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I have a bar chart in Chart.js (using the latest version), and I want to make some visual change when the mouse is hovering over a category label. How would I implement either or both of the following visual changes?
Make the cursor be a pointer while hovering over a label.
Make the label be in a different color while it is being hovered on.
A related question is here: How to detect click on chart js 3.7.1 axis label?. However, my question is about hovering over a label, without clicking on the label.
In the example below, I want something to happen when hovering on these texts: Item A, Item B, Item C.
window.onload = function() {
var ctx = document.getElementById('myChart').getContext('2d');
window.myBar = new Chart(ctx, {
type: 'bar',
data: {
labels: ['Item A', 'Item B', 'Item C'],
datasets: [{
data: [1, 2, 3],
backgroundColor: 'lightblue'
}]
},
options: {
responsive: true,
indexAxis: 'y',
plugins: {
legend: {
display: false
},
tooltip: {
enabled: false
},
}
}
});
};
.chart-container {
position: relative;
height: 90vh;
}
<script src="https://cdn.jsdelivr.net/npm/chart.js#4.2.0"></script>
<div class="chart-container">
<canvas id="myChart"></canvas>
</div>
You can just use the custom plugin from that question and ignore everything but mousemove events instead of ignoring everything but click events:
const findLabel = (labels, evt) => {
let found = false;
let res = null;
labels.forEach(l => {
l.labels.forEach((label, index) => {
if (evt.x > label.x && evt.x < label.x2 && evt.y > label.y && evt.y < label.y2) {
res = {
label: label.label,
index
};
found = true;
}
});
});
return [found, res];
};
const getLabelHitboxes = (scales) => (Object.values(scales).map((s) => ({
scaleId: s.id,
labels: s._labelItems.map((e, i) => ({
x: e.translation[0] - s._labelSizes.widths[i],
x2: e.translation[0] + s._labelSizes.widths[i] / 2,
y: e.translation[1] - s._labelSizes.heights[i] / 2,
y2: e.translation[1] + s._labelSizes.heights[i] / 2,
label: e.label,
index: i
}))
})));
const plugin = {
id: 'customHover',
afterEvent: (chart, event, opts) => {
const evt = event.event;
if (evt.type !== 'mousemove') {
return;
}
const [found, labelInfo] = findLabel(getLabelHitboxes(chart.scales), evt);
if (found) {
console.log(labelInfo);
}
}
}
Chart.register(plugin);
const options = {
type: 'line',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
borderColor: 'pink'
},
{
label: '# of Points',
data: [7, 11, 5, 8, 3, 7],
borderColor: 'orange'
}
]
},
options: {}
}
const ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);
<body>
<canvas id="chartJSContainer" width="600" height="400"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.1/chart.js"></script>
</body>
To change the cursor to a pointer when hovering over a category label in a Chart.js bar chart, you can add:
options: {
plugins: {
tooltip: {
mode: 'index',
intersect: false
},
},
interaction: {
mode: 'index',
intersect: false
},
onHover: function(evt, elements) {
if (elements.length) {
document.getElementById("myChart").style.cursor = "pointer";
} else {
document.getElementById("myChart").style.cursor = "default";
}
},
// ...
}
To change the color of a label when it is being hovered on, you can add:
options: {
plugins: {
tooltip: {
mode: 'index',
intersect: false
},
},
interaction: {
mode: 'index',
intersect: false
},
onHover: function(evt, elements) {
if (elements.length) {
var chart = evt.chart;
var datasetIndex = elements[0].datasetIndex;
var index = elements[0].index;
chart.data.labels[index] = '<span style="color: red;">' + chart.data.labels[index] + '</span>';
chart.update();
} else {
var chart = evt.chart;
chart.data.labels = ['Item A', 'Item B', 'Item C'];
chart.update();
}
},
// ...
