A canvas-based black Line chart
View the bare-bones, stripped-down version of this demo
This is quite an old demo of a Line chart but it has stood up through the years very well and still looks very presentable.
It's a black Line chart with two datasets that both use custom tickmarks.
These custom tickmarks are drawn by utilising the RGraph.path() API
function. This is a function that makes drawing with the canvas API
far less verbose than it usually is.
Before drawing commences, using the beforedraw event, the canvas
is cleared
to a plain black color. You might find this as a performance-enhancing tip
on various canvas performance articles though by the second frame you'll
not be drawing on a transparent canvas - so it might be a redundant
action.
The trace() Line chart effect is used here - but an options
object is passed
to the effects function call. This is 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 make for quicker animations that finish sooner.
The responsive() function changes the size of the text and the margins, changes the
CSS float to none and a callback function updates a global
variable that controls the size of the custom tickmarks. The callback function runs after
the chart has been redrawn so if you change anything here (as we're doing) then you need to redraw
the chart. That can be done by calling the RGraph.redraw() function.
<script src="RGraph.common.core.js"></script> <script src="RGraph.line.js"></script>Put this where you want the chart to show up:
<div style="float: right">
<canvas id="cvs" width="600" height="250" style="border-radius: 5px; box-shadow: 3px 3px 3px #ccc">[No canvas support]</canvas>
</div>
This is the code that generates the chart - it should be placed AFTER the canvas tag(s):