Scale the ImageIcon automatically to label size
Solution 1:
This is a tricky question. You highlight the fact that you are using a JLabel to show the image, which is the standard way of doing things, but, JLabel is a complex little beast, with text, icon and text alignment and positioning.
If you don't need all that extra functionality, I would simply create yourself a custom component capable of painting a scaled image...
The next question is, how do you want to scale the image? Do you want to maintain the aspect ratio of the image? Do you want to "fit" or "fill" the image to the available space.
@David is right. You should, where possible, avoid Image#getScaledInstance as it's not the fastest, but, more importantly, generally, it doesn't provide the highest quality either.
Fit vs Fill
The following example is rather simple (and borrows heavy from my library of code, so it's probably also a little convoluted ;)). It could use from a background scaling thread, but I would base the decision on the potential size of original image.
public class ResizableImage {
public static void main(String[] args) {
new ResizableImage();
}
public ResizableImage() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
try {
BufferedImage image = ImageIO.read(new File("/path/to/your/image"));
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new ScalablePane(image));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (Exception exp) {
exp.printStackTrace();
}
}
});
}
public class ScalablePane extends JPanel {
private Image master;
private boolean toFit;
private Image scaled;
public ScalablePane(Image master) {
this(master, true);
}
public ScalablePane(Image master, boolean toFit) {
this.master = master;
setToFit(toFit);
}
@Override
public Dimension getPreferredSize() {
return master == null ? super.getPreferredSize() : new Dimension(master.getWidth(this), master.getHeight(this));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Image toDraw = null;
if (scaled != null) {
toDraw = scaled;
} else if (master != null) {
toDraw = master;
}
if (toDraw != null) {
int x = (getWidth() - toDraw.getWidth(this)) / 2;
int y = (getHeight() - toDraw.getHeight(this)) / 2;
g.drawImage(toDraw, x, y, this);
}
}
@Override
public void invalidate() {
generateScaledInstance();
super.invalidate();
}
public boolean isToFit() {
return toFit;
}
public void setToFit(boolean value) {
if (value != toFit) {
toFit = value;
invalidate();
}
}
protected void generateScaledInstance() {
scaled = null;
if (isToFit()) {
scaled = getScaledInstanceToFit(master, getSize());
} else {
scaled = getScaledInstanceToFill(master, getSize());
}
}
protected BufferedImage toBufferedImage(Image master) {
Dimension masterSize = new Dimension(master.getWidth(this), master.getHeight(this));
BufferedImage image = createCompatibleImage(masterSize);
Graphics2D g2d = image.createGraphics();
g2d.drawImage(master, 0, 0, this);
g2d.dispose();
return image;
}
public Image getScaledInstanceToFit(Image master, Dimension size) {
Dimension masterSize = new Dimension(master.getWidth(this), master.getHeight(this));
return getScaledInstance(
toBufferedImage(master),
getScaleFactorToFit(masterSize, size),
RenderingHints.VALUE_INTERPOLATION_BILINEAR,
true);
}
public Image getScaledInstanceToFill(Image master, Dimension size) {
Dimension masterSize = new Dimension(master.getWidth(this), master.getHeight(this));
return getScaledInstance(
toBufferedImage(master),
getScaleFactorToFill(masterSize, size),
RenderingHints.VALUE_INTERPOLATION_BILINEAR,
true);
}
public Dimension getSizeToFit(Dimension original, Dimension toFit) {
double factor = getScaleFactorToFit(original, toFit);
Dimension size = new Dimension(original);
size.width *= factor;
size.height *= factor;
return size;
}
public Dimension getSizeToFill(Dimension original, Dimension toFit) {
double factor = getScaleFactorToFill(original, toFit);
Dimension size = new Dimension(original);
size.width *= factor;
size.height *= factor;
return size;
}
public double getScaleFactor(int iMasterSize, int iTargetSize) {
return (double) iTargetSize / (double) iMasterSize;
}
public double getScaleFactorToFit(Dimension original, Dimension toFit) {
double dScale = 1d;
if (original != null && toFit != null) {
double dScaleWidth = getScaleFactor(original.width, toFit.width);
double dScaleHeight = getScaleFactor(original.height, toFit.height);
dScale = Math.min(dScaleHeight, dScaleWidth);
