CODEWITHSUNDEEP
javaswingjava-2dpaintcomponentpaint
Jonathan
Jonathan

Reputation: 535

Painting to objects on top of each other

I am trying to paint one Oval over another oval. Here i use a select statement to draw in the paint component method.

import java.awt.*;

public class test extends JPanel{

public static final int OVAL = 1;
public static final int SOLID = 2;

private int type = LINE;

public test(int type){

    this.type = type;
}
public void piantComponent(Graphics g){
   super.paintComponent(g);

   switch(type)
   {
      case OVAL:
      g.setColor(Color.YELLOW);
      g.drawOval(0,0,150,150);
      break;

      case SOLID:
      g.setColor(Color.BLUE);
      g.fillOval(0,0,50,50);
      break;

   }
 }


}

Now in my main method i want to display a solid blue oval (SOLID) inside of a yellow oval (OVAL).

  import...;
  public class Main{
      public static void main (String [] args){
             JFrame window = new JFrame();
             window.add(new test(test.OVAL));
             window.add(new test(test.SOLID));
             window.setSize(300,300);
             window.setVisible(true);

      }

  }

This does not do what I want it to do at all. This only displays a oval and not a oval and a solid. I think that i am overloading the window to only display the oval. I have tried to display with a layout manager(gridlayout) but that does not display the two paintings over each other it displays the two paintings next to each other.

How do i fix this without loosing the switch statement.

Upvotes: 2

Views: 3197

Answers (5)

camickr
camickr

Reputation: 324128

window.add(new test(test.OVAL));
window.add(new test(test.SOLID));

Your problem has to do with ZOrder. To simplify, Swing paints components in the reverse order they are found on the panel. So in your case the SOLID gets painted BEFORE the OVAL. Since the OVAL is larger in size it covers the SOLID.

You can force Swing to paint the components in the more intuitive order by doing:

window.add(0, new test(test.OVAL));
window.add(0, new test(test.SOLID));

Now the last component added will also be painted last.

However a better design is to create separate Oval and Solid classes so you can specify size, location and color independently. Then you can add as many components to your panel as you want.

Upvotes: 1

shadotu
shadotu

Reputation: 11

  1. modification in the test class. read comments for explaination of the modifications

import java.awt.*;

public class test extends JPanel {

  public static final int OVAL = 1;
  public static final int SOLID = 2;
  **public static final int BOTH = 3;**  //instance variable to represent the 
                                         //painting of both images

  private static int type;

  public test(int type){
    this.type = type;
  }

  public void paintComponent(Graphics g){

     switch(type)
     {
        case OVAL:
           g.setColor(Color.BLACK);
           g.drawOval(0,0,150,150);
           break;

        case SOLID:
           g.setColor(Color.BLUE);
           g.fillOval(0,0,50,50);
           break;

        case BOTH:                       //statements to draw both figures
           g.setColor(Color.BLACK);
           g.drawOval(0,0,150,150);
           g.setColor(Color.BLUE);
           g.fillOval(0,0,50,50);
           break;

     }
  }//paint component

}

  1. in the main method use

    window.add( new test(test.BOTH);

Upvotes: 1

mKorbel
mKorbel

Reputation: 109813

  • Painting in Swing must be done for concrete JComponent

  • public class test{ (use proper naming convention and to change test to Text) doesn't contains any JComponents

  • use JPanel or plain JComponent

  • painting in AWT, Swing by default never returns PreferredSize, then container has zero Dimension, required to override getPreferredSize

Upvotes: 1

Skepi
Skepi

Reputation: 478

Try something like this (Just using snippets):

 private ArrayList<int> ovals = new ArrayList<int>();


 public test(int type) {
      ovals.add(type);
 }



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

      for(int oval : ovals)
      {
           switch(type)
           {
                case OVAL:
                g.setColor(Color.YELLOW);
                g.drawOval(0,0,150,150);
                break;

                case SOLID:
                g.setColor(Color.BLUE);
                g.fillOval(0,0,50,50);
                break;
           }
      }
 }

This will allow you to add as many ovals as you want (although with their static positioning it will just write over them n the canvas). You could try using a boolean array and iterating through that to see if you need to paint a specific type if you only want 1 of each.

Upvotes: 0

Filipe Fedalto
Filipe Fedalto

Reputation: 2540

Why don't you just paint one right after the other? Like that:

  g.setColor(Color.YELLOW);
  g.drawOval(0,0,150,150);
  g.setColor(Color.BLUE);
  g.fillOval(0,0,50,50);

Upvotes: 0

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