About
RGraph is a JavaScript charts library based on
HTML5 SVG and canvas. RGraph is mature (over 17 years
old) and has a wealth of features making it an ideal
choice to use for showing charts on your website.
Download
Get the latest version of RGraph (version 6.20, 1st December 2024) from
the download page. You can read the changelog here. There's also older versions available,
minified files and links to cdnjs.com hosted libraries.
License
RGraph can be used for free under the GPL or if
that doesn't suit your situation there's an
inexpensive (£129) commercial license available.The bezierCurveTo function
Like the quadraticCurveTo
function, the bezierCurveTo
function can be used to add curves to your chart. It uses the
existing pen position as the start
point and then the first two coordinates as the first control point, the second two coordinates as the second control point
and the last two coordinates that you give it as the endpoint.
The curve that is drawn will not necessarily pass through the control points.
Arguments to the function
- The X1 coordinate (of the first control point, P1 on the diagram)
- The Y1 coordinate (of the first control point, P1 on the diagram)
- The X2 coordinate (of the second control point, P2 on the diagram)
- The Y2 coordinate (of the second control point, P2 on the diagram)
- The X3 coordinate (of the end-point, P3 on the diagram)
- The Y3 coordinate (of the end-point, P3 on the diagram)
P0 is not specified on the bezierCurveTo
function - this is done by a
moveTo
call before the bezierCurveTo
call.
As shown below.
An example
<script> window.onload = function () { var canvas = document.getElementById("cvs"); var context = canvas.getContext('2d'); context.beginPath(); // This is where the curve begins (P0) context.moveTo(10, 225); context.bezierCurveTo(100,50,200,50,290,225); context.stroke(); } </script>