QGraphicsDropShadowEffect and QResizeEvent

[J.Hilk]

Hello,

I'm using a custom QLabel class that is mainly used to display images/icons and emit Signals/do Stuff with mouseevents.

My last additon was a shadow effect, using QGraphicsDropShadowEffect when the mouse hovers over the label.

The problem is, when the effect is applied, it causes a resizeeffent for the whole programm and the min-width is more or less doubled.

I could stop this with this->blockSignals(true); during the effect creations. But the labels are part of a QPropertyAnimation and as soon as the animation starts the resize is triggered again.

Is there a way to prevent this? Is QGraphicsDropShadowEffect actually the correct why to archiv my goal - shadow of the label while mouse over - or should I do something else?
Like, load a different pixmap that has a drawn shadow and swap between those two.

{
connect(this, &cLabel::hover, this, &cLabel::shadowEffect);
}
//Code excerpt where the effect is applied
void cLabel::enableShadow(bool enable)
{
    m_shadowEffect = enable;
    if(enable){
        this->blockSignals(true);
        effect = new QGraphicsDropShadowEffect(this);
        effect->setColor(QColor(110,152,226,255));
        effect->setBlurRadius(10);
        effect->setOffset(5);
        effect->setEnabled(false);
        this->setGraphicsEffect(effect);
        this->blockSignals(false);
    }else{
        effect->deleteLater();
    }
}

void cLabel::shadowEffect(bool status)
{
    if(m_shadowEffect){
        if(status)
            effect->setEnabled(true);
        else
            effect->setEnabled(false);
    }
}

void cLabel::enterEvent(QEvent *event)
{
    emit hover(true);
    event->ignore();
}

void cLabel::leaveEvent(QEvent *event)
{
    emit hover(false);
    
    _Clicked = false;
    reset();
    
    event->ignore();
}

[J.Hilk]

I've tried a couple of different things.

all without success:

• Applying and handling the DropShadowEffect from the parent widget
• Disabling the effect before emitting the clicked Signal
• Delays between signal and execution
• Blocking all signals before the start of the QPropertyAnimation
• setting a fixedSize for the MainWindow, user cant change the size, but upon the animations execution the MainWindow gets the new minSize anyway

But I noticed, that it also happens when I change to a new side of my stackedwidget, but not when I click outside the application.

I'm now down to a 2nd set of Pixmaps that have a predrawn shadow effect on them. Those I swap on mouse over.

I'm not happy with it, but it works. If anyone has a better solution please tell me.

Greetings.

[J.Hilk]

Ok,

I'll mark this as solved.

I wasn't able to do it with QGraphicsDropShadowEffect, and creating all images twice and including them in the rcs-file is simply a no go.

Therefore I create a function, that draws a shadow - all 4 sides - around the the QImages, either at startup or during runtime.

Here it is, in case anyone else needs something like it.

QImage drawShadow(QImage img)
    {
        //Condition img allready has a transparent border 4 Pixel in this case

        //Create new Img with same Size
        QImage imgBGround(img.size(), img.format());

        //Fill it with transparency
        QPainter p(&imgBGround);
        QPen pen; pen.setStyle(Qt::NoPen);
        p.setPen(pen);
        p.setRenderHint(QPainter::Antialiasing);
        p.fillRect(QRect(0,0,img.width(), img.height()), QColor(255,255,255,0));

        //Draw Rounded Rectangle as Shadow
        QPainterPath path;
        path.addRoundedRect(QRect(0,0,img.width(), img.height()),15,15);
        p.fillPath(path,QColor(110,152,226));
        p.drawPath(path);

        //Draw Original Img over background
        p.drawImage(0,0,img);

        return imgBGround;
    }