I'm making a 'game' of sorts where the player has to click on an image bouncing around the screen. The catch is that the screen is in darkness and the mouse cursor is a 'flashlight' which 'light up' a small circle around it.
I have a JFrame in one class consisting of:
public class GameFrame {
public static void main(String[] args) throws IOException {
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
JFrame jf = new JFrame("Flashlight Game");
jf.setVisible(true);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.setSize(d);
jf.setLocationRelativeTo(null);
GamePanel gp = new GamePanel();
jf.add(gp);
}
}
I have another class which extends JPanel. Here are its fields relevant to my problems:
private Point mouse; //location set by a MouseMotionListener
private BufferedImage myImage;
private int imageX;
private int imageY;
private int imageSpeedX;
private int imageSpeedY;
My first problem lies in the flashlight. In my paint method, I set the graphics background color to the panel background color and use the clearRect method to clear an area around the mouse cursor.
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
super.paint(g2);
checkBounce();
move();
g2.drawImage(myImage, imageX, imageY, null);
g2.setColor(Color.BLACK);
g2.fillRect(0, 0, this.getWidth(), this.getHeight());
g2.setBackground(Color.WHITE);
g2.clearRect((int) mouse.getX() - 25, (int) mouse.getY() - 25, 50, 50);
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
repaint();
}
There are actually two problems here.
1.) How can I create a clearOval effect since a flashlight doesn't shine in a rectangle, and
2.) How can I get the bouncing image to show up through the flashlight beam? I know that calling g2.setBackground(Color.WHITE) will use the set color as the 'background' for the cleared area, but I need a way to clear all graphics except for the backmost JFrame or JPanel background color.
My last problem is sorta weird, but occasionally when I change the value of an int, the window will appear as blank and needs resizing before any of the code will execute.
The basic idea is to create a Rectangle big enough to cover the component, create a Ellipse2D to act as the "hole" or "spot light" and subtract the Ellipse2D from Rectangle so as to create a hole in it, then paint it.
You should avoid overridding paint where possible and instead, use paintComponent, paint tends to be to high in the paint chain and comes with a number of complications which are best avoided
You should avoid changing the state the state of your component or model within any paintXxx method. Paint can be called for any number of reasons, many of which you won't instantiate. This could be putting your models state into a inconsistent state. Instead, you should using something like a javax.swing.Timer to regulate when the model is updated and simply call repaint
Don't ever call Thread.sleep, Threasd.wait or perform any kind of long running loop or I/O operation within the context of the Event Dispatching Thread. Swing is a single threaded environment. That is, all the updates to the UI and event processing are done from within a single thread. If you do anything that blocks the EDT, it will be unable to process these events and update the UI until you stop blocking...
Don't call repaint or any method that might invoke a repaint from within in paintXxx method. This will place your program into a spiral of death that will see it consume your CPU...
For more details, take a look at...
Performing Custom Painting
Concurrency in Swing
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Spotlight {
public static void main(String[] args) {
new Spotlight();
}
public Spotlight() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public static final int RADIUS = 80;
private BufferedImage img;
private Point mousePoint;
public TestPane() {
try {
img = ImageIO.read(new File("C:\\hold\\thumbnails\\Rampage_Small.png"));
} catch (IOException ex) {
Logger.getLogger(Spotlight.class.getName()).log(Level.SEVERE, null, ex);
}
addMouseMotionListener(new MouseAdapter() {
#Override
public void mouseMoved(MouseEvent e) {
mousePoint = e.getPoint();
repaint();
}
});
}
#Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
x = mousePoint == null ? getWidth() / 2 : mousePoint.x;
y = mousePoint == null ? getHeight() / 2 : mousePoint.y;
Rectangle rect = new Rectangle(0, 0, getWidth(), getHeight());
Ellipse2D spot = new Ellipse2D.Float(
(float) x - (RADIUS / 2f),
(float) y - (RADIUS / 2f),
(float) RADIUS,
(float) RADIUS);
Area area = new Area(rect);
area.subtract(new Area(spot));
g2d.setColor(Color.BLACK);
g2d.fill(area);
g2d.dispose();
}
}
}
}
Related
I have a 3d-object composed of multiple polygons that I draw using graphics2D. When I rotate it it, it seems as if it has not enough time to draw the entire object at every frame since at some frames, some of the polygons are simply missing(not drawn). I don't understand how that can be since I in paintComponent first draw all the polygons onto the bufferedImage myImg, and then draw the finished image onto the screen. When I remove clearRect, this issue is resolved but then of course it doesn't remove the last frame's drawing before drawing the next.
