Java Reference
In-Depth Information
The system should make a distinction between the stroke color (the out-
line) and the fill color (the interior) of a shape. Therefore, each shape will
have a separate stroke and fill color. Lines and polylines will have only a
stroke color because they cannot be filled.
■
An option to save a drawing under a particular name should be provided
(the traditional “save as” operation).
■
Traditional keyboard shortcuts for operations such as cut, copy, and paste
should be included.
■
The system should perform checks to ensure that the user does not lose
unsaved changes to a drawing.
■
The system should present an initial “splash screen” to introduce the pro-
gram when it is executed.
These issues must be integrated into the formal description of the requirements
document for the project. Several discussions with the client, with additional
screen sketches, may be necessary before we have an accurate and solid set of
program requirements.
■
PaintBox
Architectural Design
After we have clarified the requirements with the client, we can begin to think
about some of the elements of the high-level
architectural design
of the system.
For example, many of the classes needed for the user interface can come from the
Java standard class library in the Swing package.
It also seems reasonable that a separate class could be used to represent each
shape type. Further, each individually drawn shape should be an instantiation of
the appropriate shape class. For example, we could define an
Oval
class to rep-
resent an oval, a
Line
class to represent a line, and so on. Each class should be
responsible for keeping track of the information it needs to define it, and it should
provide methods to draw itself.
A drawing may be composed of many shapes, so we need a way to keep track
of all of them. An
ArrayList
might be a good choice for this. As each new shape
is drawn, we can add the object that represents it to the list. The list will also
inherently define the order in which shapes are drawn. Since some shapes will be
drawn on top of others, the list will also keep track of the order in which shapes
are “stacked.”
The process of defining an architectural design could take a while. The key is
to make the most important and fundamental decisions that will affect the entire
system without skipping ahead to decisions that are better left to individual refine-
ments of the system.
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