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Fit image into JPanel

I'm trying scale an image so it will always fit my JPanel. Unfortunately using this method I don't always receive an Image I wanted to receive. Mostly it is zoomed and I would rather have the whole image but scaled.
Thats the class that creates the image. 600 is the PanelWidth and 400 is the PanelHeight.
Any ideas what goes wrong?
public class Image extends Component{
private BufferedImage img;
protected int width;
protected int height;
private String path;
#Override
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
double scale = getScale(600,400,img.getWidth(),img.getHeight());
double xPos = (600 - scale * img.getWidth())/2;
double yPos = (400 - scale *img.getHeight())/2;
AffineTransform at = AffineTransform.getTranslateInstance(xPos, yPos);
at.scale(scale, scale);
g2.drawRenderedImage(img, at);
System.out.println(scale);
}
public Image(String path){
try{
img = ImageIO.read(new File(path));
} catch (IOException e) { }
this.width=img.getWidth();
this.height=img.getHeight();
this.path = path;
}
public double getScale(int panelWidth, int panelHeight, int imageWidth, int imageHeight){
double scale = 1;
double xScale, yScale;
if(imageWidth > panelWidth || imageHeight > panelHeight){
xScale = (double)imageWidth/panelWidth;
yScale = (double)imageHeight/panelHeight;
scale = Math.max(xScale, yScale);
}else if(imageWidth < panelWidth && imageHeight < panelHeight){
xScale = (double)panelWidth/imageWidth;
yScale = (double)panelHeight/imageHeight;
scale = Math.max(xScale, yScale);
}else{
scale = 1;
}
return scale;
}

A JPanel is a Swing component which implies you are using Swing.
For custom painting you should extend JPanel or JComponent. Most people use JPanel because it will clear the background of the component for you.
Custom painting of a Swing component is done by overriding paintComponent(...)
so it will always fit my JPanel
Define "fit"?
Assuming you are trying to scale the image to retain its original proportions you could to something like:
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
double imageWidth = image.getWidth(null);
double imageHeight = image.getHeight(null);
double factor = Math.min(getWidth() / imageWidth, getHeight() / imageHeight);
int width = (int)(image.getWidth(null) * factor);
int height = (int)(image.getHeight(null) * factor);
g.drawImage(image, 0, 0, width, height, this);
}
If you are just trying to fit the image on the panel then you do:
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(image, 0, 0, getWidth(), getHeight(), this);
}

You don't need to use float if you do your operations in the right order. Assuming imageWidth, imageHeight, panelWidth are all int:
// Calculate the width of the scaled image; if the image is wider than the
// panel, use the panel width, otherwise use the image width (i.e. don't upscale)
int scaledWidth = Math.min(imageWidth, panelWidth);
// Given the scaled width, calculate the scaled height
// Force it to be at least 1 pixel, since if you have an image that's wider than
// the panel and only 1 pixel tall, this will scale to zero height, which you
// don't want
int scaledHeight = Math.max(1, imageHeight * scaledWidth / imageWidth);
The above assumes you want to fit the width and will be providing a scrolling mechanism if the image height exceeds the panel height. If you want to fit height instead (and horizontal scroll for overflow) just make the necessary changes in variables.

How do I make a dynamic image in Java Swing?

How can i make my image dynamic; My code :
public void paint(Graphics g){
super.paint(g);
//this.setBackground(Color.white);
g.drawImage(bg,300 , 70, 800, 100, null);
}
That creates an image but when i open the window and i enlarge it; the images takes the right position.

First look at the method you are calling.
drawImage(Image img, int x, int y, int width, int height, ImageObserver observer)
It sounds like you need to know x and y values to paint your image in the correct location. Lets pretend this paint method is inside of a component.
//based on your description.
int imageWidth = 800;
int imageHeight = 100;
int x = (getWidth() - imageWidth)/2;
int y = (getHeight() - imageHeight)/2;
g.drawImage(bg, x, y, imageWidth, imageHeight, this);
That should center your image when the component is resized and repainted. Of course there are better ways to do this, such as using a JLabel and a layout manager.

