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Drawing lines in loop

How to draw horizontal lines between those four lines and have same space between them like on image.
DrawPanel.java:
import java.awt.Graphics;
import javax.swing.JPanel;
public class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
int width = getWidth();
int height = getHeight();
int pieces = 5;
g.drawLine(0, height/2, width/2, 0);
g.drawLine(width/2, 0, width, height/2);
g.drawLine(0, height, width/2, height/2);
g.drawLine(width/2, height/2, width, height);
for (int i = 0; i < pieces; i++) {
int y = height * i/pieces;
if (y > height / 2)
g.drawLine(0, y, width / 2, y);
}
}
}
DrawPanelTest.java:
import javax.swing.JFrame;
public class DrawPanelTest {
public static void main(String[] args) {
DrawPanel panel = new DrawPanel();
JFrame application = new JFrame();
application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
application.add(panel);
application.setSize(1280,720);
application.setVisible(true);
}
}
What i've got so far:
how to make those lines in bottom left corner fit between lines not in the for loop (something like show above)?

You could draw the bottom triangle to overwrite the lines, or you can calculate the distance away from the center that you need to start/end drawing the lines.
Since we know the height and width of the triangle (half the pyramid) you can calculate the top angle. Once you know the top angle, you can use that to calculate the width of the bottom side at each iteration of the line.
public class PyramidLinesTest {
public static void main(String[] args) {
DrawPanel panel = new DrawPanel();
JFrame application = new JFrame();
application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
application.add(panel);
application.setSize(1280,720);
application.setVisible(true);
}
static class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
int width = getWidth();
int height = getHeight();
int pieces = 5;
drawPyramids(g, width, height);
drawLines(g, width, height, pieces);
}
private void drawPyramids(Graphics g, int width, int height) {
g.drawLine(0, height/2, width/2, 0);
g.drawLine(width/2, 0, width, height/2);
g.drawLine(0, height, width/2, height/2);
g.drawLine(width/2, height/2, width, height);
}
private void drawLines(Graphics g, int width, int height, int pieces) {
// Determine the size of the side and bottom (adjacent and opposite)
double halfY = height / 2;
double halfW = width / 2;
// Tan = O / A
// Tan = halfW / halfY
double tanTheta = halfW / halfY;
double theta = Math.atan(tanTheta); // Radians Math.toDegrees()
double dist = halfY / pieces;
for (int i = 0; i < pieces; i++) {
// Start at halfY and move down by I distance
int y = (int) (halfY + (i * dist));
// Calculate the distance away from halfX using theta
// tan(theta) = O / A
// O = tan(theta) * A
int fromHalfW = (int) (Math.tan(theta) * (i * dist));
// Draw the lines accordingly
g.drawLine(0, y, (int) (halfW - fromHalfW), y);
g.drawLine((int) (halfW + fromHalfW), y, width, y);
}
}
}
}

How to make some of my rectangles Golden (Ratio)?

i'm not too sure on how to make it so when a rectangle is drawn onto the screen, there's a chance that it will be golden. Here's the current code i have for my game to randomly produce random rectangles:
public void drawRectangle() {
rects.clear();
int x = (int) (Math.random() * getWidth());
int y = (int) (Math.random() * getHeight());
int width = (int) (Math.random() * (getWidth() / 4));
int height = (int) (Math.random() * (getHeight() / 4));
if (x + width > getWidth()) {
x = getWidth() - width;
}
if (y + height > getHeight()) {
y = getHeight() - height;
}
Color color = new Color(
(int) (Math.random() * 255),
(int) (Math.random() * 255),
(int) (Math.random() * 255));
rects.add(new Rect(x, y, width, height, color));
repaint();
}
And heres the code i tried using to make it golden, although this was taken from online, i was jsut trying to get it working: EDIT: This code below is effectively now useless, but i'll keep it in the psot in case its of use
public static double golden(int n) {
if (n == 0) return 1;
return 1.0 + 1.0 / golden(n-1);
}
public static void main(String[] args) {
int n = Integer.parseInt(args[0]);
System.out.println(golden(n));
}
Any help is greatly appreciated! Thanks a bunch yet again

