将ImageIcon自动缩放到标签大小
在我的JFrame上，我使用以下代码在Panel上显示图像：
ImageIcon img= new ImageIcon("res.png");
jLabel.setIcon(img);
我想在标签中“自动调整”图片。实际上，有时图像尺寸只有几个像素，有时甚至更多。
有没有办法设置标签的大小，然后自动调整标签中的图像？
7 个答案:
答案 0 :(得分：41)
这是一个棘手的问题。您强调了使用JLabel来显示图像的事实，这是标准的处理方式，但JLabel是一个复杂的小野兽，具有文本，图标和文本对齐和定位
如果您不需要所有额外功能，我只需创建一个能够绘制缩放图像的自定义组件......
接下来的问题是，您希望如何缩放图像？你想保持图像的宽高比吗？您想要将图像“适合”或“填充”到可用空间。
@David是对的。在可能的情况下，您应该避免Image#getScaledInstance，因为它不是最快的，但更重要的是，它通常也不会提供最高质量。
Fit vs Fill
以下示例相当简单（并且从我的代码库中借用了很多，所以它可能也有点复杂;））。它可以使用背景缩放线程，但我会根据原始图像的潜在大小做出决定。
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;
}
}
}
答案 1 :(得分：25)
有没有办法设置标签的大小
覆盖getPreferredSize()的{{1}}并返回您想要的JLabel，
但由于Dimension会根据其内容调整自己的大小，因此您只需要调整添加到JLabel的图片的大小。
然后自动调整标签中的图像？
您必须根据所需的宽度和高度调整图片大小（而不是简单地将其添加到JLabel，JLabel的大小将适合图片。
我不建议JLabel在此处阅读更多内容：
Image.getScaledInstance(..)未返回完成的缩放图像。它 当图像像素出现时，大部分缩放工作都会延迟 使用。
以下是我用来规避Image.getScaledInstance()：
getScaledInstance您可以通过以下方式创建任意大小的图像：
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;
}
答案 2 :(得分：7)
也可以通过覆盖paintComponent的{{1}}方法并绘制JLabel的宽度和高度为image的方法来完成。如果您希望在调整父JLabel大小时调整图像大小，则可以在父容器上应用container，并在每次父容器时应用WindowListener repaint实例调整大小。
这是演示：
Jlabel答案 3 :(得分：3)
您可以使用Stretch Icon。
图像将自动调整大小以填充标签可用的空间。您可以控制图像是按比例缩放还是完全填充该区域。
使用StretchIcon比在其他链接中建议的自定义绘画更灵活，因为您可以从支持Icon的任何组件上自动调整大小。
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;
}
}
答案 4 :(得分：0)
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;
}
答案 5 :(得分：0)
尝试此功能：
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);
答案 6 :(得分：-1)
easywayprogramming.com如何在java中调整imageicon的大小
当我们将图像图标应用于任何组件（如按钮，标签或面板）时，由于该图像的大小，它无法正确应用。我们可以通过两种方式调整图像图标的大小。
-
第一种方式： Image img = myIcon2.getImage（）;图像newimg = img.getScaledInstance（230,310，java.awt.Image.SCALE_SMOOTH）;
newIcon = new ImageIcon（newimg）; -
第二种方式：
Image img = myIcon2.getImage（）; BufferedImage bi = new BufferedImage（img.getWidth（null），img.getHeight（null），BufferedImage.TYPE_INT_ARGB）;
newIcon = new ImageIcon（bi）;
尝试以下链接easywayprogramming.blogspot.in： easywayprogramming.blogspot.in ho to resize image icon in java
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