Develop Reference

How do you use re-size all Graphic2D

In java how can you make a game fully realizable! But so logic and graphics can work with it? I have tried using SCALE methods. But this doesn't allow perfect full-screen for every computer. So I made this:
public void resize(int WIDTH, int HEIGHT, boolean UNDECORATED) {
frame.setPreferredSize(new Dimension(WIDTH, HEIGHT));
frame.setMaximumSize(new Dimension(WIDTH, HEIGHT));
frame.setMinimumSize(new Dimension(WIDTH, HEIGHT));
this.WIDTH = WIDTH;
this.HEIGHT = HEIGHT;
frame.setUndecorated(UNDECORATED);
frame.setSize(WIDTH, HEIGHT);
}
So you can set your screen size to whatever you want! It works but the graphics will not work with it? Is there a way in Graphics2D to stretch all the graphics so it fits? For example if there was a method that existed like:
G2D.resize(WIDTH, HEIGHT, Image.NEAREST_PARENT_RESCALE);
Any idea?
Things I have tried:
Drawing all graphics to a Buffered-image then drawing that Image onto the screen size.
Just using SCALE and doing WIDTH * SCALE etc.
Lots of math
Things I do not mind
If you have a WIDE-SCREEN it stretches graphic2D objects to the size.
If you have a SQUARE-SCREEN it squishes graphics2D objects to the size.
So how can I make a perfectly resealable game using Graphics2D, JFrame.

