisLabelFontSize') + 3 > this.height) {
label.style.bottom = "0px";
} else {
label.style.top = top + "px";
}
if (tick[0] === 0) {
label.style.left = (this.area.x - this.attr_('yAxisLabelWidth') - this.attr_('axisTickSize')) + "px";
label.style.textAlign = "right";
} else if (tick[0] == 1) {
label.style.left = (this.area.x + this.area.w +
this.attr_('axisTickSize')) + "px";
label.style.textAlign = "left";
}
label.style.width = this.attr_('yAxisLabelWidth') + "px";
this.container.appendChild(label);
this.ylabels.push(label);
}
// 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.attr_('axisLabelFontSize');
var bottom = parseInt(bottomTick.style.top, 10) + fontSize;
if (bottom > this.height - fontSize) {
bottomTick.style.top = (parseInt(bottomTick.style.top, 10) -
fontSize / 2) + "px";
}
}
// draw a vertical line on the left to separate the chart from the labels.
var axisX;
if (this.attr_('drawAxesAtZero')) {
var r = this.dygraph_.toPercentXCoord(0);
if (r > 1 || r < 0) r = 0;
axisX = halfUp(this.area.x + r * this.area.w);
} else {
axisX = halfUp(this.area.x);
}
context.beginPath();
context.moveTo(axisX, halfDown(this.area.y));
context.lineTo(axisX, 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.attr_('drawXAxis')) {
if (this.layout.xticks) {
for (i = 0; i < this.layout.xticks.length; i++) {
tick = this.layout.xticks[i];
x = this.area.x + tick[0] * this.area.w;
y = this.area.y + this.area.h;
/* Tick marks are currently clipped, so don't bother drawing them.
context.beginPath();
context.moveTo(halfUp(x), halfDown(y));
context.lineTo(halfUp(x), halfDown(y + this.attr_('axisTickSize')));
context.closePath();
context.stroke();
*/
label = makeDiv(tick[1], 'x');
label.style.textAlign = "center";
label.style.top = (y + this.attr_('axisTickSize')) + 'px';
var left = (x - this.attr_('axisLabelWidth')/2);
if (left + this.attr_('axisLabelWidth') > this.width) {
left = this.width - this.attr_('xAxisLabelWidth');
label.style.textAlign = "right";
}
if (left < 0) {
left = 0;
label.style.textAlign = "left";
}
label.style.left = left + "px";
label.style.width = this.attr_('xAxisLabelWidth') + "px";
this.container.appendChild(label);
this.xlabels.push(label);
}
}
context.beginPath();
var axisY;
if (this.attr_('drawAxesAtZero')) {
var r = this.dygraph_.toPercentYCoord(0, 0);
if (r > 1 || r < 0) r = 1;
axisY = halfDown(this.area.y + r * this.area.h);
} else {
axisY = halfDown(this.area.y + this.area.h);
}
context.moveTo(halfUp(this.area.x), axisY);
context.lineTo(halfUp(this.area.x + this.area.w), axisY);
context.closePath();
context.stroke();
}
context.restore();
};
DygraphCanvasRenderer.prototype._renderChartLabels = function() {
var div, class_div;
// Generate divs for the chart title, xlabel and ylabel.
// Space for these divs has already been taken away from the charting area in
// the DygraphCanvasRenderer constructor.
if (this.attr_('title')) {
div = document.createElement("div");
div.style.position = 'absolute';
div.style.top = '0px';
div.style.left = this.area.x + 'px';
div.style.width = this.area.w + 'px';
div.style.height = this.attr_('titleHeight') + 'px';
div.style.textAlign = 'center';
div.style.fontSize = (this.attr_('titleHeight') - 8) + 'px';
div.style.fontWeight = 'bold';
class_div = document.createElement("div");
class_div.className = 'dygraph-label dygraph-title';
class_div.innerHTML = this.attr_('title');
div.appendChild(class_div);
this.container.appendChild(div);
this.chartLabels.title = div;
}
if (this.attr_('xlabel')) {
div = document.createElement("div");
div.style.position = 'absolute';
div.style.bottom = 0; // TODO(danvk): this is lazy. Calculate style.top.
