[SOLVED] QPropertyAnimation "text" property in QLabel

[AlekseyK]

QLabel animation does not work - need to implement text blinking (flashing) after some time periods. What I'm doing wrong?

Code is following:

m_p1stHeaderAnimation = new QPropertyAnimation(ui.m_labelHeader1, "text", this);
    m_p3rdHeaderAnimation = new QPropertyAnimation(ui.m_labelHeader3, "text", this);
...
m_p1stHeaderAnimation->setDuration(1300);
	m_p1stHeaderAnimation->setKeyValueAt(0, "Flashing text 1");
	m_p1stHeaderAnimation->setKeyValueAt(0.77, "");
	m_p1stHeaderAnimation->setKeyValueAt(1, "");
	m_p1stHeaderAnimation->setLoopCount(5);
 
	/// Setups 3rd header animation
	m_p3rdHeaderAnimation->setDuration(1300);
	m_p3rdHeaderAnimation->setKeyValueAt(0, "Flashing text 3");
	m_p3rdHeaderAnimation->setKeyValueAt(0.77, "");
	m_p3rdHeaderAnimation->setKeyValueAt(1, "");
	m_p3rdHeaderAnimation->setLoopCount(5);
...
	// Start next header animation after previous
	connect(m_p1stHeaderAnimation, SIGNAL(finished()), m_p3rdHeaderAnimation, SLOT(start()));
	connect(m_p3rdHeaderAnimation, SIGNAL(finished()), m_p1stHeaderAnimation, SLOT(start()));
...
	m_p1stHeaderAnimation->start();

m_p1stHeaderAnimation = new QPropertyAnimation(ui.m_labelHeader1, "text", this);
    m_p3rdHeaderAnimation = new QPropertyAnimation(ui.m_labelHeader3, "text", this);
...
m_p1stHeaderAnimation->setDuration(1300);
	m_p1stHeaderAnimation->setKeyValueAt(0, "Flashing text 1");
	m_p1stHeaderAnimation->setKeyValueAt(0.77, "");
	m_p1stHeaderAnimation->setKeyValueAt(1, "");
	m_p1stHeaderAnimation->setLoopCount(5);
 
	/// Setups 3rd header animation
	m_p3rdHeaderAnimation->setDuration(1300);
	m_p3rdHeaderAnimation->setKeyValueAt(0, "Flashing text 3");
	m_p3rdHeaderAnimation->setKeyValueAt(0.77, "");
	m_p3rdHeaderAnimation->setKeyValueAt(1, "");
	m_p3rdHeaderAnimation->setLoopCount(5);
...
	// Start next header animation after previous
	connect(m_p1stHeaderAnimation, SIGNAL(finished()), m_p3rdHeaderAnimation, SLOT(start()));
	connect(m_p3rdHeaderAnimation, SIGNAL(finished()), m_p1stHeaderAnimation, SLOT(start()));
...
	m_p1stHeaderAnimation->start();

To copy to clipboard, switch view to plain text mode 

m_labelHeader1 and m_labelHeader3 - QLabel class objects.

I even tied signals valueChanged to repaint slots just to be safe:

disconnect(m_p1stHeaderAnimation, SIGNAL(valueChanged(QVariant)), ui.m_labelHeader1, SLOT(repaint()));
    disconnect(m_p3rdHeaderAnimation, SIGNAL(valueChanged(QVariant)), ui.m_labelHeader3, SLOT(repaint()));

disconnect(m_p1stHeaderAnimation, SIGNAL(valueChanged(QVariant)), ui.m_labelHeader1, SLOT(repaint()));
    disconnect(m_p3rdHeaderAnimation, SIGNAL(valueChanged(QVariant)), ui.m_labelHeader3, SLOT(repaint()));

To copy to clipboard, switch view to plain text mode 

but it does not work anyway. Why?

[wysota]

QPropertyAnimation doesn't know how to animate text.

[AlekseyK]

I see:

Not all QVariant types are supported. Below is a list of currently supported QVariant types:

• Int
• Double
• Float
• QLine
• QLineF
• QPoint
• QPointF
• QSize
• QSizeF
• QRect
• QRectF
• QColor

If you need to interpolate other variant types, including custom types, you have to implement interpolation for these yourself.

---

Added after 43 minutes:

Probably QStateMachine could help here but I do not understand how currently?

[AlekseyK]

I implemented correctly, only need to add Interpolator for QString like this for example:

qRegisterAnimationInterpolator<QString>(StringInterpolator);
 
QVariant StringInterpolator(const QString &start, const QString &end, qreal progress)
 {
     if(progress < 1.0)
        return start;
     else
         return end;
 }

qRegisterAnimationInterpolator<QString>(StringInterpolator);

QVariant StringInterpolator(const QString &start, const QString &end, qreal progress)
 {
     if(progress < 1.0)
        return start;
     else
         return end;
 }

To copy to clipboard, switch view to plain text mode 

Animations for any other types are possible with such approach.