}
return dScale;
}
public double getScaleFactorToFill(Dimension masterSize, Dimension targetSize) {
double dScaleWidth = getScaleFactor(masterSize.width, targetSize.width);
double dScaleHeight = getScaleFactor(masterSize.height, targetSize.height);
return Math.max(dScaleHeight, dScaleWidth);
}
public BufferedImage createCompatibleImage(Dimension size) {
return createCompatibleImage(size.width, size.height);
}
public BufferedImage createCompatibleImage(int width, int height) {
GraphicsConfiguration gc = getGraphicsConfiguration();
if (gc == null) {
gc = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
}
BufferedImage image = gc.createCompatibleImage(width, height, Transparency.TRANSLUCENT);
image.coerceData(true);
return image;
}
protected BufferedImage getScaledInstance(BufferedImage img, double dScaleFactor, Object hint, boolean bHighQuality) {
BufferedImage imgScale = img;
int iImageWidth = (int) Math.round(img.getWidth() * dScaleFactor);
int iImageHeight = (int) Math.round(img.getHeight() * dScaleFactor);
if (dScaleFactor <= 1.0d) {
imgScale = getScaledDownInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
} else {
imgScale = getScaledUpInstance(img, iImageWidth, iImageHeight, hint, bHighQuality);
}
return imgScale;
}
protected BufferedImage getScaledDownInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = (img.getTransparency() == Transparency.OPAQUE)
? BufferedImage.TYPE_INT_RGB : BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
if (targetHeight > 0 || targetWidth > 0) {
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w > targetWidth) {
w /= 2;
if (w < targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h > targetHeight) {
h /= 2;
if (h < targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(Math.max(w, 1), Math.max(h, 1), type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
} while (w != targetWidth || h != targetHeight);
} else {
ret = new BufferedImage(1, 1, type);
}
return ret;
}
protected BufferedImage getScaledUpInstance(BufferedImage img,
int targetWidth,
int targetHeight,
Object hint,
boolean higherQuality) {
int type = BufferedImage.TYPE_INT_ARGB;
BufferedImage ret = (BufferedImage) img;
int w, h;
if (higherQuality) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = img.getWidth();
h = img.getHeight();
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = targetWidth;
h = targetHeight;
}
do {
if (higherQuality && w < targetWidth) {
w *= 2;
if (w > targetWidth) {
w = targetWidth;
}
}
if (higherQuality && h < targetHeight) {
h *= 2;
if (h > targetHeight) {
h = targetHeight;
}
}
BufferedImage tmp = new BufferedImage(w, h, type);
Graphics2D g2 = tmp.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, hint);
g2.drawImage(ret, 0, 0, w, h, null);
g2.dispose();
ret = tmp;
tmp = null;
} while (w != targetWidth || h != targetHeight);
return ret;
}
}
}
Solution 2:
Is there a way to set the size of the label
Override getPreferredSize() of JLabel and return the Dimensions you want,
but because a JLabel will size itself to its content you will just need to resize the picture you add to the JLabel.
and then to autosize the image in the label?
You will have to resize your image according to the width and height you want (than simply add it to the JLabel and the JLabel will size to fit the image).
I do not recommend Image.getScaledInstance(..) have a read here for more:
- The Perils of Image.getScaledInstance() Mainly the problem outlined is:
Image.getScaledInstance()does not return a finished, scaled image. It leaves much of the scaling work for a later time when the image pixels are used.
Here is a custom method Ive been using to circumvent the issues created by getScaledInstance:
public static BufferedImage resize(BufferedImage image, int width, int height) {
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, width, height, null);
g2d.dispose();
return bi;
}
you would create an image to whatever size you want via:
BufferedImage image=ImageIO.read(..);
BufferedImage resizedImage=resize(image,100,100);//resize the image to 100x100
Solution 3:
It can also be done by overriding the paintComponent method of JLabel and drawing the image having width and height as that of JLabel. And if you wish to resize the image when the parent container is resized you can apply the WindowListener on the parent container and repaint the Jlabel instance each time the parent container is resized.
