/**
* This is an experimental Highcharts module that draws long data series on a canvas
* in order to increase performance of the initial load time and tooltip responsiveness.
*
* Compatible with HTML5 canvas compatible browsers (not IE < 9).
*
* Author: Torstein Honsi
*
*
* Development plan
* - Column range.
* - Heatmap.
* - Treemap.
* - Check how it works with Highstock and data grouping.
* - Check inverted charts.
* - Check reversed axes.
* - Chart callback should be async after last series is drawn. (But not necessarily, we don't do
that with initial series animation).
* - Cache full-size image so we don't have to redraw on hide/show and zoom up. But k-d-tree still
* needs to be built.
* - Test IE9 and IE10.
* - Stacking is not perhaps not correct since it doesn't use the translation given in
* the translate method. If this gets to complicated, a possible way out would be to
* have a simplified renderCanvas method that simply draws the areaPath on a canvas.
*
* If this module is taken in as part of the core
* - All the loading logic should be merged with core. Update styles in the core.
* - Most of the method wraps should probably be added directly in parent methods.
*
* Notes for boost mode
* - Area lines are not drawn
* - Point markers are not drawn
* - Zones and negativeColor don't work
* - Columns are always one pixel wide. Don't set the threshold too low.
*
* Optimizing tips for users
* - For scatter plots, use a marker.radius of 1 or less. It results in a rectangle being drawn, which is
* considerably faster than a circle.
* - Set extremes (min, max) explicitly on the axes in order for Highcharts to avoid computing extremes.
* - Set enableMouseTracking to false on the series to improve total rendering time.
* - The default threshold is set based on one series. If you have multiple, dense series, the combined
* number of points drawn gets higher, and you may want to set the threshold lower in order to
* use optimizations.
*/
/*global document, Highcharts, HighchartsAdapter, setTimeout */
(function (H, HA) {
'use strict';
var noop = function () { return undefined; },
Color = H.Color,
Series = H.Series,
seriesTypes = H.seriesTypes,
each = H.each,
extend = H.extend,
addEvent = HA.addEvent,
fireEvent = HA.fireEvent,
merge = H.merge,
pick = H.pick,
wrap = H.wrap,
plotOptions = H.getOptions().plotOptions,
CHUNK_SIZE = 50000;
function eachAsync(arr, fn, callback, chunkSize, i) {
i = i || 0;
chunkSize = chunkSize || CHUNK_SIZE;
each(arr.slice(i, i + chunkSize), fn);
if (i + chunkSize < arr.length) {
setTimeout(function () {
eachAsync(arr, fn, callback, chunkSize, i + chunkSize);
});
} else if (callback) {
callback();
}
}
// Set default options
each(['area', 'arearange', 'column', 'line', 'scatter'], function (type) {
if (plotOptions[type]) {
plotOptions[type].boostThreshold = 5000;
}
});
/**
* Override a bunch of methods the same way. If the number of points is below the threshold,
* run the original method. If not, check for a canvas version or do nothing.
*/
each(['translate', 'generatePoints', 'drawTracker', 'drawPoints', 'render'], function (method) {
function branch(proceed) {
var letItPass = this.options.stacking && (method === 'translate' || method === 'generatePoints');
if ((this.processedXData || this.options.data).length < (this.options.boostThreshold || Number.MAX_VALUE) ||
letItPass) {
// Clear image
if (method === 'render' && this.image) {
this.image.attr({ href: '' });
this.animate = null; // We're zooming in, don't run animation
}
proceed.call(this);
// If a canvas version of the method exists, like renderCanvas(), run
} else if (this[method + 'Canvas']) {
this[method + 'Canvas']();
}
}
wrap(Series.prototype, method, branch);
// A special case for some types - its translate method is already wrapped
if (method === 'translate') {
if (seriesTypes.column) {
wrap(seriesTypes.column.prototype, method, branch);
}
if (seriesTypes.arearange) {
wrap(seriesTypes.arearange.prototype, method, branch);
}
}
});
/**
* Do not compute extremes when min and max are set.
* If we use this in the core, we can add the hook to hasExtremes to the methods directly.
*/
wrap(Series.prototype, 'getExtremes', function (proceed) {
if (!this.hasExtremes()) {
proceed.apply(this, Array.prototype.slice.call(arguments, 1));
}
});
wrap(Series.prototype, 'setData', function (proceed) {
if (!this.hasExtremes(true)) {
proceed.apply(this, Array.prototype.slice.call(arguments, 1));
}
});
wrap(Series.prototype, 'processData', function (proceed) {
if (!this.hasExtremes(true)) {
proceed.apply(this, Array.prototype.slice.call(arguments, 1));
}
});
H.extend(Series.prototype, {
pointRange: 0,
hasExtremes: function (checkX) {
var options = this.options,
data = options.data,
xAxis = this.xAxis.options,
yAxis = this.yAxis.options;
return data.length > (options.boostThreshold || Number.MAX_VALUE) && typeof yAxis.min === 'number' && typeof yAxis.max === 'number' &&
(!checkX || (typeof xAxis.min === 'number' && typeof xAxis.max === 'number'));
},
/**
* If implemented in the core, parts of this can probably be shared with other similar
* methods in Highcharts.
*/
destroyGraphics: function () {
var series = this,
points = this.points,
point,
i;
for (i = 0; i < points.length; i = i + 1) {
point = points[i];
if (point && point.graphic) {
point.graphic = point.graphic.destroy();
}
}
each(['graph', 'area'], function (prop) {
if (series[prop]) {
series[prop] = series[prop].destroy();
}
});
},
/**
* Create a hidden canvas to draw the graph on. The contents is later copied over
* to an SVG image element.
*/
getContext: function () {
var width = this.chart.plotWidth,
height = this.chart.plotHeight;
if (!this.canvas) {
this.canvas = document.createElement('canvas');
this.image = this.chart.renderer.image('', 0, 0, width, height).add(this.group);
this.ctx = this.canvas.getContext('2d');
} else {
this.ctx.clearRect(0, 0, width, height);
}
this.canvas.setAttribute('width', width);
this.canvas.setAttribute('height', height);
this.image.attr({
width: width,
height: height
});
return this.ctx;
},
/**
* Draw the canvas image inside an SVG image
*/
canvasToSVG: function () {
this.image.attr({ href: this.canvas.toDataURL('image/png') });
},
cvsLineTo: function (ctx, clientX, plotY) {
ctx.lineTo(clientX, plotY);
},
renderCanvas: function () {
var series = this,
options = series.options,
chart = series.chart,
xAxis = this.xAxis,
yAxis = this.yAxis,
ctx,
i,
c = 0,
xData = series.processedXData,
yData = series.processedYData,
rawData = options.data,
xExtremes = xAxis.getExtremes(),
xMin = xExtremes.min,
xMax = xExtremes.max,
yExtremes = yAxis.getExtremes(),
yMin = yExtremes.min,
yMax = yExtremes.max,
pointTaken = {},
lastClientX,
sampling = !!series.sampling,
points,
r = options.marker && options.marker.radius,
cvsDrawPoint = this.cvsDrawPoint,
cvsLineTo = options.lineWidth ? this.cvsLineTo : false,
cvsMarker = r <= 1 ? this.cvsMarkerSquare : this.cvsMarkerCircle,
enableMouseTracking = options.enableMouseTracking !== false,
lastPoint,
threshold = options.threshold,
yBottom = yAxis.getThreshold(threshold),
hasThreshold = typeof threshold === 'number',
translatedThreshold = yBottom,
doFill = this.fill,
isRange = series.pointArrayMap && series.pointArrayMap.join(',') === 'low,high',
isStacked = !!options.stacking,
cropStart = series.cropStart || 0,
loadingOptions = chart.options.loading,
requireSorting = series.requireSorting,
wasNull,
connectNulls = options.connectNulls,
useRaw = !xData,
minVal,
maxVal,
minI,
maxI,
fillColor = series.fillOpacity ?
