in groups/master/ggd/flask/static/smoothie.js [544:794]
SmoothieChart.prototype.render = function(canvas, time) {
var nowMillis = new Date().getTime();
if (!this.isAnimatingScale) {
// We're not animating. We can use the last render time and the scroll speed to work out whether
// we actually need to paint anything yet. If not, we can return immediately.
// Render at least every 1/6th of a second. The canvas may be resized, which there is
// no reliable way to detect.
var maxIdleMillis = Math.min(1000/6, this.options.millisPerPixel);
if (nowMillis - this.lastRenderTimeMillis < maxIdleMillis) {
return;
}
}
this.resize();
this.lastRenderTimeMillis = nowMillis;
canvas = canvas || this.canvas;
time = time || nowMillis - (this.delay || 0);
// Round time down to pixel granularity, so motion appears smoother.
time -= time % this.options.millisPerPixel;
var context = canvas.getContext('2d'),
chartOptions = this.options,
dimensions = { top: 0, left: 0, width: canvas.clientWidth, height: canvas.clientHeight },
// Calculate the threshold time for the oldest data points.
oldestValidTime = time - (dimensions.width * chartOptions.millisPerPixel),
valueToYPixel = function(value) {
var offset = value - this.currentVisMinValue;
return this.currentValueRange === 0
? dimensions.height
: dimensions.height - (Math.round((offset / this.currentValueRange) * dimensions.height));
}.bind(this),
timeToXPixel = function(t) {
if(chartOptions.scrollBackwards) {
return Math.round((time - t) / chartOptions.millisPerPixel);
}
return Math.round(dimensions.width - ((time - t) / chartOptions.millisPerPixel));
};
this.updateValueRange();
context.font = chartOptions.labels.fontSize + 'px ' + chartOptions.labels.fontFamily;
// Save the state of the canvas context, any transformations applied in this method
// will get removed from the stack at the end of this method when .restore() is called.
context.save();
// Move the origin.
context.translate(dimensions.left, dimensions.top);
// Create a clipped rectangle - anything we draw will be constrained to this rectangle.
// This prevents the occasional pixels from curves near the edges overrunning and creating
// screen cheese (that phrase should need no explanation).
context.beginPath();
context.rect(0, 0, dimensions.width, dimensions.height);
context.clip();
// Clear the working area.
context.save();
context.fillStyle = chartOptions.grid.fillStyle;
context.clearRect(0, 0, dimensions.width, dimensions.height);
context.fillRect(0, 0, dimensions.width, dimensions.height);
context.restore();
// Grid lines...
context.save();
context.lineWidth = chartOptions.grid.lineWidth;
context.strokeStyle = chartOptions.grid.strokeStyle;
// Vertical (time) dividers.
if (chartOptions.grid.millisPerLine > 0) {
context.beginPath();
for (var t = time - (time % chartOptions.grid.millisPerLine);
t >= oldestValidTime;
t -= chartOptions.grid.millisPerLine) {
var gx = timeToXPixel(t);
if (chartOptions.grid.sharpLines) {
gx -= 0.5;
}
context.moveTo(gx, 0);
context.lineTo(gx, dimensions.height);
}
context.stroke();
context.closePath();
}
// Horizontal (value) dividers.
for (var v = 1; v < chartOptions.grid.verticalSections; v++) {
var gy = Math.round(v * dimensions.height / chartOptions.grid.verticalSections);
if (chartOptions.grid.sharpLines) {
gy -= 0.5;
}
context.beginPath();
context.moveTo(0, gy);
context.lineTo(dimensions.width, gy);
context.stroke();
context.closePath();
}
// Bounding rectangle.
if (chartOptions.grid.borderVisible) {
context.beginPath();
context.strokeRect(0, 0, dimensions.width, dimensions.height);
context.closePath();
}
context.restore();
// Draw any horizontal lines...
if (chartOptions.horizontalLines && chartOptions.horizontalLines.length) {
for (var hl = 0; hl < chartOptions.horizontalLines.length; hl++) {
var line = chartOptions.horizontalLines[hl],
hly = Math.round(valueToYPixel(line.value)) - 0.5;
context.strokeStyle = line.color || '#ffffff';
context.lineWidth = line.lineWidth || 1;
context.beginPath();
context.moveTo(0, hly);
context.lineTo(dimensions.width, hly);
context.stroke();
context.closePath();
}
}
// For each data set...
for (var d = 0; d < this.seriesSet.length; d++) {
context.save();
var timeSeries = this.seriesSet[d].timeSeries,
dataSet = timeSeries.data,
seriesOptions = this.seriesSet[d].options;
// Delete old data that's moved off the left of the chart.
