Re: paint program using canvas

From:

Andy Cho <dogmeat37@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 16 Aug 2009 07:12:28 -0700 (PDT)

Message-ID:

<408fe468-ba28-4eda-83df-3cf4ea328833@z31g2000yqd.googlegroups.com>

On 8=BF=F916=C0=CF, =BF=C0=C8=C43=BD=C322=BA=D0, Knute Johnson <nos...@rabb=
itbrush.frazmtn.com>
wrote:

Andy Cho wrote:

Hello all
I'm developing small paint program using canvas class.
But I don't know how retain lines which I draw.
All lines are disapeared when another window is on top of my paint
window.

And how can I control the thickness of lines.

Plaease give me an idea.
Thanks

Andy

import java.awt.*;
import java.awt.event.*;

public class test extends Canvas {
     public test() {
         setPreferredSize(new Dimension(640,480));
     }

     public void paint(Graphics g2d) {
         Graphics2D g = (Graphics2D)g2d;

         g.setColor(Color.GREEN);
         g.drawLine(10,getHeight()/2,getWidth()-10,getHeight()/2);

         g.setColor(Color.RED);
         g.setStroke(new BasicStroke(6.0f));
         g.drawLine(10,10,getWidth()-10,getHeight()-10);

         g.setColor(Color.BLUE);
         g.setStroke(new BasicStroke(2.0f));
         g.drawLine(getWidth()-10,10,10,getHeight()-10);
     }

     public static void main(String[] args) {
         final Frame f = new Frame();
         f.addWindowListener(new WindowAdapter() {
             public void windowClosing(WindowEvent we) {
                 f.dispose();
             }
         });

         test t = new test();
         f.add(t,BorderLayout.CENTER);
         f.pack();
         f.setVisible(true);
     }

}

--

Knute Johnson
email s/nospam/knute2009/

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I meet another problems.
If I dragged mouse faster, lines become discrete.

My code is here,

    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        if ( p2 == null || p3 == null ) {
            return;
        }
        g2.setStroke(new BasicStroke(5));
        Line2D line = new Line2D.Double(p2.x, p2.y, p3.x, p3.y);
        g2.draw(line);
        return;
    }

Thanks in advance
Andy