In the most generic form, one can consider this as a classical problem of graphics programming, namely, as the transformation from world coordinates to screen coordinates. You have an object that has a size of "1.0 x 1.0" in your world coordinate system (regardless of which unit this has). And this object should be painted so that it has a size of, for example, "600 pixels * 600 pixels" on the screen.
Broadly speaking, there are at least three options to achieve this in Swing:
You can draw into an image, and then draw a scaled version of the image
You can draw into a scaled Graphics2D object
You can draw scaled objects
Each of this has possible advantages and disadvantages, and hidden caveats.
Drawing into an image, and drawing a scaled version of the image:
This might look like a simple solution, but has a potential drawback: The image itself has a certain resolution (size). If the image is too small, and you are scaling it up to fill the screen, it may appear blocky. If the image is too large, and you are scaling it down to fit into the screen, pixels of the image may be lost.
In both cases, there are several tuning parameters for the process of scaling the image. In fact, scaling an image is far more tricky than it looks at the first glance. For details, one may refer to the article The Perils of Image.getScaledInstance() by Chris Campbell.
Drawing into a scaled Graphics2D object
The Graphics2D class already offers the full functionality that is necessary to create the transformation between the world coordinate system and the screen coordinate system. This is accomplished by the Graphics2D class by internally storing an AffineTransform, which describes this transformation. This AffineTransform may be modified directly via the Graphics2D object:
void paintSomething(Graphics2D g) {
...
g.draw(someShape);
// Everything that is painted after this line will
// be painted 3 times as large:
g.scale(3.0, 3.0);
g.draw(someShape); // Will be drawn larger
}
Some care has to be taken to properly manage the transform that is stored in the Graphics2D object. In general, one should create a backup of the original AffineTransform before applying additional transformations, and restore this original transform afterwards:
// Create a backup of the original transform
AffineTransform oldAT = g.getTransform();
// Apply some transformations
g.scale(3.0, 4.0);
g.translate(10.0, 20.0);
// Do custom painting the the transformed graphics
paintSomething(g):
// Restore the original transformation
g.setTransform(oldAT);
(Another advice for the last method: The Graphics2D#setTransform method should never be used to apply a new coordinate transform on top of an existing transform. It is solely intended for restoring an "old" transform, as shown in this example (and in the documentation of this method)).
One potential drawback of scaling with the Graphics2D class is that afterwards, everything will be scaled. Particularly, this scaling will also affect line widths (that is, the width of the Stroke). For example, consider a sequence of calls like this one:
// By default, this will paint a line with a width (stroke) of 1.0:
g.draw(someLine);
// Apply some scaling...
g.scale(10.0, 10.0);
// Now, this will paint the same line, but with a width of 10.
g.draw(someLine);
The second call will cause a line to be drawn that is 10 pixels wide. This may not be desired in many cases. This effect can be avoided with the third alternative:
Drawing scaled objects
The transformation between the world coordinate system and the screen coordinate system can also be maintained manually. It is convenient to represent this as an AffineTransform. The AffineTransform class can be used to create transformed versions of Shape object, that can then be drawn directly into an (un-transformed) Graphics2D object. This is accomplished with the AffineTransform#createTransformedShape method:
void paintSomething(Graphics2D g) {
...
// Draw some shape in its normal size
g.draw(someShape);
// Create a scaling transform
AffineTransform at = AffineTransform.getScaleInstance(3.0, 3.0);
// Create a scaled version of the shape
Shape transformedShape = at.createTransformedShape(someShape);
// Draw the scaled shape
g.draw(transformedShape);
}
This is probably the most versatile approach. The only potential drawback is that, when many small, simple shapes are drawn, this will cause many, small temporary transformed shapes to be created, which may cause reduced performance. (There are ways to alleviate this problem, but detailed performance considerations and optimizations are beyond the scope of this answer).
Summary
The follwing image shows the comparison of all approaches. Some example objects (represented as Shape objects) are drawn. Each row compares the three different scaling methods mentioned above. With their "default" size, the objects fill a rectangle in world coordinates that has a size of 100x100. In the first two rows, they are scaled up to fill an area on the screen of 190x190 pixels. In the last two rows, they are scaled down to fill an area on the screen of 60x60 pixels. (These sizes have been chosen in order to have some "odd" scaling factors of 1.9 and 0.6. Certain effects (artifacts) may not appear when the scaling factors are whole numbers, or exactly 0.5, for example).
For the upscaling and the downscaling, there additionally is a comparison between the "standard" way of painting, and "high quality" painting (indicated by the "(HQ)" in the title of each panel). The "high quality" here simply means that the rendering hints
KEY_ANTIALIAS = VALUE_ANTIALIAS_ON
KEY_RENDERING = VALUE_RENDER_QUALITY
have been set:
Here is the corresponding program, as an MCVE:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.List;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class ScalingMethodComparison
{
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().setLayout(new GridLayout(0,1));
Dimension larger = new Dimension(190,190);
Dimension smaller = new Dimension(60,60);
f.getContentPane().add(createPanel(larger, false));
f.getContentPane().add(createPanel(larger, true));
f.getContentPane().add(createPanel(smaller, false));
f.getContentPane().add(createPanel(smaller, true));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private static JPanel createPanel(Dimension d, boolean highQuality)
{
JPanel p = new JPanel(new GridLayout(1,3));
for (ScalingMethodComparisonPanel.ScalingMethod scalingMethod :
ScalingMethodComparisonPanel.ScalingMethod.values())
{
p.add(createPanel(d, scalingMethod, highQuality));
}
return p;
}
private static JPanel createPanel(
Dimension d, ScalingMethodComparisonPanel.ScalingMethod scalingMethod,
boolean highQuality)
{
JPanel p = new JPanel(new GridLayout(1,1));
p.setBorder(BorderFactory.createTitledBorder(
scalingMethod.toString()+(highQuality?" (HQ)":"")));
JPanel scalingMethodComparisonPanel =
new ScalingMethodComparisonPanel(
createObjects(), d, scalingMethod, highQuality);
p.add(scalingMethodComparisonPanel);
return p;
}
// Returns a list of objects that should be drawn,
// occupying a rectangle of 100x100 in WORLD COORDINATES
private static List<Shape> createObjects()
{
List<Shape> objects = new ArrayList<Shape>();
objects.add(new Ellipse2D.Double(10,10,80,80));
objects.add(new Rectangle2D.Double(20,20,60,60));
objects.add(new Line2D.Double(30,30,70,70));
return objects;
}
}
class ScalingMethodComparisonPanel extends JPanel
{
private static final Color COLORS[] = {
Color.RED, Color.GREEN, Color.BLUE,
};
enum ScalingMethod
{
SCALING_IMAGE,
SCALING_GRAPHICS,
SCALING_SHAPES,
}
private final List<Shape> objects;
private final ScalingMethod scalingMethod;
private final boolean highQuality;
private final Dimension originalSize = new Dimension(100,100);
private final Dimension scaledSize;
private BufferedImage image;
public ScalingMethodComparisonPanel(
List<Shape> objects,
Dimension scaledSize,
ScalingMethod scalingMethod,
boolean highQuality)
{
this.objects = objects;
this.scaledSize = new Dimension(scaledSize);
this.scalingMethod = scalingMethod;
this.highQuality = highQuality;
}
#Override
public Dimension getPreferredSize()
{
return new Dimension(scaledSize);
}
#Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
Graphics2D g = (Graphics2D)gr;
g.setColor(Color.WHITE);
g.fillRect(0,0,getWidth(), getHeight());
if (highQuality)
{
g.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setRenderingHint(
RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
}
if (scalingMethod == ScalingMethod.SCALING_IMAGE)
{
paintByScalingImage(g);
}
else if (scalingMethod == ScalingMethod.SCALING_GRAPHICS)
{
paintByScalingGraphics(g);
}
else if (scalingMethod == ScalingMethod.SCALING_SHAPES)
{
paintByScalingShapes(g);
}
}
private void paintByScalingImage(Graphics2D g)
{
if (image == null)
{
image = new BufferedImage(
originalSize.width, originalSize.height,
BufferedImage.TYPE_INT_ARGB);
}
Graphics2D ig = image.createGraphics();
paintObjects(ig, null);
ig.dispose();
g.drawImage(image, 0, 0, scaledSize.width, scaledSize.height, null);
}
private void paintByScalingGraphics(Graphics2D g)
{
AffineTransform oldAT = g.getTransform();
double scaleX = (double)scaledSize.width / originalSize.width;
double scaleY = (double)scaledSize.height / originalSize.height;
g.scale(scaleX, scaleY);
paintObjects(g, null);
g.setTransform(oldAT);
}
private void paintByScalingShapes(Graphics2D g)
{
double scaleX = (double)scaledSize.width / originalSize.width;
double scaleY = (double)scaledSize.height / originalSize.height;
AffineTransform at =
AffineTransform.getScaleInstance(scaleX, scaleY);
paintObjects(g, at);
}
private void paintObjects(Graphics2D g, AffineTransform at)
{
for (int i=0; i<objects.size(); i++)
{
Shape shape = objects.get(i);
g.setColor(COLORS[i%COLORS.length]);
if (at == null)
{
g.draw(shape);
}
else
{
g.draw(at.createTransformedShape(shape));
}
}
}
}

