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why isn't an oval displayed in my jPanel? [duplicate]

This question already has answers here:
Can not draw oval on a JPanel
(2 answers)
Closed 2 years ago.
I'm trying to add a circle to my JPanel, but it won't draw the cricle.
the code below creates a JFrame, creates a JPanle and calls a function to add a circle to the JPanel(pgame), but it doesn't actually add it.
Help appreciated
fgame = new JFrame("Backgammon");
fgame.setSize(1000, 1000);
pgame = new JPanel();
pgame.setPreferredSize(new Dimension(1000, 687));
pgame.setLayout(new GridLayout(3, 10));
pgame.setBorder(BorderFactory.createEmptyBorder(309,460,150,460));
Circle Circlepanel = new Circle();
pgame.add(Circlepanel);
Circlepanel.setVisible(true);
fgame.add(pgame,BorderLayout.CENTER);
fgame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
fgame.setTitle("Backgammon");
fgame.pack();
fgame.setVisible(true);
public class Circle extends JPanel {
public void paint(Graphics g) {
g.drawOval(500, 500, 100, 100);
g.setColor(Color.RED);
g.fillOval(500, 500, 100, 100);
}
}

First of all variable names should NOT start with an upper case character. Most of you names are correct, but not all. Learn Java conventions and be consistent!
Your create a GridLayout
pgame.setLayout(new GridLayout(3, 10));
Which will attempt to allocate space for 3 components vertically in the frame.
Then you create a Border:
pgame.setBorder(BorderFactory.createEmptyBorder(309,460,150,460));
which will give your component a height of 459 and a width of 920.
Finally you try to draw the oval at (500, 500) from the top left of the panel.
g.drawOval(500, 500, 100, 100);
Well, the problem is that you have weird random numbers and the size of your component isn't large enough to paint the oval in the space of the component.
To demonstrate this add and retest:
Circlepanel.setBackground( Color.YELLOW );
You will see a yellow panel. Next change:
//pgame.setLayout(new GridLayout(3, 10));
pgame.setLayout(new GridLayout(1, 0));
and you will see a taller yellow panel in the middle of the frame because you are only allocating space for a single component.
Next change:
//pgame.setBorder(BorderFactory.createEmptyBorder(309,460,150,460));
pgame.setBorder(BorderFactory.createEmptyBorder(50,50,50,50));
and you will see part of the oval because you have reserved less space for the border.
Next change:
//g.fillOval(500, 500, 100, 100);
g.fillOval(0, 0, 100, 100);
and you will see the oval at the top of the panel.
The point is that specifying the:
grid size
border size
oval location
all affect the size of the component and how it is painted.
Other issues:
override the getPreferredSize() method of your Circle class to return the desired size of the panel
custom painting is done by overriding paintComponent(), not paint();
you need to invoke super.paintComponent(..) at the start of the method.
Read the section from the Swing tutorial on Custom Painting for more information and working examples.

How to ignore JFrame opacity?

I need to achieve the effect of "lights off" while displaying animation. It's currently been done with transparent Jframe, black background with 50% opacity the size of the monitor. then, there is this canvas component which should draw RGBA buffered-image.
Problems pops up when the the JFrame opacity effects the Canvas as well, making it semi transparent. That's what i'm trying to avoid.
//** Window class extends Canvas
public Window(){
GraphicsDevice gd = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice();
int hostMonitorWidth = gd.getDisplayMode().getWidth();
int hostMonitorHeight = gd.getDisplayMode().getHeight();
Dimension dimension = new Dimension(hostMonitorWidth, hostMonitorHeight);
super.setPreferredSize(dimension);
window = new JFrame();
window.setUndecorated(true);
window.setOpacity(0.55f);
window.setLayout(new GridLayout());
window.setSize(hostMonitorWidth, hostMonitorHeight);
window.add(this);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setLocationRelativeTo(null);
window.setVisible(true);
window.requestFocus();
window.setFocusableWindowState(true);
super.createBufferStrategy(3);
}
public void draw(){
BufferStrategy buffer = super.getBufferStrategy();
java.awt.Graphics g = buffer.getDrawGraphics();
g.setColor(Color.BLACK);
g.fillRect(0,0, super.getWidth(), super.getHeight());
g.drawImage(batch.getImage(), 0, 0, super.getWidth(), super.getHeight(), null);
g.dispose();
buffer.show();
}
I have tried couple combinations of the following code with Jpanel, Layered Panes, Jlabel and what not. It's always seems to keep the opacity / throwing unexplainable exceptions / not working for any reason.
Am i doing it the correct way? what am i missing here?

Don't use setOpacity, use setBackground on the JFrame and pass it a alpha based color. This will allow the frame to become transparent without affecting the other components.
You may, however, find that Canvas doesn't like alpha based colors (as it only has an opaque state)

Why is my JPanel smaller than it should be?