}
To make the cursor a pointer while hovering over a label, you can try to assign a CSS cursor value to event.native.target.style.cursor when hover is triggered.
event.native.target.style.cursor = 'pointer';
To make the label a different color while it is being hovered on, you can try this
myChart.config.options.scales.y.ticks.color = hoverColors; // ['black','red','black'], ['black','black','red'], ['red','black','black']
UPDATE
Thanks to LeeLenalee for giving an almost correct answer. I've edited the code above so it fits what is required in the problem. Don't forget to change source of the library in the HTML from :
https://cdn.jsdelivr.net/npm/chart.js#4.2.0
to :
https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.1/chart.js
Updated code:
window.onload = function() {
const findLabel = (labels, evt) => {
let found = false;
let res = null;
try {
labels.forEach(l => {
l.labels.forEach((label, index) => {
if (evt.x > label.x && evt.x < label.x2 && evt.y > label.y && evt.y < label.y2) {
res = {
label: label.label,
index
};
found = true;
}
});
});
} catch (e) {}
return [found, res];
};
const getLabelHitboxes = (scales) => {
try {
return Object.values(scales).map((s) => ({
scaleId: s.id,
labels: s._labelItems.map((e, i) => ({
x: e.translation[0] - s._labelSizes.widths[i],
x2: e.translation[0] + s._labelSizes.widths[i] / 2,
y: e.translation[1] - s._labelSizes.heights[i] / 2,
y2: e.translation[1] + s._labelSizes.heights[i] / 2,
label: e.label,
index: i
}))
}));
} catch (e) {}
};
const changeCursorAndLabelColor = (event, chart, index, hoverMode) => {
// your hover color here
// const hoverColor = '#ff0000';
const hoverColor = 'red';
const hoverColors = [];
for (let i = 0; i < myChart.data.datasets[0].data.length; i++) {
if (hoverMode) {
// change cursor
event.native.target.style.cursor = 'pointer';
if (index === i) {
hoverColors.push(hoverColor);
} else {
hoverColors.push(defaultLabelColor);
}
} else {
// change cursor
event.native.target.style.cursor = 'default';
hoverColors.push(defaultLabelColor);
}
}
// change label to your hover color
myChart.config.options.scales.y.ticks.color = hoverColors;
// update chart when hover is triggered
myChart.update();
}
let foundMode = false;
const plugin = {
id: 'customHover',
afterEvent: (chart, event, opts) => {
const evt = event.event;
if (evt.type !== 'mousemove') {
return;
}
const [found, labelInfo] = findLabel(getLabelHitboxes(chart.scales), evt);
if (found && myChart.data.labels.includes(labelInfo.label)) {
changeCursorAndLabelColor(evt, chart, labelInfo.index, true);
foundMode = true;
} else {
if (foundMode) changeCursorAndLabelColor(evt, chart, null, false);
foundMode = false;
}
}
}
Chart.register(plugin);
var ctx = document.getElementById('myChart');
const myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ['Item A', 'Item B', 'Item C'],
datasets: [{
label: 'My Data',
data: [1, 2, 3],
backgroundColor: 'lightblue'
}]
},
options: {
responsive: true,
indexAxis: 'y',
plugins: {
legend: {
display: false
},
tooltip: {
enabled: false
},
},
onHover: (event, chart) => {
if (foundMode) changeCursorAndLabelColor(event, chart, null, false);
foundMode = false;
}
}
});
const defaultLabelColor = myChart.config.options.scales.y.ticks.color;
};
.chart-container {
position: relative;
height: 90vh;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.1/chart.js"></script>
<div class="chart-container">
<canvas id="myChart"></canvas>
</div>
Related
I have tried the events provided in the documentation as well as some suggestions in some answers but they only work when the bar is clicked not the label. When I click on the label I only get an empty array on "element".
Here is what worked for me so far from clicking on the data bar but doesn't work on label click :
setOptions({
...
onClick: function (evt, element) {
// Get the index clicked:
const index = element[0]?.index;
},
});
Any help would be appreciated.