Setting the background using a JLabel and an image inserted into it

I've been working on a small project for fun, i'm currently working on the background however it is really small, to change this i'm setting the dimensions to the max screen size (the project is full screen)
public void setBackground(JLabel bg) {
bg = new JLabel(new ImageIcon(this.getClass().getResource("/Background.gif")));
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
int width = (int) d.getWidth();
int height = (int) d.getHeight();
bg.setSize(width, height);
add(bg);
}
However, it does increase the JLabel size but not the actual image size, why is this?
EDIT:
i've found a way to do this, but it doesn't seem to find the specified path! i had made a resources folder where it is stored (a source folder in eclipse) i put it in there but it can't read the input file.
public void setBackground(JLabel bg) {
try {
img = ImageIO.read(new File("/Background.gif"));
} catch(Exception e) {
e.printStackTrace();
}
ImageIcon imgi = new ImageIcon(fitimage(img, bg.getWidth(), bg.getHeight()));
bg.setIcon(imgi);
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
int width = (int) d.getWidth();
int height = (int) d.getHeight();
bg.setSize(width, height);
add(bg);
}
private Image fitimage(Image img , int w , int h) {
BufferedImage resizedimage = new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = resizedimage.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2.drawImage(img, 0, 0,w,h,null);
g2.dispose();
return resizedimage;
}

You may need to resize your image first before using it in your application. It must be the same size as your label. Whatever the actual size of your image is, that's the size Java will display it as and will not auto-resize it respectively to your label

Java, using AffineTransform not rotating exactly centered

I'm trying to rotate an image, but it's getting slightly messed up when I'm rotating it, and it looks like it's not rotating it on center. So if I go around it looks like it's being truncated. Is there a better method to get the "center" of the image?
public void RotateImageLeft() {
try {
BufferedImage newImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), originalImage.getType());
AffineTransform tx = new AffineTransform();
tx.rotate(Math.toRadians(-90.0), originalImage.getWidth() / 2, originalImage.getHeight() / 2);
Graphics2D g2 = newImage.createGraphics();
g2.drawImage(originalImage, tx, null);
originalImage = newImage;
this.repaint();
g2.dispose();
} catch (Exception ex) {
ex.toString();
}
//g2d.drawImage(getResImage(), rescale, x, y);
}
For full code disclosure, here's more code. Here's my painComponent overridden method:
public void paintComponent(Graphics g) {
super.paintComponent(g);
resizeImage();
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(getResImage(), rescale, x, y);
}
Here's the resizeImage() method that gets called:
public void resizeImage() {
Graphics g = getResImage().getGraphics();
g.setColor(Color.WHITE);
g.fillRect(0, 0, getResImage().getWidth(), getResImage().getHeight());
int scaledWidth = (int) ((getOriginalImage().getWidth() * getHeight()
/ getOriginalImage().getHeight()));
if (scaledWidth < getWidth()) {
int leftOffset = getWidth() / 2 - scaledWidth / 2;
int rightOffset = getWidth() / 2 + scaledWidth / 2;
g.drawImage(getOriginalImage(),
leftOffset, 0, rightOffset, getHeight(),
0, 0, getOriginalImage().getWidth(), getOriginalImage().getHeight(),
null);
} else {
int scaledHeight = (getOriginalImage().getHeight() * getWidth())
/ getOriginalImage().getWidth();
int topOffset = getHeight() / 2 - scaledHeight / 2;
int bottomOffset = getHeight() / 2 + scaledHeight / 2;
g.drawImage(getOriginalImage(),
0, topOffset, getWidth(), bottomOffset,
0, 0, getOriginalImage().getWidth(), getOriginalImage().getHeight(),
null);
}
}
I'm using the ResizeImage method since I want any image to fit correctly on my 720/432 panel.
Here's some example pictures.
Pre-rotated
Post-rotated:
New code: (new image is the correct height/width of rotated image, still getting black bars. Screens below.
public void RotateImageLeft() {
try {
BufferedImage newImage = new BufferedImage( originalImage.getHeight(),originalImage.getWidth(), originalImage.getType());
AffineTransform tx = new AffineTransform();
tx.rotate(Math.toRadians(-90.0), newImage.getWidth() / 2, (newImage.getHeight() / 2));
Graphics2D g2 = newImage.createGraphics();
g2.drawImage(originalImage, tx, null);
originalImage = newImage;
this.repaint();
g2.dispose();
} catch (Exception ex) {
ex.toString();
}
}
Post rotate:

From my answer to another similar question
If you're rotating then this will work for 90 degrees.
move image so centered "around" the origin
plain rotate() call with no extra parameters
Move image back into the center remembering that now width = old height and height = old width.
Also remember the affine transform steps work in reverse order.
AffineTransform tx = new AffineTransform();
// last, width = height and height = width
tx.translate(originalImage.getHeight() / 2,originalImage.getWidth() / 2);
tx.rotate(Math.PI / 2);
// first - center image at the origin so rotate works OK
tx.translate(-originalImage.getWidth() / 2,-originalImage.getHeight() / 2);

If you want to rotate an image without cropping you need to add black bars around it first, since a rotated rectangle will always have a bigger bounding box than an axis-aligned one (exception: rotating a square by multiples of 90 degrees).
So what you want to do is do some trigonometric calculations beforehand to decide the maximum Width/Height of the rotated image, and combine that with the original Width/Height. Resize your image (centering it) using those dimensions, rotate it, and then crop it back to the Width/Height of the rotated image.

