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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Chart.js Redraw Example</title> | |
| <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.0/jquery.min.js"></script> | |
| <script type="text/javascript" charset="utf-8" src="chart.min.js"></script> | |
| <script type="text/javascript" charset="utf-8"> | |
| window.chartOptions = { | |
| segmentShowStroke: false, | |
| percentageInnerCutout: 75, | |
| animation: false | |
| }; | |
| var chartUpdate = function(value) { | |
| console.log("Updating Chart: ", value); | |
| // Replace the chart canvas element | |
| $('#chart').replaceWith('<canvas id="chart" width="300" height="300"></canvas>'); | |
| // Draw the chart | |
| var ctx = $('#chart').get(0).getContext("2d"); | |
| new Chart(ctx).Doughnut([ | |
| { value: value, | |
| color: '#4FD134' }, | |
| { value: 100-value, | |
| color: '#DDDDDD' }], | |
| window.chartOptions); | |
| // Schedule next chart update tick | |
| setTimeout (function() { chartUpdate(value - 1); }, 1000); | |
| } | |
| $(document).ready(function() { | |
| setTimeout (function() { chartUpdate(99); }, 1000); | |
| }) | |
| </script> | |
| </head> | |
| <body> | |
| <canvas id="chart" width="300" height="300"></canvas> | |
| </body> | |
| </html> |
Do you need to do line #19? Woudln't it be enough with generating a new chart object? Or if you don't do that it will be drawn on top of it?
I get my data from a MySQL db, via PHP. Is there any way to keep the chart live-updated with the latest results from PHP?
@JJ it looks as if you do, because otherwise the height of the chart changes.
@xavbabe You would do an AJAX request and then on AJAX success you update the values.
good
I have been looking for a solution for live updates of graphs. I stumbled across this and noticed that to do the update, you are creating a new graph and replacing the previous canvas.
This looks OK on your demo, but if you re-enable animations this redraws the animations rather than smoothly updating.
We can alter the segment data and utilise the .update() method (keeping the same canvas and chart object making the updates smooth and without replacing elements, giving an easy way to pull updates via ajax)
--- updated example ---
<!DOCTYPE html>
<html>
<head>
<title>Chart.js Live Update Example</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.0/jquery.min.js"></script>
<script type="text/javascript" charset="utf-8" src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/1.0.2/Chart.js"></script>
<script type="text/javascript" charset="utf-8">
$(document).ready(function() {
var max_value = 60
chartOptions = {
segmentShowStroke: false,
percentageInnerCutout: 75,
animation: false
};
chartData = [{
value: 0,
color: '#4FD134'
},{
value: max_value,
color: '#DDDDDD'
}];
var ctx = $('#chart').get(0).getContext("2d");
var theChart = new Chart(ctx).Doughnut(chartData,chartOptions);
theInterval = setInterval(function(){
if (theChart.segments[0].value == max_value) {
clearInterval(theInterval);
} else {
theChart.segments[0].value = theChart.segments[0].value+1
theChart.segments[1].value = theChart.segments[1].value-1
theChart.update()
}
}, 1000);
});
</script>
</head>
<body>
<canvas id="chart" width="300" height="300"></canvas>
</body>
</html>
Hi! I am new to js and other web development tools. Can you please tell me at what part of your code you are accessing your database server to plot the real-time graph?
Thanks in advance. :)
@Siddhant08 He isn't, he is using:
setTimeout (function() { chartUpdate(value - 1); }, 1000);
at the end of chartUpdate to call the function again with a different value, this is also known as recursive programming.
Replacing the canvas to update the chart is brilliant! I tried with Chart.update() but never got it to work.
Hi this is a cool chart.
Is it possible if you can tell me how to do this with the bar graph?