Here is the Demo:
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import javax.swing.SwingUtilities;
import java.awt.Graphics;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class LabelDemo extends JFrame
{
ImageIcon imageIcon;
MyJLabel jLabel ;
public LabelDemo ()
{
super("JLabel Demo");
}
public void createAndShowGUI()
{
imageIcon = new ImageIcon("apple.png");
jLabel = new MyJLabel(imageIcon);
getContentPane().add(jLabel);
addWindowListener( new WindowAdapter()
{
public void windowResized(WindowEvent evt)
{
jLabel.repaint();
}
});
setSize(300,100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
jLabel.repaint();
}
public static void main(String st[])
{
SwingUtilities.invokeLater( new Runnable()
{
@Override
public void run()
{
LabelDemo demo = new LabelDemo();
demo.createAndShowGUI();
}
});
}
}
class MyJLabel extends JLabel
{
ImageIcon imageIcon;
public MyJLabel(ImageIcon icon)
{
super();
this.imageIcon = icon;
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(imageIcon.getImage(),0,0,getWidth(),getHeight(),this);
}
}
Solution 4:
You can use the Stretch Icon.
The image will automatically be resized to fill the space available to the label. You can control whether the image is scaled proportionally or completely fills the area.
Using the StretchIcon is more flexible than doing custom painting as suggested in the other links as you can benefit from the automatic resizing on any component that supports an Icon.
StretchIcon.java:
import java.awt.Component;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.net.URL;
import javax.swing.ImageIcon;
/**
* An <CODE>Icon</CODE> that scales its image to fill the component area, excluding any border or insets, optionally maintaining the image's
* aspect ratio by padding and centering the scaled image horizontally or vertically.
* <P>
* The class is a drop-in replacement for <CODE>ImageIcon</CODE>, except that the no-argument constructor is not supported.
* <P>
* As the size of the Icon is determined by the size of the component in which it is displayed, <CODE>StretchIcon</CODE> must only be used
* in conjunction with a component and layout that does not depend on the size of the component's Icon.
*
* @version 1.1 01/15/2016
* @author Darryl
*/
public class StretchIcon extends ImageIcon
{
/**
*
*/
private static final long serialVersionUID = 1L;
/**
* Determines whether the aspect ratio of the image is maintained. Set to <code>false</code> to allow th image to distort to fill the
* component.
*/
protected boolean proportionate = true;
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes.
*
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
*
* @see ImageIcon#ImageIcon(byte[])
*/
public StretchIcon(byte[] imageData)
{
super(imageData);
}
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes with the specified behavior.
*
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(byte[])
*/
public StretchIcon(byte[] imageData, boolean proportionate)
{
super(imageData);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes.
*
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(byte[], java.lang.String)
*/
public StretchIcon(byte[] imageData, String description)
{
super(imageData, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from an array of bytes with the specified behavior.
*
* @see ImageIcon#ImageIcon(byte[])
* @param imageData an array of pixels in an image format supported by the AWT Toolkit, such as GIF, JPEG, or (as of 1.3) PNG
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(byte[], java.lang.String)
*/
public StretchIcon(byte[] imageData, String description, boolean proportionate)
{
super(imageData, description);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image.
*
* @param image the image
*
* @see ImageIcon#ImageIcon(java.awt.Image)
*/
public StretchIcon(Image image)
{
super(image);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image with the specified behavior.
*
* @param image the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(java.awt.Image)
*/
public StretchIcon(Image image, boolean proportionate)
{
super(image);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image.
*
* @param image the image
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(java.awt.Image, java.lang.String)
*/
public StretchIcon(Image image, String description)
{
super(image, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the image with the specified behavior.
