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Charting Quick Overview

1 Overview

This document provides a quick overview of the Graphics Server's .Net Charting engine.  The following sections will discuss the high level architecture of the various components within the Charting engine and the areas of the engine that are extensible.

2 Chart Object

The Graphics Server charting engine is completely encapsulated within the Chart object.  The diagram below shows a high level view of the Chart object, the major components inside the Chart object and some of the major method calls supported by the Chart object.

The innovation to notice here is that the charting engine is built independent of any Win Form or Web Form user interface control.  This design provides the application developer the flexibility to attach the Chart object to any design or viewing surface their architecture requires.

3 Win and Web Form Control Wrappers (i.e. User Controls)

Many .Net developers do not require the flexibility the architecture allows via the stand alone Chart object.  These developers simply want to drop a chart on a windows form or a web form, bind to some data and quickly set some properties.  Graphics Server provides developers with two custom controls for this purpose, one for windows forms and one for web forms.

The simple diagram below shows how Graphics Server utilizes the Charting engine architecture by wrapping the Chart Object inside both of the mentioned custom controls.

The diagram also illustrates that the Chart Object can be easily wrapped by a 3rd Party user to fulfill any special development needs that their application requires.

4 Connecting Data to the Chart

Graphics Server has designed a flexible Charting Engine Architecture.  But where and how does the chart engine access data?  An equally flexible and robust Series Data Architecture has been implemented to provide the chart engine with data.  The high level diagram below illustrates the Series Data Architecture and how it hooks into the Charting Engine Architecture.  The following sub sections describe this diagram in more detail.

4.1 Data Provider Layer

Graphics Server provides a set of well defined .Net interfaces that describe the concept of a Data Provider.  The current charting product contains several Data Provider implementations with more to come in the future. 

By creating a set of well defined .Net interfaces for the Data Provider layer, Graphics Server has provided the user with the ability to extend this layer and create their own custom Data Providers for direct access to their data.  This is very useful when the 3rd party's data store does not quite fit into one of the provided Data Provider mechanisms.

Note also that each Data Provider object is a stand alone object.  In other words a user can instantiate one of these objects and use it outside of the charting architecture to access data simply by calling the various methods provided in the well defined set of interfaces.

4.2 Series Object

The Series object provides the glue between the chart engine and the data provider layer.  As the name implies this object represents the data for a single charting series.  Only the data is represented by this object and not any properties that dictate how the series draws when placed in a chart.  The concept of the series drawing properties will be discussed later.

A Series object is essentially empty until data is attached to one or more of the components within the Series.  The diagram below shows the X component attached to a Dataset Data Provider and the Y component attached to a OleDb Data Provider.  The Series Component concept will be discussed in more detail below.

When a Series Component is attached to a Data Provider it must be attached to a specified field source within that Data Provider.  For example, if there is Dataset that contains a table called Employee you might want to graph the salary (i.e. the salary field would be the field source) of all the employees.  This would be accomplished by placing the Dataset into a DataSetDataProvider, creating a Series object and attaching the Y component of the Series object to the salary field source within the DataSetDataProvider.

The diagram above also shows that different components in a Series object can be attached to different Data Provider objects (which may or may not be of the same Data Provider type).  Also shown in the diagram is a case where different components in a Series object are attached to different field sources in the same Data Provider.

The diagram below shows yet another variation where different Series objects can feed from the same Data Provider using different field sources.  This scenario even works if both Series are accessing the same exact field source (not pictured).

There are of course other variations of connecting Data Providers to Series Components that have not been mentioned.  These variations are left to the imagination of the user.

4.3 Series Component

What exactly is a Series Component and why do they exist?  The following is a list of the Series Component types that exist in a Series:

X	x-axis component
Y	y-axis component
Z	z-axis component
Angle	angular component of a polar coordinate (theta)
Radius	radial component of a polar coordinate or radius value for Bubble series
Open	opening value over a given interval
High	high value over a given interval
Low	low value over a given interval
Close	closing value over a given interval
Label	string that can be used to label an axis

Attaching data to a component or components in a Series defines which chart types can render that Series once the Series is attached to a Chart object.  For example, if a Series object contains the Y Component only (meaning data has been attached to the Y Component) then many of the line, bar and scatter chart types will be able to render that Series.  However, the Bubble chart type will not be able to render the Series because it requires data to be attached to the Radius Component along with the Y Component.  The High/Low chart type for graphing financial data will not be able to render the Series because that chart requires the High, Low, Open and Close components (see the help documentation concerning each chart type and the required components).

This may seem like a limitation but note that the following diagram shows a valid scenario.

This scenario shows a Series object that contains multiple components.  This configuration above allows a series object to be rendered by many more chart types if such a requirement existed in an application.

4.4 Attaching the Series Object to the Chart Object

Now that the Series Object has been created and contains components which are attached to data, the Series Object can be attached to a Chart Object.

The picture above shows two Chart Objects.  One chart has three attached Series Objects and the other chart has two attached Series Objects.  Note that both Chart Objects share a common Series Object.  Since the Series Object and the Chart Object are both stand alone objects it is valid to share a Series Object among many Chart Objects.

A great example for sharing the same Series Object between many charts is a situation where the user wants to view the same data as four different chart types simultaneously on the same form.

4.5 Series Drawing Object

Note that when a Series Object is attached to a Chart Object, the series is wrapped inside a Series Drawing Object and placed into the chart's Series Drawing Collection.  The Series Drawing Object contains the properties that control how the series renders in the chart.

For example, if a series is attached to two different charts then that series can be displayed as a green bar in one chart and as a red line in the other chart.  The Series Drawing object has a large and robust collection of properties.  Please consult the help documentation for more information on this subject.