The basic idea is, you want to, randomly, create a golden rectangle (and possibly, randomly create the width or height)
You could use Math.random and if it's within a specified range (ie 0.75-1.0), generate a golden rectangle, but I'm lazy, so I'd use Random#nextBoolean to make the decision itself, for example...
private Random random = new Random(System.currentTimeMillis());
public void drawRectangle() {
rects.clear();
double x = (Math.random() * getWidth());
double y = (Math.random() * getHeight());
double width = 0;
double height = 0;
if (random.nextBoolean()) {
if (random.nextBoolean()) {
width = (Math.random() * (getWidth() / 4));
height = width * 1.618;
} else {
height = (Math.random() * (getHeight() / 4));
width = height * 1.618;
}
} else {
width = (Math.random() * (getWidth() / 4));
height = (Math.random() * (getHeight() / 4));
}
if (x + width > getWidth()) {
x = getWidth() - width;
}
if (y + height > getHeight()) {
y = getHeight() - height;
}
Color color = new Color(
(int) (Math.random() * 255),
(int) (Math.random() * 255),
(int) (Math.random() * 255));
rects.add(new Rect(x, y, width, height, color));
repaint();
}
Because the calculation of the golden width/height will generate a double value, I've opted to use doubles, you'll find that Rectangle2D.Double will be useful here and Graphics2D can paint Shape objects (see Graphics2D#draw and Graphics2D#fill)

Repainting an instance of a class from an ArrayList

Ok so I am very new to Java Swing and a beginner in Java in general. My current problem is I have designed a "cityscape". I am working on a UFO flying around, but my randomly generated buildings continue to get regenerated. I am wondering if there is a way to save my instance of buildings to an ArrayList as I have attempted, and paint that selection from that list each time paint is called. I tried what I thought of and I believe it just crashed it when run, because it didn't even open a JFrame and instead produced errors upon errors. Here is what I have:
CityScape class (the main class):
import java.awt.*;
import javax.swing.*;
public class CityScape extends JPanel
{
Buildings a = new Buildings ();
UFO b = new UFO();
#Override
public void paint (Graphics g)
{
//RememberBuildings.buildingList.get(1).paint(g);
a.paint(g);
b.paint(g);
}
public void move()
{
b.move();
}
public static void main(String[] args) throws InterruptedException
{
JFrame frame = new JFrame("Frame");
CityScape jpe = new CityScape();
frame.add(jpe);
frame.setSize(800, 750);
frame.setBackground(Color.BLACK);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
System.out.println(frame.getContentPane().getSize());
while (true)
{
jpe.move(); //Updates the coordinates
jpe.repaint(); //Calls the paint method
Thread.sleep(10); //Pauses for a moment
}
}
}
Buildings class (the class that generates the buildings):
import java.awt.*;
public class Buildings
{
private int maxX = 784;
private int maxY = 712;
private int width = (int)(Math.random()*100+100);
private int height = (int)(Math.random()*350+100);
private int rows = Math.round((height)/25);
private int columns = Math.round(width/25);
public void addBuilding()
{
RememberBuildings.addBuilding();
}
public void paint(Graphics g)
{
Graphics2D g2d = (Graphics2D) g;
Color transYellow = new Color (255, 255, 0, 59);
g2d.setColor(Color.BLACK);
g2d.fillRect(0, 0, maxX, maxY);
g2d.setColor(Color.WHITE);
g2d.fillRect(5, 5, 25, 25);
int a = 0;
for (int i =10; i<634; i+=(a+10))//buildings
{
g2d.setColor(Color.GRAY);
g2d.drawRect(i, maxY-height, width, height);
g2d.fillRect(i, maxY-height, width, height);
rows = Math.round((height)/25);
columns = Math.round(width/25);
for (int j = 1; j<=columns; j++)//windows
{
for (int k = 1; k<=rows; k++)
{
g2d.setColor(Color.BLACK);
g2d.drawRect(i+5*j+20*(j-1), (maxY-height)+5*k+20*(k-1), 20, 20);
if (Math.random()<0.7)
{
g2d.setColor(Color.YELLOW);
g2d.fillRect(i+5*j+20*(j-1), (maxY-height)+5*k+20*(k-1), 20, 20);
}
else
{
g2d.setColor(Color.BLACK);
g2d.fillRect(i+5*j+20*(j-1), (maxY-height)+5*k+20*(k-1), 20, 20);
g2d.setColor(transYellow);
g2d.fillRect(i+5*j+20*(j-1), (maxY-height)+5*k+20*(k-1), 20, 20);
}
}
}
addBuilding();
a = width;
height = (int)(Math.random()*462+100);
width = (int)(Math.random()*100+100);
}
}
}
RememberBuildings class (the point of this is to add an instance to an ArrayList):
import java.util.*;
public class RememberBuildings
{
public static ArrayList<Buildings> buildingList = new ArrayList<Buildings>();
public static void addBuilding()
{
buildingList.add(new Buildings());
}
}
And finally my UFO class (creates the UFO flying by):
import java.awt.*;
import javax.swing.*;
public class UFO extends JPanel
{
private int x = 20; //x and y coordinates of the ball
private int y = 20;
private int xa = 1;
public void move() //Increase both the x and y coordinates
{
if (x + xa < 0) {
xa = 1;
}
if (x + xa > 784-75)
{
xa = -1;
}
x = x + xa;
}
public void paint(Graphics g)
{
super.paint(g); //Clears the panel, for a fresh start
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.LIGHT_GRAY);
g2d.fillOval(x,y,75,25); //Draw the ball at the desired point
}
}

