Chart.js - Increase spacing between bottom legend and chart - chart.js

i'm trying to achieve something like this but with legend on bottom.
When i try adding it at most i can get something like this:
i'm considering separating legend to another div like
<div id="js-legend" class="chart-legend"></div>
but it would be nice to achieve it with the former solution.
Thanks in advance for the help

I think something like this should work.
plugins: [{
beforeInit: (chart, options) => {
chart.legend.afterFit = () => {
if (chart.legend.margins) {
// Put some padding around the legend/labels
chart.legend.options.labels.padding = 20;
// Because you added 20px of padding around the whole legend,
// you will need to increase the height of the chart to fit it
chart.height += 40;
}
};
}
}]

you can use margin-top for #js-legend.

Related

How to align ticks label in chartJS 3.x?

is possible with chartJS chenge the align position of tick labels for scaleY and for scaleX?
In the image attached i want 300,150,60, 0 on top of the grid line and 9:56 aligned on the right of the first tick.
I try to modify the code in this answer, but without success.
After some research i adapted the method showned here to works with ChartJS 3.x:
plugins: [{
afterDraw: function (c) {
var yScale = c.scales['y'];
yScale.ticks.forEach(function (o, i) {
// top tick label indent
var yT_O = yScale.getPixelForTick(i) - 9;
// left tick label indent
var xT_O = c.width - 35;
c.ctx.fillStyle = "#707070"
c.ctx.fillText(o.label, xT_O, yT_O);
});
}
}]
Actually i'm not sure this is the best plugin event where do that.
I also had to put "display: false" on the ticks options in order to hide the originals tick labels.

Legends for line charts in Chart.js

I'd like to customize a legend for line data so that the legend graphic is a line (styled like the actually data line) rather than a box.
As far as I can tell from the source, the graphic can be a point or a box, and the height of the box is fixed to the font size. The 'generateLabels' option does not seem to allow for extending around these contraints.
Version 2.2.1.
Thanks for any help.
NOTE: This solution only works if you have a local version of Chart.js since it needs to edit a function in the source code of the library, which can't be done if you import it form a CDN.
To achieve what you want, you will need to edit the drawLegendBox function (link to source here).
First, as if you wanted to do a pointStyle legend, add the useLineStyle and set it to true like this :
options: {
legend: {
labels : {
useLineStyle: true
}
}
}
Then you need to go to your local version of Chart.js (obvisouly, you cannot edit it if you import it from a CDN) and search for the function drawLegendBox (on Chart.js v2.2.1, it is roughly line 6460; in Chart.js v2.9.4 search for labelOpts && labelOpts.usePointStyle).
Scroll down a little bit to see something like this :
if (opts.labels && opts.labels.usePointStyle) {
// Recalulate x and y for drawPoint() because its expecting
// x and y to be center of figure (instead of top left)
var radius = fontSize * Math.SQRT2 / 2;
var offSet = radius / Math.SQRT2;
var centerX = x + offSet;
var centerY = y + offSet;
// Draw pointStyle as legend symbol
Chart.canvasHelpers.drawPoint(ctx, legendItem.pointStyle, radius, centerX, centerY);
}
// --- NEW CONDITION GOES HERE ---
else {
// Draw box as legend symbol
ctx.strokeRect(x, y, boxWidth, fontSize);
ctx.fillRect(x, y, boxWidth, fontSize);
}
And add this between the two conditions :
else if (opts.labels && opts.labels.useLineStyle) {
ctx.beginPath();
ctx.moveTo(x, y + fontSize * 0.45);
ctx.lineTo(x + boxWidth, y + fontSize * 0.45);
ctx.stroke();
}
With this edit, everytime you will set useLineStyle to true, legend boxes will be drawn as lines, as the following screenshot :
I was able to use pointStyle: line, in the dataset and then under options use labels: {usePointStyle: true,},
Just to improve on this solution from tektiv.
If you want to show a dashed line too use this code in the same spot.
(chartJs 2.7.2 around Line 16289):
if (opts.labels && opts.labels.usePointStyle) {
// CHARTJS CODE
} else if (opts.labels && opts.labels.useLineStyle) {
if (legendItem.borderDash) {
ctx.setLineDash(legendItem.borderDash);
}
ctx.beginPath();
ctx.moveTo(x, y + fontSize / 2);
ctx.lineTo(x + boxWidth, y + fontSize / 2);
ctx.stroke();
} else {
// CHARTJS CODE
}
chart.js v3
For this version, none of the previously mentioned built-in configurations work. You can set boxHeight: 0 on the legend labels in order to get a line instead of a box:
{
legend: {
labels: {
boxHeight: 0
}
}
}
You can make line legend by changing width of legend box (for example 2px), it will be vertical line but it's looks nice too
plugins: {
legend: {
display: true,
labels: {
boxWidth: 2
}
}
}

