我想制作一个半透明的JPanel
,我可以选择x坐标,y坐标,宽度和高度。我发现一些材料制作了半透明的JPanel
填充其父容器,但我不需要这种效果。我需要一个半透明的JPanel
,其位置可以在父容器中指定,这样只有这个区域是半透明的,而父容器中的其他区域是不透明的。我试过这段代码,但是不正确。结果区域小于我想要的区域。有什么不对,或者我怎么能得到这种效果?
public class TranslucentJPanel extends JPanel {
private float transparency;
public TranslucentJPanel(){
}
/**set the transparency
*
* @param transparency:the transparency you want to set
*
* @return void
*/
public void setTransparent(float transparency) {
this.transparency = transparency;
}
@Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D graphics2d = (Graphics2D) g.create();
graphics2d.setComposite(AlphaComposite.SrcOver.derive(transparency));
graphics2d.fill(getBounds());
graphics2d.dispose();
}
}
答案 0 :(得分:3)
所以,立即想到两件事......
首先,不要使用getBounds
,Grapghics
上下文已经转换为组件x
/ y
位置,因此您将其翻倍。相反,只需使用0x0
并提供width
和height
,例如...
graphics2d.fillRect(0, 0, getWidth(), getHeight());
另外,请记住,默认情况下,大多数Swing组件都是不透明的,包括JList
,JScrollPane
和JViewport
,如果您需要它们,则需要将它们设置为透明完全可以看透。
此外,JList
使用的“默认”渲染器也会将其自身呈现为不透明,因此如果您希望项目透明,则需要提供自己的渲染...
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.DefaultListCellRenderer;
import javax.swing.DefaultListModel;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
DefaultListModel<String> model = new DefaultListModel<>();
model.addElement("Bananas");
model.addElement("Apples");
model.addElement("Pears");
model.addElement("Grapes");
model.addElement("Tim Tams");
JList list = new JList(model);
list.setCellRenderer(new DefaultListCellRenderer() {
@Override
public Component getListCellRendererComponent(JList<?> list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
setOpaque(isSelected);
return this;
}
});
list.setOpaque(false);
JScrollPane sp = new JScrollPane(list);
sp.setOpaque(false);
sp.getViewport().setOpaque(false);
TranslucentPane tp = new TranslucentPane();
tp.setLayout(new GridBagLayout());
tp.setLayout(new BorderLayout());
tp.add(sp);
JFrame frame = new JFrame("Testing");
frame.setContentPane(new BackgroundPane());
frame.setLayout(new GridBagLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(tp);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TranslucentPane extends JPanel {
private float alpha = 0.75f;
public TranslucentPane() {
setOpaque(false);
setBorder(new EmptyBorder(5, 5, 5, 5));
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.SrcOver.derive(alpha));
g2d.setColor(getBackground());
g2d.fillRect(0, 0, getWidth(), getHeight());
g2d.dispose();
}
}
public class BackgroundPane extends JPanel {
private BufferedImage background;
public BackgroundPane() {
try {
background = ImageIO.read(new File("C:\\Users\\shane\\Dropbox\\MegaTokyo\\thumnails\\megatokyo_omnibus_1_3_cover_by_fredrin-d4oupef.jpg"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
@Override
public Dimension getPreferredSize() {
return new Dimension(background.getWidth(), background.getHeight());
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int x = (getWidth() - background.getWidth()) / 2;
int y = (getHeight() - background.getHeight()) / 2;
g.drawImage(background, x, y, this);
}
}
}