Restricting the drawing area on a JPanel and saving graphics states

Question

The purpose of the black JPanel is drawing.

How can I restrict the drawing to the radius of the circle formed by the lines?
Is there a way to save the graphics object state so that more drawing can be added to it as well as adding an undo function?

public void paintComponent(Graphics g)
{
    super.paintComponent(g);

    sectors = 12;

    Graphics2D g2d = (Graphics2D) g;    
    g2d.setColor(Color.RED);

    sector = new Line2D.Double(getWidth()/2, 0, getWidth()/2, getHeight());
    //g2d.setClip(new Ellipse2D.Double(getWidth()/2,getHeight()/2, radius, radius));


    //draws the sectors on the screen
    for(int i=0; i<sectors; i++)
    {   
        g2d.draw(sector);
        g2d.rotate(Math.toRadians(30),getWidth()/2,getHeight()/2);
    }

    //draws the doily
    if(dragging)
    {
        for(int i=0; i<sectors; i++)
        {
            g2d.fillOval((int) draw.getX(), (int) draw.getY(),20, 20);
            g2d.rotate(Math.toRadians(30), getWidth()/2, getHeight()/2);
        }

        //saves the current drawing in a stack
        graphics.push(g2d);
    }
}

I just set its color to black and give it a size. Everything else is in paintComponent() — Radoslav Todorov, Mar 05 '17 at 14:58
1) For better help sooner, post a [MCVE] or [Short, Self Contained, Correct Example](http://www.sscce.org/). 2) *"How can I restrict the drawing to the radius of the circle formed by the lines?"* [`Graphics.setClip(Shape)`](http://docs.oracle.com/javase/8/docs/api/java/awt/Graphics.html#setClip-java.awt.Shape-) 3) *"Is there a way.."* Whoah! This is a Q&A site, not a help desk. Each specific question should be self contained, and on its own question thread. I suggest you [edit] this post to remove the 2nd question, or it's in risk of being closed as 'too broad'. — Andrew Thompson, Mar 05 '17 at 15:10
*"I have no problems taking risks."* You just took a risk on a down vote. Congrats! You won one. And a tip: Tip: Add @Kennedy (or whoever, the `@` is important) to *notify* the person of a new comment. — Andrew Thompson, Mar 05 '17 at 16:44

score 0 · Accepted Answer · edited May 23 '17 at 11:53

0

For your first question,

You would need to read up on Java's Custom Painting http://docs.oracle.com/javase/tutorial/uiswing/painting/

Not to discourage you but this is a tricky process, To answer your question there is a similar post here Java Change shape of JPanel

edited May 23 '17 at 11:53

Community

1
1

answered Mar 05 '17 at 15:21

Kennedy

547
4
23

Restricting the drawing area on a JPanel and saving graphics states

1 Answers1