How to make brackground transparent

fifth

I've built a custom QScrollArea-based widget, but it's default background was some color. I'd like to make background transparent so that it could display widgets which were even under it if overlapped.
However I didn't see there's a transparent role in setBackgroundRole(), then how could I do?

thx.

giesbert

You can try, setting these attributes on the widget:

setAttribute(Qt::WA_NoBackground);

setAttribute(Qt::WA_NoSystemBackground);

setAttribute(Qt::WA_TranslucentBackground);

additionally, you could set setAutoFillbackground(false).

fifth

setAutoFillBackground didn't simply work.
WA_NoBackground was obsolete and the successor WA_OpaquePaintEvent said in opposite way, and didn't work either.
WA_NoSystemBackground and WA_TranslucentBackground ended up with a little bit repainting issue, since it never automatically updated newly exposed area, for instance. Then the tough part would turn to that I have to paint everything underneath the widget.

If memory severed me, QFrame is by default transparent, don't know how it get that.

[quote author="Gerolf" date="1295255973"]You can try, setting these attributes on the widget:

setAttribute(Qt::WA_NoBackground);

setAttribute(Qt::WA_NoSystemBackground);

setAttribute(Qt::WA_TranslucentBackground);

additionally, you could set setAutoFillbackground(false).[/quote]

giesbert

I hope you know that a QScrollArea consists of two widgets?
it has the scroll area itself and the viewport widget. Both must be transparent....

fifth

I was aware of that. I set those attribute on both widget.

[quote author="Gerolf" date="1295265476"]I hope you know that a QScrollArea consists of two widgets?
it has the scroll area itself and the viewport widget. Both must be transparent....[/quote]

MrNoway

its little bit old, but the problem seems to be still up to date.

if you use

scroll->setStyleSheet("background-color:transparent;");

its working pretty good, but the "Scroll Bar" is getting transparent too,
making it pretty hard to scroll.

if someone knows how to fix it, please post.

b1gsnak3

try adding
@scroll->verticalScrollBar()->setStyleSheet("border, background and what else you need")@

MrNoway

maybe it would work, but there is a syntax error
@scroll->verticalScrollBar()->setStyleSheet("...")@

"pointer-to-incomplete"

MrNoway

my fault, I didnt
#include <qscrollbar.h>

@scroll_gunshop->verticalScrollBar()->setStyleSheet("background-color:red");@

but there is still a little "pattern" in there.
the part where the scroll bar is not covered.

http://img534.imageshack.us/img534/2594/ddddiw.jpg

but looks almost perfect.

thanks*

€ or maybe this is just the normal "natural" scroll bar pattern
if you use white it's gone.

b1gsnak3

You can customize everything in the scrollbar just by using css... try taking a look "here":http://doc.qt.digia.com/qt/stylesheet-examples.html#customizing-qscrollbar and try out different css commands...

vittalonline

hope this will be helpful to you

setAttribute(Qt::WA_TranslucentBackground);

setAttribute(Qt::WA_NoSystemBackground,false);

setWindowFlags(Qt::FramelessWindowHint);

setStyleSheet("font-weight:bold;color:white;"
              "background-color: rgba(0,0,0,80%);"
              "font: bold 20px;"
              "font-weight:bold;"
              );

pal_vic

QPalette pal;
pal.setColor(QPalette::Window,QColor(0,0,0,0));
z_scroll->setPalette(pal);
z_scroll->setBackgroundRole(QPalette::Window);
z_scroll->widget()->setPalette(pal);
z_scroll->widget()->setBackgroundRole(QPalette::Window);