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I've gone through and made classes for my objects and calls to them in my paint component, but I cant actually get them to move. Here is my move and check walls program that is in the object class:
public void move()
{
ballX += dx;
ballY += dy;
checkWalls();
}
//bounce of top/bottom, pass through left/right
public void checkWalls() {
//left-right
if(ballX > w) {
ballX = -diam;
}
else if(ballX < -diam) {
ballX = w;
}
//top-bottom
if(ballY < 0) {
dy *= -1;
}
else if(ballY + diam > h) {
dy *= -1;
}
}
And here is my call to them:
while(true) // infinite loop
{
jelly1.move();
frame.repaint();
try
{
Thread.sleep(10);
}
catch(Exception e){}
}
Also i feel the need to mention i have a background and a background component. The while(true) is in the background component because that's where the objects are created. And the frame is set visible in the background where the main method is.
Paint component is as follows:
public class BackgroundComponent extends JComponent {
Jellyfish jelly1;
Jellyfish jelly2;
Jellyfish jelly3;
Diver diver;
public BackgroundComponent() {
diver = new Diver(100, 300);
jelly1 = new Jellyfish(450, 450);
jelly2 = new Jellyfish(150, 300);
jelly3 = new Jellyfish(350, 75);
diver = new Diver(100, 300);
}
public void paintComponent(Graphics g){
//Drawing instructions go here
//Recover Graphics2D
Graphics2D g2 = (Graphics2D)g;
//Make gradient
g2.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
int w = getWidth();
int h = getHeight();
Color color1 = Color.CYAN;
Color color2 = Color.BLACK;
GradientPaint gp = new GradientPaint(0, 0, color1, 0, h, color2);
g2.setPaint(gp);
g2.fillRect(0, 0, w, h);
//Constructs rectangles on edge of screen and draws them
Rectangle box = new Rectangle(0,0,75,700);
g.setColor(Color.LIGHT_GRAY);
g2.fill(box);
Rectangle box2 = new Rectangle(625, 0, 75, 700);
g.setColor(Color.LIGHT_GRAY);
g2.fill(box2);
//Draws lines, with a stroke of 5, over rectangles
Line2D.Double segment = new Line2D.Double(10, 0, 10, 700);
g2.setStroke(new BasicStroke(5));
g.setColor(Color.GRAY);
g2.draw(segment);
Line2D.Double segment2 = new Line2D.Double(30, 0, 30, 700);
g.setColor(Color.GRAY);
g2.draw(segment2);
Line2D.Double segment3 = new Line2D.Double(50, 0, 50, 700);
g.setColor(Color.GRAY);
g2.draw(segment3);
Line2D.Double segment4 = new Line2D.Double(70, 0, 70, 700);
g.setColor(Color.GRAY);
g2.draw(segment4);
Line2D.Double segment5 = new Line2D.Double(690, 0, 690, 700);
g.setColor(Color.GRAY);
g2.draw(segment5);
Line2D.Double segment6 = new Line2D.Double(670, 0, 670, 700);
g.setColor(Color.GRAY);
g2.draw(segment6);
Line2D.Double segment7 = new Line2D.Double(650, 0, 650, 700);
g.setColor(Color.GRAY);
g2.draw(segment7);
Line2D.Double segment8 = new Line2D.Double(630, 0, 630, 700);
g.setColor(Color.GRAY);
g2.draw(segment8);
//Draws rectangle around title with thick boarder
Rectangle box3 = new Rectangle(40,40,620,75);
g.setColor(Color.WHITE);
g2.setStroke(new BasicStroke(5));
g2.draw(box3);
//Drawing text
String title = "Through the Depths";
//Sets font, font size, and color
g.setFont(new Font("Purisa", Font.BOLD, 50));
g.setColor(Color.DARK_GRAY);
g2.drawString(title, (50), 100);
//Places same text slightly up and over
g.setFont(new Font("Purisa", Font.BOLD, 50));
g.setColor(Color.WHITE);
g2.drawString(title, 53, 97);
//Draws ellipses with a stroke of 2 (these are the bubbles)
Ellipse2D.Double ellipse = new Ellipse2D.Double(450, 200, 150, 150);
g2.setStroke(new BasicStroke(2));
g2.draw(ellipse);
Ellipse2D.Double ellipse2 = new Ellipse2D.Double(510, 375, 90, 90);
g2.draw(ellipse2);
Ellipse2D.Double ellipse3 = new Ellipse2D.Double(470, 485, 70, 70);
g2.draw(ellipse3);
Ellipse2D.Double ellipse4 = new Ellipse2D.Double(510, 580, 45, 45);
g2.draw(ellipse4);
// Draws curves for bubbles
QuadCurve2D q = new QuadCurve2D.Float();
q.setCurve(548, 210, 607, 240, 590, 295);
g2.setStroke(new BasicStroke(3));
g2.draw(q);
QuadCurve2D q2 = new QuadCurve2D.Float();
q2.setCurve(575, 387, 607, 415, 585, 445);
g2.draw(q2);
QuadCurve2D q3 = new QuadCurve2D.Float();
g2.setStroke(new BasicStroke(2));
q3.setCurve(515, 493, 545, 511, 528, 540);
g2.draw(q3);
QuadCurve2D q4 = new QuadCurve2D.Float();
g2.setStroke(new BasicStroke(1));
q4.setCurve(538, 585, 558, 595, 545, 617);
g2.draw(q4);
// Sets color to pink before drawing jellyfish
g.setColor(Color.PINK);
//draws jellyfish
jelly1.draw(g);
jelly2.draw(g);
jelly3.draw(g);
// Draws diver
diver.draw(g);
while(true) // infinite loop
{
jelly1.move();
repaint();
try
{
Thread.sleep(10);
}
catch(Exception e){}
}
}
}

while(true){ ... } and Thread.Sleep inside a paintComponent implementation is completely the wrong way of doing things. By doing this, you are blocking the Event Dispatching Thread completely which means that your UI will no longer be updated properly and the UI will no longer be responsive.
What you should do:
Remove the while(true){ ... } loop from the paintComponent override
Create a javax.swing.Timer, set it to run every 10 milliseconds
In the ActionListener.actionPerformed implementation - the action that will be performed each 10 ms - move the jelly and call for a repaint
Start this timer after initialization is done, eg at the end of your constructor or initialization method (not paintComponent).
Stop the timer when it is no longer needed
Simplified example for this Timer, based on your snippet:
new javax.swing.Timer( 10, new ActionListener( ) {
#override
public void actionPerformed( ActionEvent e ) {
jelly1.move();
repaint();
}
}).start();

How can I paint a custom circular JComponent without an "invisible box" around it?

I'm writing a JApplet that displays a diagram with numbers in circles and lines connecting the circles. I've created a class that extends JComponent to act as the circles. I overrode the paintComponent() method to draw a circle with the numbers inside, and I placed these circles on my applet, on which I drew the lines in the paint() method.
However, if the lines hit the circle at an angle, they cut out early, before the circle, at the square that outlines the entire JComponent, even though the background should be transparent. this forms an "invisible box" around the circle.
I've prepared a smaller program to demonstrate the issue:
And here is the code for that example:
import java.awt.*;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import javax.swing.*;
public class Circle extends JApplet {
private static final long serialVersionUID = 1L;
myCircle myC = new myCircle(10, 215, 215); // custom circle
Container c;
public void init() {
setSize(500, 500);
c = getContentPane();
c.setLayout(null);
c.setBackground(Color.lightGray);
c.add(myC);
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(Color.black);
g2d.setStroke(new BasicStroke(2f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER));
//draw lines
g2d.draw(new Line2D.Double(0f, 0f, 500f, 500f));
g2d.draw(new Line2D.Double(0f, 500f, 500f, 0f));
g2d.draw(new Line2D.Double(0f, 250f, 500f, 250f));
g2d.draw(new Line2D.Double(250f, 0f, 250f, 500f));
g2d.draw(new Line2D.Double(150f, 0f, 350f, 500f));
myC.repaint(); // put the circle on top
}
public class myCircle extends JComponent {
private static final long serialVersionUID = 1L;
int number; // number to display
public myCircle(int num, int x, int y) {
this.number = num;
this.setLocation(x, y);
this.setSize(75, 75);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(
RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(2f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER));
g2d.setColor(Color.white);
g2d.fill(new Ellipse2D.Float(1f, 1f, 70f, 70f));
g2d.setColor(Color.black);
g2d.draw(new Ellipse2D.Float(1f, 1f, 70f, 70f));
g2d.drawString(Integer.toString(number), 15f, 20f);
}
}
}

I wouldn't use a component to represent the circle shape alone. Instead, just paint it all on one JPanel (I'm using a JFrame instead of an applet):
public class Circle extends JPanel {
int number = 10;
float size = 500f;
float rad = 70f;
float stringLocX = 15f, stringLocy = 20f;
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.LIGHT_GRAY);
g2d.fillRect(0, 0, getWidth(), getHeight());
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
g2d.setStroke(new BasicStroke(2f, BasicStroke.CAP_BUTT, BasicStroke.JOIN_MITER));
g2d.setColor(Color.BLACK);
g2d.draw(new Line2D.Double(0f, 0f, size, size));
g2d.draw(new Line2D.Double(0f, size, size, 0f));
g2d.draw(new Line2D.Double(0f, size / 2, size, size / 2));
g2d.draw(new Line2D.Double(size / 2, 0f, size / 2, size));
g2d.draw(new Line2D.Double(150f, 0f, 350f, 500f));
Ellipse2D.Float circle = new Ellipse2D.Float((size - rad) / 2, (size - rad) / 2, rad, rad);
g2d.setColor(Color.WHITE);
g2d.fill(circle);
g2d.setColor(Color.BLACK);
g2d.draw(circle);
g2d.drawString(Integer.toString(number), (size - rad) / 2 + stringLocX,
(size - rad) / 2 + stringLocy);
}
#Override
public Dimension getPreferredSize() {
return new Dimension((int) size, (int) size);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
frame.add(new Circle());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
});
}
}
Depending on how many circles you have and what data they must contain, you can just keep a list of those numbers, then iterate over the list in painComponent and draw them.
Notes:
Don't use null layout.
Better to keep the hard coded numbers as fields so you can change them more easily, possibly make them final.

You need to look at the length of the line being drawn. From the edge of your figure to the circle is longer at an angle than at the sides. Recall for a triangle with 45 degrees, 45 degree, and 90 degree angles the ratio of the length of the sides is 1:1:sqrt(2)

Drawing a shape but keeping the most previous shape on screen in java

I've created a function to where I can click somewhere in a Jpanel and it draws a shape at the position where the mouse clicked. The problem I am having is when I click in a new position, it moves the shape and redraws it. I would like the previous shape to "Burn" into the screen and stay there. It doesn't have to have any data tied to it, I just want the image of the shape to show where it used to be each time. I have tried many different things, but no success. here is what I mean:
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.BLUE);
g2.fillRect(n, m, 32, 32); //I want each one of these shapes to be new, not
//moving, but redrawn
////////////////////////////////////////////////
//This is just drawing a grid and doing other things(irrelevant)
g2.fill(new Ellipse2D.Double(x, y, 32, 32));
for (int i = 0; i < 500; i += 32) {
g2.drawRect(i, j, 32, 32);
for (int j = 0; j < 500; j += 32) {
g2.drawRect(i, j, 32, 32);
}
}
if (paintColBlock){
System.out.println("Drawing Block at " + n +"," + m);
paintColBlock = false;
}
/////////////////////////////////////////////////////////////////////
}

Keep an ArrayList of Points like this:
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.BLUE);
for(Point p : points)
g2.fillRect(p.x, p.y, 32, 32);
Adding a new Point to the array at each mouse click, and call repaint():
public void mousePressed(MouseEvent evt){
points.add(new Point(evt.getX(),evt.getY());
repaint();
}

Transparent JButton still painting its background

I have a translucent JPanel. I have created a custom JButton by extending JButton as I required a button with rounded corners and wanted to add some effects to it. I have made the button non-opaque. When I add this button to my translucent JPanel it apears fine. But on rollover a black patch is painted behind the button which looks really crappy. I searched the net for a solution but could'nt find a useful one . This problem is also described at http://www.java.net/node/661798 but i was not able really make kirillcool's suggestion work out.....Any help will be appreciated

I believe you need to add:
button.setContentAreaFilled( false );

not sure if someone is still interested...
you can fix the problem by overriding the paintComponent() method to let Java draw the JButton in any Shape you like. you just need to set the background of the Graphics object to transparent with setBackground() method. also you need to clear the Graphics object BEFORE drawing on it with clearRect() method and then fill it again with the alpha level of the background of your JButton. here is my piece of code.. it shows the overriden paintComponent(). by pasting it into your JButton you should get a JButton with rounded edges even if its on semi-transparant background
private int outerRoundRectSize = 10;
private int innerRoundRectSize = 8;
public void paintComponent(Graphics g)
{
int h = getHeight();
int w = getWidth();
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
Color GP = null;
//////////////get rid of the black background////////////////////////
g2d.setBackground(new Color(0,0,0,0.0f));
g2d.clearRect(0, 0, w, h);
g2d.setPaint(new Color(0,0,0,0.3f));
g2d.fillRect(0, 0, w, h);
//////////////get rid of the black background////////////////////////
ButtonModel model = getModel();
if(!model.isEnabled())
{
setForeground(Color.GRAY);
GP = new Color(0.5f,0.2f,0.6f);
}
else
{
setForeground(Color.WHITE);
if(model.isRollover())
{
GP = new Color(0.5f,0.2f,0.6f);
}
else
{
GP = new Color(0.0f,1.0f,0.0f);
}
}
g2d.setPaint(GP);
Color p1 = null;
Color p2 = null;
if(getModel().isPressed())
{
GP = new Color(1.0f,0.0f,0.0f);
g2d.setPaint(GP);
p1=new Color(0.12f,0.7f,0.3f);
p2=new Color(0.7f,0.5f,0.6f);
}
else
{
p1=new Color(0.0f,0.5f,0.7f);
p2=new Color(0.0f,1.0f,1.0f);
GP = new Color(0.0f,0.0f,1.0f);
}
RoundRectangle2D.Float r2d = new RoundRectangle2D.Float(0, 0, w - 1, h - 1, outerRoundRectSize, outerRoundRectSize);
Shape clip = g2d.getClip();
g2d.clip(r2d);
//g2d.fillRect(0, 0, w, h);
g2d.fillRoundRect(0, 0, w, h, outerRoundRectSize, outerRoundRectSize);
g2d.setClip(clip);
g2d.setPaint(p1);
g2d.drawRoundRect(0, 0, w - 1, h - 1, outerRoundRectSize,outerRoundRectSize);
g2d.setPaint(p2);
g2d.drawRoundRect(1, 1, w - 3, h - 3, innerRoundRectSize,innerRoundRectSize);
g2d.dispose();
super.paintComponent(g);
}

Java (AWT): fitting text in a box

I have an application that extends a Frame. Then, it'll display a few lines of text using:
Font f = new Font("Arial", Font.PLAIN, 10);
g.setFont(f);
g.drawString("Test|great Yes ^.", x, y + 10);
Now what happens is that the text doesn't fit in the box around. E.g. I'm expecting the text to fit in [x,y]-[x+width, y+10] (don't care about the width) but it falls somewhat below the y+10 line. Now for most characters ('T', 'e', etc.) this fits but '|' and 'g' don't! They go below the y+10-line. It seems you can't use: draw at y + characterHeight. But what does work?
To see what I mean, here's some sample code:
import java.awt.*;
public class test extends Frame
{
public test()
{
/* retrieve max window size */
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice[] gs = ge.getScreenDevices();
GraphicsConfiguration [] gc = gs[0].getConfigurations();
Rectangle r = gc[0].getBounds();
setSize(r.width, r.height);
setVisible(true);
}
public void paint(Graphics g)
{
final int windowWidth = getSize().width;
final int windowHeight = getSize().height;
g.setColor(Color.BLUE);
g.fillRect(0, 0, windowWidth, windowHeight);
g.setColor(Color.WHITE);
g.fillRect(0, 100, windowWidth, 110);
int textHeight = 100;
Font f = new Font("Arial", Font.PLAIN, textHeight);
g.setFont(f);
g.setColor(Color.BLACK);
g.drawString("Test|great Yes ^.", 10, 100 + textHeight);
}
public void guiLoop()
{
for(;;) { try { Thread.sleep(1000); } catch(Exception e) { } }
}
public static void main(String [] args)
{
new test().guiLoop();
}
}
I tried the following code as well:
public void paint(Graphics g)
{
final int windowWidth = getSize().width;
final int windowHeight = getSize().height;
g.setColor(Color.BLUE);
g.fillRect(0, 0, windowWidth, windowHeight);
g.setColor(Color.WHITE);
g.fillRect(0, 100, windowWidth, 110);
int textHeight = 100;
String str = "Test|great Yes ^.";
Font f = new Font("Arial", Font.PLAIN, textHeight);
Rectangle2D boundingRectangle = f.getStringBounds(str, 0, str.length(), new FontRenderContext(null, false, false));
f = f.deriveFont((float)(textHeight * (textHeight / boundingRectangle.getHeight())));
boundingRectangle = f.getStringBounds(str, 0, str.length(), new FontRenderContext(null, false, false));
g.drawString(str, 10, 100 + (int)boundingRectangle.getHeight());
g.setFont(f);
g.setColor(Color.BLACK);
g.drawString(str, 10, 100 + textHeight);
}
This is somewhat better: the text is smaller so it might fit, but there's still the problem that the y-position is incorrect.
All help is appreciated!

What about using FontMetrics? You can obtain it from Graphics object with g.getFontMetrics().
Than you can retrieve max descent or ascent or directly height (using getHeight), so your implementation will be font-indipendent and it should work fine.. check documentation here!
EDIT (to explain comments):
there is no a direct way to tell to a string to draw itself in a manner that can fit a box. You have to do it by yourself.. like start from a max font size and check if width fits the box, otherwise decrement size and try again. For height you should FIRST decide (or obtain) max font height, then you can set how many pixel should the box be.

I think I solved it somewhat:
boundingBoxHeight: height of box in which the text should fit
yOffset where to start drawing the font
Font f = new Font("Arial", Font.PLAIN, boundingBoxHeight);
g.setFont(f);
FontMetrics fm = g.getFontMetrics();
double shrink = ((double)textHeight / (double)fm.getHeight());
double newSize = (double)textHeight * shrink;
double newAsc = (double)fm.getAscent() * shrink;
int yOffset = (int)newAsc - fm.getLeading();
f = f.deriveFont((float)newSize);
g.setFont(f);
g.drawString(str, 10, 100 + yOffset);
There's quite a bit of whitespace above the text though.