new Color(series.color).setOpacity(pick(options.fillOpacity, 0.75)).get() :
series.color,
stroke = function () {
if (doFill) {
ctx.fillStyle = fillColor;
ctx.fill();
} else {
ctx.strokeStyle = series.color;
ctx.lineWidth = options.lineWidth;
ctx.stroke();
}
},
drawPoint = function (clientX, plotY, yBottom) {
if (c === 0) {
ctx.beginPath();
}
if (wasNull) {
ctx.moveTo(clientX, plotY);
} else {
if (cvsDrawPoint) {
cvsDrawPoint(ctx, clientX, plotY, yBottom, lastPoint);
} else if (cvsLineTo) {
cvsLineTo(ctx, clientX, plotY);
} else if (cvsMarker) {
cvsMarker(ctx, clientX, plotY, r);
}
}
// We need to stroke the line for every 1000 pixels. It will crash the browser
// memory use if we stroke too infrequently.
c = c + 1;
if (c === 1000) {
stroke();
c = 0;
}
// Area charts need to keep track of the last point
lastPoint = {
clientX: clientX,
plotY: plotY,
yBottom: yBottom
};
},
addKDPoint = function (clientX, plotY, i) {
// The k-d tree requires series points. Reduce the amount of points, since the time to build the
// tree increases exponentially.
if (enableMouseTracking && !pointTaken[clientX + ',' + plotY]) {
points.push({
clientX: clientX,
plotX: clientX,
plotY: plotY,
i: cropStart + i
});
pointTaken[clientX + ',' + plotY] = true;
}
};
// If we are zooming out from SVG mode, destroy the graphics
if (this.points) {
this.destroyGraphics();
}
// The group
series.plotGroup(
'group',
'series',
series.visible ? 'visible' : 'hidden',
options.zIndex,
chart.seriesGroup
);
series.getAttribs();
series.markerGroup = series.group;
addEvent(series, 'destroy', function () {
series.markerGroup = null;
});
points = this.points = [];
ctx = this.getContext();
series.buildKDTree = noop; // Do not start building while drawing
// Display a loading indicator
if (rawData.length > 99999) {
chart.options.loading = merge(loadingOptions, {
labelStyle: {
backgroundColor: 'rgba(255,255,255,0.75)',
padding: '1em',
borderRadius: '0.5em'
},
style: {
backgroundColor: 'none',
opacity: 1
}
});
chart.showLoading('Drawing...');
chart.options.loading = loadingOptions; // reset
if (chart.loadingShown === true) {
chart.loadingShown = 1;
} else {
chart.loadingShown = chart.loadingShown + 1;
}
}
// Loop over the points
i = 0;
eachAsync(isStacked ? series.data : (xData || rawData), function (d) {
var x,
y,
clientX,
plotY,
isNull,
low,
isYInside = true;
if (useRaw) {
x = d[0];
y = d[1];
} else {
x = d;
y = yData[i];
}
// Resolve low and high for range series
if (isRange) {
if (useRaw) {
y = d.slice(1, 3);
}
low = y[0];
y = y[1];
} else if (isStacked) {
x = d.x;
y = d.stackY;
low = y - d.y;
}
isNull = y === null;
// Optimize for scatter zooming
if (!requireSorting) {
isYInside = y >= yMin && y <= yMax;
}
if (!isNull && x >= xMin && x <= xMax && isYInside) {
clientX = Math.round(xAxis.toPixels(x, true));
if (sampling) {
if (minI === undefined || clientX === lastClientX) {
if (!isRange) {
low = y;
}
if (maxI === undefined || y > maxVal) {
maxVal = y;
maxI = i;
}
if (minI === undefined || low < minVal) {
minVal = low;
minI = i;
}
}
if (clientX !== lastClientX) { // Add points and reset
if (minI !== undefined) { // then maxI is also a number
plotY = yAxis.toPixels(maxVal, true);
yBottom = yAxis.toPixels(minVal, true);
drawPoint(
clientX,
hasThreshold ? Math.min(plotY, translatedThreshold) : plotY,
hasThreshold ? Math.max(yBottom, translatedThreshold) : yBottom
);
addKDPoint(clientX, plotY, maxI);
if (yBottom !== plotY) {
addKDPoint(clientX, yBottom, minI);
}
}
minI = maxI = undefined;
lastClientX = clientX;
}
} else {
plotY = Math.round(yAxis.toPixels(y, true));
drawPoint(clientX, plotY, yBottom);
addKDPoint(clientX, plotY, i);
}
}
wasNull = isNull && !connectNulls;
i = i + 1;
if (i % CHUNK_SIZE === 0) {
series.canvasToSVG();
}
}, function () {
var loadingDiv = chart.loadingDiv,
loadingShown = +chart.loadingShown;
stroke();
series.canvasToSVG();
fireEvent(series, 'renderedCanvas');
// Do not use chart.hideLoading, as it runs JS animation and will be blocked by buildKDTree.
