Change the color of QRubberBand

[franco.amato]

Hi to all I need to select a region over my waveform display so someone suggested to me to use QRubberBand. I tried it and it works but I would change the selection color to transparent red so I found in internet this class


class WfRubberBand : public QRubberBand
{
public:

WfRubberBand( Shape s, QWidget * p = 0 ) : QRubberBand( s, p )
{
QPalette palette;
//palette.setBrush( QPalette::WindowText, QBrush( Qt::red ) );
palette.setBrush( QPalette::Foreground, QBrush( Qt::red ) );
setPalette(palette);
}

protected:

virtual void paintEvent( QPaintEvent * )
{
QStylePainter painter(this);

QStyleOptionFocusRect option;
option.initFrom( this );

painter.drawControl(QStyle::CE_FocusFrame, option);
}
};

I tested it and effectively it draw a red rectangle but filled and not transparent so I added this line

setWindowOpacity( 0.0 ); without any effects.

How can I do to have a transparency?
May be should I use composition instead of rubberband?
Best Regards,
Franco

[aamer4yu]

Try this -
painter.setOpacity(0.5)... in the paintEvent

[franco.amato]

Try this -
painter.setOpacity(0.5)... in the paintEvent

It doesn't work.
Here the new code:


class WfRubberBand : public QRubberBand
{
public:

WfRubberBand( Shape s, QWidget * p = 0 ) : QRubberBand( s, p )
{
QPalette palette;
//palette.setBrush( QPalette::WindowText, QBrush( Qt::red ) );
palette.setBrush( QPalette::Foreground, QBrush( Qt::red ) );
setPalette(palette);
}

protected:

virtual void paintEvent( QPaintEvent * )
{
QStylePainter painter(this);

QStyleOptionFocusRect option;
option.initFrom( this );

painter.drawControl(QStyle::CE_FocusFrame, option);
painter.setOpacity(0.5); // from aamer4yu
}
};

Which can be the problem?

[franco.amato]

Well seems that this problem has no solutions. So I definitively have to use composition to select a region with a color and transparency different from the default in case of rubberBand.

[Lykurg]

Maybe you wanna call setOpacity() before you paint the rect.

[franco.amato]

Maybe you wanna call setOpacity() before you paint the rect.

Yes this solved the problem thank you very much.
Another interesting question. Is possible to give to the selection a border of a specified color?

Regards

[Lykurg]

Is possible to give to the selection a border of a specified color?

Of course: QPainter::setPen().

[aamer4yu]

Quote:
Originally Posted by aamer4yu View Post
Try this -
painter.setOpacity(0.5)... in the paintEvent
It doesn't work.
Hope it does now :cool:

[franco.amato]

Hope it does now :cool:

Sure, thank you.
I would also change the border color.
Lykurg suggested to me to use QPainter::setPen() but how? I only would
draw the border of a specified color and not all.

Best

[Lykurg]

Lykurg suggested to me to use QPainter::setPen() but how?

Come on, that's not a big deal, it like you set the opacity. And since you obviously don't need a style aware rubber band, get rid of that QStyleOptionFocusRect stuff and draw that rubber rect yourself using QPainter::drawRect(). This will also increase your speed.

[franco.amato]

Come on, that's not a big deal, it like you set the opacity. And since you obviously don't need a style aware rubber band, get rid of that QStyleOptionFocusRect stuff and draw that rubber rect yourself using QPainter::drawRect(). This will also increase your speed.

But wich QRect must I pass to the drawRect method?

[franco.amato]

I changed the code so but it doesn't work well:


class WfRubberBand : public QRubberBand
{
public:

WfRubberBand( Shape s, QWidget * p = 0 ) : QRubberBand( s, p )
{
QPalette palette;
//palette.setBrush( QPalette::WindowText, QBrush( Qt::red ) );
palette.setBrush( QPalette::Foreground, QBrush( Qt::red ) );
setPalette(palette);
}

protected:

virtual void paintEvent( QPaintEvent *pe )
{
QStylePainter painter( this );
QRect rect = pe->rect();

QPen pen( Qt::blue, 1 ); // blue solid line, 1 pixels wide
painter.setPen( pen );
// QStyleOptionFocusRect option;
// option.initFrom( this );
painter.setOpacity( 0.3 );
// painter.drawControl(QStyle::CE_FocusFrame, option);
painter.drawRect( rect );
}
};

The rect is not filled with the red color, but it's empty.
Where my code is wrong?

[Lykurg]

Use QPainter instead of QStylePainter since you don't use it's possibilities. And then use QPainter::setBrush() to define the fill color.

[franco.amato]

Use QPainter instead of QStylePainter since you don't use it's possibilities. And then use QPainter::setBrush() to define the fill color.

It works,
thank you

[clement]

Hi

just for those not wanting to re-implement a paint event for changing colors:

calling
setStyleSheet("selection-background-color: yellow"); on a QRubberBand changes the background color of the selected area to yellow as expected.

Hope this will help someone.

Clément.