How to rotate markers in qwt

[alperyazir]

I want to rotate my marker in my plot but i cant. Here is my code to adding images to plot:

QPixmap pixmap("image");
 
        QwtSymbol *symbol = new QwtSymbol;
        symbol->setPixmap(pixmap);
 
        marker = new QwtPlotMarker;
        marker->setSymbol( symbol);
        marker->attach(this);

QPixmap pixmap("image");

        QwtSymbol *symbol = new QwtSymbol;
        symbol->setPixmap(pixmap);

        marker = new QwtPlotMarker;
        marker->setSymbol( symbol);
        marker->attach(this);

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I tried to rotate with QTransform but i couldnt achive. Is there any trick to solve this problem?

Thanks.

[Cah]

I have not tried anything close to this...
You could...

QwtPlotMarker * marker;
....
....
 
QMatrix m...
m.rotate(angleOfRotation);
 
const QwtSymbol* oldSymbol = marker->symbol();
 
QwtSymbol* newSymbol = new QwtSymbol(m.map(oldSymbol->path()), oldSymbol->brush(), oldSymbol->pen());
 
marker->setSymbol(newSymbol);
...

QwtPlotMarker * marker;
....
....

QMatrix m...
m.rotate(angleOfRotation);

const QwtSymbol* oldSymbol = marker->symbol();

QwtSymbol* newSymbol = new QwtSymbol(m.map(oldSymbol->path()), oldSymbol->brush(), oldSymbol->pen());

marker->setSymbol(newSymbol);
...

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---

Added after 32 minutes:

Or
...

CustSymbol : public QwtSymbol
{
public:
...
double rotation()const
{
 return _rotation;
}
 
void seRotation(double angle)
{
_rotation = angle;
}
 
protected:
virtual void drawSymbols( QPainter *, const QPointF *, int numPoints ) const;
double  _rotation;
};

CustSymbol : public QwtSymbol
{
public:
...
double rotation()const
{
 return _rotation;
}

void seRotation(double angle)
{
_rotation = angle;
}

protected:
virtual void drawSymbols( QPainter *, const QPointF *, int numPoints ) const;
double  _rotation;
};

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and reimplement drawSymbols( )

void CustSymbol::drawSymbols( QPainter *, const QPointF *, int numPoints ) 
{
...
}

void CustSymbol::drawSymbols( QPainter *, const QPointF *, int numPoints ) 
{
...
}

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[Uwe]

Your question is more or less unrelated to QwtSymbol/QwtMarker - what you want to know is how to rotate an image.

When the source of your image is made from vectors ( SVG graphics or something you create in code yourself f.e a QwtGraphic ) rotating can be done without any loss in quality - simply by creating the rotated image from this source with a rotating transformation. If the source is based on some raster graphic format all you can do without losing quality is to mirror the image ( QImage::mirrored() ). For all other angles you have to use QImage::transformed().

Uwe