There is getGraphics method in both javax.swing.JPanel and java.awt.Canvas. Th e proper Jess code

would be (within some function, or from Jess prompt)

(bind ?jp (new JPanel))

(bind ?g (?jp getGraphics))

(?g drawLine .....

To display you would need frame, ...  for example:

(import javax.swing.*)
(bind ?f (new JFrame))
(?f setSize 400 400)
(?f setVisible TRUE)
(bind ?jp (?f getContentPane))
(bind ?g (?jp getGraphics))
(?g drawLine 100 200 300 400)

Dusan Sormaz

At 08:58 AM 11/29/2005, you wrote:

I'm traying to make a GUI on wich I can plot some objekts.  I have made
the basic GUI I want by using java-commands through jess. I have made a
panel on wich I wish to be able to draw on, when a function is called.

My problem is that I can figure out how to make a variable of the type
Graphics in jess. If I write:

(defglobal ?*graph* = (new Graphics))

in the same way I have made the JPanels, I get an error massege saying the
constuctor is not found. And I have importes java.awt .

I have tryid to make a canves:
(defglobal ?*canvas* = (new jess.awt.Canvas painter (engine)))

and then use getGraphics on it, but I just can't make it work.

Does anyone have any ideas on how to make a function I can call, that will
be able to use the drawRect(...) and functions like that, in the library?

Basicly I just want to be able to draw a square of a given size and
position, on my panel when I want to.

I want to be able to call this function (because when that works I can
change it to whatever shape I want). It is the ?graph variable that is the
problem to create):

(deffunction draw ()
    ;;(new Graphics ?graph getGraphics)) ;; doesn't work
    ;;(?graph = (getGraphics ?*canvas*)) ;; doesn't work

    (?graph setColor (get-member java.awt.Color red))
    (?graph drawLine 0 0 600 600)
    (?graph drawLine 600 0 0 600)
    (?*f* repaint))

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* Dušan Šormaz, PhD, Associate Professor                     
* Ohio University
* Industrial and Manufacturing Systems Engineering Department
* 277 Stocker Center, Athens, OH 45701-2979
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