A black line chart
This is quite an old demo of a Line chart but has stood up through the years (months...?) very well and still looks very presentable.
Its simply a black line chart with two datasets that both use custom tickmarks. These custom tickmarks are drawn by utilising the RGraph.path2() API function. This is a function that makes drawing with the canvas API (on a canvas...) far less verbose than it usually is.
Before drawing commences, using the beforedraw event, the canvas is cleared to a plain black colour. You might find this as a performance enhancing tip on variopus canvas performance articles though by the second frame you'll not be drawing on a transparent canvas - so it might be a superfluous action.
The trace() Line chart effect is used here - but an options object is passed to the effect function call. This just a regular JavaScript object which contains a single property - frames. As the name suggests this stipulates the number of frames in the animation. Lower numbers mean for quicker animations that finish sooner.
This goes in the documents header:<script src="RGraph.common.core.js"></script> <script src="RGraph.line.js"></script>Put this where you want the chart to show up:
<canvas id="cvs" width="600" height="250" style="border-radius: 5px; box-shadow: 3px 3px 3px #ccc">
[No canvas support]
</canvas>
This is the code that generates the chart:
<script>
new RGraph.Line({
id: 'cvs',
data: [
[7.0,6.9,9.5,14.5,18.2,21.5,25.2,26.5,23.3,18.3,13.9,9.6],
[0.2,0.8,5.7,11.3,17.0,22.0,24.8,24.1,20.1,14.1,8.6, 2.5]
],
options: {
xaxisLabels: ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'],
shadow: false,
backgroundGridBorder: true,
axes: false,
colors: ['#0f0','#76D0FF'],
tickmarksStyle: function (obj, data, value, index, x, y, color, prevX, prevY)
{
RGraph.path2(
obj.context,
'b lw 2 a % % 6 0 % false f null s black',
x,
y,
RGraph.TWOPI
);
},
linewidth: 3,
textColor: '#eee',
marginLeft: 40,
marginBottom: 40,
marginTop: 40,
marginRight: 40
}
}).on('beforedraw', function (obj)
{
RGraph.clear(obj.canvas, 'black');
}).trace2({frames: 15});
</script>