我正在尝试创建一个小部件，到目前为止，它仅跟踪时钟并显示小时。我发现背景很丑陋，并决定使其透明。我仍然是Java的初学者，尽管挣扎（很多），但还是设法做到了。
但是，文本无法正确更新，并且下一个小时会在前一个小时的上方绘制，依此类推。我发现的唯一答案是对mylabel.setOpaque（false），但它不起作用。
下面是我使用的代码：
package timetracker.widget.com;
import java.awt.*;
import java.util.Calendar;
import java[enter image description here][1].util.GregorianCalendar;
import javax.swing.*;
import static java.awt.GraphicsDevice.WindowTranslucency.*;
public class GradientTranslucentWindow extends JFrame {
public GradientTranslucentWindow() {
super("GradientTranslucentWindow");
initComponents();
jPanel1.setOpaque(false);
setBackground(new Color(0,0,0,0));
setSize(new Dimension(300,200));
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
if (g instanceof Graphics2D) {
final int R = 240;
final int G = 240;
final int B = 240;
Paint p =
new GradientPaint(0.0f, 0.0f, new Color(R, G, B, 0),
0.0f, getHeight(), new Color(R, G, B, 0), true);
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(p);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
}
};
setContentPane(panel);
setLayout(new GridBagLayout());
add(Clock);
new Thread(){
public void run()
{
while(true)
{
Calendar cal = new GregorianCalendar();
int hour = cal.get(Calendar.HOUR);
int min = cal.get(Calendar.MINUTE);
int sec = cal.get(Calendar.SECOND);
String hourStr = "";
String minStr = "";
String secStr = "";
if(hour < 10) {
hourStr = "0" + hour;
}
else {
hourStr = hour + "";
}
if(min < 10) {
minStr = "0" + min;
}
else {
minStr = min + "";
}
if(sec < 10) {
secStr = "0" + sec;
}
else {
secStr = sec + "";
}
time_spent = hourStr+":"+minStr+":"+secStr;
Clock.setText(time_spent);
Clock.setForeground(Color.BLACK);
Clock.setFont(new Font("Serif", Font.BOLD, 70));
Clock.setHorizontalAlignment(SwingConstants.CENTER);
Clock.setVerticalAlignment(SwingConstants.CENTER);
getContentPane().setBackground(Color.BLACK);
}
}
}.start();
}
public static void main(String[] args) {
// Determine what the GraphicsDevice can support.
GraphicsEnvironment ge =
GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice gd = ge.getDefaultScreenDevice();
boolean isPerPixelTranslucencySupported =
gd.isWindowTranslucencySupported(PERPIXEL_TRANSLUCENT);
//If translucent windows aren't supported, exit.
if (!isPerPixelTranslucencySupported) {
System.out.println(
"Per-pixel translucency is not supported");
System.exit(0);
}
JFrame.setDefaultLookAndFeelDecorated(false);
// Create the GUI on the event-dispatching thread
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
GradientTranslucentWindow gtw = new
GradientTranslucentWindow();
// Display the window.