Avoid overriding paint, use paintComponent instead. Always call the super paint method before you do any custom painting to ensure that the paint chain is maintained. See Painting in AWT and Swing and Performing Custom Painting for more details
Beware, Swing is not thread safe and it's unwise to update any component (or any variable that a component may rely on) from outside the context of the Event Dispatching Thread. A simple solution might be to use a Swing Timer instead of a while (true) loop and Thread.sleep. See How to use Swing Timers for more details.
You should also only create and modify UI components from within the context of the event dispatching thread, see Initial Threads for more details
If you have a problem with your code not working, you should consider providing a runnable example which demonstrates your problem. This is not a code dump, but an example of what you are doing which highlights the problem you are having. This will result in less confusion and better responses. Providing code which is not runnable and is missing classes makes it difficult to know why it's not working and how to fix it.

A few things here:
To address the paintComponent note and view an example, check out this other thread: Concerns about the function of JPanel: paintcomponent()
There seems to be a bit of a disconnect between the logic you've got going and the object-oriented programming logic that I think will help sort things out (for general info on OOP: https://en.wikipedia.org/wiki/Object-oriented_programming):
What You've Got:
The Structure you've got going is as follows:
CityScape :: here's where you've extended JPanel and setup the main function
UFO :: an object class that represents 1 UFO
Building :: a class that has methods for drawing randomized buildings and calling methods in RememberBuildings
RememberBuildings :: I think this is intended to track buildings that have been drawn
The issue here is that your Building class's paint method continually draws multiple newly randomized buildings instead of a set building that retains its structure.
My Suggestion:
There are plenty of solutions to this issue and different ways to implement each solution, but my recommendation is to remodel your Building class in an OOP fashion, meaning that it would represent 1 single building (truer to the name of the class). This would contain a constructor that initializes all of the randomized dimensions of that single building once and draws that single building on the jpanel. Then you would need to keep an array or list of some sort in the cityscape that contains buildings that are part of the cityscape, eliminating the need for a "RememberBuildings" class. so roughly:
CityScape extends JPanel:
variables:
Building[] buildings; //might be useful to use an arraylist/stack/queue instead of an array depending on implementation
UFO craft;
constructor:
setup new Building objects and add to list buildings
initialize craft to new UFO
paintComponent:
calls the paint methods for each building & the ufo craft
Building:
variables:
int x, y; // position of building
int height, width; // of this building
constructor:
initializes x, y // probably needs to be inputed from CityScape with this setup
calc height and width randomly // stored in this.height/width
paint:
paints single building based on it's variables
//side-note, you'll probably need getters for the x/y/width to build each building from CityScape
Everything else should be much the same.
Good Luck !

So, every time Buildings#paint is called, it regenerates all the builds, which is done randomly.
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Color transYellow = new Color(255, 255, 0, 59);
g2d.setColor(Color.BLACK);
g2d.fillRect(0, 0, maxX, maxY);
g2d.setColor(Color.WHITE);
g2d.fillRect(5, 5, 25, 25);
int a = 0;
for (int i = 10; i < 634; i += (a + 10))//buildings
{
g2d.setColor(Color.GRAY);
g2d.drawRect(i, maxY - height, width, height);
g2d.fillRect(i, maxY - height, width, height);
rows = Math.round((height) / 25);
columns = Math.round(width / 25);
for (int j = 1; j <= columns; j++)//windows
{
for (int k = 1; k <= rows; k++) {
g2d.setColor(Color.BLACK);
g2d.drawRect(i + 5 * j + 20 * (j - 1), (maxY - height) + 5 * k + 20 * (k - 1), 20, 20);
if (Math.random() < 0.7) {
g2d.setColor(Color.YELLOW);
g2d.fillRect(i + 5 * j + 20 * (j - 1), (maxY - height) + 5 * k + 20 * (k - 1), 20, 20);
} else {
g2d.setColor(Color.BLACK);
g2d.fillRect(i + 5 * j + 20 * (j - 1), (maxY - height) + 5 * k + 20 * (k - 1), 20, 20);
g2d.setColor(transYellow);
g2d.fillRect(i + 5 * j + 20 * (j - 1), (maxY - height) + 5 * k + 20 * (k - 1), 20, 20);
}
}
}
addBuilding();
a = width;
height = (int) (Math.random() * 462 + 100);
width = (int) (Math.random() * 100 + 100);
}
}
There's two ways you might be able to solve this, which you use will depend on what you want to achieve. You could render the buildings directly to a BufferedImage and simply paint that on each paint cycle or you could cache the information you need in order to re-create the buildings.
The BufferedImage approach is quicker, but can't be animated, so if you want to animate the buildings in some way (make the lights flicker), you will need to build up a series of information which allows you to simply repaint them.
I'm going for the second, as you've asked about painting assets from a ArrayList.
I started by translating your "paint" code into a single concept of a virtual building, which has also has information about it's own lights.
public class Building {
protected static final Color TRANS_YELLOW = new Color(255, 255, 0, 59);
private int x, y, width, height;
private List<Light> lights;
public Building(int x, int y, int width, int height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
lights = new ArrayList<>(25);
int rows = Math.round((height) / 25);
int columns = Math.round(width / 25);
for (int j = 1; j <= columns; j++)//windows
{
for (int k = 1; k <= rows; k++) {
Color color = null;
if (Math.random() < 0.7) {
color = Color.YELLOW;
} else {
color = TRANS_YELLOW;
}
lights.add(new Light(x + 5 * j + 20 * (j - 1), y + 5 * k + 20 * (k - 1), color));
}
}
}
public void paint(Graphics2D g2d) {
g2d.setColor(Color.GRAY);
g2d.drawRect(x, y, width, height);
g2d.fillRect(x, y, width, height);
for (Light light : lights) {
light.paint(g2d);
}
}
public class Light {
private int x, y;
private Color color;
public Light(int x, int y, Color color) {
this.x = x;
this.y = y;
this.color = color;
}
public void paint(Graphics2D g2d) {
g2d.setColor(Color.BLACK);
g2d.fillRect(x, y, 20, 20);
g2d.setColor(color);
g2d.fillRect(x, y, 20, 20);
}
}
}
This allows you to generate the primary parameters for the Building and simple cache the results and when needed, simply paint it.
For example...
public class Buildings {
private int maxX = 784;
private int maxY = 712;
private List<Building> buildings;
public Buildings() {
buildings = new ArrayList<>(25);
for (int i = 10; i < 634; i += 10)//buildings
{
int width = (int) (Math.random() * 100 + 100);
int height = (int) (Math.random() * 350 + 100);
int x = i;
int y = maxY - height;
buildings.add(new Building(x, y, width, height));
}
}
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
for (Building building : buildings) {
building.paint(g2d);
}
}
}
I also changed your UFO class so it no longer extends from JPanel, as it just doesn't need to and is probably the primary cause of confusion with your painting.
I then updated your paint method in your CityScape to use paintComponent instead...
public class CityScape extends JPanel {
Buildings a = new Buildings();
UFO b = new UFO();
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
a.paint(g);
b.paint(g);
}
As a runnable example...
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class CityScape extends JPanel {
Buildings a = new Buildings();
UFO b = new UFO();
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); //To change body of generated methods, choose Tools | Templates.
a.paint(g);
b.paint(g);
}
public void move() {
b.move();
}
public static void main(String[] args) throws InterruptedException {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Frame");
CityScape jpe = new CityScape();
frame.add(jpe);
frame.setSize(800, 750);
frame.setBackground(Color.BLACK);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
System.out.println(frame.getContentPane().getSize());
Timer timer = new Timer(10, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
jpe.move(); //Updates the coordinates
jpe.repaint(); //Calls the paint method
}
});
timer.start();
}
});
}
public class Buildings {
private int maxX = 784;
private int maxY = 712;
private List<Building> buildings;
public Buildings() {
buildings = new ArrayList<>(25);
for (int i = 10; i < 634; i += 10)//buildings
{
int width = (int) (Math.random() * 100 + 100);
int height = (int) (Math.random() * 350 + 100);
int x = i;
int y = maxY - height;
buildings.add(new Building(x, y, width, height));
}
}
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
for (Building building : buildings) {
building.paint(g2d);
}
}
}
public static class Building {
protected static final Color TRANS_YELLOW = new Color(255, 255, 0, 59);
private int x, y, width, height;
private List<Light> lights;
public Building(int x, int y, int width, int height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
lights = new ArrayList<>(25);
int rows = Math.round((height) / 25);
int columns = Math.round(width / 25);
for (int j = 1; j <= columns; j++)//windows
{
for (int k = 1; k <= rows; k++) {
Color color = null;
if (Math.random() < 0.7) {
color = Color.YELLOW;
} else {
color = TRANS_YELLOW;
}
lights.add(new Light(x + 5 * j + 20 * (j - 1), y + 5 * k + 20 * (k - 1), color));
}
}
}
public void paint(Graphics2D g2d) {
g2d.setColor(Color.GRAY);
g2d.drawRect(x, y, width, height);
g2d.fillRect(x, y, width, height);
for (Light light : lights) {
light.paint(g2d);
}
}
public class Light {
private int x, y;
private Color color;
public Light(int x, int y, Color color) {
this.x = x;
this.y = y;
this.color = color;
}
public void paint(Graphics2D g2d) {
g2d.setColor(Color.BLACK);
g2d.fillRect(x, y, 20, 20);
g2d.setColor(color);
g2d.fillRect(x, y, 20, 20);
}
}
}
public class UFO {
private int x = 20; //x and y coordinates of the ball
private int y = 20;
private int xa = 1;
public void move() //Increase both the x and y coordinates
{
if (x + xa < 0) {
xa = 1;
}
if (x + xa > 784 - 75) {
xa = -1;
}
x = x + xa;
}
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.LIGHT_GRAY);
g2d.fillOval(x, y, 75, 25); //Draw the ball at the desired point
}
}
}

How to adjust graphics on Swing progress indicator?

The lower source code, with the pictured example, from the post
Circular Progress Bar for Java Swing not working, is a great Swing feature.
I'd like to be able to use it with a "transparent" JFrame or glass pane
but the graphic "petals", in paint(), want to interact with the background,
so if the opacity of the background is very low, you can barely
see the "petals". Not being familiar with the Graphics2D functions there, I've taken many stabs in the dark to try to adjust the code, but no luck, so could someone who knows how those functions work,
suggest changes so that the "petals" don't interact with the background,
and start out solid white, and gradually fade, as the code does?
I also don't need any fade-in or fade-out delays, and I'm also
having difficulty with that, but if someone could just suggest
modifications for the "petals", that would be great!
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import javax.swing.*;
import javax.swing.plaf.LayerUI;
public class Loading_Test {
static final WaitLayerUI layerUI = new WaitLayerUI();
JFrame frame = new JFrame("JLayer With Animated Gif");
public Loading_Test() {
JPanel panel = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 300);
}
};
JLayer<JPanel> jlayer = new JLayer<>(panel, layerUI);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(jlayer);
frame.pack();
frame.setVisible(true);
layerUI.start();
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
Loading_Test loading_Test = new Loading_Test();
}
});
}
}
class WaitLayerUI extends LayerUI<JPanel> implements ActionListener {
private boolean mIsRunning;
private boolean mIsFadingOut;
private Timer mTimer;
private int mAngle;
private int mFadeCount;
private int mFadeLimit = 15;
#Override
public void paint(Graphics g, JComponent c) {
int w = c.getWidth();
int h = c.getHeight();
super.paint(g, c); // Paint the view.
if (!mIsRunning) {
return;
}
Graphics2D g2 = (Graphics2D) g.create();
float fade = (float) mFadeCount / (float) mFadeLimit;
Composite urComposite = g2.getComposite(); // Gray it out.
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .5f * fade));
g2.fillRect(0, 0, w, h);
g2.setComposite(urComposite);
int s = Math.min(w, h) / 5;// Paint the wait indicator.
int cx = w / 2;
int cy = h / 2;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(new BasicStroke(s / 4, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
g2.setPaint(Color.white);
g2.rotate(Math.PI * mAngle / 180, cx, cy);
for (int i = 0; i < 12; i++) {
float scale = (11.0f - (float) i) / 11.0f;
g2.drawLine(cx + s, cy, cx + s * 2, cy);
g2.rotate(-Math.PI / 6, cx, cy);
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, scale * fade));
}
g2.dispose();
}
#Override
public void actionPerformed(ActionEvent e) {
if (mIsRunning) {
firePropertyChange("tick", 0, 1);
mAngle += 3;
if (mAngle >= 360) {
mAngle = 0;
}
if (mIsFadingOut) {
if (--mFadeCount == 0) {
mIsRunning = false;
mTimer.stop();
}
} else if (mFadeCount < mFadeLimit) {
mFadeCount++;
}
}
}
public void start() {
if (mIsRunning) {
return;
}
mIsRunning = true;// Run a thread for animation.
mIsFadingOut = false;
mFadeCount = 0;
int fps = 24;
int tick = 1000 / fps;
mTimer = new Timer(tick, this);
mTimer.start();
}
public void stop() {
mIsFadingOut = true;
}
#Override
public void applyPropertyChange(PropertyChangeEvent pce, JLayer l) {
if ("tick".equals(pce.getPropertyName())) {
l.repaint();
}
}
}

One problem I see is that the code is setting the composite in the wrong place in the loop. It works, but as you've discovered, it's difficult to maintain or change.
g2.setComposite is being called at the end of the loop. This sets the alpha for the next petal drawn. This means there is no easy change you can make to adjust the alpha of the very first petal.
First, I would make the code more in line with the way humans think (at least, the way I think): Set the alpha of the line you're about to draw, right before you draw it:
for (int i = 0; i < 12; i++) {
float scale = (12 - i) / 12f;
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, scale * fade));
g2.drawLine(cx + s, cy, cx + s * 2, cy);
g2.rotate(-Math.PI / 6, cx, cy);
}
Now, making it work with any arbitrary background alpha is easy. We merely adjust the value of scale:
float componentAlpha = 0.5f;
for (int i = 0; i < 12; i++) {
float scale = (12 - i) / 12f;
// Give petals the same relative alpha as the component
// they're overlaying.
scale *= componentAlpha;
g2.setComposite(AlphaComposite.getInstance(
AlphaComposite.SRC_OVER, scale * fade));
g2.drawLine(cx + s, cy, cx + s * 2, cy);
g2.rotate(-Math.PI / 6, cx, cy);
}

How to make star shape in Java?

I'm trying to make some shapes with Java. I created two rectangles with two different colors but I want to create a star shape and I can't find useful source to help me doing this.
Here is my code:
import java.awt.*;
import javax.swing.*;
public class shapes extends JPanel{
#Override
public void paintComponent(Graphics GPHCS){
super.paintComponent(GPHCS);
GPHCS.setColor(Color.BLUE);
GPHCS.fillRect(25,25,100,30);
GPHCS.setColor(Color.GRAY);
GPHCS.fillRect(25,65,100,30);
GPHCS.setColor(new Color(190,81,215));
GPHCS.drawString("This is my text", 25, 120);
}
}

You could try using a polygon and some basic math:
int midX = 500;
int midY = 340;
int radius[] = {118,40,90,40};
int nPoints = 16;
int[] X = new int[nPoints];
int[] Y = new int[nPoints];
for (double current=0.0; current<nPoints; current++)
{
int i = (int) current;
double x = Math.cos(current*((2*Math.PI)/max))*radius[i % 4];
double y = Math.sin(current*((2*Math.PI)/max))*radius[i % 4];
X[i] = (int) x+midX;
Y[i] = (int) y+midY;
}
g.setColor(Color.WHITE);
g.fillPolygon(X, Y, nPoints);

You can also use existing classes e.g. http://java-sl.com/shapes.html for regular polygons and stars.

The Polygon class can be considered as a legacy class that has been there since Java 1.0, but should hardly be used any more in new code. The odd way of specifying the x/y coordinates in separate arrays, and, more importantly, the fact that it only supports int[] arrays limits its application areas. Although it implements the Shape interface, there are more modern implementations of this interface that can be used to represent polygons. In most cases, describing the polygon as a Path2D is easier and more flexible. One can create a Path2D p = new Path2D.Double(); and then do a sequence of moveTo and lineTo calls to geneate the desired shape.
The following program shows how the Path2D class may be used to generate star shapes. The most important method is the createStar method. It is very generic. It receives
the center coordinates for the star
the inner and outer radius of the star
the number of rays that the star should have
the angle where the first ray should be (i.e. the rotation angle of the star)
If desired, a simpler method may be wrapped around this one - as with the createDefaultStar example in the code below.
The program shows different stars, painted as lines and filled with different colors and radial gradient paints, as examples:
The complete program as a MCVE:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RadialGradientPaint;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Path2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class DrawStarShape
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
createAndShowGUI();
}
});
}
private static void createAndShowGUI()
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(new DrawStarShapePanel());
f.setSize(600, 600);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class DrawStarShapePanel extends JPanel
{
#Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
Graphics2D g = (Graphics2D) gr;
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(), getHeight());
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(Color.BLACK);
g.draw(createDefaultStar(50, 200, 200));
g.setPaint(Color.RED);
g.fill(createStar(400, 400, 40, 60, 10, 0));
g.setPaint(new RadialGradientPaint(
new Point(400, 200), 60, new float[] { 0, 1 },
new Color[] { Color.RED, Color.YELLOW }));
g.fill(createStar(400, 200, 20, 60, 8, 0));
g.setPaint(new RadialGradientPaint(
new Point(200, 400), 50, new float[] { 0, 0.3f, 1 },
new Color[] { Color.RED, Color.YELLOW, Color.ORANGE }));
g.fill(createStar(200, 400, 40, 50, 20, 0));
}
private static Shape createDefaultStar(double radius, double centerX,
double centerY)
{
return createStar(centerX, centerY, radius, radius * 2.63, 5,
Math.toRadians(-18));
}
private static Shape createStar(double centerX, double centerY,
double innerRadius, double outerRadius, int numRays,
double startAngleRad)
{
Path2D path = new Path2D.Double();
double deltaAngleRad = Math.PI / numRays;
for (int i = 0; i < numRays * 2; i++)
{
double angleRad = startAngleRad + i * deltaAngleRad;
double ca = Math.cos(angleRad);
double sa = Math.sin(angleRad);
double relX = ca;
double relY = sa;
if ((i & 1) == 0)
{
relX *= outerRadius;
relY *= outerRadius;
}
else
{
relX *= innerRadius;
relY *= innerRadius;
}
if (i == 0)
{
path.moveTo(centerX + relX, centerY + relY);
}
else
{
path.lineTo(centerX + relX, centerY + relY);
}
}
path.closePath();
return path;
}
}