You can use a custom plugin to achieve this:
const findLabel = (labels, evt) => {
let found = false;
let res = null;
labels.forEach(l => {
l.labels.forEach(label => {
if (evt.x > label.x && evt.x < label.x2 && evt.y > label.y && evt.y < label.y2) {
res = {
label: label.label,
index: label.index
};
found = true;
}
});
});
return [found, res];
};
const getLabelHitboxes = (scales) => (Object.values(scales).map((s) => ({
scaleId: s.id,
labels: s._labelItems.map((e, i) => ({
x: e.translation[0] - s._labelSizes.widths[i] / 2,
x2: e.translation[0] + s._labelSizes.widths[i] / 2,
y: e.translation[1] - s._labelSizes.heights[i] / 2,
y2: e.translation[1] + s._labelSizes.heights[i] / 2,
label: e.label,
index: i
}))
})));
const options = {
type: 'line',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
borderColor: 'pink'
},
{
label: '# of Points',
data: [7, 11, 5, 8, 3, 7],
borderColor: 'orange'
}
]
},
options: {},
plugins: [{
id: 'customHover',
afterEvent: (chart, event, opts) => {
const evt = event.event;
if (evt.type !== 'click') {
return;
}
const [found, labelInfo] = findLabel(getLabelHitboxes(chart.scales), evt);
if (found) {
console.log(labelInfo);
}
}
}]
}
const ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);
<body>
<canvas id="chartJSContainer" width="600" height="400"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.7.1/chart.js"></script>
</body>
I have few values like A and B now I have pair of them I am showing them on chart-js like this
Now for my use case, I am calculating the third value using A and B. E.g a=100 and b=50, and dividing them will give me c=2.0. Now I want to show this c value on top of A and B bar as a common label like this
"chart.js": "^3.3.0",
react-js
const newChartInstance = new Chart(chartContainer.current, {
type: "bar",
options: {
scales: {
yAxes: [
{
ticks: {
beginAtZero: true,
},
},
],
},
...config.options,
onClick: (e) => {
const points = newChartInstance.getElementsAtEventForMode(
e,
"nearest",
{ intersect: true },
true
);
if (points.length) {
const firstPoint = points[0];
var type =
newChartInstance.data.datasets[firstPoint.datasetIndex].label;
var label = newChartInstance.data.labels[firstPoint.index];
var value =
newChartInstance.data.datasets[firstPoint.datasetIndex].data[
firstPoint.index
];
// This is the result that you will use to breakdown the chart
//console.log(label, value, type);
dispatch(setClickedBar({ label, value, type, tile: props.tile }));
}
},
},
data: data,
});
You can use a custom plugin for that:
var options = {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: 'red'
},
{
label: '# of Points',
data: [7, 11, 5, 8, 3, 7],
backgroundColor: 'blue'
}
]
},
options: {
plugins: {
customValue: {
name: 'ROI',
}
}
},
plugins: [{
id: 'customValue',
afterDraw: (chart, args, opts) => {
const {
ctx,
data: {
datasets
},
_metasets
} = chart;
datasets[0].data.forEach((dp, i) => {
let barValue = `${(datasets[1].data[i] + dp) / 2}%`;
const lineHeight = ctx.measureText('M').width;
const textVal = opts.name || 'fill'
ctx.textAlign = 'center';
ctx.fillText(barValue, _metasets[0].data[i].x, (_metasets[0].data[i].y - lineHeight * 1.5), _metasets[0].data[i].width);
ctx.fillText(textVal, _metasets[0].data[i].x, (_metasets[0].data[i].y - lineHeight * 3), _metasets[0].data[i].width);
});
}
}]
}
var ctx = document.getElementById('chartJSContainer').getContext('2d');
new Chart(ctx, options);
<body>
<canvas id="chartJSContainer" width="600" height="400"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.4.1/chart.js"></script>
</body>
I have a line chart and I set up my tooltip like this
options: {
tooltips:{
mode: 'x',
intersect: false,
callbacks: {
footer: function(tooltipItem, data) {
return 'some text'
}
}
},
}
It works fine. The problem I have is that when I move my cursor to the x-axis ticks, which are outside the main plot/canvas, the tooltips stills appear. I've tried to set intersect: true but then the tooltip only shows up when I hover directly over the points. Ideally I want the tooltips to appear whenever I hover over the vertical gridlines (happens when intersect:false), but to not appear when my cursor moves outside of the main canvas. Is it possible?
Fiddle: https://jsfiddle.net/dqdqdq/yp47oL9t/47/
You can use the onHover callback in the options to check if the mouse is in the chartArea if so set the tooltip to enabled else disable the tooltip.
