But, let??™s get back to the technology??”how is this implemented?
The resource and data retrieval tiers are the same as for the text-based price history
pane you saw previously. If you??™ve skipped ahead, you should return to the ???Creating the
Price History Pane??? section, which describes the DataTier web service and how you can
use it to retrieve the price history of a stock.
To implement the charts, the example uses the ZedGraph open source library.
Using the ZedGraph Library Charting Engine
ZedGraph (http://zedgraph.org) is an open source set of classes, written in C#, that enable
the creation of various 2D graphs of arbitrary datasets. Because the set is class-based, it has
a high degree of programmatic flexibility, and you can modify almost every aspect of a
graph, including features such as scale ranges, scale types, step sizes, and so on, to be overridden
from their defaults. It also allows for multirange, multitype, multiaxis graphs to be
overlaid in a single chart. See Figure 10-13 for an example of a single chart that includes
stacked bars, transparent overlays, filled lines, legends, and annotations.
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