How to remove background

[marcel]

to durbrak:

CTestWidget::CTestWidget(QWidget* parent )
:QWidget( parent )
{
    setWindowFlags( Qt::FramelessWindowHint );
    setFixedSize( 400, 400 );
    mPixmap = QPixmap( "C:\\ellipse.png" );
    QBitmap mask = mPixmap.createHeuristicMask(true);
    setMask( mask );
}
 
CTestWidget::~CTestWidget()
{
}
 
void CTestWidget::paintEvent(QPaintEvent* e)
{
    QPainter p( this );
    p.drawPixmap( 0, 0, mPixmap );
}

CTestWidget::CTestWidget(QWidget* parent )
:QWidget( parent )
{
    setWindowFlags( Qt::FramelessWindowHint );
    setFixedSize( 400, 400 );
    mPixmap = QPixmap( "C:\\ellipse.png" );
    QBitmap mask = mPixmap.createHeuristicMask(true);
    setMask( mask );
}

CTestWidget::~CTestWidget()
{
}

void CTestWidget::paintEvent(QPaintEvent* e)
{
    QPainter p( this );
    p.drawPixmap( 0, 0, mPixmap );
}

To copy to clipboard, switch view to plain text mode 

I knew I did it some time ago.
I attached a screen of how it looks.
The png is just a black ellipse on a white background.
The method is limited because it does not work when the image you want to display contains transparent shadings ( such as shadows ).
However, you can give the whole masked widget a shadow if you set the flags Qt::FramessWindowHint | Qt::Popup.

Although, never tested it on Mac.

regards