graphics lab

Some problems lend themselves very nicely to description in terms of objects. This is one of them. This is also an example of how quickly a simple class can become large and inefficient.

 

Approach:

Step 1: list all properties and actions required to implement the library (pretty much done in the Assignment specification and below)

 

Step 2: identify those things that are objects in this problem.

Each object has:

- responsibilities:

- consists of .. (is/ has)

- keeps track of...

- behaviour:

- what it can do

- what it does for others

- reports on...

 

Step 3: identify the relationships and/or hierarchy between the classes

 

Step 4: examine the set for message passing requirements

- which classes need to transfer information between each other?

- which direction is the transfer (into, out of, both ways)?

 

Vector Graphics

<graphics> (Sometimes called "object-oriented" graphics, though it's nothing to do with object-oriented programming). A drawing program which deals with separate shapes such as lines, polygons and text and groups of such objects as opposed to a painting program which stores only bitmaps. The advantage is that it is possible to change any element of the picture at any time since each part is stored as an independent object whereas once something in a bitmap has been overwritten it cannot in general be retrieved.

(Source: http://wombat.doc.ic.ac.uk/foldoc/foldoc.cgi?vector+graphics)

 

The display for this assignment will be implemented as an n x m array of ASCII characters where each character represents one pixel. (Suggestion: use '*'). For the basic requirements pixels need only be "black" ('*') or "white" (' ').