eZ component: Graph, Requirements
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:Author:   Derick Rethans
:Revision: $Revision$
:Date:     $Date$

Introduction
============

Description
-----------

The purpose of this component is to generate different kinds of diagrams from
different kinds of data. The diagrams' appearance needs to be slick and
customizable.

Requirements
============
The first version of the component should cover the following types of
charts:

Piechart
--------
A diagram showing values as elements of a piechart. It should support:

- highlighted parts (shown as a little bit outwards of the pie)
- setting a tresh hold under which values are combined together in an "others"
  part
- automatic colours, but they should be able to set manually too
- automatic legenda generation and label placement
- 2D view, like:
  http://www.eia.doe.gov/neic/brochure/gas04/images/pie%20chart.gif
- 3D view, like: http://www.chambersfund.org/images/piechart.jpg
- background image and/or colours

Linechart
---------
A diagram with a variable y-axis showing values for a finite set of data
points. The chart should be able to show different data sets, but all measured
only in the same unit. 

Line charts should support:

- automatic colours and styles, but each dataset should be able to be styled
  manually
- automatic scaling of the x and y-axis
- automatic legenda generation
- automatic label placement for both x and y-axis
- options for setting when to draw vertical and horizontal lines, and in which
  style they should be drawn
- 2D view, like: http://www.swiftchart.com/line_ex5.jpg
- 3D view, like: http://www.jspwiki.org/attach/LineChart/Line+Chart+3D.png
- background image and/or colours

Special Considerations
======================

The component should be flexible enough to allow averaging and other analysis
methods to work on datasets and add rendered data to the resulting graph. This
can for example be trend analysis or mean average etc.

Formats
=======

Graphs should be rendered as PNGs in the first version, but it should be
possible to have different renders to render to f.e. SVG or flash in later
versions of the component.


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