This is actually quite easy in Java. In a Graphics2d environment, the logical coordinate system (the coordinates you use in the drawing routines) and the physical coordinate system (the coordinates as they appear) on the screen are completely unrelated. Every time you draw onto a Graphics2d object, the logical coordinates are first translated to the physical coordinates by an AffineTransform object, and this AffineTransform object can be modified. For this you can use the Graphics2D.scale(double,double), Graphics2D.rotate(double), Graphics2D.translate(double,double) and Graphics2D.shear(double,double) methods.
So if you first call
g2d.scale(2.0,2.0);
then all your graphics that you subsequently draw will be twice as large in both directions.

If I understood you correctly all you want is to draw your graphics in different resolutions without removing or adding any content.
Well one of the "things you have tried" can do that.
Drawing to a fixed size BufferedImage will ensure that all your components are visible within that BufferedImage (assuming you draw them correctly and relative to it's fixed size) then you can just draw the image to your flexible size screen.
Here's a full runnable code example that does that:
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Test extends Canvas implements Runnable {
// fixed size for the image
private static final int WIDTH = 640;
private static final int HEIGHT = 480;
private BufferedImage image;
private boolean running;
private Thread t;
public Test(Dimension dims) {
super();
setPreferredSize(dims); // actual screen size
image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
running = false;
}
public synchronized void start() {
if (running)
return;
t = new Thread(this);
running = true;
t.start();
}
public synchronized void stop() {
if (!running)
return;
running = false;
boolean retry = true;
while (retry) {
try {
t.join();
retry = false;
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
private void render() {
// draw to your image
Graphics2D g2d = (Graphics2D) image.getGraphics().create();
g2d.fillRect((WIDTH / 2) - 25, (HEIGHT / 2) - 25, 50, 50);
g2d.dispose();
// draw the image to your screen
BufferStrategy bs = getBufferStrategy();
if (bs == null) {
createBufferStrategy(3);
return;
}
g2d = (Graphics2D) bs.getDrawGraphics().create();
g2d.drawImage(image, 0, 0, getWidth(), getHeight(), null);
g2d.dispose();
bs.show();
}
public void run() {
// approximately sync rendering to 60 FPS don't use it as it is.
// there are much better ways to do this.
long startTime = System.currentTimeMillis();
long frameTime = 1000 / 60;
long tick = 0;
while (running) {
while ((System.currentTimeMillis() - startTime) > tick) {
render();
tick += frameTime;
}
try {
Thread.sleep(20);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args) {
Test test = new Test(new Dimension(800, 600));
JFrame frame = new JFrame("Fit to screen");
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
test.stop();
frame.dispose();
super.windowClosing(e);
}
});
frame.getContentPane().add(test);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setVisible(true);
SwingUtilities.invokeLater(new Runnable() {
public void run() {
test.start();
}
});
}
}
This is only a quick implementation there are things that can be done better in that code bu you get the picture. Hope this helps.

