CS476/576

Assignment #2

Due Midnight, Tuesday   Oct  5, 1999

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NAME

 
gDraw - group Draw: a white board for a group

        gDraw user1 user2 .....

DESCRIPTION

The program creates a top level window T on the displays
specified in the program arguments: user1, user2, ...
Each argument is in the form: name@host e.g., wahab@budyonny.

The top level window T contains:
 

 1) a window  W called the white board,
 2) a push button F  called the Floor control button,
 3) a push button C called the Clear button
 4) a push button Q called the quit button.
 
 See  Figure 1  bellow as a guide for the GUI inteface.

The Floor control button
 
1) Initially, F state is FREE:  its background color is YELLOW
   and its  labele is  "FREE". This state indicates
   that no one is currently using the white board.

2) If F  is  FREE , then any person, say X, can click on F
   and then use the white board. In such case, F state changes to BUSY.
   In the busy state, the label of  F changes to X.
   For example:  if X is wahab@budyonny, then F's label changes
   from "FREE" to "wahab@budyonny".
   However, the background color of F is GREEN for X
   and RED for all other participants.

3) If F is BUSY,   then F will not react to any person
   other than the person X whose label appears on F.
   If X clicks on F, then F state changes back to FREE.
 
 The WhiteBoard Commands
 

Here is the list of commands available to the users of  the white board W:

 Chalk:   Press and move the left button.
 Eraser:  Press and move the right button.
 Text:     Type text at the cursor position.

The Clear  Button

Only the person who has the floor can click on that button to erase
the content of the whiteboard.

The Quit Button
 
Any user can leave the program at any time by clicking on the
quit button Q. If the departing user's name appears on F,
then F's state changes to FREE.
The program terminates when the last person quits the program.