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);
	}
};

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);
	}
};

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

setWindowOpacity( 0.0 );

setWindowOpacity( 0.0 );

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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
	}
};

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
	}
};

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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

[franco.amato]

Hope it does now

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 );
	}
};

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 );
	}
};

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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");

setStyleSheet("selection-background-color: yellow");

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on a QRubberBand changes the background color of the selected area to yellow as expected.

Hope this will help someone.

Clément.