By using the clip() function the Line chart can be drawn in
two passes so that it's colored differently on each pass.
Update
There's information on this HOWTO page
about creating dual color Line charts using
gradients. It's very simple and can be done using either the
RGraph Gradient() shortcut or more directly with the canvas linear gradient functionality.
<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: 1px solid #ccc">
[No canvas support]
</canvas>
This is the code that generates the chart: