import javax.swing.JFrame;
import java.awt.*;
import java.awt.image.*;
class Screen extends Canvas {
public static JFrame window(int width,int height,String title) {
System.out.println("window()");
JFrame window = new JFrame(title);
window.setSize(width,height);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(false);
window.setVisible(true);
return window;
}
public static Canvas canvas(int width,int height) {
System.out.println("canvas()");
Canvas canvas = new Canvas();
canvas.setSize(width, height);
return canvas;
}
public static Graphics createGraphics(Canvas window,BufferStrategy strategy) {
System.out.println("createGraphics()");
Graphics graphics = strategy.getDrawGraphics();
return graphics;
}
public static BufferStrategy createStrategy(JFrame window) {
window.createBufferStrategy(2);
BufferStrategy strategy = window.getBufferStrategy();
return strategy;
}
public static void main(String[] args) {
JFrame window = window(800,600,"Application");
Canvas canvas = canvas(800,600);
BufferStrategy strategy = createStrategy(window);
window.add(canvas);
while(true) {
Graphics g = createGraphics(canvas,strategy);
g.fillRect(0, 0, 20, 20);
g.dispose();
strategy.show();
}
}
}
I was expecting to draw something on the screen but it didn't work. I don't know if Graphics and Bufferstrategy have to be used in the same place. Check my code, logically I think there is no problem.My goal is to draw a square on the screen
`import javax.swing.JFrame;
import java.awt.*;
import java.awt.image.*;
import java.util.concurrent.TimeUnit;
class Screen extends Canvas {
public static JFrame window(int width,int height,String title) {
System.out.println("window()");
JFrame window = new JFrame(title);
window.setSize(width,height);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setResizable(false);
window.setVisible(true);
return window;
}
public static Canvas canvas(int width,int height) {
System.out.println("canvas()");
Canvas canvas = new Canvas();
canvas.setSize(width, height);
return canvas;
}
public static void player(Graphics graphics,int player_x,int player_y) {
graphics.fillRect(player_x,player_y , 50, 50);
}
public static void main(String[] args) {
JFrame window = window(800,600,"Application");
Canvas canvas = canvas(800,600);
int p_x = 20;
int p_y = 20;
window.add(canvas);
while(true) {
Graphics graphics = canvas.getGraphics();
// Worked
// graphics.drawanything()
}
}
}`
This worked.
Related
package drawinglinebymethods;
import java.awt.*;
import javax.swing.JFrame;
public class DrawingLineByMethods extends Frame {
public JFrame f=new JFrame();
void fra_size()
{
f.setSize(450, 300);
}
void fra_visible()
{
f.setVisible(true);
}
void fra_title()
{
f.setTitle(" java frame");
}
void exit()
{
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void line(Graphics g) {
g.drawLine(10, 10, 20, 300);
}
public static void main(String[] args) {
DrawingLineByMethods obj = new DrawingLineByMethods();
obj.fra_size();
obj.fra_title();
obj.fra_visible();
obj.fra_exit();
obj.line(g); // <-- error here
}
}
Your question suggests that you are not yet clear on how graphics and drawing works in Swing GUI's. Some suggestions for you:
Don't have your class extend java.awt.Frame as this makes no sense. You're not creating an AWT Frame window and have no need of this.
Create a class that extends JPanel and draw in its paintComponent method as the Swing painting tutorials (link now added) show you.
You never call drawing code directly but rather it is indirectly called by the JVM.
If you want to draw from outside of the GUI itself, then draw to a BufferedImage, one that is then displayed within the GUI.
Don't use a Graphics object obtained by calling getGraphics() on a GUI component as the object thus obtained will not persist, and this risks you creating unstable graphics or worse -- throwing a NullPointerException.
For example:
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.*;
#SuppressWarnings("serial")
public class LineDraw extends JPanel {
private static final int PREF_W = 450;
private static final int PREF_H = 300;
public LineDraw() {
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// use rendering hints to draw smooth lines
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// do drawing here
g.drawLine(10, 10, 20, 300);
}
private static void createAndShowGui() {
LineDraw mainPanel = new LineDraw();
JFrame frame = new JFrame("Line Draw");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
createAndShowGui();
});
}
}
If you want to add lines as the program runs, again, use a BufferedImage that is drawn within the JPanel's paintComponent method. When you need to add a new line to the GUI, extract the Graphics or Graphics2D object from the BufferedImage using getGraphics() or createGraphics() respectively (it's OK to do this), draw with this Graphics object, dispose of the Graphics object, and repaint the GUI. For example in the code below, I draw a new line when the button is pressed by adding code within the JButton's ActionListener (actually its AbstractAction which is similar to an ActionListener but more powerful):
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import javax.swing.*;
#SuppressWarnings("serial")
public class LineDraw extends JPanel {
private static final int PREF_W = 450;
private static final int PREF_H = 300;
private BufferedImage img;
private int yDistance = 20;
private int deltaY = 10;
public LineDraw() {
img = new BufferedImage(PREF_W, PREF_H, BufferedImage.TYPE_INT_ARGB);
add(new JButton(new DrawLineAction("Draw Line", KeyEvent.VK_D)));
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// draw the buffered image here
if (img != null) {
g.drawImage(img, 0, 0, this);
}
// use rendering hints to draw smooth lines
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// do drawing here
g.drawLine(10, 10, 20, 300);
}
public void drawNewLines() {
Graphics2D g2 = img.createGraphics();
g2.setColor(Color.BLACK);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
yDistance += deltaY;
g2.drawLine(10, 10, yDistance, PREF_H);
g2.dispose();
repaint();
}
private class DrawLineAction extends AbstractAction {
public DrawLineAction(String name, int mnemonic) {
super(name); // give button its text
putValue(MNEMONIC_KEY, mnemonic); // alt-hot key for button
}
#Override
public void actionPerformed(ActionEvent e) {
drawNewLines();
}
}
private static void createAndShowGui() {
LineDraw mainPanel = new LineDraw();
JFrame frame = new JFrame("Line Draw");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
createAndShowGui();
});
}
}
Line is a non-static method, the only way to call it from a static method (main here) is to have an instance of the class.
For a school project I have to create a simple canvas on which I have to draw random circles. For this I am using a for loop where I kept spawning circles. To keep my PC from crashing, I used the Thread.sleep(20) method. It worked well but had one flaw: it is unable to close itself using the close button.
public class CanvasDraw extends Canvas {
private Random rand = new Random();
public void paint(Graphics graph){
setBackground(new Color(rand.nextInt(255), rand.nextInt(255), rand.nextInt(255)));
for(int i = 0; i<9999; i++){
graph.setColor(new Color(rand.nextInt(255),
rand.nextInt(255), rand.nextInt(255)));
graph.fillOval(rand.nextInt(480), rand.nextInt(480), 120, 120);
}
}
public static void main(String[] args) throws InterruptedException {
JFrame frame = new JFrame();
CanvasDraw drawing = new CanvasDraw();
frame.setSize(600, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.getContentPane().add(drawing);
}
}
How can I fix this?
In your code you paint 10000 ovals each time paint is invoked (which can be quite often). This will clog the event dispatch thread. Paint your ovals on a BufferedImage in your main, and paint that instead. Also extend JComponent instead of Canvas and overwrite paintComponent instead of paint.
Here you go:
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.Random;
public class CircleDraw {
public static void main(String[] args) throws InterruptedException {
Random rand = new Random();
BufferedImage bufferedImage = new BufferedImage(600, 600, BufferedImage.TYPE_INT_RGB);
Graphics g = bufferedImage.getGraphics();
g.setColor(new Color(rand.nextInt(255), rand.nextInt(255), rand.nextInt(255)));
g.fillRect(0, 0, bufferedImage.getWidth(), bufferedImage.getHeight());
for (int i = 0; i < 9999; i++) {
g.setColor(new Color(rand.nextInt(255), rand.nextInt(255), rand.nextInt(255)));
g.fillOval(rand.nextInt(480), rand.nextInt(480), 120, 120);
}
JComponent component = new JComponent() {
#Override
protected void paintComponent(Graphics g) {
g.drawImage(bufferedImage, 0, 0, null);
}
};
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.getContentPane().add(component);
frame.setSize(bufferedImage.getWidth(), bufferedImage.getHeight());
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
Try running your spawning circles loop to run on separate thread.
Don't run it on MAIN thread!!
I created a simple circle animation using Java Swing. Here's what the GUI looks like.
The circle repaints every second with a different color and a different circle radius. The drawing area is 420 x 420 pixels. The color varies randomly. The circle radius varies randomly from 42 pixels to 140 pixels.
The JFrame is created in the run method of the CircleAnimation class.
The drawing panel Is created in the DrawingPanel class. All of the custom painting happens in the paintComponent method of the DrawingPanel class.
