A black line chart

[No canvas support]

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: {
            labels: ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'],
            shadow: false,
            noxaxis: true,
            noyaxis: true,
            colors: ['#0f0','#76D0FF'],
            tickmarks: 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',
            gutterLeft: 40,
            gutterBottom: 40,
            gutterTop: 40,
            gutterRight: 40
            
        }
    }).on('beforedraw', function (obj)
    {
        RGraph.clear(obj.canvas, 'black');

    }).trace2({frames: 15});
</script>