QGraphicsOpacityEffect animation on QPushButton not working in some cases

[kalos80]

Hi,

I have a button whose opacity changes when the mouse moves on top of the it.
I’m using a QGraphicsOpacityEffect to change the button opacity and I’m animating the opacity using a QPropertyAnimation.

The animation works greatly unless I add a QGLWidget in the same window where the button is.

I wrote a very simple application for debugging. It is a dialog with a QGLWidget and two opacity animated buttons, one inside the QGLWidget and one outside it.
If the QGlWidget is not created then the button animation is working very well. When I create the QGLWidget and add it to the dialog the button animation stops working.
The QGLWidget does nothing, it just draws a black background.

Here is the code:

static const qreal START_OPACITY = 0.3;
 
 
// PushButtonAnimated code
PushButtonAnimated::PushButtonAnimated(QWidget * parent)
 : QPushButton(parent)
{
 QGraphicsOpacityEffect *effect = new QGraphicsOpacityEffect(this);
 effect->setOpacity(START_OPACITY);
 setGraphicsEffect(effect);
 
 animation = new QPropertyAnimation(effect, "opacity");
 animation->setDuration(500);
 animation->setStartValue(START_OPACITY);
 animation->setEndValue(1.0);
}
 
void PushButtonAnimated::enterEvent(QEvent *e)
{
 if( animation->state() == QAbstractAnimation::Running )
  animation->pause();
 animation->setDirection(QAbstractAnimation::Forward);
 
 animation->start();
}
 
void PushButtonAnimated::leaveEvent(QEvent *e)
{
 if( animation->state() == QAbstractAnimation::Running )
  animation->pause();
 animation->setDirection(QAbstractAnimation::Backward);
 
 animation->start();
}

static const qreal START_OPACITY = 0.3;


// PushButtonAnimated code
PushButtonAnimated::PushButtonAnimated(QWidget * parent)
 : QPushButton(parent)
{
 QGraphicsOpacityEffect *effect = new QGraphicsOpacityEffect(this);
 effect->setOpacity(START_OPACITY);
 setGraphicsEffect(effect);

 animation = new QPropertyAnimation(effect, "opacity");
 animation->setDuration(500);
 animation->setStartValue(START_OPACITY);
 animation->setEndValue(1.0);
}

void PushButtonAnimated::enterEvent(QEvent *e)
{
 if( animation->state() == QAbstractAnimation::Running )
  animation->pause();
 animation->setDirection(QAbstractAnimation::Forward);

 animation->start();
}

void PushButtonAnimated::leaveEvent(QEvent *e)
{
 if( animation->state() == QAbstractAnimation::Running )
  animation->pause();
 animation->setDirection(QAbstractAnimation::Backward);

 animation->start();
}

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// QGLWidget, has an animated button
// just draws a black background
MyGLWidget::MyGLWidget(QWidget *parent)
: QGLWidget(parent)
{
 PushButtonAnimated *pb = new PushButtonAnimated(this);
 pb->setIcon( QIcon("icon.png") );
}
 
void MyGLWidget::initializeGL()
{
 // Set up the rendering context, define display lists etc.:
 qglClearColor( Qt::black );
 // Setting the Hidden Surface Removal process
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
}
 
void MyGLWidget::resizeGL(int w, int h)
{
 // setup viewport, projection etc.:
 glViewport(0, 0, (GLint)w, (GLint)h);
}
 
void MyGLWidget::paintGL()
{
 // draw the scene:
 // ...
 glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

// QGLWidget, has an animated button
// just draws a black background
MyGLWidget::MyGLWidget(QWidget *parent)
: QGLWidget(parent)
{
 PushButtonAnimated *pb = new PushButtonAnimated(this);
 pb->setIcon( QIcon("icon.png") );
}

void MyGLWidget::initializeGL()
{
 // Set up the rendering context, define display lists etc.:
 qglClearColor( Qt::black );
 // Setting the Hidden Surface Removal process
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
}

void MyGLWidget::resizeGL(int w, int h)
{
 // setup viewport, projection etc.:
 glViewport(0, 0, (GLint)w, (GLint)h);
}

void MyGLWidget::paintGL()
{
 // draw the scene:
 // ...
 glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}

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// this is the main
int main( int argc, char *argv[] )
{
 QApplication appMain(argc, argv);
 
 // build interface
 QDialog *dg = new QDialog();
 
 PushButtonAnimated *pb = new PushButtonAnimated(dg);
 pb->setIcon( QIcon(":/test/icon.png") );
 QSpacerItem *spacer = new QSpacerItem(10, 10, QSizePolicy::Expanding, QSizePolicy::Minimum);
 
 
 QGridLayout *layout = new QGridLayout(dg);
 layout->addItem(spacer, 1, 0);
 layout->addWidget(pb, 1, 1);
 
 bool showOgl = false;
 // bool showOgl = true;
 if( showOgl )
 {
  // IF THIS CODE IS ENABLED THEN
  // THE BUTTON ANIMATION IS NO MORE WORKING
  MyGLWidget *glWidget = new MyGLWidget(dg);
  QSizePolicy sizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
  glWidget->setSizePolicy(sizePolicy);
  layout->addWidget(glWidget, 0, 0);
 }
 
 dg->show();
 dg->resize(500, 500);
 
 return appMain.exec()
}

// this is the main
int main( int argc, char *argv[] )
{
 QApplication appMain(argc, argv);

 // build interface
 QDialog *dg = new QDialog();
 
 PushButtonAnimated *pb = new PushButtonAnimated(dg);
 pb->setIcon( QIcon(":/test/icon.png") );
 QSpacerItem *spacer = new QSpacerItem(10, 10, QSizePolicy::Expanding, QSizePolicy::Minimum);

 
 QGridLayout *layout = new QGridLayout(dg);
 layout->addItem(spacer, 1, 0);
 layout->addWidget(pb, 1, 1);

 bool showOgl = false;
 // bool showOgl = true;
 if( showOgl )
 {
  // IF THIS CODE IS ENABLED THEN
  // THE BUTTON ANIMATION IS NO MORE WORKING
  MyGLWidget *glWidget = new MyGLWidget(dg);
  QSizePolicy sizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
  glWidget->setSizePolicy(sizePolicy);
  layout->addWidget(glWidget, 0, 0);
 }

 dg->show();
 dg->resize(500, 500);

 return appMain.exec()
}

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Do you have any hint on how to have both buttons animation working?

Thanks in advance for your help

P.S.
attached is the full example code