setWindowOpacity()

[TheKedge]

wow,
I was calling
<QmainWindow>setWindowOpacity();
repeatedly for a fade out in my qt 4.0.1 app and it was fine.

I've just updated to qt 4.1.0 and it's terrible - slow, jumpy and 100%cpu.

Am I doing something wrong?

K

[high_flyer]

did you rebuilt your project agaist the new version of Qt?

[TheKedge]

Yep. and if I comment out the setWindowOpactiy() call thingts go quickly (without fading, of course)

K

[Everall]

I've just updated to qt 4.1.0 and it's terrible - slow, jumpy and 100%cpu.

Oops, I suggested you to go to version 4.1 in another post

this is a bug already filed to the trolls. You could try the latest snapshot instead seems it's resolved in 4.1.1

bug 94296 - setWindowOpacity flickers and deactivates window on Windows

Using the following code to fade in a window works fine with 4.0, but produces an unacceptable flicker and activation-change for each call to setWindowOpacity with 4.1-RC1:
 
 #include <QtGui>
 
 class CFadeWidget : public QWidget
 {
     Q_OBJECT
 
 public:
     CFadeWidget(QWidget * apParent = NULL) : QWidget(apParent)
     {
         setAutoFillBackground(true);
         setAttribute(Qt::WA_NoSystemBackground, false);
         setWindowOpacity(0.0);
         mFadeTimer.setInterval(50);
         connect(&mFadeTimer, SIGNAL(timeout()), this, 
             SLOT(nextFadeStep()));
         mFadeTimer.start();
     }
 
 
 protected slots:
     virtual void nextFadeStep()
     {
         qreal opacity = windowOpacity()+0.1;
 
         setWindowOpacity(opacity);
 
         if (opacity >= 1.0)
         {
             mFadeTimer.stop();
             emit opaque();
         }
     }
 
 
 signals:
     void opaque();
     void transparent();
 
 
 private:
     QTimer mFadeTimer;
 
 };
 
 #include "main.moc"
 
 int main(int argc, char **argv)
 {
     QApplication a(argc, argv);
 
     QWidget w;
     w.show();
 
     CFadeWidget fader;
     fader.show();
 
     return a.exec();
 }

Using the following code to fade in a window works fine with 4.0, but produces an unacceptable flicker and activation-change for each call to setWindowOpacity with 4.1-RC1:
 
 #include <QtGui>
 
 class CFadeWidget : public QWidget
 {
     Q_OBJECT
         
 public:
     CFadeWidget(QWidget * apParent = NULL) : QWidget(apParent)
     {
         setAutoFillBackground(true);
         setAttribute(Qt::WA_NoSystemBackground, false);
         setWindowOpacity(0.0);
         mFadeTimer.setInterval(50);
         connect(&mFadeTimer, SIGNAL(timeout()), this, 
             SLOT(nextFadeStep()));
         mFadeTimer.start();
     }
     
     
 protected slots:
     virtual void nextFadeStep()
     {
         qreal opacity = windowOpacity()+0.1;
         
         setWindowOpacity(opacity);
         
         if (opacity >= 1.0)
         {
             mFadeTimer.stop();
             emit opaque();
         }
     }
     
     
 signals:
     void opaque();
     void transparent();
     
     
 private:
     QTimer mFadeTimer;
     
 };
 
 #include "main.moc"
 
 int main(int argc, char **argv)
 {
     QApplication a(argc, argv);
 
     QWidget w;
     w.show();
 
     CFadeWidget fader;
     fader.show();
 
     return a.exec();
 }

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[TheKedge]

Oops, I suggested you to go to version 4.1 in another post

Yes, you did
but I can't hold it against you - this is a peace, love and help your neighbour type of place - a techno-hippy place. The forum is great.

thanks for your help,
K