就个人而言，我可以在将其应用于标签之前调整其大小，或者使用aJPanel进行绘画。JLabel必须拖延很多功能。
举例来说，您遇到的问题是您实际上是在使用 该图像setIcon来设置图像，但是却 在其顶部paintComponent绘制了另一个（初始）图像
您的自定义标签将aImageIcon作为初始参数并将其绘制为初始参数
private static class MyJLabel extends JLabel {
private ImageIcon img = null;
public MyJLabel(ImageIcon img) {
super();
this.img = img;
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img.getImage(), 0, 0, getWidth(), getHeight(), this);
}
}
You initialise it as such…
label = new MyJLabel(new ImageIcon(img));
It should be noted that if you used the Icon support of JLabel, this…
label.setPreferredSize(dims);
会无关紧要，因为JLabel会使用图标的大小来确定其 首选的大小……但无论如何……
然后，使用此按钮更新图标。
img = image;
if (label != null) {
label.setIcon(new ImageIcon(img));
label.repaint();
}
应该指出的是，根据您的示例，这实际上是在EDT之外调用的，这很危险，并可能导致油漆变脏。
但setIcon永远不会改变的价值img范围内MyLabel，所以当你的paintComponent方法被调用时，你实际上是画了你的图标 已经在更新提供…
// Paint the new Icon
super.paintComponent(g);
// Paint the old/initial image...
g.drawImage(img.getImage(), 0, 0, getWidth(), getHeight(), this);
就个人而言，我要做的是使用a之类的东西创建一个自定义组件，JPanel并根据 面板的当前大小缩放原始图像，例如……
现在，通常情况下，在执行图像缩放时，我更喜欢使用Java中演示的分治方法：维护JPanel 背景图像的宽高比，但是在此示例中，我只是AffineTransform为了简单起见使用
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ScalableImageExample {
public static void main(String[] args) {
new ScalableImageExample();
}
public ScalableImageExample() {
EventQueue.invokelater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | illegalaccessexception | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
try {
ResizableImagePane pane = new ResizableImagePane();
pane.setImage(...);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
frame.add(pane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
public class ResizableImagePane extends JPanel {
private Image img;
public ResizableImagePane() {
}
public void setImage(Image value) {
if (img != value) {
Image old = img;
this.img = value;
firePropertyChange("image", old, img);
revalidate();
repaint();
}
}
public Image getImage() {
return img;
}
@Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(this), img.getHeight(this));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
Graphics2D g2d = (Graphics2D) g.create();
int width = getWidth();
int height = getHeight();
double scaleFactor = getScaleFactorToFit(new Dimension(img.getWidth(this), img.getHeight(this)), getSize());
int x = (int)((width - (img.getWidth(this) * scaleFactor)) / 2);
int y = (int)((height - (img.getHeight(this) * scaleFactor)) / 2);
AffineTransform at = new AffineTransform();
at.translate(x, y);
at.scale(scaleFactor, scaleFactor);
g2d.setTransform(at);
g2d.drawImage(img, 0, 0, this);
g2d.dispose();
}
}
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;
}
}
}
602392714
清零编程群