gtw.setVisible(true);
}
});
}
public void initComponents() {
jPanel1 = new javax.swing.JPanel();
Clock = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setUndecorated(true);
setBounds(new java.awt.Rectangle(200, 200, 200, 200));
setSize(300, 300);
setVisible(true);
Clock.setFont(new java.awt.Font("DejaVu Sans", 0, 11)); // NOI18N
Clock.setForeground(new java.awt.Color(0, 0, 0, 0));
Clock.setText("0:00:00");
jPanel1.add(Clock);
Clock.setBounds(0, 4, 280, 100);
Clock.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
public void mouseDragged(java.awt.event.MouseEvent evt) {
jLabelMouseDragged(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
getAccessibleContext().setAccessibleName("myJframe");
setBounds(0, 0, 299, 109);
}
private void jLabelMouseDragged(java.awt.event.MouseEvent evt) {
int x = evt.getXOnScreen();
int y = evt.getYOnScreen();
this.setLocation(x, y);
}
// Variables declaration - do not modify
static javax.swing.JLabel Clock;
private javax.swing.JPanel jPanel1;
String time_spent = null;
// End of variables declaration
}
答案 0 :(得分：0)
我想这就是你想要的：
import java.awt.*;
import java.util.Calendar;
import java.util.GregorianCalendar;
import javax.swing.*;
import static java.awt.GraphicsDevice.WindowTranslucency.*;
public class GradientTranslucentWindow extends JFrame {
public GradientTranslucentWindow() {
super("GradientTranslucentWindow");
initComponents();
jPanel1.setOpaque(false);
setBackground(new Color(0,0,0,0));
setSize(new Dimension(300,200));
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
if (g instanceof Graphics2D) {
final int R = 240;
final int G = 240;
final int B = 240;
Paint p =
new GradientPaint(0.0f, 0.0f, new Color(R, G, B, 0),
0.0f, getHeight(), new Color(R, G, B, 0), true);
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(p);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
}
};
panel.setOpaque(false);
panel.setBackground(new Color(0,0,0,0));
setContentPane(panel);
setLayout(new GridBagLayout());
add(Clock);
new Thread(){
public void run()
{
while(true)
{
Calendar cal = new GregorianCalendar();
int hour = cal.get(Calendar.HOUR);
int min = cal.get(Calendar.MINUTE);
int sec = cal.get(Calendar.SECOND);
String hourStr = "";
String minStr = "";
String secStr = "";
if(hour < 10) {
hourStr = "0" + hour;
}
else {
hourStr = hour + "";
}
if(min < 10) {
minStr = "0" + min;
}
else {
minStr = min + "";
}
if(sec < 10) {
secStr = "0" + sec;
}
else {
secStr = sec + "";
}
time_spent = hourStr+":"+minStr+":"+secStr;
//panel.repaint();
Clock.setText(time_spent);
Clock.setForeground(Color.BLACK);
Clock.setFont(new Font("Serif", Font.BOLD, 70));
Clock.setHorizontalAlignment(SwingConstants.CENTER);
Clock.setVerticalAlignment(SwingConstants.CENTER);
getContentPane().setBackground(Color.BLACK);
}
}
}.start();
}
public static void main(String[] args) {
// Determine what the GraphicsDevice can support.
GraphicsEnvironment ge =
GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice gd = ge.getDefaultScreenDevice();
boolean isPerPixelTranslucencySupported =
gd.isWindowTranslucencySupported(PERPIXEL_TRANSLUCENT);
//If translucent windows aren't supported, exit.
if (!isPerPixelTranslucencySupported) {
System.out.println(
"Per-pixel translucency is not supported");
System.exit(0);
}
JFrame.setDefaultLookAndFeelDecorated(false);
// Create the GUI on the event-dispatching thread
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
GradientTranslucentWindow gtw = new
GradientTranslucentWindow();
// Display the window.
gtw.setVisible(true);
}
});
}
public void initComponents() {
jPanel1 = new javax.swing.JPanel();
Clock = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setUndecorated(true);
setBounds(new java.awt.Rectangle(200, 200, 200, 200));
setSize(300, 300);
setVisible(true);
Clock.setFont(new java.awt.Font("DejaVu Sans", 0, 11)); // NOI18N
Clock.setForeground(new java.awt.Color(0, 0, 0, 0));
Clock.setText("0:00:00");
jPanel1.add(Clock);
Clock.setBounds(0, 4, 280, 100);
Clock.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
public void mouseDragged(java.awt.event.MouseEvent evt) {
jLabelMouseDragged(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
);
getAccessibleContext().setAccessibleName("myJframe");
setBounds(0, 0, 299, 109);
}
private void jLabelMouseDragged(java.awt.event.MouseEvent evt) {
int x = evt.getXOnScreen();
int y = evt.getYOnScreen();
this.setLocation(x, y);
}
// Variables declaration - do not modify
static javax.swing.JLabel Clock;
private javax.swing.JPanel jPanel1;
String time_spent = null;
// End of variables declaration
}
我添加的关键行是在创建panel之后：
panel.setOpaque(false);
panel.setBackground(new Color(0,0,0,0));
如果您有任何疑问，请告诉我。
答案 1 :(得分：0)
如果您不打算从JPanel中清除Graphics2d（带填充），则必须调用super：
JPanel panel = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
//Rest as the same