How can I draw dotted line using chartjs?

I would like to draw dotted line using chartjs. I did not see any options in creating dotted lines. I feel we need to extend the chartjs to support this. Can some one help me in this?
In Chart.js 2.1+, use the borderDash option within your dataset. It takes an array of two numbers. See this codepen
For dotted lines use borderDash and borderCapStyle. The following example creates a dotted line (3px diameter):
data: {
datasets: [
{
data : data,
borderWidth : 3, // set diameter of dots here
borderColor : '#ccc',
fill : false,
pointRadius : 0,
borderDash : [0,6], // set 'length' of dash/dots to zero and
// space between dots (center to center)
// recommendation: 2x the borderWidth
borderCapStyle : 'round' // this is where the magic happens
}
]
}
Output
Output (better contrast for demonstration)
Drawing a Dotted Line
You don't need to extend the chart, but it would be cleaner to do it that way.
Preview
Script
Chart.types.Line.extend({
name: "LineAlt",
initialize: function () {
Chart.types.Line.prototype.initialize.apply(this, arguments);
var ctx = this.chart.ctx;
var originalBezierCurveTo = ctx.bezierCurveTo;
ctx.bezierCurveTo = function () {
ctx.setLineDash([10, 10]);
originalBezierCurveTo.apply(this, arguments)
}
}
});
...
new Chart(ctx).LineAlt(chartData);
Fiddle - https://jsfiddle.net/ahj6u14e/
Note - the alternative would be to just override bezierCurveTo using the chart object.
This works because bezierCurveTo is only used to draw the line. If you wanted to do this for straight lines it wouldn't work because lineTo is used for other stuff (axis, grid lines...)
Chart.js 2.0 had a borderDash option when I last checked (see https://stackoverflow.com/a/31428640/360067)