I am trying to learn Swing and have made a panel (with help from other StackOverflow code). I added a checkerboard design on a frame, but I have found that the frame is not as big as it should be.
Here is my code:
#Override
protected void paintComponent(Graphics g) {
int width = getWidth(), height = getHeight();
g.clearRect(0, 0, width, height);
g.setColor(Color.BLACK);
for (int i=0;i<=width;i+=50) {
g.drawLine(0,i,width,i);
}
for (int i=0;i<=height;i+=50) {
g.drawLine(i,0,i,height);
}
label.setText("H = "+ getHeight() +" W = "+ getWidth()); // check actual size
add(label);
}
private void gui(Pan window) {
frame = new JFrame();
Container container = frame.getContentPane();
container.add(window);
frame.setSize(400, 400); // size written here
frame.setVisible(true);
}
If you run it, you'll see the size of the window. It will be 362 by 384, instead of 400 by 400 as written in the code.
If I change the dimensions to 500 by 500, the window will be 462 by 484.
Q: Why are the dimensions off by 38 and 16?

It will be 362 by 384, instead of 400 by 400
Because the size of the frame include the title bar and borders. Don't use the setSize() method.
Instead override the getPreferredSize() method of your custom panel to return the size that you want the panel to be.
Then you use:
frame.pack();
Then the size of the frame will be the preferred size of your panel, plus the size of the title bar and borders.

How to resize image Height to JFrame Height?

I have an image that is too tall for my JFrame even when it is maximized. I want to dynamically resize it so that the image will never be clipped by the top or bottom of the JFrame. I have inserted the image within a JLabel as an ImageIcon. I have tried setting the maximum size to no avail. How do I ensure that the height of the image will never be larger than the JFrame? I would ideally like to keep the ratio of height to width constant. The image is in a portrait orientation. Any ideas?
public class myClass extends JFrame {
private void initGUI(){
pane = getContentPane();
pane.setLayout(new BorderLayout());
next = new JButton("Next");
previous = new JButton("Previous");
page = new JLabel(loadImg());
page.setMaximumSize(this.getSize());
pane.add(next, BorderLayout.EAST);
pane.add(previous, BorderLayout.WEST);
pane.add(page, BorderLayout.CENTER);
}
}

I would ideally like to keep the ratio of height to width constant.
Check out Darryl's Stretch Icon. It will shrink/grow depending on the space available, while maintaining the width/height ratio.

You can try overriding the paintComponent(Graphics g) method and drawing the resized image yourself.
page = new JLabel(loadIMG()){
#Override
paintComponent(Graphics g)
{
//So we don't kill default behaviour
super.paintComponent(g);
int scaledWidth, scaledHeight;
//pseudo-code
scale and store into scaledWidth and scaledHeight;
render with g.drawImage(icon, x, y, scaledWidth, scaledHeight, null);
}
};

JPanel rendered behind the paint() method

I am trying to create a board game. The left side of my windows is my actual board game while on the right side I was going to have a few buttons and timers. I paint my board using the paint method but when I try to create a new JPanel thats rendered in the background. I know because I can see some black around the edges of the game.
This is my main code that creates my JFrame and calls my board class.
frame.setSize(864, 480);
frame.add(new Board());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setResizable(false);
frame.setLocationRelativeTo(null);
frame.setCursor(frame.getToolkit().createCustomCursor(new BufferedImage(3, 3, BufferedImage.TYPE_INT_ARGB), new Point(0, 0), "null"));
JPanel panel = new JPanel();
frame.add(panel);
panel.setBackground(Color.BLACK);
This is my code that paints the go board image. This is in my Board class
super.paint(g);
s.location = MouseInfo.getPointerInfo();
s.mouse = s.location.getLocation();
s.updateBlackX(s.mouse);
s.updateBlackY(s.mouse);
s.updateWhiteX(s.mouse);
s.updateWhiteY(s.mouse);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(board, 0, 0, null);
paintArray(g2d);
if (turn == 1)
g2d.drawImage(s.getBlackStone(), s.getBlackX() - f.getX() - 15, s.getBlackY() - f.getY() - 35, null);
else
g2d.drawImage(s.getWhiteStone(), s.getWhiteX() - f.getX() - 15, s.getWhiteY() - f.getY() - 35, null);
This is my game during run-time with further explanation as to my problem.
http://imgur.com/cAIS9aR
Thank you in advance for any and all help!

I am trying to create a board game. The left side of my windows is my actual board game while on the right side I was going to have a few buttons and timers.
Create two panels, one for the Board class and the other for the buttons then add them to the frame as follows:
frame.add(gamePanel, BorderLayout.CENTER);
frame.add(buttonPanel, BorderLayout.EAST);
That is don't try to do all you custom painting and game playing on a single panel.