QGraphicsDropShadowEffect on form widget

janfaroe

Greetings all. I'm having trouble showing a drop shadow on my form widgets. A quick test with a QLabel poses no problem; the shadow shows fine.

I should mention that the widgets are laid out with my own layout manager - also that I am applying the shadow as I am adding the widgets to the layout. I tried applying shadow before and after adding to layout; no difference.

Is there anything I should be beware of in order to make this work? Or does shadows only work with "simple" widgets?

janfaroe

Ok, it works if adding the shadow in the form widget constructor:

ui->setupUi(this);
QGraphicsDropShadowEffect* dropShadowEffect = new QGraphicsDropShadowEffect(this);
this->setGraphicsEffect(dropShadowEffect);

But, now all sub widgets inherits the effect. Calling QWidget::setGraphicsEffect(NULL) for subitems does not change anything.

Suggestions?

SGaist

Hi,

Did you try:

@dropShadowEffect->setEnabled(false);@

?

janfaroe

Um, I'm not sure how that would work. I'm having one instance of the effect, which is applied only on the top level widget. Disabling it would sort of defeat the purpose.

Chris Kawa

You can explicitly set a background color on the top level widget. This will force the drop shadow effect to treat it as a opaque rectangle (or whatever the shape is) and apply the effect around it leaving children unchanged.

janfaroe

I suppose you mean with a stylesheet? Just did this on the top level widget; did not stop the effect from propagating to the children:

#MediaItemForm {
background-color:#FFFFFF;
}

SGaist

Sorry, I misread your post.

From the documentation of QWidget::setGraphicsEffect:

bq. Note: This function will apply the effect on itself and all its children.

janfaroe

SGaist: Yes, but how to avoid it? It would be a terrible solution to subclass all child elements to ignore the effect.

Chris Kawa

Hm, that's weird. This is what I'm getting with and without the background:
!http://img46.imageshack.us/img46/9097/ifgk.jpg(drop shadow example)!

raven-worx

[quote author="janfaroe" date="1383368356"]SGaist: Yes, but how to avoid it? It would be a terrible solution to subclass all child elements to ignore the effect.[/quote]

you can try a method which sets the effect for you (untested):
@
setDropShadowEffectOnWidgetOnly(QWidget* w)
{
if( ! w ) return;

w->setGraphicsEffect( new QGraphicsDropShadowEffect );
foreach( QWidget* child, this->findChildren<QWidget*>() )
     child->setGraphicsEffect(0);   //unset effect for children

}
@

janfaroe

Chris Kawa: That's odd indeed. And you set bg color with style sheet? Could it be one of these things that despite all are platform dependent? Or because I'm using 5.2 beta?

[quote author="Chris Kawa" date="1383555753"]Hm, that's weird. This is what I'm getting with and without the background:
!http://img46.imageshack.us/img46/9097/ifgk.jpg(drop shadow example)![/quote]

janfaroe

Thanks for the suggestion. However, since I'm rendering quite a few parent widgets, it does not seem terribly efficient? But of course, if anything else fails, I might resort to it.

[quote author="raven-worx" date="1383557940"][quote author="janfaroe" date="1383368356"]SGaist: Yes, but how to avoid it? It would be a terrible solution to subclass all child elements to ignore the effect.[/quote]

you can try a method which sets the effect for you (untested):
@
setDropShadowEffectOnWidgetOnly(QWidget* w)
{
if( ! w ) return;

w->setGraphicsEffect( new QGraphicsDropShadowEffect );
foreach( QWidget* child, this->findChildren<QWidget*>() )
     child->setGraphicsEffect(0);   //unset effect for children

}
@[/quote]

raven-worx

[quote author="janfaroe" date="1383558917"]Thanks for the suggestion. However, since I'm rendering quite a few parent widgets, it does not seem terribly efficient?
[/quote]
yes most probably.

Chris Kawa

[quote author="janfaroe" date="1383558759"]Chris Kawa: That's odd indeed. And you set bg color with style sheet? Could it be one of these things that despite all are platform dependent? Or because I'm using 5.2 beta?
[/quote]

I'm using Qt5.1.1 with both VS2012 and MinGW. This is basically all the code I wrote:
@
ui->frame->setStyleSheet("QFrame { background-color: palette(window)}");
ui->frame->setGraphicsEffect(new QGraphicsDropShadowEffect(this));
ui->frame_2->setGraphicsEffect(new QGraphicsDropShadowEffect(this));
@