Rotating BufferedImage instances

I am having trouble getting a rotated BufferedImage to display. I think the rotation is working just fine, but I can't actually draw it to the screen. My code:
Class extends JPanel {
BufferedImage img;
int rotation = 0;
public void paintComponent(Graphics g) {
g.clearRect(0, 0, getWidth(), getHeight());
img2d = img.createGraphics();
img2d.rotate(Math.toRadians(rotation), img.getWidth() / 2, img.getHeight() / 2);
g.drawImage(img, imgx, imgy, null);
this.repaint();
}
}
This is not working for me. I could not find any way to draw the rotated img2d onto g.
EDIT: I have multiple objects that are being drawn onto g, so I can't rotate that. I need to be able to rotate things individually.

Maybe you should try using AffineTransform like this:
AffineTransform transform = new AffineTransform();
transform.rotate(radians, bufferedImage.getWidth() / 2, bufferedImage.getHeight() / 2);
AffineTransformOp op = new AffineTransformOp(transform, AffineTransformOp.TYPE_BILINEAR);
bufferedImage = op.filter(bufferedImage, null);
Hope this helps.

I would use Graphics2D.drawImage(image, affinetranform, imageobserver).
The code example below rotates and translates an image to the center of the component. This is a screenshot of the result:
public static void main(String[] args) throws IOException {
JFrame frame = new JFrame("Test");
frame.add(new JComponent() {
BufferedImage image = ImageIO.read(
new URL("http://upload.wikimedia.org/wikipedia/en/2/24/Lenna.png"));
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
// create the transform, note that the transformations happen
// in reversed order (so check them backwards)
AffineTransform at = new AffineTransform();
// 4. translate it to the center of the component
at.translate(getWidth() / 2, getHeight() / 2);
// 3. do the actual rotation
at.rotate(Math.PI / 4);
// 2. just a scale because this image is big
at.scale(0.5, 0.5);
// 1. translate the object so that you rotate it around the
// center (easier :))
at.translate(-image.getWidth() / 2, -image.getHeight() / 2);
// draw the image
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(image, at, null);
// continue drawing other stuff (non-transformed)
//...
}
});
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 400);
frame.setVisible(true);
}

You are rotating the graphics for drawing into your image, not the image. Thats why you see no effect. Apply the rotation to the graphics you are painting on and it will draw the image rotated:
public void paintComponent(Graphics g) {
g.clearRect(0, 0, getWidth(), getHeight());
g.rotate(Math.toRadians(rotation), img.getWidth() / 2, img.getHeight() / 2);
g.drawImage(img, imgx, imgy, null);
this.repaint();
}
This will probably not draw entirely what you expect, the rotation will revolve around the coordinate origin. For the image to be rotate around its center you need to apply a coordinate translation before the rotation, for example:
g.translate(imgx >> 1, imgy >> 1);
The Graphics2D Tutorial has some more examples.

I know this question is old but I came up with a solution that has some advantages:
creates image of correct size.
correct offset.
does not unnecessarily rotate by 0° or 360°.
works for negative angles (e.g. -90°).
works when input is BufferedImage.TYPE_CUSTOM.
As it is, it is assumed that the angle is a multiple of 90°. The only improvement that one might need is to use an Enum for angle instead of just int.
Here's my code:
public static BufferedImage rotateBufferedImage(BufferedImage img, int angle) {
if (angle < 0) {
angle = 360 + (angle % 360);
}
angle %= 360;
if (angle == 0) {
return img;
}
final boolean r180 = angle == 180;
if (angle != 90 && !r180 && angle != 270)
throw new IllegalArgumentException("Invalid angle.");
final int w = r180 ? img.getWidth() : img.getHeight();
final int h = r180 ? img.getHeight() : img.getWidth();
final int type = img.getType() == BufferedImage.TYPE_CUSTOM ? BufferedImage.TYPE_INT_ARGB : img.getType();
final BufferedImage rotated = new BufferedImage(w, h, type);
final Graphics2D graphic = rotated.createGraphics();
graphic.rotate(Math.toRadians(angle), w / 2d, h / 2d);
final int offset = r180 ? 0 : (w - h) / 2;
graphic.drawImage(img, null, offset, -offset);
graphic.dispose();
return rotated;
}
public static BufferedImage rotateBufferedImage(String img, int angle) throws IOException {
return rotateBufferedImage(Paths.get(img), angle);
}
public static BufferedImage rotateBufferedImage(Path img, int angle) throws IOException {
return rotateBufferedImage(ImageIO.read(img.toFile()), angle);
}