timeSeries.dropOldData(oldestValidTime, chartOptions.maxDataSetLength);
// Set style for this dataSet.
context.lineWidth = seriesOptions.lineWidth;
context.strokeStyle = seriesOptions.strokeStyle;
// Draw the line...
context.beginPath();
// Retain lastX, lastY for calculating the control points of bezier curves.
var firstX = 0, lastX = 0, lastY = 0;
for (var i = 0; i < dataSet.length && dataSet.length !== 1; i++) {
var x = timeToXPixel(dataSet[i][0]),
y = valueToYPixel(dataSet[i][1]);
if (i === 0) {
firstX = x;
context.moveTo(x, y);
} else {
switch (chartOptions.interpolation) {
case "linear":
case "line": {
context.lineTo(x,y);
break;
}
case "bezier":
default: {
// Great explanation of Bezier curves: http://en.wikipedia.org/wiki/Bezier_curve#Quadratic_curves
//
// Assuming A was the last point in the line plotted and B is the new point,
// we draw a curve with control points P and Q as below.
//
// A---P
// |
// |
// |
// Q---B
//
// Importantly, A and P are at the same y coordinate, as are B and Q. This is
// so adjacent curves appear to flow as one.
//
context.bezierCurveTo( // startPoint (A) is implicit from last iteration of loop
Math.round((lastX + x) / 2), lastY, // controlPoint1 (P)
Math.round((lastX + x)) / 2, y, // controlPoint2 (Q)
x, y); // endPoint (B)
break;
}
case "step": {
context.lineTo(x,lastY);
context.lineTo(x,y);
break;
}
}
}
lastX = x; lastY = y;
}
if (dataSet.length > 1) {
if (seriesOptions.fillStyle) {
// Close up the fill region.
context.lineTo(dimensions.width + seriesOptions.lineWidth + 1, lastY);
context.lineTo(dimensions.width + seriesOptions.lineWidth + 1, dimensions.height + seriesOptions.lineWidth + 1);
context.lineTo(firstX, dimensions.height + seriesOptions.lineWidth);
context.fillStyle = seriesOptions.fillStyle;
context.fill();
}
if (seriesOptions.strokeStyle && seriesOptions.strokeStyle !== 'none') {
context.stroke();
}
context.closePath();
}
context.restore();
}
// Draw the axis values on the chart.
if (!chartOptions.labels.disabled && !isNaN(this.valueRange.min) && !isNaN(this.valueRange.max)) {
var maxValueString = chartOptions.yMaxFormatter(this.valueRange.max, chartOptions.labels.precision),
minValueString = chartOptions.yMinFormatter(this.valueRange.min, chartOptions.labels.precision),
maxLabelPos = chartOptions.scrollBackwards ? 0 : dimensions.width - context.measureText(maxValueString).width - 2,
minLabelPos = chartOptions.scrollBackwards ? 0 : dimensions.width - context.measureText(minValueString).width - 2;
context.fillStyle = chartOptions.labels.fillStyle;
context.fillText(maxValueString, maxLabelPos, chartOptions.labels.fontSize);
context.fillText(minValueString, minLabelPos, dimensions.height - 2);
}
// Display timestamps along x-axis at the bottom of the chart.
if (chartOptions.timestampFormatter && chartOptions.grid.millisPerLine > 0) {
var textUntilX = chartOptions.scrollBackwards
? context.measureText(minValueString).width
: dimensions.width - context.measureText(minValueString).width + 4;
for (var t = time - (time % chartOptions.grid.millisPerLine);
t >= oldestValidTime;
t -= chartOptions.grid.millisPerLine) {
var gx = timeToXPixel(t);
// Only draw the timestamp if it won't overlap with the previously drawn one.
if ((!chartOptions.scrollBackwards && gx < textUntilX) || (chartOptions.scrollBackwards && gx > textUntilX)) {
// Formats the timestamp based on user specified formatting function
// SmoothieChart.timeFormatter function above is one such formatting option
var tx = new Date(t),
ts = chartOptions.timestampFormatter(tx),
tsWidth = context.measureText(ts).width;
textUntilX = chartOptions.scrollBackwards
? gx + tsWidth + 2
: gx - tsWidth - 2;
context.fillStyle = chartOptions.labels.fillStyle;
if(chartOptions.scrollBackwards) {
context.fillText(ts, gx, dimensions.height - 2);
} else {
context.fillText(ts, gx - tsWidth, dimensions.height - 2);
}
}
}
}
context.restore(); // See .save() above.
};