div.style.left = this.area.x + 'px';
div.style.width = this.area.w + 'px';
div.style.height = this.attr_('xLabelHeight') + 'px';
div.style.textAlign = 'center';
div.style.fontSize = (this.attr_('xLabelHeight') - 2) + 'px';
class_div = document.createElement("div");
class_div.className = 'dygraph-label dygraph-xlabel';
class_div.innerHTML = this.attr_('xlabel');
div.appendChild(class_div);
this.container.appendChild(div);
this.chartLabels.xlabel = div;
}
var that = this;
function createRotatedDiv(axis, classes, html) {
var box = {
left: 0,
top: that.area.y,
width: that.attr_('yLabelWidth'),
height: that.area.h
};
// TODO(danvk): is this outer div actually necessary?
div = document.createElement("div");
div.style.position = 'absolute';
if (axis == 1) {
div.style.left = box.left;
} else {
div.style.right = box.left;
}
div.style.top = box.top + 'px';
div.style.width = box.width + 'px';
div.style.height = box.height + 'px';
div.style.fontSize = (that.attr_('yLabelWidth') - 2) + 'px';
var inner_div = document.createElement("div");
inner_div.style.position = 'absolute';
inner_div.style.width = box.height + 'px';
inner_div.style.height = box.width + 'px';
inner_div.style.top = (box.height / 2 - box.width / 2) + 'px';
inner_div.style.left = (box.width / 2 - box.height / 2) + 'px';
inner_div.style.textAlign = 'center';
// CSS rotation is an HTML5 feature which is not standardized. Hence every
// browser has its own name for the CSS style.
var val = 'rotate(' + (axis == 1 ? '-' : '') + '90deg)';
inner_div.style.transform = val; // HTML5
inner_div.style.WebkitTransform = val; // Safari/Chrome
inner_div.style.MozTransform = val; // Firefox
inner_div.style.OTransform = val; // Opera
inner_div.style.msTransform = val; // IE9
if (typeof(document.documentMode) !== 'undefined' &&
document.documentMode < 9) {
// We're dealing w/ an old version of IE, so we have to rotate the text
// using a BasicImage transform. This uses a different origin of rotation
// than HTML5 rotation (top left of div vs. its center).
inner_div.style.filter =
'progid:DXImageTransform.Microsoft.BasicImage(rotation=' +
(axis == 1 ? '3' : '1') + ')';
inner_div.style.left = '0px';
inner_div.style.top = '0px';
}
class_div = document.createElement("div");
class_div.className = classes;
class_div.innerHTML = html;
inner_div.appendChild(class_div);
div.appendChild(inner_div);
return div;
}
var div;
if (this.attr_('ylabel')) {
div = createRotatedDiv(1, 'dygraph-label dygraph-ylabel',
this.attr_('ylabel'));
this.container.appendChild(div);
this.chartLabels.ylabel = div;
}
if (this.attr_('y2label') && this.dygraph_.numAxes() == 2) {
div = createRotatedDiv(2, 'dygraph-label dygraph-y2label',
this.attr_('y2label'));
this.container.appendChild(div);
this.chartLabels.y2label = div;
}
};
DygraphCanvasRenderer.prototype._renderAnnotations = function() {
var annotationStyle = {
"position": "absolute",
"fontSize": this.attr_('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 ||
p.canvasy < this.area.y || p.canvasy > this.area.y + this.area.h) {
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;
this.dygraph_.addEvent(div, 'click',
bindEvt('clickHandler', 'annotationClickHandler', p, this));
this.dygraph_.addEvent(div, 'mouseover',
bindEvt('mouseOverHandler', 'annotationMouseOverHandler', p, this));
this.dygraph_.addEvent(div, 'mouseout',
bindEvt('mouseOutHandler', 'annotationMouseOutHandler', p, this));
this.dygraph_.addEvent(div, 'dblclick',