Maybe this will help :
Scaling graphics2D that contains basic shapes has a drawback : thickness of lines are doubled if the scale is doubled, that's a problem in an application implementing a zoom feature...
The only way I found is to make the preferred size of the container bigger and then, draw the shapes.
Here's a zoom function using mouse wheel and the pixel of the object pointed by the mouse stays under the mouse pointer.
It took me a long time to figure out how to do that properly, but I finally found out...(the application is an astrolabe and I wanted to zoom in and out)
The graphics2D belongs to a JPanel that is contained in the bottom part of a JSplitPane :
public void mouseWheelMoved(MouseWheelEvent e) {
Dimension dim = new Dimension(), oldDim = this.getPreferredSize();
double newX, newY;
Rectangle rect, oldRect;
if(this.mousewheel >= 0){
this.mousewheel += -e.getWheelRotation() * this.mousewheelSensibility;
}
else {
this.mousewheel = 0;
}
dim.setSize(this.astro.splitBottomDimension.getWidth() + this.mousewheel, this.astro.splitBottomDimension.getHeight() + this.mousewheel);
oldRect = this.getVisibleRect();
this.mouseX = e.getX();
this.mouseY = e.getY();
this.setPreferredSize(dim);
newX = this.mouseX / oldDim.getWidth() * dim.getWidth();
newY = this.mouseY / oldDim.getHeight() * dim.getHeight();
rect = new Rectangle((int)newX - (this.mouseX - oldRect.x), (int)newY - (this.mouseY - oldRect.y), oldRect.width, oldRect.height);
this.scrollRectToVisible(rect);
this.revalidate();

I cant view a BufferedImage image on a JPanel

I am having a problem with the code below. If I load the image directly into the JPanel I can see it. But when I try to draw it first to the BufferedImage before drawing the BufferedImage on the JPanel the image is not visible. What am I doing wrong?
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import java.awt.*;
import javax.swing.JPanel;
/**
*
* #author Duafeb
*/
public class RTester {
BufferedImage backBuffer;
Graphics2D g2;
Pane pain;
Image img;
public RTester(){
JFrame frame=new JFrame("Sprite Tester");
frame.setSize(1200, 700);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
backBuffer= new BufferedImage(1200,700,BufferedImage.TYPE_INT_RGB);
g2=backBuffer.createGraphics();
pain=new Pane();
frame.add(pain);
Toolkit tk=Toolkit.getDefaultToolkit();
img=tk.getImage(this.getClass().getResource("running.png"));
frame.setVisible(true);
}
public class Pane extends JPanel{
#Override
public void paintComponent(Graphics g){
Graphics2D g3=(Graphics2D)g;
g3.drawImage(backBuffer, 0, 0, this);
}
}
public void display(){
g2.setColor(Color.yellow);
g2.fillRect(0, 0, pain.getWidth(), pain.getHeight());
g2.drawImage(img, 0, 0, pain);
pain.repaint();
}
public static void main(String[] args){
RTester test=new RTester();
test.display();
}
}

