How to resize images inside the application when resizing the application window?

Question

When I maximize my application, the images inside JPanel do not change with it. How can I customize JPanel and its contents at maximum window magnification?

EDIT: I am using BufferedImage

Answer 1

This is an open question.

Do you want to scale to fill or scale to fit the area, or doesn't the aspect ratio matter to you?

The difference between the scale for filling and scaling to match

This example will respond to frame size changes and scale the image in real time.

public class TestScaling { public static void main(String[] args) { new TestScaling(); } public TestScaling() { 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) { } JFrame frame = new JFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setLayout(new BorderLayout()); frame.add(new ScalingPane()); frame.setSize(200, 200); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public class ScalingPane extends javax.swing.JPanel { private BufferedImage image; public ScalingPane() { try { image = ImageIO.read(getClass().getResource("/AtDesk.png")); } catch (IOException ex) { ex.printStackTrace(); } setBackground(Color.red); } public double getScaleFactor(int iMasterSize, int iTargetSize) { double dScale = 1; dScale = (double) iTargetSize / (double) iMasterSize; return dScale; } 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); double dScale = Math.max(dScaleHeight, dScaleWidth); return dScale; } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); double scaleFactor = Math.min(1d, getScaleFactorToFit(new Dimension(image.getWidth(), image.getHeight()), getSize())); // double scaleFactor = Math.min(1d, getScaleFactorToFill(new Dimension(image.getWidth(), image.getHeight()), getSize())); int scaleWidth = (int) Math.round(image.getWidth() * scaleFactor); int scaleHeight = (int) Math.round(image.getHeight() * scaleFactor); Image scaled = image.getScaledInstance(scaleWidth, scaleHeight, Image.SCALE_SMOOTH); int width = getWidth() - 1; int height = getHeight() - 1; int x = (width - scaled.getWidth(this)) / 2; int y = (height - scaled.getHeight(this)) / 2; g.drawImage(scaled, x, y, this); } } } 

The best solution would be to have a background stream that can respond to component size changes and scale the original image in the background, providing low quality and quality scale.

It should also be noted that Image.getScaledInstance is neither the fastest nor the highest quality scaling algorithm. See The Perils of Image.getScaledInstance for more information.

You can also find the following interesting

Java: saving JPanel image format

Answer 2

One rough way.

 public void paintComponent(Graphics g) { super.paintComponent(g); g.draw(image,0,0,getWidth(),getHeight(),this); // ..