我正在尝试用半透明的JFrame在Java中做动画。我已经修改了Oracle Java Tutorials here中的演示代码。特别是GradientTranslucentWindowDemo。
以下代码适用于最高8的Windows XP SP3和Mac OS X Mountain Lion,甚至Linux 。 Linux中的问题,以及我需要帮助的是,动画是闪烁的。
我正在使用nVidia驱动程序,Metacity和Compiz运行Ubuntu Linux 12.04 LTS 64bit。 PERPIXEL_TRANSLUCENT报告为真,并且运行良好。
以下代码中是否存在我缺少的内容,或者我需要更改Linux方面的内容?我在JPanel上尝试了setDoubleBuffered(true),但它没有消除闪烁。
请将我的代码更改引用到以下演示:
import static java.awt.GraphicsDevice.WindowTranslucency.PERPIXEL_TRANSLUCENT;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.Paint;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class GradientTranslucentWindowDemo extends JFrame implements ActionListener {
private Timer timer = new Timer(100, this);
private double percentage = 0.0;
private JPanel surface = new JPanel() {
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (g instanceof Graphics2D) {
final int R = 0;
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, 255), false);
Graphics2D g2d = (Graphics2D)g;
// CHANGE 1
// Clear the previous graphics using a completely transparent fill
g2d.setBackground(new Color(0, 0, 0, 0));
g2d.clearRect(0, 0, getWidth(), getHeight());
g2d.setPaint(p);
// CHANGE 2
// Only do a gradient fill for the current percentage of the width
g2d.fillRect(0, 0, (int)Math.ceil(getWidth() * percentage), getHeight());
}
}
};
public GradientTranslucentWindowDemo() {
super("GradientTranslucentWindow");
setBackground(new Color(0,0,0,0));
setSize(new Dimension(300,200));
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// CHANGE 3
// I thought this might remove the flicker, nope
this.surface.setDoubleBuffered(true);
// CHANGE 4
// This seems to be required or the g2d.clearRect doesn't do anything
this.surface.setOpaque(false);
setContentPane(this.surface);
setLayout(new GridBagLayout());
add(new JButton("I am a Button"));
}
// CHANGE 5
// On each tick of the timer increment the percentage until its
// more than one and always repaint
@Override
public void actionPerformed(ActionEvent event) {
this.percentage += 0.05;
if (this.percentage > 1.0) {
this.percentage = 0.0;
}
this.surface.repaint();
}
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(true);
// Create the GUI on the event-dispatching thread
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
GradientTranslucentWindowDemo gtw = new GradientTranslucentWindowDemo();
// Display the window.
gtw.setVisible(true);
// CHANGE 6
// Wait until the window is visible to start the timer
gtw.timer.start();
}
});
}
}
更新1: 删除半透明度并选择黑色背景可修复闪烁问题。闪烁肯定与具有半透明窗口有关。我还注意到随着窗口的扩大,闪烁变得更糟。
更新2:
行this.surface.setOpaque(false);
是造成问题的原因。如果这被注释掉,动画不会闪烁,并且有半透明效果。 但是,在动画的每次迭代中,它都会与之前的颜色混合(在重新绘制之前不会清除内容)。除非设置g2d.setBackground(new Color(0, 0, 0, 0));
,否则g2d.clearRect(0, 0, getWidth(), getHeight());
和this.surface.setOpaque(false);
无效。它几乎就像这行禁用了linux上的双缓冲。
拥有半透明窗口是的要求。