There are a few things that don't feel right about this...
The first is, you create a Graphics context to BufferedImage, but never dispose of it. Be careful, on some systems this can prevent the contents from been rendered, but this might relate to the screen device rather than a BufferedImage
For example, if I alter you code to paint the contents directly within the paintComponent method instead of to the BufferedImage, the image will be displayed (all bit a split second after the window becomes visible).
I'm not sure what it is you're trying to achieve by using the BufferedImage, but you could achieve the same thing straight through the paintComponent method
Instead of using Toolkit.getImage, you could use ImageIO.read, which guarantees that when it returns, the image is fully loaded (or will throw an IOException if it fails) or as #Reimeus had previously suggested, using a MediaTracker to ensure that the image is properly loaded before you continue using it.
So, you have four options....
One
Use a MediaTracker to wait for the image to be loaded...
MediaTracker mt = new MediaTracker(frame);
mt.addImage(img, 1);
try {
mt.waitForAll();
} catch (InterruptedException ex) {
ex.printStackTrace();
}
Two
Use ImageIO.read instead...
img = ImageIO.read(this.getClass().getResource("running.png"));
Three
Render output directly in the paintComponent method...
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g3 = (Graphics2D) g;
g3.setColor(Color.yellow);
g3.fillRect(0, 0, pain.getWidth(), pain.getHeight());
g3.drawImage(img, 0, 0, obsever);
}
Four
Use you own ImageObserver to ensure that when the image is updated, you re-render it to the backing buffer...
private MyImageObsever obsever;
public void display() {
if (obsever == null) {
obsever = new MyImageObsever(this);
}
g2.setColor(Color.yellow);
g2.fillRect(0, 0, pain.getWidth(), pain.getHeight());
g2.drawImage(img, 0, 0, obsever);
pain.repaint();
}
public class MyImageObsever implements ImageObserver {
private RTester tester;
public MyImageObsever(RTester tester) {
this.tester = tester;
}
#Override
public boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height) {
tester.display();
return (infoflags & (ALLBITS|ABORT)) == 0;
}
}

How to stop JComponent from clearing?

I am making a molecule designing application. I can draw the lines and circles, but it clears the old lines each time you click, so basically, you can only design molecules with 2 atoms.
Also, the mouseEvents don't deliver if you click very fast which is also a problem.
Here is the code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.image.BufferedImage;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class MoleculeDesigner extends JComponent implements MouseListener {
private Point op, cp;
private boolean first = true;
public static final Color linecolor = new Color(0, 255, 0);
private static final long serialVersionUID = 1L;
private BufferedImage img = new BufferedImage(100, 100, BufferedImage.TYPE_INT_RGB);
public MoleculeDesigner() {
JFrame f = new JFrame("Molecule Designer");
f.setBackground(Color.WHITE);
f.addMouseListener(this);
f.add(this);
f.setSize(100, 100);
f.setDefaultCloseOperation(3);
f.setVisible(true);
}
public static void main(String[] args) {
new MoleculeDesigner();
}
#Override
protected void paintComponent(Graphics g) {
if(op != null && cp != null) {
Graphics2D g2 = img.createGraphics();
super.paintComponent(g2);
g2.setColor(linecolor);
g2.drawLine((int) op.getX(), (int) op.getY(), (int) cp.getX(), (int) cp.getY());
g2.setColor(Color.BLACK);
g2.fillOval((int) cp.getX(), (int) cp.getY(), 10, 10);
op = (Point) cp.clone();
g2.dispose();
}
}
#Override
public Dimension getPreferredSize() {
return getParent().getMaximumSize();
}
#Override
public void mouseClicked(MouseEvent e) {
if(!first) {
cp = e.getPoint();
cp.setLocation(cp.getX(), cp.getY() - 8);
}
else {
op = e.getPoint();
first = false;
}
repaint();
}
#Override public void mousePressed(MouseEvent e) {}
#Override public void mouseReleased(MouseEvent e) {}
#Override public void mouseEntered(MouseEvent e) {}
#Override public void mouseExited(MouseEvent e) {}
}
All help appreciated!

Either 1) draw in a BufferedImage which is then displayed inside of your paintComponent override, or 2) put your data into an ArrayList or other collection, and then iterate through the collection inside of paintComponent. I'd do the latter if I needed the data for other purposes. Also, never ever do this:
public void update(Graphics g) {
paintComponent(g);
}
This is not how Swing graphics are supposed to be done and is potentially dangerous code. Please read:
Basic Swing Graphics Tutorial
Advanced Swing Graphics Information
Edit
More detail regarding option 1:
Create a BufferedImage using one of its constructors.
Do your drawing on the image.
When you need to draw, get a Graphics object from the BufferedImage using getGraphics() or createGrahpics() (for a Graphics2D object)
Draw with this Graphics object
Then dispose() the Graphics object.
Then call repaint() to ask the JVM to repaint the component.
Draw the image in your paintComponent method by calling g.drawImage(...), passing in your buffered image.
Benefits: often the drawing is quicker, and I often use this to draw background images.
Drawbacks: the data points are not available, and so if you need to do manipulation or animation of your data points, this is not the way to go.