*
* @param image the image
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(java.awt.Image, java.lang.String)
*/
public StretchIcon(Image image, String description, boolean proportionate)
{
super(image, description);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file.
*
* @param filename a String specifying a filename or path
*
* @see ImageIcon#ImageIcon(java.lang.String)
*/
public StretchIcon(String filename)
{
super(filename);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file with the specified behavior.
*
* @param filename a String specifying a filename or path
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(java.lang.String)
*/
public StretchIcon(String filename, boolean proportionate)
{
super(filename);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file.
*
* @param filename a String specifying a filename or path
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(java.lang.String, java.lang.String)
*/
public StretchIcon(String filename, String description)
{
super(filename, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified file with the specified behavior.
*
* @param filename a String specifying a filename or path
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(java.awt.Image, java.lang.String)
*/
public StretchIcon(String filename, String description, boolean proportionate)
{
super(filename, description);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL.
*
* @param location the URL for the image
*
* @see ImageIcon#ImageIcon(java.net.URL)
*/
public StretchIcon(URL location)
{
super(location);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL with the specified behavior.
*
* @param location the URL for the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(java.net.URL)
*/
public StretchIcon(URL location, boolean proportionate)
{
super(location);
this.proportionate = proportionate;
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL.
*
* @param location the URL for the image
* @param description a brief textual description of the image
*
* @see ImageIcon#ImageIcon(java.net.URL, java.lang.String)
*/
public StretchIcon(URL location, String description)
{
super(location, description);
}
/**
* Creates a <CODE>StretchIcon</CODE> from the specified URL with the specified behavior.
*
* @param location the URL for the image
* @param description a brief textual description of the image
* @param proportionate <code>true</code> to retain the image's aspect ratio, <code>false</code> to allow distortion of the image to
* fill the component.
*
* @see ImageIcon#ImageIcon(java.net.URL, java.lang.String)
*/
public StretchIcon(URL location, String description, boolean proportionate)
{
super(location, description);
this.proportionate = proportionate;
}
/**
* Paints the icon. The image is reduced or magnified to fit the component to which it is painted.
* <P>
* If the proportion has not been specified, or has been specified as <code>true</code>, the aspect ratio of the image will be preserved
* by padding and centering the image horizontally or vertically. Otherwise the image may be distorted to fill the component it is
* painted to.
* <P>
* If this icon has no image observer,this method uses the <code>c</code> component as the observer.
*
* @param c the component to which the Icon is painted. This is used as the observer if this icon has no image observer
* @param g the graphics context
* @param x not used.
* @param y not used.
*
* @see ImageIcon#paintIcon(java.awt.Component, java.awt.Graphics, int, int)
*/
@Override
public synchronized void paintIcon(Component c, Graphics g, int x, int y)
{
Image image = getImage();
if (image == null)
{
return;
}
Insets insets = ((Container) c).getInsets();
x = insets.left;
y = insets.top;
int w = c.getWidth() - x - insets.right;
int h = c.getHeight() - y - insets.bottom;
if (proportionate)
{
int iw = image.getWidth(c);
int ih = image.getHeight(c);
if ((iw * h) < (ih * w))
{
iw = (h * iw) / ih;
x += (w - iw) / 2;
w = iw;
}
else
{
ih = (w * ih) / iw;
y += (h - ih) / 2;
h = ih;
}
}
ImageObserver io = getImageObserver();
/*
* Added this code to generate nicer looking results when scaling. - bspkrs
* BEGIN CHANGES
*/
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_4BYTE_ABGR);
Graphics2D g2d = bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, w, h, io == null ? c : io);
g2d.dispose();
/*
* END CHANGES
*/
g.drawImage(bi, x, y, w, h, io == null ? c : io);
}
/**
* Overridden to return 0. The size of this Icon is determined by the size of the component.
*
* @return 0
*/
@Override
public int getIconWidth()
{
return 0;
}
/**
* Overridden to return 0. The size of this Icon is determined by the size of the component.
*
* @return 0
*/
@Override
public int getIconHeight()
{
return 0;
}
}