Chart.JS spacing and padding

Is it possible to get some more space between the chart and the x-axis?
Is it possible to get some more space between the right side of the chart and the end of the canvas area? I want to add some more elements to the canvas right beside the chart but this is not possible because the chart takes the whole canvas width so it would overlap.
Shifting x axis Labels Vertically
The easiest way to do 1. is by adding spaces to your x labels. You can extend your chart type and override your initialize function to do this (increase 30 to something larger if your labels are long to start with anyway)
initialize: function(data){
data.labels.forEach(function(item, index) {
data.labels[index] += Array(Math.max(30 - item.length, 0)).join(" ");
})
Chart.types.Bar.prototype.initialize.apply(this, arguments);
},
Edit : As pointed out in the comments, this causes a horizontal shift as well and the label ends no longer align with the x axis markers.
Since both the x axis and the x labels are drawn in a single function and you have no other variables you can mess around with (safely) this means you'll have to change the actual scale draw function.
Look for a ctx.translate towards the end of the draw function and change it to
ctx.translate(xPos, (isRotated) ? this.endPoint + 22 : this.endPoint + 18);
You'll also have to adjust the endpoint (which drives the y limits) a bit so that the additional y offset doesn't cause the labels to overflow the chart (look for the line adjusting this in the draw override for 2.).
Leaving a gap on the Right Side
To do 2, you override your draw function (in your extended chart) and change xScalePaddingRight. However since this doesn't affect your horizontal grid lines you have to overlay a filled rectangle once your draw is complete. Your complete draw function would look like this
draw: function(){
// this line is for 1.
if (!this.scale.done) {
this.scale.endPoint -= 20
// we should do this only once
this.scale.done = true;
}
var xScalePaddingRight = 120
this.scale.xScalePaddingRight = xScalePaddingRight
Chart.types.Bar.prototype.draw.apply(this, arguments);
this.chart.ctx.fillStyle="#FFF";
this.chart.ctx.fillRect(this.chart.canvas.width - xScalePaddingRight, 0, xScalePaddingRight, this.chart.canvas.height);
}
Original fiddle - https://jsfiddle.net/gvdmxc5t/
Fiddle with modified Scale draw function - https://jsfiddle.net/xgc6a77a/ (I turned off animation in this one so that the endpoint is shifted only once, but you could just hard code it, or add some extra code so that it's done only once)
The 'tickMarkLength' option extends the grid lines outside the chart and pushes the ticks down.
xAxes: [
{
gridLines: {
tickMarkLength: 15
},
}
]
use this for chartjs 2.0
scales: {
xAxes: [{
barPercentage: 0.9,
categoryPercentage: 0.55
}]
Reference
In chartjs v3, there is an "offset" flag that you can set to true. This will create padding.
scales: {
x: {
offset: true,
}
}
If true, extra space is added to the both edges and the axis is scaled to fit into the chart area. This is set to true for a bar chart by default.
Documentation

How to change the color of the text of a QProgressBar with its value?

I don't know how to change the color of the text partially in the progress bar when its value becomes nearly 50%. This effect comes automatically in the fusion style progress bar (picture below). Does anyone know how this is done ?
Too lazy to write working example code, much less making a screenshot. Not even for 50 reps. :-)
However, the question was somewhat interesting. I had no idea how such a two colored text could be done. So I checked:
http://qt.gitorious.org/qt/qtbase/blobs/stable/src/widgets/styles/qfusionstyle.cpp
Line 1450ff (http://qt.gitorious.org/qt/qtbase/blobs/stable/src/widgets/styles/qfusionstyle.cpp#line1450).
QRegion rightRect = rect;
rightRect = rightRect.subtracted(leftRect);
painter->setClipRegion(rightRect);
painter->setPen(flip ? alternateTextColor : textColor);
painter->drawText(rect,
bar->text,
QTextOption(Qt::AlignAbsolute|
Qt::AlignHCenter|
Qt::AlignVCenter));
if (!leftRect.isNull())
{
painter->setPen(flip ? textColor : alternateTextColor);
painter->setClipRect(leftRect);
painter->drawText(rect,
bar->text,
QTextOption(Qt::AlignAbsolute|
Qt::AlignHCenter|
Qt::AlignVCenter));
}
Basically the text is drawn two times into the same rectangle. Each time with an appropriate clipping. Easy if you know how. :-)
From my point of view the best, and probably the easiest, way to do this is to change the pallet for the QProgressBar widget:
QPalette palette = progressBar->palette()
palette.setColor(QPalette::Text, textColor)
palette.setColor(QPalette::HighlightedText, textColor)
progressBar->setPalette(palette)
"The setBackgroundRole method let you use a color role for the background, which means one of the predefined color of the style applied to the widget. So your are basically limited to the style and its colors."
Background solution:
value = 65
self.progressBar.setProperty("value", value)
if value < 50:
self.progressBar.setStyleSheet("QProgressBar::chunk { background-color: black; }")
else:
self.progressBar.setStyleSheet("QProgressBar::chunk { background-color: black; } QProgressBar { color: white; }")
You can use stylesheet on the Container Widget :
myMainWidget.setStyleSheet(QString("QProgressBar {color: red}"));