How to make certain areas transparent with the desktop?

[Sir Rogers]

Hey guys,

so I want to make a widget transparent so that the desktop background behind the widget can be seen. How is this possible?

I've tried some paintEvent examples that I found but I didn't get any of them to work properly. If needed the whole widget can be transparent and then I can put a mask on it for the regions that i want to be completely invisible.

The widget is without a windowmanager, so no frame around the form. I'm looking forward to hearing from you.


Regards,
Sir Rogers

[manojmka]

Were you able to achieve that finally? I am also facing the same issue, I am trying it with Qt::WA_TranslucentBackground

[Sir Rogers]

Nope unfortunately not. It seems that QT is not supporting this feature at the moment due to lack of cross platform compatibility.

It would be a great feature to have even if it only works on Windows and OS X.


Regards,
Rogers

[manojmka]

May be you can try setMast(). This works well if you don't want mouse events in masked area but for my case this is not the solution.

[laurent]

I'm using Qt 4.6.2 on windows and I was able to make a drop shadow for my window using Qt::WA_TranslucentBackground and a ARGB png in the Designer.

In myApp constructor I set the mask with my ARGB background I used in the designer:

QPixmap _pixmap(QString::fromUtf8(":/Background_/Background_/myApp_shadow.png"));
	this->setMask(_pixmap.mask());

QPixmap _pixmap(QString::fromUtf8(":/Background_/Background_/myApp_shadow.png"));
	this->setMask(_pixmap.mask());

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Here is where I start my QApplication and where I set the flag:

int myApp::Start(int argc, char *argv[])
{
	QApplication a(argc, argv);
	myApp* w = new myApp(NULL);
	w->show();
	w->setAttribute(Qt::WA_TranslucentBackground);
	return a.exec();
}

int myApp::Start(int argc, char *argv[])
{
	QApplication a(argc, argv);
	myApp* w = new myApp(NULL);
	w->show();
	w->setAttribute(Qt::WA_TranslucentBackground);
	return a.exec();
}

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Hope I helped you like you helped me

[laurent]

I forgot to mention that the widget you want to be translucent can't be the top widget, it has to be a child of something here is a working exemple:

m_widgetFrame= new QWidget(0, Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint);
	m_widgetFrame->setGeometry(0, 0, 100, 100);
	m_widgetFrame->setAttribute(Qt::WA_TranslucentBackground);
 
	m_widgetContent = new QWidget(m_widgetFrame);
	m_widgetContent ->setStyleSheet(QString::fromUtf8("QWidget{background-color: qlineargradient(spread:reflect, x1:0, y1:1, x2:0,y2:0,stop:0 rgba(255, 255, 255, 255),stop:1 rgba(255, 255, 255, 0));}"));
	m_widgetContent ->setGeometry(0,0,m_widgetFrame->width(),m_widgetFrame->height());
 
	m_widgetFrame->show();

m_widgetFrame= new QWidget(0, Qt::WindowStaysOnTopHint | Qt::FramelessWindowHint);
	m_widgetFrame->setGeometry(0, 0, 100, 100);
	m_widgetFrame->setAttribute(Qt::WA_TranslucentBackground);

	m_widgetContent = new QWidget(m_widgetFrame);
	m_widgetContent ->setStyleSheet(QString::fromUtf8("QWidget{background-color: qlineargradient(spread:reflect, x1:0, y1:1, x2:0,y2:0,stop:0 rgba(255, 255, 255, 255),stop:1 rgba(255, 255, 255, 0));}"));
	m_widgetContent ->setGeometry(0,0,m_widgetFrame->width(),m_widgetFrame->height());

	m_widgetFrame->show();

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