Jump to content
  • Advertisement
Sign in to follow this  
PsionicTransvection

Problem with Background (JAVA)

This topic is 2313 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I wrote a class that is suppose to draw a red rectangle in a JPanel with and the background of the panel is suppose to be black here is my code


import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Graphics;

public class View extends JFrame
{
private JPanel panel = new JPanel();
public void paint(Graphics g)
{
g.setColor(Color.RED);
g.drawRect(20, 50, 100, 100);
}
public View()
{
setSize(640, 480);
setResizable(true);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setBackground(Color.BLACK);
panel.setSize(640, 480);
panel.setBackground(Color.BLACK);
panel.paint(null);
this.add(panel);
}

public static void main(String[] args)
{
View view = new View();



}
}


and here is what I get as a result there appears to be some glitch in the background

[attachment=7847:WTF.PNG]
(this is a screen of the gui from my code not a minimized Eclipse)

and here is how it is without the paint method it does as it suppose to making a window with a black background

[attachment=7848:without paint method.PNG]


Is it something wrong with my code that it does like that or there is something wrong with my computer ?

Share this post


Link to post
Share on other sites
Advertisement
The "paint()" method you've implemented is overriding the paint of the JFrame.
So when the window is rendered, you're telling it to draw a red box.

In this case I think it would be better to override paintComponent, as this won't interfere with the draw order of the container and child components.

You need todo something like this, but there are many other ways:


private JPanel panel = new JPanel()
{
public void paintComponent(Graphics g)
{
g.setColor(Color.RED);
g.drawRect(20, 50, 100, 100);
}
};


The extra braces create an anonymous class which extends JPanel and overrides it's paintComponent method.

Also if you're relying on Swing to draw everything, don't call any paints directly from your own code (Unless for buferring). Use something like repaint(), to request a render.
E.g. You have "panel.paint(null);" in the constructor.
This is very bad, it won't work correctly and will cause lots of bugs.
Assuming you avoid the NullPointerException; do some research on the "AWT Event dispatch thread".

In the future you may want to consider "Active Rendering". I only mention it because someone else usually does anyway smile.png

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!