I have 2 method.
1)
public static Bitmap drawStar(int W, int H, int color, boolean andRing)
{
Path path = new Path();
Bitmap output = Bitmap.createBitmap(W, H, Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(color);
float midW ,min ,fat ,half ,radius;
if(andRing)
{
midW = W / 2;
min = Math.min(W, H);
half = min / 2;
midW = midW - half;
fat = min / 17;
radius = half - fat;
paint.setStrokeWidth(fat);
paint.setStyle(Paint.Style.STROKE);
canvas.drawCircle(midW + half, half, radius, paint);
path.reset();
paint.setStyle(Paint.Style.FILL);
path.moveTo( half * 0.5f, half * 0.84f);
path.lineTo( half * 1.5f, half * 0.84f);
path.lineTo( half * 0.68f, half * 1.45f);
path.lineTo( half * 1.0f, half * 0.5f);
path.lineTo( half * 1.32f, half * 1.45f);
path.lineTo( half * 0.5f, half * 0.84f);
}
else
{
min = Math.min(W, H);
half = min/2;
path.reset();
paint.setStyle(Paint.Style.FILL);
path.moveTo( half * 0.1f , half * 0.65f);
path.lineTo( half * 1.9f , half * 0.65f);
path.lineTo( half * 0.40f , half * 1.65f);
path.lineTo( half , 0 );
path.lineTo( half * 1.60f, half * 1.65f);
path.lineTo( half * 0.1f, half * 0.65f);
}
canvas.drawPath(path, paint);
return output;
}
2)
public static Bitmap drawStar(int W,int H,int spikes,int innerRadius,int outerRadius, int backColor,boolean border, int borderColor)
{
if(W < 10)
W = 10;
if(H < 10)
H = 10;
if(spikes < 5)
spikes = 5;
int smallL = W;
if(H < W)
smallL = H;
if(outerRadius > smallL/2)
outerRadius = smallL/2;
if(innerRadius < 5)
innerRadius = 5;
if(border)
{
outerRadius -=2;
innerRadius -=2;
}
Path path = new Path();
Bitmap output = Bitmap.createBitmap(W, H, Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(backColor);
int cx = W/2;
int cy = H/2;
double rot = Math.PI / 2 * 3;
float x,y;
double step = Math.PI / spikes;
path.moveTo(cx, cy - outerRadius);
for (int i = 0; i < spikes; i++)
{
x = (float) (cx + Math.cos(rot) * outerRadius);
y = (float) (cy + Math.sin(rot) * outerRadius);
path.lineTo(x, y);
rot += step;
x = (float) (cx + Math.cos(rot) * innerRadius);
y = (float) (cy + Math.sin(rot) * innerRadius);
path.lineTo(x, y);
rot += step;
}
path.lineTo(cx, cy - outerRadius);
path.close();
canvas.drawPath(path, paint);
if(border)
{
paint.setStyle(Style.STROKE);
paint.setStrokeWidth(2);
paint.setColor(borderColor);
canvas.drawPath(path, paint);
}
return output;
}