Semi-transparent QFrame

Morris

I need to make a QFrame semi-transparent when the mouse is not hovering on it. And make it opaque when the mouse moves on it.
I have try QWidget::setWindowOpacity() which doesn't work. Obviously, the setWindowOpacity() works on a widget which has a Qt::Window flag.
So, how can I make the QFrame semi-transparent.
PS: I have set the css of the QFrame object, it has a png as its background.

tony

Hi,

it's not a full solution, but I think that it can be an idea for you.

I've written a sample code, that is a widget, with a custom paint method.

@

class Widget : public QWidget
{
Q_OBJECT

bool _over;
bool _prevOver;

protected:
void paintEvent(QPaintEvent *event);
void mouseMoveEvent(QMouseEvent *event);

public:
Widget(QWidget *parent = 0);
};
@

@

Widget::Widget(QWidget *parent)
: QWidget(parent),
_over(false),
_prevOver(false)
{
setMouseTracking(true);
}

void Widget::mouseMoveEvent(QMouseEvent *event)
{
_over = QRect(rect().center()-QPoint(100,100),rect().center()+QPoint(100,100)).contains(event->pos());
QWidget::mouseMoveEvent(event);
if (_over != _prevOver)
{
_prevOver = _over;
update();
}
}

void Widget::paintEvent(QPaintEvent *event)
{
QPainter p(this);

p.drawText(rect(),"Hello world!",QTextOption(Qt::AlignCenter | Qt::AlignVCenter));
p.fillRect(rect(),QColor(255,0,0,(_over)? 255 : 100));
}
@

If you move the cursor out of a 100x100 pixel square from the center, you can see "Hello world!" covered with a semi-transparent color (so you can see it).
If you move in the square, the color fully covers the text.

So, you should modify the alpha of the png in a temporary QPixmap, and paint it, or something similar, if the transparent condition happens.

Tony.

Morris

Thanks for the example. So I need to override the paintEvent.