You don't, nor should you.
paint in Swing is a destructive process, this is the way it was designed. That is, there is an expectation that when you component is requested to paint itself, it will clean up the Graphics context before painting anything (this is slightly different for transparent components though).
Swing has no concept of what was painted on your component before and because the Graphics context is shared amongst all the components been painted, unless you clear the graphics first, you could end up with unwanted paint artifacts
Possible solutions might include...
Painting to some kind of backing buffer (such as a BufferedImage), which you use the paintComponent method to draw. This is limited in the fact that it just acts like a paint program, painting pixels to the image. You will also need to provide functionality when the size of the viewable area changes, as the BufferedImage won't know.
Place each object you wanted painted into some kind of List and iterate this list when paintComponent is called. This is a little more flexible in that you can control the order of the objects drawn, remove objects and insert new ones where you like

Overlaying semitransparent layer on a background with Java 3D

I'm using Java3D to visualize a room with some primitives in it. I have an image background that I tile so that it fills the entire frame using background.setImageScaleMode(Background.SCALE_REPEAT);. Now I would like to add another semitransparent background on top of this background, and I would like to stretch it to cover the screen using SCALE_FIT_ALL. This will create an image effect that I cannot otherwise achieve. However, when I try to do this Java 3D complains that Group.addChild: child already has a parent.
Other ways of doing the same thing without using backgrounds (e.g. draw it on a 2D primitive) would be a interest too.
So my question is how can I achieve what I want with Java3D?
MWE: Image are available here. I want to draw bg-stars.png with Background.SCALE_REPEAT and then on top of that bg-glow.png with Background.SCALE_FIT_ALL.

Probably not what you actually want to achieve, but too long for a comment:
I did a test of adding multiple Backgrounds, and it "worked" basically (that is: it did not cause an error message). But the documentation of Background says
If multiple Background nodes are active, the Background node that is "closest" to the eye will be used.
Thus, I assume that it is not possible at all to display multiple backgrounds simulataneously at all.
Depending on what you want to achieve, there are probably several possibilities. The following it one approach that might be "close" to what you want. But I am not familiar with Backgrounds in Java3D, and assume that there are more elegant, efficient, flexible (or simply: better) approaches (like creating a huge, semi-transparent quad with the overlay texture or whatever...)
However, the idea here was to create the background as a single image. Composing BufferedImages is rather easy and offers a lot of possibilities. So I'm taking the bg-stars.png image and create a "tiled" version of this image (large enough to fill a certain area - in practice, this could simply be made as large as the maximum screen size). Then I'm composing this with the "overlay" image, bg-glow.png, by just painting it over the tiled image.
The resulting image can then be used to create the Background.
At the first glance, the result may look like what you want to achieve, but of course, there may be some caveats. E.g. one has to think about how this could be implemented to adapt to changes of the window size. (Listening for this with a ComponentListener and updating the image would be easy, but ... well).
And again: There certainly are better solutions. But maybe this can at least serve as a workaround until you find the better solution.
import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.media.j3d.Background;
import javax.media.j3d.BoundingSphere;
import javax.media.j3d.BranchGroup;
import javax.media.j3d.Canvas3D;
import javax.media.j3d.ImageComponent2D;
import javax.media.j3d.Transform3D;
import javax.media.j3d.TransformGroup;
import com.sun.j3d.utils.applet.MainFrame;
import com.sun.j3d.utils.geometry.ColorCube;
import com.sun.j3d.utils.image.TextureLoader;
import com.sun.j3d.utils.universe.SimpleUniverse;
public class SimpleBackgroundTest extends Applet
{
private static final int WIDTH = 1200;
private static final int HEIGHT = 1200;
public static void main(String[] args) throws IOException
{
System.setProperty("sun.awt.noerasebackground", "true");
Frame frame = new MainFrame(new SimpleBackgroundTest(), WIDTH, HEIGHT);
}
public SimpleBackgroundTest()
{
setLayout(new BorderLayout());
Canvas3D c = new Canvas3D(SimpleUniverse.getPreferredConfiguration());
add("Center", c);
BranchGroup group = new BranchGroup();
group.addChild(createSomeCube());
BufferedImage stars = null;
BufferedImage glow = null;
try
{
stars = ImageIO.read(new File("bg-stars.png"));
glow = ImageIO.read(new File("bg-glow.png"));
}
catch (IOException e)
{
e.printStackTrace();
}
BufferedImage tiled = createTiled(stars, WIDTH, HEIGHT);
BufferedImage overlay = createOverlay(tiled, glow);
Background background = createBackground(overlay);
group.addChild(background);
SimpleUniverse universe = new SimpleUniverse(c);
universe.addBranchGraph(group);
universe.getViewingPlatform().setNominalViewingTransform();
}
private static BufferedImage createTiled(
BufferedImage image, int targetSizeX, int targetSizeY)
{
BufferedImage result = new BufferedImage(
targetSizeX, targetSizeY,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g = result.createGraphics();
for (int x = 0; x < targetSizeX; x += image.getWidth())
{
for (int y = 0; y < targetSizeY; y += image.getHeight())
{
g.drawImage(image, x, y, null);
}
}
g.dispose();
return result;
}
private static BufferedImage createOverlay(
BufferedImage image, BufferedImage overlay)
{
BufferedImage result = new BufferedImage(
image.getWidth(), image.getHeight(),
BufferedImage.TYPE_INT_ARGB);
Graphics2D g = result.createGraphics();
g.drawImage(image, 0, 0, null);
g.drawImage(overlay, 0, 0, image.getWidth(), image.getHeight(), null);
g.dispose();
return result;
}
private static Background createBackground(BufferedImage image)
{
TextureLoader textureLoader = new TextureLoader(image);
ImageComponent2D imageComponent = textureLoader.getImage();
Background background = new Background();
background.setImage(imageComponent);
background.setImageScaleMode(Background.SCALE_FIT_ALL);
background.setCapability(Background.ALLOW_IMAGE_WRITE);
background.setApplicationBounds(new BoundingSphere());
return background;
}
private TransformGroup createSomeCube()
{
ColorCube cube = new ColorCube(0.5f);
Transform3D t = new Transform3D();
t.rotY(0.2);
t.setScale(0.1);
TransformGroup tg = new TransformGroup();
tg.setTransform(t);
tg.removeAllChildren();
tg.addChild(cube);
return tg;
}
}