Note: I'm an amateur but I've tried really hard understanding and so this is my last resort and would be really glad to get some help. The code (with unnecessary code removed is as follows) :
public class Main {
long temp = System.currentTimeMillis() + frameRate;
public static void main(String[] args) {
myGUI = new GUI(width, height);
while(true) {
if (System.currentTimeMillis() >= temp) {
temp += frameRate;
rotateObject();
myGUI.myCanvas.myLabel.repaint();
}
}
}
}
public class GUI extends JFrame {
public Canvas myCanvas;
public GUI(int w, int h) {
this.setSize(w, h);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myCanvas = new Canvas(w, h);
this.getContentPane().add(myCanvas);
this.setVisible(true);
this.pack();
}
}
public class Canvas extends JPanel {
public BufferedImage myImg;
public Graphics2D g2d;
public JLabel myLabel;
public Canvas(int w, int h) {
myImg = new BufferedImage(w, h, BufferedImage.TYPE_4BYTE_ABGR);
myLabel = new JLabel(new ImageIcon(myImg));
this.add(myLabel);
g2d = myImg.createGraphics();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g2d.clearRect(0, 0, myImg.getWidth(), myImg.getHeight());
g2d.setColor(Color.RED));
g2d.fillPolygon(pointsX, pointsY, 3);
g.drawImage(myImg, 0, 0, null);
}
}
This is how my object is flickering
You really need to take the time to read through:
Performing Custom Painting
Painting in AWT and Swing
2D Graphics
Concurrency in Swing
How to Use Swing Timers
These aren't "beginner" topics and a reasonable understanding of Swing in general and the language in particular would be very advantageous.
Don't, ever, use getGraphics on a component. This is simply a bad idea (and I have no idea why this method is public).
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
public class TestPane extends JPanel {
private BufferedImage myImg;
private double rotation;
public TestPane() throws IOException {
myImg = ImageIO.read(getClass().getResource("/images/happy.png"));
Timer timer = new Timer(33, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
rotation += Math.toRadians(5);
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
AffineTransform at = AffineTransform.getTranslateInstance((getWidth() - myImg.getWidth()) / 2, (getHeight() - myImg.getHeight()) / 2);
at.rotate(rotation, myImg.getWidth() / 2, myImg.getHeight() / 2);
g2d.transform(at);
g2d.drawImage(myImg, 0, 0, this);
g2d.dispose();
}
}
}
I have managed to save a print of the JPanel to a BufferedImage with ScreenImage class,which just use the function:
Panel.paint(Graphics g)
My problem is that I need to perform the scale on the BufferedImage, so I lose quality. If I do the scale on the graphics object I don't lose quality. Here is my code so far:
private void drawReflex(){
BufferedImage firstimg = new BufferedImage(getWidth() , getHeight(), BufferedImage.TYPE_3BYTE_BGR);
Graphics2D g1 = firstimg.createGraphics();
this.paint(g1); // this method is inside a class which extends JPanel
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.scale(3,3);
drawReflex();
g2.scale(1,1);
}
Unfortunately I don't get any scale with the above code. What am I doing wrong?
Scaling will also generate some level or artifacts, generally speaking one step scaling is bad idea and even at the simplest of solutions, you should try and perform a factor of 2 scaling operation, stepping up/down to your desired target, something which is demonstrated here, you might even consider using something like imgscalr instead
The following example provides you with the ability to scale a Graphics context from 10% up to 300% through the use of a JSlider.
I simply generates BufferedImage at the desired scaled sized (based on the current size of the component), scales the Graphics context and then uses printAll to generate a snapshot. It then saves the resulting image in the current directly using the "scale" as part of the name
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ScalingTest {
public static void main(String[] args) {
new ScalingTest();
}
public ScalingTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
ImagePane pane = new ImagePane();
JButton btn = new JButton("Scale");
JSlider slider = new JSlider(10, 300);
slider.setMinorTickSpacing(5);
slider.setMajorTickSpacing(10);
slider.setSnapToTicks(true);
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
try {
float scale = slider.getValue() / 100f;
Dimension size = pane.getSize();
System.out.println("Original = " + size);
size.width *= scale;
size.height *= scale;
System.out.println("Scaled = " + size);
BufferedImage scaled = new BufferedImage(size.width, size.height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = scaled.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
g2d.scale(scale, scale);
pane.printAll(g2d);
g2d.dispose();
ImageIO.write(scaled, "png", new File("Scaledx" + scale + ".png"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
JPanel panel = new JPanel(new GridLayout(2, 1));
panel.add(slider);
panel.add(btn);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(pane);
frame.add(panel, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ImagePane extends JPanel {
private BufferedImage bg;
public ImagePane() {
try {
bg = ImageIO.read(new File("/Volumes/Disk02/Dropbox/MegaTokyo/issue194.jpg"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return bg == null ? new Dimension(200, 200) : new Dimension(bg.getWidth(), bg.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - bg.getWidth()) / 2;
int y = (getHeight() - bg.getHeight()) / 2;
g2d.drawImage(bg, x, y, this);
g2d.dispose();
}
}
}
Personally, I'd grab the shap shot at a scale of 1:1 and scaling the resulting image as I think you'll still get a better result, but that's me. You might find The Perils of Image.getScaledInstance() of interest as to why scaling a BufferedImage doesn't always return a decent result
In Java, there is the Graphics2D.fillRect(x, y, width, height) function. In my program, I am looking for something similar, yet completely opposite.
I need to fill everything on the screen except this certain x, y, width, height, sort of like an anti-fillRect. Is there a built in function that I am overlooking, or can you point me in the right direction to create one?
Not required, but it would be a nice bonus if it could work with other Java 2D shapes.
There are a few ways that might be achieved, the easiest might be to use
java.awt.geom.Area which is a highly versatile Shape implementation, which allows you to add and subtract Areas from it, for example...
I've left the fill color slightly translucent to prove the point ;)
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.Area;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class CutExample {
public static void main(String[] args) {
new CutExample();
}
public CutExample() {
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("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private BufferedImage img;
public TestPane() {
try {
img = ImageIO.read(...);
} catch (IOException ex) {
Logger.getLogger(CutExample.class.getName()).log(Level.SEVERE, null, ex);
}
}
#Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
if (img != null) {
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getWidth()) / 2;
g2d.drawImage(img, x, y, this);
Area outter = new Area(new Rectangle(0, 0, getWidth(), getHeight()));
x = (getWidth() / 2) - 100;
y = (getHeight() / 2) - 100;
Rectangle inner = new Rectangle(x, y, 200, 200);
outter.subtract(new Area(inner));
g2d.setColor(new Color(0, 0, 0, 192));
g2d.fill(outter);
}
g2d.dispose();
}
}
}
I should also mention that you can use any other Shape you want...
This question already has an answer here:
netBeans gui problem
(1 answer)
Closed 8 years ago.
I'm trying to use canvas in java. I'm using netbeans GUI builder to add several canvases to the window but I'm not sure how to for example draw the line or rectangle on them. I read several manuals how to do that but I'm still beginner in Java and I didn't quite understand what am I supposed to do. The constructor of the class looks like this:
public Classname() {
initComponents();
canvas1.setBackground(Color.red); // That works.
// Now I want to (for example) draw a line on the canvas1 (or some other canvas)
}
Could somebody please explain me what code should I write and where to put it? Thanks in advance. (Sorry for my english.)