// CSS animation looks good, but then it must be deleted in timeout. If we add the module to core,
// change hideLoading so we can skip this block.
if (loadingShown === 1) {
extend(loadingDiv.style, {
transition: 'opacity 250ms',
opacity: 0
});
chart.loadingShown = false;
setTimeout(function () {
if (loadingDiv.parentNode) { // In exporting it is falsy
loadingDiv.parentNode.removeChild(loadingDiv);
}
chart.loadingDiv = chart.loadingSpan = null;
}, 250);
}
if (loadingShown) {
chart.loadingShown = loadingShown - 1;
}
// Pass tests in Pointer.
// TODO: Replace this with a single property, and replace when zooming in
// below boostThreshold.
series.directTouch = false;
series.options.stickyTracking = true;
delete series.buildKDTree; // Go back to prototype, ready to build
series.buildKDTree();
// Don't do async on export, the exportChart, getSVGForExport and getSVG methods are not chained for it.
}, chart.renderer.forExport ? Number.MAX_VALUE : undefined);
}
});
seriesTypes.scatter.prototype.cvsMarkerCircle = function (ctx, clientX, plotY, r) {
ctx.moveTo(clientX, plotY);
ctx.arc(clientX, plotY, r, 0, 2 * Math.PI, false);
};
// Rect is twice as fast as arc, should be used for small markers
seriesTypes.scatter.prototype.cvsMarkerSquare = function (ctx, clientX, plotY, r) {
ctx.moveTo(clientX, plotY);
ctx.rect(clientX - r, plotY - r, r * 2, r * 2);
};
seriesTypes.scatter.prototype.fill = true;
extend(seriesTypes.area.prototype, {
cvsDrawPoint: function (ctx, clientX, plotY, yBottom, lastPoint) {
if (lastPoint && clientX !== lastPoint.clientX) {
ctx.moveTo(lastPoint.clientX, lastPoint.yBottom);
ctx.lineTo(lastPoint.clientX, lastPoint.plotY);
ctx.lineTo(clientX, plotY);
ctx.lineTo(clientX, yBottom);
}
},
fill: true,
fillOpacity: true,
sampling: true
});
extend(seriesTypes.column.prototype, {
cvsDrawPoint: function (ctx, clientX, plotY, yBottom) {
ctx.rect(clientX - 1, plotY, 1, yBottom - plotY);
},
fill: true,
sampling: true
});
/**
* Return a point instance from the k-d-tree
*/
wrap(Series.prototype, 'searchPoint', function (proceed, e) {
var point = proceed.call(this, e),
ret = point;
if (point && !(point instanceof this.pointClass)) {
ret = (new this.pointClass()).init(this, this.options.data[point.i]);
ret.dist = point.dist;
ret.category = ret.x;
ret.plotX = point.plotX;
ret.plotY = point.plotY;
}
return ret;
});
}(Highcharts, HighchartsAdapter));