Drawing Filled Rectangle over a BufferedImage

So I am attempting to create an application that can black-out sections of a survey that contains sensitive information. However I've run into a bit of a problem.
What I want to do is draw filled black rectangles over a BufferedImage given x, y, width, and height of desired region to black out, then write that new image back to my filesystem. Here's my code.
File imageFile = new File("images/template.jpg");
BufferedImage img = ImageIO.read(imageFile);
Graphics2D graph = img.createGraphics();
graph.setColor(Color.BLACK);
graph.fill(new Rectangle(x, y, width, height));
graph.dispose();
ImageIO.write(img, "jpg", new File("images/template.jpg"));
For whatever reason the image in the resource doesn't change after this code segment. Any ideas on what I'm doing wrong?

I created a runnable example of your code, and it worked fine for me. I ran this code using Java 8.
Here's the altered image. I drew the black square on an image I had.
And here's the code I ran. I read the original image directly from my file system.
package com.ggl.testing;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ImageProcessing implements Runnable {
public static void main(String[] args) {
new ImageProcessing().run();
}
#Override
public void run() {
File imageFile = new File("C:\\Users\\Owner\\Pictures\\Saved Pictures\\Analog Clock Calendar.jpg");
BufferedImage img;
try {
img = ImageIO.read(imageFile);
} catch (IOException e1) {
e1.printStackTrace();
return;
}
Graphics2D graph = img.createGraphics();
graph.setColor(Color.BLACK);
graph.fill(new Rectangle(100, 100, 100, 100));
graph.dispose();
try {
ImageIO.write(img, "jpg",
new File("altered.jpg"));
} catch (IOException e) {
e.printStackTrace();
}
}
}
My conclusion is that you either didn't read the image correctly, your x, y, width, and/or height were outside the limits of the image, or something else that I'm missing.

I know is an old question, but maybe it can be useful to someone,
I think you shoud use this
graph.drawImage(x,y,width,height); //First you draw the image
graph.setColor(Color.black); //Then set the color to black
graph.fillRect(img.getX(), img.getY(), img.getWidth(), img.getHeight());// Finally draw a black rectangle on it
By the way is hard to find a solution without a little more code.
Hope it will be usefull.

Very late to this answer but you are saving the image and not the graph you are creating. I think it must be a BufferedImage again to save

You have just to replace this line:
Graphics2D graph = img.createGraphics();
with this:
Graphics2D graph = img.getGraphics();