bindEvt('dblClickHandler', 'annotationDblClickHandler', p, this));
this.container.appendChild(div);
this.annotations.push(div);
var ctx = this.elementContext;
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();
}
};
DygraphCanvasRenderer.makeNextPointStep_ = function(
connect, points, start, end) {
if (connect) {
return function(j) {
while (++j + start < end) {
if (!(points[start + j].yval === null)) break;
}
return j;
}
} else {
return function(j) { return j + 1 };
}
};
DygraphCanvasRenderer.isNullOrNaN_ = function(x) {
return (x === null || isNaN(x));
};
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);
ctx.save();
if (strokeWidth && !stepPlot && (!strokePattern || strokePattern.length <= 1)) {
this._drawTrivialLine(ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, drawPointCallback, pointSize, drawPoints, drawGapPoints);
} else {
this._drawNonTrivialLine(ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, strokePattern, drawPointCallback, pointSize, drawPoints, drawGapPoints, stepPlot);
}
ctx.restore();
};
DygraphCanvasRenderer.prototype._drawNonTrivialLine = function(
ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, strokePattern, drawPointCallback, pointSize, drawPoints, drawGapPoints, stepPlot) {
var prevX = null;
var prevY = null;
var nextY = null;
var point, nextPoint;
var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
var next = DygraphCanvasRenderer.makeNextPointStep_(
this.attr_('connectSeparatedPoints'), points, firstIndexInSet,
firstIndexInSet + setLength);
for (var j = 0; j < setLength; j = next(j)) {
point = points[firstIndexInSet + j];
nextY = (next(j) < setLength) ?
points[firstIndexInSet + next(j)].canvasy : null;
if (DygraphCanvasRenderer.isNullOrNaN_(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.attr_('strokeWidth');
this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
ctx.stroke();
}
// 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 && DygraphCanvasRenderer.isNullOrNaN_(nextY));
if (drawGapPoints) {
// Also consider a point to be is "isolated" if it's adjacent to a
// null point, excluding the graph edges.
if ((j > 0 && !prevX) ||
(next(j) < setLength && DygraphCanvasRenderer.isNullOrNaN_(nextY))) {
isIsolated = true;
}
}
if (prevX === null) {
prevX = point.canvasx;
prevY = point.canvasy;
} else {
// Skip over points that will be drawn in the same pixel.
if (Math.round(prevX) == Math.round(point.canvasx) &&
Math.round(prevY) == Math.round(point.canvasy)) {
continue;
}
// TODO(antrob): skip over points that lie on a line that is already
// going to be drawn. There is no need to have more than 2
// consecutive points that are collinear.
if (strokeWidth) {
ctx.beginPath();
ctx.strokeStyle = color;
ctx.lineWidth = strokeWidth;
if (stepPlot) {
this._dashedLine(ctx, prevX, prevY, point.canvasx, prevY, strokePattern);
prevX = point.canvasx;
}
this._dashedLine(ctx, prevX, prevY, point.canvasx, point.canvasy, strokePattern);
prevX = point.canvasx;
prevY = point.canvasy;
ctx.stroke();
}
}
if (drawPoints || isIsolated) {
pointsOnLine.push([point.canvasx, point.canvasy]);
}
}
}
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._drawTrivialLine = function(
ctx, points, setLength, firstIndexInSet, setName, color, strokeWidth, drawPointCallback, pointSize, drawPoints, drawGapPoints) {
var prevX = null;
var prevY = null;
var nextY = null;
var pointsOnLine = []; // Array of [canvasx, canvasy] pairs.
