Subversion Repositories Applications.papyrus

Rev

Rev 1987 | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
1318 alexandre_ 1
Dojo Charting Engine
2
=========================================================================
3
The Dojo Charting Engine is a (fairly) complex object structure, designed
4
to provide as much flexibility as possible in terms of chart construction.
5
To this end, the engine details the following structure:
6
 
7
Chart
8
---PlotArea[]
9
------Plot[]
10
---------Axis (axisX)
11
---------Axis (axisY)
12
---------Series[]
13
 
14
 
15
A Chart object is the main entity; it is the entire graphic.  A Chart may
16
have any number of PlotArea objects, which are the basic canvas against
17
which data is plotted.  A PlotArea may have any number of Plot objects,
18
which is a container representing up to 2 axes and any number of series
19
to be plotted against those axes; a Series represents a binding against
20
two fields from a data source (initial rev, this data source is always of
21
type dojo.collections.Store but this will probably change once dojo.data
22
is in production).
23
 
24
The point of this structure is to allow for as much flexibility as possible
25
in terms of what kinds of charts can be represented by the engine.  The
26
current plan is to accomodate up to analytical financial charts, which tend
27
to have 3 plot areas and any number of different types of axes on each one.
28
 
29
The main exception to this is the pie chart, which will have it's own
30
custom codebase.  Also, 3D charts are not accounted for at this time,
31
although the only thing that will probably need to be altered to make
32
that work would be Plot and Series (to accomodate the additional Z axis).
33
 
34
Finally, a Plot will render its series[] through the use of Plotters, which
35
are custom methods to render specific types of charts.
36
-------------------------------------------------------------------------
37
In terms of widgets, the basic concept is that there is a central, super-
38
flexible Chart widget (Chart, oddly enough), and then any number of preset
39
chart type widgets, that are basically built to serve a simple, easy
40
purpose.  For instance, if someone just needs to plot a series of lines,
41
they would be better off using the LineChart widget; but if someone needed
42
to plot a combo chart, that has 2 Y Axes (one linear, one log) against the
43
same X Axis, using lines and areas, then they will want to use a Chart widget.
44
Note also that unlike other widgets, the Charting engine *can* be called
45
directly from script *without* the need for the actual widget engine to be
46
loaded; the Chart widgets are thin wrappers around the charting engine.