You might want to check also if the value you are setting is already the correct value since it will save a lot of unesesarry updates
Example (V2):
const updateTooltipShow = (chart, enabled) => {
chart.options.tooltips.enabled = enabled;
chart.update();
}
const ctx = document.getElementById('myChart').getContext('2d');
const myChart = new Chart(ctx, {
type: 'line',
data: {
labels: [1, 2, 3, 4],
datasets: [{
data: [1, 2, 3, 4],
backgroundColor: "rgba(153,255,51,0.6)"
},
]
},
options: {
onHover: function(e, activeElements) {
const {
bottom,
top,
right,
left
} = this.chartArea;
if (e.x >= left && e.x <= right && e.y <= bottom && e.y >= top) {
updateTooltipShow(this, true)
} else {
updateTooltipShow(this, false)
}
},
tooltips: {
mode: 'x',
intersect: false,
callbacks: {
footer: function(tooltipItem, data) {
return 'some text'
}
}
},
}
});
<canvas id="myChart"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.1/Chart.bundle.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/chartjs-plugin-datalabels#0.2.0/dist/chartjs-plugin-datalabels.min.js"></script>
Example (V3):
const updateTooltipShow = (chart, enabled) => {
chart.options.plugins.tooltip.enabled = enabled;
chart.update();
}
const ctx = document.getElementById('myChart').getContext('2d');
const myChart = new Chart(ctx, {
type: 'line',
data: {
labels: [1, 2, 3, 4],
datasets: [{
data: [1, 2, 3, 4],
backgroundColor: "rgba(153,255,51,0.6)"
},
]
},
options: {
onHover: (e, activeElements, chart) => {
const {
bottom,
top,
right,
left
} = chart.chartArea;
if (e.x >= left && e.x <= right && e.y <= bottom && e.y >= top) {
updateTooltipShow(chart, true)
} else {
updateTooltipShow(chart, false)
}
},
plugins: {
tooltip: {
mode: 'x',
intersect: false,
callbacks: {
footer: function(tooltipItem, data) {
return 'some text'
}
}
},
}
}
});
<canvas id="myChart"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/3.4.0/chart.js"></script>
I wrote a simple plugin for hiding the caption when you move your cursor out of the main canvas:
plugins: [{
id: "toolbarHider",
afterEvent: (chart: any, evt: any, opts: any) => {
const { left, right, bottom, top } = chart.chartArea;
const e = evt.event;
const status = e.x >= left && e.x <= right && e.y <= bottom && e.y >= top;
if (status !== chart.options.plugins.tooltip.enabled) {
chart.options.plugins.tooltip.enabled = status;
chart.update();
}
}
}]
More about Chart.js plugins.
I'm trying to show weight_id retrieved from mysql data in a chart.js tooltip (shown as (weight_ids[index]) in the image). And later, I intend to show a modal instead of a tooltip to let users update or delete that data. I presume I cannot achieve that without linking the linechart's point data with id stored in mysql. How can I incorporate this id data?
I would appreciate any help very much.
enter image description here
My code is as follows:
<canvas id="myChart"></canvas>
<script src="https://cdn.jsdelivr.net/npm/chart.js#2.9.4/dist/Chart.min.js"></script>
{{-- グラフを描画--}}
<script>
//ラベル
const labels = #json($date_labels);
// id
const weight_ids = #json($weight_ids);
//体重ログ
const weight_logs = #json($weight_logs);
const aryMax = function(a, b) {
return Math.max(a, b);
};
const aryMin = function(a, b) {
return Math.min(a, b);
};
let min_label = Math.floor((weight_logs).reduce(aryMin) - 0.5);
let max_label = Math.ceil((weight_logs).reduce(aryMax) + 0.5);
console.log(weight_ids);
console.log(weight_logs);
console.log(min_label, max_label);
//グラフを描画
var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
type: 'line',
data : {
labels: labels, // x軸ラベル
datasets: [
{
label: `Weight (weight_ids[index])`,
data: weight_logs,
tension: 0,
borderColor: "rgba(37,78,255,1)",
backgroundColor: "rgba(0,0,0,0)",
pointRadius: 3
}
]
},
options: {
title: {
display: false,
text: ''
},
legend: {
display: false,
},
scales: {
yAxes: [
{
ticks: {
min: min_label, // ラベル最小値
max: max_label, // ラベル最大値
},
scaleLabel: {
display: true,
fontSize: 16,
labelString: '体重 (kg)'
}
}
],
},
hover: {
mode: 'point'
},
onClick: function clickHandler(evt) {
var firstPoint = myChart.getElementAtEvent(evt)[0];
if (firstPoint) {
var label = myChart.data.labels[firstPoint._index];
var value = myChart.data.datasets[firstPoint._datasetIndex].data[firstPoint._index];
console.log(label);
console.log(value);
if (value) {
$('#weidhtModal').modal('show');
}
}
}
}
});
</script>
Thank you!