Assuming your mean java.awt.Canvas, I'd recommend that you shouldn't be using it. Two main reasons, one, it's a heavy weight component, which introduces a list of issues when mixed with Swing/lightweight components and two, it's not double buffered, which just adds additional overheads you're going to have to deal with.
The preferred means by which to perform custom painting is to generally create a new class that extends from JPanel and the override it's paintComponent method for example
public class PaintPane extends JPanel {
public PaintPane () {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);
g2d.dispose();
}
}
This will draw a simple line across the middle of the panel.
You can then drag the class from the "Projects" tab into the form editor (and onto an existing form container), like you would with components from the palette
Take a look at Performing Custom Painting and 2D Graphics for more details
Updated with example based on comments
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class DrawExample {
public static void main(String[] args) {
new DrawExample();
}
private DrawPane drawPane;
public DrawExample() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
drawPane = new DrawPane();
JButton addRect = new JButton("Add Rectangle");
addRect.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
int width = drawPane.getWidth() - 1;
int height = drawPane.getHeight() - 1;
int x = (int)(Math.random() * (width - 5));
int y = (int)(Math.random() * (height - 5));
width -= x;
height -= y;
int rectWidth = (int)(Math.random() * width);
int rectHeight = (int)(Math.random() * height / 2);
drawPane.addRect(x, y, rectWidth, rectHeight);
}
});
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(drawPane);
frame.add(addRect, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class DrawPane extends JPanel {
private List<Shape> shapes;
public DrawPane() {
shapes = new ArrayList<Shape>(25);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
for (Shape shape : shapes) {
g2d.draw(shape);
}
g2d.dispose();
}
public void addRect(int x, int y, int width, int height) {
shapes.add(new Rectangle(x, y, width, height));
repaint();
}
}
}
So Im drawing a BufferedImage 'bird' but I want to rotate it according to the angle that it is falling. I have a bird object which contains the BufferedImage and a render() method which draw it rotated.
public void render(Graphics2D g, ImageObserver io) {
double theta = Math.tan((height - pastHeight) / .875);
System.out.println(theta);
Graphics2D g2 = (Graphics2D) bird.getGraphics();
g2.drawImage(bird, 100, (int) height, null);
g2.rotate(theta);
g2.drawImage(bird, 100, (int) height, io);
}
I call this as such
bird.render(g2, ???);
in my paintcomponent method in my jcomponent.
only problem is I dont know what to use as my ImageObserver... I've tried passing in my JFrame and my JComponent but the image no longer appears when I do that... what would I pass in for the image to appear in my window and/or how else would I achieve this rotation?
Assuming that you are doing this in something that extends JComponent, you should use
bird.render(g2, this);
As JComponent implements ImageObserver
The problem with the image disappearing isn't an issue with the ImageObserver but the point around which the rotation is occurring, which I believe is the top/left corner of the Graphics context.
Try using Graphics2D#rotate(double, int, int) which will allow you to specify the origin points of the rotation (pivot point).
Don't forget to reset your translations, as they will effect everything that is painted after your supply them and may be re-used in subsequent paint cycles.
Updated with simple example
This is a basic example that demonstrates the different uses of rotate.
First, I simply used Graphics#rotate(double)
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class RotateImage {
public static void main(String[] args) {
new RotateImage();
}
public RotateImage() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private BufferedImage img;
private double angel = 0d;
public TestPane() {
try {
img = ImageIO.read(...);
} catch (IOException ex) {
ex.printStackTrace();
}
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
angel += 5;
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.rotate(Math.toRadians(angel));
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
g2d.dispose();
}
}
}
}
Then I replaced g2d.rotate(Math.toRadians(angel)); with g2d.rotate(Math.toRadians(angel), getWidth() / 2, getHeight() / 2);, which used the center position of the component (or the Graphics context) as the anchor point around which the rotation would occur...
Now, because you only want to rotate your image, you're going to need to calculate the anchor point around the current position of the image's center position (assuming you want it to rotate around the middle)