Escala o ImageIcon automaticamente para o tamanho da etiqueta

No meu JFrame, estou usando o seguinte código para exibir uma imagem no painel:

ImageIcon img= new ImageIcon("res.png"); jLabel.setIcon(img); 

Gostaria de “dimensionar automaticamente” a imagem no marcador. De fato, às vezes o tamanho da imagem é de apenas alguns pixels, às vezes bem mais.

Existe uma maneira de definir o tamanho do label e, em seguida, dimensionar automaticamente a imagem no label?

Esta é uma pergunta complicada. Você destaca o fato de estar usando um JLabel para mostrar a imagem, que é a maneira padrão de fazer as coisas, mas o JLabel é uma pequena fera complexa, com alinhamento e posicionamento de texto, ícone e texto.

Se você não precisa de toda essa funcionalidade extra, eu simplesmente criaria um componente personalizado capaz de pintar uma imagem dimensionada …

A próxima pergunta é: como você deseja dimensionar a imagem? Você deseja manter a proporção da imagem? Você quer “encheckboxr” ou “preencher” a imagem no espaço disponível.

@ David está certo. Você deve, sempre que possível, evitar o Image#getScaledInstance já que não é o mais rápido, mas, o que é mais importante, geralmente não fornece a mais alta qualidade.

Ajuste vs preenchimento

insira a descrição da imagem aqui

O exemplo a seguir é bastante simples (e pega emprestado da minha biblioteca de código, então provavelmente também é um pouco complicado;)). Ele poderia ser usado a partir de um thread de escala de fundo, mas eu basearia a decisão no tamanho potencial da imagem original.

 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; } } } 

Existe uma maneira de definir o tamanho do label

Substitua getPreferredSize() de JLabel e retorne as Dimension você deseja, mas como um JLabel se dimensionará para seu conteúdo, você só precisará resize a imagem adicionada ao JLabel .

e, em seguida, para autosize a imagem no label?

Você terá que resize sua imagem de acordo com a largura e a altura desejadas (do que simplesmente adicioná-la ao JLabel e o tamanho do JLabel será ajustado à imagem).

Eu não recomendo Image.getScaledInstance(..) ler aqui para mais:

  • Os perigos de Image.getScaledInstance () Principalmente o problema descrito é:

Image.getScaledInstance() não retorna uma imagem finalizada e dimensionada. Ele deixa muito do trabalho de dimensionamento para um momento posterior, quando os pixels da imagem são usados.

Aqui está um método personalizado que tenho usado para contornar os problemas criados por 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; } 

você criaria uma imagem para qualquer tamanho desejado:

 BufferedImage image=ImageIO.read(..); BufferedImage resizedImage=resize(image,100,100);//resize the image to 100x100 

Isso também pode ser feito substituindo o método paintComponent do JLabel e desenhando a image com largura e altura como a do JLabel . E se você desejar resize a imagem quando o container pai for redimensionado, poderá aplicar o WindowListener no contêiner pai e repaint a instância do Jlabel toda vez que o contêiner pai for redimensionado. Aqui está a demonstração:

 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); } } 

Você pode usar o ícone Stretch .

A imagem será automaticamente redimensionada para preencher o espaço disponível para o label. Você pode controlar se a imagem é dimensionada proporcionalmente ou se preenche completamente a área.

Usando o StretchIcon é mais flexível do que fazer pintura personalizada, como sugerido nos outros links, como você pode se beneficiar do redimensionamento automático em qualquer componente que suporte um ícone.

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 Icon 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. * 

* The class is a drop-in replacement for ImageIcon, except that the no-argument constructor is not supported. *

* As the size of the Icon is determined by the size of the component in which it is displayed, StretchIcon 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 false to allow th image to distort to fill the * component. */ protected boolean proportionate = true; /** * Creates a StretchIcon 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 StretchIcon 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 true to retain the image's aspect ratio, false 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 StretchIcon 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 StretchIcon 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 true to retain the image's aspect ratio, false 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 StretchIcon from the image. * * @param image the image * * @see ImageIcon#ImageIcon(java.awt.Image) */ public StretchIcon(Image image) { super(image); } /** * Creates a StretchIcon from the image with the specified behavior. * * @param image the image * @param proportionate true to retain the image's aspect ratio, false 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 StretchIcon 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 StretchIcon from the image with the specified behavior. * * @param image the image * @param description a brief textual description of the image * @param proportionate true to retain the image's aspect ratio, false 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 StretchIcon 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 StretchIcon from the specified file with the specified behavior. * * @param filename a String specifying a filename or path * @param proportionate true to retain the image's aspect ratio, false 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 StretchIcon 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 StretchIcon 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 true to retain the image's aspect ratio, false 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 StretchIcon 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 StretchIcon from the specified URL with the specified behavior. * * @param location the URL for the image * @param proportionate true to retain the image's aspect ratio, false 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 StretchIcon 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 StretchIcon 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 true to retain the image's aspect ratio, false 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. *

* If the proportion has not been specified, or has been specified as true, 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. *

* If this icon has no image observer,this method uses the c 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; } }

Experimente esta function:

 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; } BufferedImage image1=ImageIO.read(url.openStream()); BufferedImage resizedImage=resize(image,100,100); System.out.println("Load image into frame..."); icon=new ImageIcon(resizedImage); 
 private Image fitimage(Image img, int w, int h) { int width = img.getWidth(this); int height = img.getHeight(this); BufferedImage resizedimage; if (width > w && height > h) { 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(); } else { resizedimage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g2 = resizedimage.createGraphics(); g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR); g2.drawImage(img, 0, 0, width, height, null); g2.dispose(); } return resizedimage; } 

easywayprogramming.com como resize imageicon em java

Quando aplicamos o ícone de imagem a qualquer componente, como botão, label ou painel, ele não se aplica adequadamente devido ao tamanho da imagem. Podemos resize o ícone da imagem de duas maneiras.

  1. primeira maneira: Image img = myIcon2.getImage (); Imagem newimg = img.getScaledInstance (230, 310, java.awt.Image.SCALE_SMOOTH);
    newIcon = new ImageIcon (newimg);

  2. segunda maneira:

    Imagem img = myIcon2.getImage (); BufferedImage bi = new BufferedImage (img.getWidth (nulo), img.getHeight (nulo), BufferedImage.TYPE_INT_ARGB);
    newIcon = new ImageIcon (bi);

Tente seguir o link easywayprogramming.blogspot.in: easywayprogramming.blogspot.in ho para resize o ícone da imagem em java