The animation is set up as a java.swing.Timer after the JFrame is created. The Animation class holds the ActionListener for the Timer. The actionPerformed method creates a new random color and circle radius.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class CircleAnimation implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new CircleAnimation());
}
#Override
public void run() {
JFrame frame = new JFrame("Circle Animation");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DrawingPanel drawingPanel = new DrawingPanel();
frame.add(drawingPanel, BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
Timer timer = new Timer(1000, new Animation(drawingPanel));
timer.setInitialDelay(1000);
timer.start();
}
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
private int radius;
private Color color;
private Random random;
public DrawingPanel() {
this.setBackground(Color.WHITE);
this.setPreferredSize(new Dimension(420, 420));
this.random = new Random();
setRandomColorAndRadius();
}
public void setRandomColorAndRadius() {
this.color = new Color(getRandom(0, 255),
getRandom(0, 255), getRandom(0, 255));
int start = getPreferredSize().width / 10;
int limit = getPreferredSize().width / 3;
this.radius = getRandom(start, limit);
}
private int getRandom(int start, int limit) {
return random.nextInt(limit - start) + start;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int x = getWidth() / 2 - radius;
int y = getHeight() / 2 - radius;
int width = radius + radius;
int height = width;
g.setColor(color);
g.fillOval(x, y, width, height);
}
}
public class Animation implements ActionListener {
private DrawingPanel drawingPanel;
public Animation(DrawingPanel drawingPanel) {
this.drawingPanel = drawingPanel;
}
#Override
public void actionPerformed(ActionEvent event) {
drawingPanel.setRandomColorAndRadius();
drawingPanel.repaint();
}
}
}
I'm using java awt to render a simple rectangle. I also have a rectangle to be used as the background of the window. The thing is, even though the background rectangle is set to the window's width and height, it still doesn't fit the whole thing. I've tried to Google this, but found results irrelevant to my needs. What's causing this?
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.image.BufferStrategy;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Game implements Runnable{
final int WIDTH = 640;
final int HEIGHT = 480;
JFrame frame;
Canvas canvas;
BufferStrategy bufferStrategy;
boolean running = false;
public Game(){
frame = new JFrame("Prototyping");
JPanel panel = (JPanel) frame.getContentPane();
panel.setPreferredSize(new Dimension(WIDTH, HEIGHT));
panel.setLayout(null);
canvas = new Canvas();
canvas.setBounds(0, 0, WIDTH, HEIGHT);
canvas.setIgnoreRepaint(true);
panel.add(canvas);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
canvas.createBufferStrategy(2);
bufferStrategy = canvas.getBufferStrategy();
canvas.requestFocus();
}
public void run(){
running = true;
while(running)
render();
}
private void render() {
Graphics2D g = (Graphics2D) bufferStrategy.getDrawGraphics();
g.clearRect(0, 0, WIDTH, HEIGHT);
render(g);
g.dispose();
bufferStrategy.show();
}
protected void update(){
}
protected void render(Graphics2D g){
g.setColor(Color.GRAY);
g.fillRect(0, 0, WIDTH, HEIGHT);
g.setColor(Color.BLUE);
g.fillRect(100, 0, 200, 200);
}
public static void main(String [] args){
Game game = new Game();
new Thread(game).start();
}
}
This works flawlessly here. Go through it carefully for differences, since I've forgotten what is changed.
import java.awt.*;
import java.awt.image.BufferStrategy;
import javax.swing.*;
public class Game implements Runnable{
final int WIDTH = 640;
final int HEIGHT = 480;
JFrame frame;
Canvas canvas;
BufferStrategy bufferStrategy;
boolean running = false;
public Game(){
frame = new JFrame("Prototyping");
JPanel panel = (JPanel) frame.getContentPane();
panel.setPreferredSize(new Dimension(WIDTH, HEIGHT));
panel.setLayout(new GridLayout());
canvas = new Canvas();
//canvas.setBounds(0, 0, WIDTH, HEIGHT);
canvas.setIgnoreRepaint(true);
panel.add(canvas);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setResizable(false);
frame.setVisible(true);
canvas.createBufferStrategy(2);
bufferStrategy = canvas.getBufferStrategy();
canvas.requestFocus();
}
public void run(){
running = true;
while(running)
render();
}
private void render() {
Graphics2D g = (Graphics2D) bufferStrategy.getDrawGraphics();
g.clearRect(0, 0, WIDTH, HEIGHT);
render(g);
g.dispose();
bufferStrategy.show();
}
protected void render(Graphics2D g){
g.setColor(Color.GRAY);
g.fillRect(0, 0, WIDTH, HEIGHT);
g.setColor(Color.BLUE);
g.fillRect(100, 0, 200, 200);
}
public static void main(String [] args){
Game game = new Game();
new Thread(game).start();
}
}
So I am testing out a JSlider for a bigger project and can't get it to work. The slider is supposed to adjust the size of a circle, and it's not working. I thought I might have an issue with the creation of the circle, and I am trying to use setFrame, and it's giving an error saying it's "undefined." Can anyone see why? Since it should take in either float or double as parameters. Or if you can see why it's not adjusting the size of the shape that would help a lot too... Here's what I have:
public class DrawShape extends JPanel{
private float width = 300;
private Shape circle = new Ellipse2D.Float(100, 20, width, 300);
public DrawShape() {
}
public DrawShape(float width) {
this.width = width;
}
public void setWidth(int w) {
this.width = w;
circle.setFrame(100, 20, width, 300);//This is where the error is
}
public void paintComponent (Graphics g) {
super.paintComponents(g);
Graphics2D graphics = (Graphics2D)g;
graphics.setColor(Color.black);
graphics.fill(circle);
}//end paintComponent
}//end class
Class with main:
public class SliderTest extends JFrame{
private static DrawShape circle = new DrawShape();
JSlider slider;
JLabel label;
public SliderTest() {
setLayout(new FlowLayout());
slider = new JSlider(JSlider.HORIZONTAL, 150, 450, 300);//orientation, min val, max value, starting val
slider.setMajorTickSpacing(50);//every 5 integers will be a new tick position
slider.setPaintTicks(true);
add(slider);
label = new JLabel("Current value 300");
add(label);
event e = new event();
slider.addChangeListener(e);;
}//end cons
public class event implements ChangeListener{
public void stateChanged(ChangeEvent e) {
JSlider slider = (JSlider)e.getSource();
int value = slider.getValue();
label.setText("Current Value " + value);
circle.setWidth(value);
repaint();
}//end stateChanged
}//end class event
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("Circle");
frame.add(circle);
frame.setSize(500,400);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
JFrame frame1 = new SliderTest ();
frame1.setTitle("Toolbar");
frame1.setSize(300,200);
frame1.setLocation(200,100);
frame1.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame1.setVisible(true);
}
}
Shape does not have a setFrame method. RectangularShape does...
Instead of
private Shape circle = new Ellipse2D.Float(100, 20, width, 300);
You might try using...
private Ellipse2D circle = new Ellipse2D.Float(100, 20, width, 300);
instead...
Your public DrawShape(float width) { constructor is also wrong, as it does not actually do anything.
You should also consider overriding the getPreferredSize method so it can return the width of the shape as a part of the preferred size.
I'm not sure you actually need to maintain the width reference as you can ascertain this from the circle directly...IMHO
For Example
I've not tested this...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import javax.swing.JPanel;
public class DrawShape extends JPanel {
private final Ellipse2D circle = new Ellipse2D.Float(100, 20, 300, 300);
public DrawShape() {
}
public DrawShape(float width) {
circle.setFrame(100, 20, width, 300);
}
public void setWidth(int w) {
circle.setFrame(100, 20, w, 300);
revalidate();
}
#Override
public Dimension getPreferredSize() {
Dimension size = super.getPreferredSize();
size.width = circle.getBounds().width;
return size;
}
#Override
public void paintComponent(Graphics g) {
super.paintComponents(g);
Graphics2D graphics = (Graphics2D) g;
graphics.setColor(Color.black);
graphics.fill(circle);
}//end paintComponent
}//end class
I am trying to draw a circle of a radius 60 centerd in the lower right quarter of the frame, and a square of radius 50 centered in the upper half of the frame.
The frame size is 300 x 300.
I've done this till now.
import java.awt.*;
import javax.swing.*;
import java.awt.geom.*;
public class Test {
public static void main ( String[] args){
JFrameTest5 frame = new JFrameTest5();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setTitle("Test");
}
}
class JFrameTest5 extends JFrame {
public JFrameTest5()
{
setLocation(0,0);
setSize(300,300);
PanelTest1 panel = new PanelTest1();
add(panel);
}
}
class PanelTest1 extends JPanel
{
public void paintComponent(Graphics g)
{
Graphics2D g2 = (Graphics2D)g;
Ellipse2D circle = new Ellipse2D.Double(250, 225, 120,120);
g2.draw(circle);
Rectangle2D rect = new Rectangle2D.Double(75,0,100,100);
g2.draw(rect);
}
}
The problem is the circle and the rectangle don't seem to be right , are there another methods to set the exact radius ?
The example below includes several important changes:
Use constants wherever possible.
Use panel-relative geometry.
Use initial threads correctly.
Use pack() to size the enclosing frame.
Code:
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
/** #see http://stackoverflow.com/a/10255685/230513 */
public class Test {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrameTest frame = new JFrameTest();
}
});
}
}
class JFrameTest extends JFrame {
public JFrameTest() {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setTitle("Test");
this.add(new JPanelTest());
this.pack();
this.setLocationByPlatform(true);
this.setVisible(true);
}
}
class JPanelTest extends JPanel {
private static final int R = 60;
private static final int D = 2 * R;
private static final int W = 50;
private static final int E = 2 * W;
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
Ellipse2D circle = new Ellipse2D.Double(
getWidth() - D, getHeight() - D, D, D);
g2.draw(circle);
Rectangle2D rect = new Rectangle2D.Double(0, 0, E, E);
g2.draw(rect);
}
}