I found a way to retrieve weight_id using the following function.
onClick: function clickHandler(evt, activeElements) {
if (activeElements.length) {
var element = this.getElementAtEvent(evt);
var index = element[0]._index;
var _datasetIndex = element[0]._datasetIndex;
var weightId = weight_ids[index];
var weightLog = weight_logs[index];
console.log(index);
console.log(weightId);
console.log(this.data.labels[index]);
console.log(weightLog);
}
}
I'm trying to get chartjs to hide pie slices on click; the same behavior seen when clicking on the legend.
Here is the code I'm using - I commented out the code that actually removes the data from the chart since it doesn't re-render the pie chart correctly.
const values = [50, 55, 60, 33];
const data = {
labels: ["India", "China", "US", "Canada"],
datasets: [{
data: values,
backgroundColor: [
"#4b77a9",
"#5f255f",
"#d21243",
"#B27200"
],
borderColor: "#fff"
}]
};
const options = {
tooltips: {
enabled: false
},
legend: {
enabled: true,
position: 'bottom'
},
animation: false,
onClick: handleClick,
plugins: {
datalabels: {
formatter: (value = 0, ctxx) => {
const sum = values.reduce((acc, val = 0) => (acc + val), 0);
return `${(value * 100 / sum).toFixed(2)}%`;
},
color: '#fff',
}
}
};
const ctx = document.getElementById("pie-chart").getContext('2d');
const myChart = new Chart(ctx, {
type: 'pie',
data,
options: options
});
function handleClick(e, slice) {
setTimeout(() => {
const legend = myChart.legend.legendItems;
if (slice && slice[0]) {
// get clicked on slice index
const sliceIndex = slice[0]._index;
// Removing the data "really" messes up the chart
// myChart.data.labels.splice(sliceIndex, 1);
// myChart.data.datasets[0].data.splice(sliceIndex, 1);
legend[sliceIndex].hidden = true;
chart.update();
}
const visibleSlices = legend.filter(l => !l.hidden);
console.log('visible slices', visibleSlices);
});
}
<script src="https://cdn.jsdelivr.net/npm/chartjs-plugin-datalabels#0.4.0/dist/chartjs-plugin-datalabels.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<canvas id="pie-chart"></canvas>
It seems like setting the hidden flag then updating the chart should work because that's what the plugin is doing: https://github.com/chartjs/Chart.js/blob/master/src/plugins/plugin.legend.js#L20-L30.
The code below is hiding a slice by the index
myChart.getDatasetMeta(0).data[sliceIndex].hidden = true
const values = [50, 55, 60, 33];
const data = {
labels: ["India", "China", "US", "Canada"],
datasets: [{
data: values,
backgroundColor: [
"#4b77a9",
"#5f255f",
"#d21243",
"#B27200"
],
borderColor: "#fff"
}]
};
const options = {
tooltips: {
enabled: false
},
legend: {
enabled: true,
position: 'bottom'
},
animation: false,
onClick: handleClick,
plugins: {
datalabels: {
formatter: (value = 0, ctxx) => {
const sum = values.reduce((acc, val = 0) => (acc + val), 0);
return `${(value * 100 / sum).toFixed(2)}%`;
},
color: '#fff',
}
}
};
const ctx = document.getElementById("pie-chart").getContext('2d');
const myChart = new Chart(ctx, {
type: 'pie',
data,
options: options
});
function handleClick(e, slice) {
setTimeout(() => {
const legend = myChart.legend.legendItems;
if (slice && slice[0]) {
const sliceIndex = slice[0]._index;
myChart.getDatasetMeta(0).data[sliceIndex].hidden = true
myChart.update();
}
});
}
<script src="https://cdn.jsdelivr.net/npm/chartjs-plugin-datalabels#0.4.0/dist/chartjs-plugin-datalabels.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<canvas id="pie-chart"></canvas>