GraphViz Charts (Experimental)

This document describes how to create GraphViz charts using the Chart API.

Important: The GraphViz chart is still experimental and subject to change.

Overview

GraphViz is a package of open source tools for visualizing connectivity graphs. You can create GraphViz graphs using the DOT language and your choice of layout engines.

GraphViz charts support a different set of required parameters. Here are the supported parameters:

Parameter	Required or Optional	Description
`cht=gv[:<opt_engine>]`	Required	Specifies a GraphViz chart. You can optionally specify a GraphViz engine. If you want to specify a layout engine, include the semicolon : mark and specify one of the following strings for <opt_engine>: `dot` - The default engine `neato` `twopi` `circo` `fdp` See the GraphViz website for a description of these different engines.
`chs=<width>x<height>`	Optional	If you don't specify a size, the chart will be sized automatically.
`chl=<DOT_string>`	Required	The chart to draw, in DOT language notation. You can find the DOT language reference on the GraphViz website.
`chd`	NOT USED	GraphViz codes are unusual in that the chd parameter is ignored. Don't include it in your URL.
`chof=<output_format>`	Optional	An output format for the chart. See the parameter description to learn what output formats are supported. If you specify `chof=json`, you will get back a JSON representation of the chart as HTML image map that you can use to add links or interactivity to the chart. See Creating a Chart Image Map for details.
`callback=<handling_function_name>`	Optional	If you specify `chof=json`, you can also specify a function to call with the returned JSON that includes the image map of the chart. Your function must accept a single JSON parameter, which will be a JSON representation of the chart. Your page can then specify your chart as an `<img>` element to render the chart, and also call the same URL with `chof=json&callback=somefunc`, and include a function called `somefunc()` that will parse the returned JSON and add links or interactivity.

Examples:

Description	Example
dot engine example (default).	`cht=gv chl=digraph{A->B->C->A} chs=150x150`
neato engine example of the same chart.	`cht=gv:neato chl=digraph{A->B->C->A} chs=150x150`
A dot chart, with no size specified. The chart is sized automatically.	`cht=gv chl=graph{a--b--c;b--d}`
A more complex chart.	`cht=gv chl= graph{C_0--H_0[type=s];C_0--H_1[type=s];C_0--H_2[type=s];C_0--C_1[type=s];C_1--H_3[type=s];C_1--H_4[type=s];C_1--H_5[type=s]}`

Here are some tips and known limitations in the current GraphViz charts:

The graph attribute size should be not be used; use the Chart API parameter chs instead.
The maximum number of nodes is 200, and the maximum for edges is 400.
Anti-aliasing, transparency, and alternate fonts are not supported.
The node attributes image and shapefile are not supported, and will result in an error if present.
The graph attributes ratio, margin, and pad are not supported, and will be ignored if present.

Image Charts (Deprecated)

Overview

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