This is the intended behavior (assuming you're on windows).
For every repaint the window is re-rendered into a buffer which
is then copied into the layered GDI window.
Thanks,
Dmitri
jav...@javadesktop.org wrote:
There seems to be a performance issue for non-opaque windows (Java6u10 or
above). The test case below demonstrates the issue. As soon as the mouse moves
over the button the red panel will be repainted. Is this the correct behavior
or is there a way to minimize repaints? If the window is opaque everything
works fine. Unnecessary repaints are a big problem for real apps with many
components because the whole app performance slows extremely down.
[code]
public class NonOpaqueWindowRepaintTest extends JFrame
{
public NonOpaqueWindowRepaintTest()
{
super();
setLayout(new FlowLayout());
JPanel p = new JPanel(){
@Override
protected void paintComponent(Graphics g){
System.err.println("Red panel repaint - " + g.getClipBounds());
super.paintComponent(g);
}
};
p.setBorder(new LineBorder(Color.GREEN));
p.setBackground(Color.RED);
p.setPreferredSize(new Dimension(200,200));
add(p);
add(new JButton("Test"));
setWindowNonOpaque(this);
setTitle(getClass().getSimpleName());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400, 300);
setLocationRelativeTo(null);
setVisible(true);
}
private void setWindowNonOpaque(Window w)
{
try
{
Class<?> c = Class.forName("com.sun.awt.AWTUtilities");
Method m = c.getMethod("setWindowOpaque", Window.class, boolean.class);
m.invoke(null, w, false);
}
catch (Exception e)
{
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception
{
EventQueue.invokeLater(new Runnable(){
public void run()
{
JFrame.setDefaultLookAndFeelDecorated(true);
new NonOpaqueWindowRepaintTest();
}
});
}
}
[/code]
Thanks,
Wolfgang
[Message sent by forum member 'wzberger' (wzberger)]
http://forums.java.net/jive/thread.jspa?messageID=321379
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