ctx.beginPath();
ctx.strokeStyle = color;
ctx.lineWidth = strokeWidth;
for (var j = firstIndexInSet; j < firstIndexInSet + setLength; ++j) {
var point = points[j];
nextY = (j + 1 < firstIndexInSet + setLength) ? points[j + 1].canvasy : null;
if (DygraphCanvasRenderer.isNullOrNaN_(point.canvasy)) {
prevX = prevY = null;
} else {
var isIsolated = (!prevX && DygraphCanvasRenderer.isNullOrNaN_(nextY));
if (drawGapPoints) {
// Also consider a point to be is "isolated" if it's adjacent to a
// null point, excluding the graph edges.
if ((j > firstIndexInSet && !prevX) ||
((j + 1 < firstIndexInSet + setLength) && DygraphCanvasRenderer.isNullOrNaN_(nextY))) {
isIsolated = true;
}
}
if (prevX === null) {
prevX = point.canvasx;
prevY = point.canvasy;
if (j === firstIndexInSet) {
ctx.moveTo(point.canvasx, point.canvasy);
}
} else {
ctx.lineTo(point.canvasx, point.canvasy);
}
if (drawPoints || isIsolated) {
pointsOnLine.push([point.canvasx, point.canvasy]);
}
}
}
ctx.stroke();
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._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;
// TODO(konigsberg): Turn this into one call, and then consider inlining drawStyledLine.
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));
};
/**
* Actually draw the lines chart, including error bars.
* TODO(danvk): split this into several smaller functions.
* @private
*/
DygraphCanvasRenderer.prototype._renderLineChart = function() {
// TODO(danvk): use this.attr_ for many of these.
var ctx = this.elementContext;
var fillAlpha = this.attr_('fillAlpha');
var errorBars = this.attr_("errorBars") || this.attr_("customBars");
var fillGraph = this.attr_("fillGraph");
var stackedGraph = this.attr_("stackedGraph");
var stepPlot = this.attr_("stepPlot");
var points = this.layout.points;
var pointsLength = points.length;
var point, i, j, prevX, prevY, prevYs, color, setName, newYs, err_color, rgb, yscale, axis;
var setNames = this.layout.setNames;
var setCount = setNames.length;
// TODO(danvk): Move this mapping into Dygraph and get it out of here.
this.colors = {};
for (i = 0; i < setCount; i++) {
this.colors[setNames[i]] = this.colorScheme_[i % this.colorScheme_.length];
}
// Update Points
// TODO(danvk): here
//
// 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.
for (i = pointsLength; i--;) {
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
if (errorBars) {
ctx.save();
if (fillGraph) {
this.dygraph_.warn("Can't use fillGraph option with error bars");
}
for (i = 0; i < setCount; i++) {
setName = setNames[i];
axis = this.dygraph_.axisPropertiesForSeries(setName);
color = this.colors[setName];
var firstIndexInSet = this.layout.setPointsOffsets[i];
var setLength = this.layout.setPointsLengths[i];
var afterLastIndexInSet = firstIndexInSet + setLength;
var next = DygraphCanvasRenderer.makeNextPointStep_(
this.attr_('connectSeparatedPoints'), points,
afterLastIndexInSet);
// setup graphics context
prevX = NaN;
prevY = NaN;
prevYs = [-1, -1];
yscale = axis.yscale;
// should be same color as the lines but only 15% opaque.
rgb = new RGBColor(color);
err_color = 'rgba(' + rgb.r + ',' + rgb.g + ',' + rgb.b + ',' +
fillAlpha + ')';
ctx.fillStyle = err_color;
ctx.beginPath();
for (j = firstIndexInSet; j < afterLastIndexInSet; j = next(j)) {
point = points[j];
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) {
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();
}
prevYs = newYs;
prevX = point.canvasx;
}
}
ctx.fill();
}
ctx.restore();
} else if (fillGraph) {
ctx.save();
var baseline = {}; // for stacked graphs: baseline for filling
var currBaseline;
// process sets in reverse order (needed for stacked graphs)
for (i = setCount - 1; i >= 0; i--) {
setName = setNames[i];
color = this.colors[setName];
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 afterLastIndexInSet = firstIndexInSet + setLength;