Programming questions

[Casper Boemann]

On Sunday 10 July 2005 09:52, Michael Thaler wrote:
> Hello,
>
> I still try to port the cubism filter and I have some questions:
>
> I wrote a KisPolygon class, that basically stores points and can rotate and
> translate the points:
>
> class KisPolygon
> {
>         public:
>                 KisPolygon();
>                 void addPoint(double x, double y);
>                 void translate(double tx, double ty);
>                 void rotate(double theta);
>                 Q_INT32 extents(double &minX, double &minY, double &maxX,
> double &maxY);
>                 void clear();
>                 Q_INT32 numberOfPoints();
>         private:
>                 typedef QValueVector<KisPoint> KisPointVector;
>                 KisPointVector* m_data;
> };
>
> KisPolygon::KisPolygon()
> {
>         m_data = new KisPointVector(4);
> }
>
> void KisPolygon::addPoint(double x, double y)
> {
>         KisPoint point(x, y);
>         m_data->append(point);
> }
>
> void KisPolygon::translate(double tx, double ty)
> {
>         KisPointVector::iterator it;
>
>         for( it = m_data->begin(); it != m_data->end(); ++it )
>         {
>                 (*it).setX( (*it).x() + tx );
>                 (*it).setY( (*it).y() + ty );
>         }
> }
>
> and so on. Now I have the following function
>
> void KisCubismFilter::fillPolyColor (KisPaintDeviceSP src, KisPaintDeviceSP
> dst, KisPolygon* poly, Q_UINT8* col, Q_UINT8* dest)
>
> which gets a pointer to my KisPolygon class. When I try to access the first
> point in the KisPolygon class
>
> poly[0].x();
>
> I get the following error
>
> KisCubismFilter::fillPolyColor(KSharedPtr<KisPaintDevice>,
>    KSharedPtr<KisPaintDevice>, KisPolygon*, Q_UINT8*, Q_UINT8*)':
> kis_cubism_filter.cc:171: error: `x' undeclared (first use this function)
> kis_cubism_filter.cc:171: error: (Each undeclared identifier is reported
> only once for each function it appears in.)
>
> poly[0]->x(); does not work either:
>
> Then I get
>
> KisCubismFilter::fillPolyColor(KSharedPtr<KisPaintDevice>,
>    KSharedPtr<KisPaintDevice>, KisPolygon*, Q_UINT8*, Q_UINT8*)':
> kis_cubism_filter.cc:171: error: base operand of `->' has non-pointer type
> ` KisPolygon'
>
> In http://doc.trolltech.org/3.3/qvaluevector.html#details it is explained
> that you can access elements with []. Whoever, they did create the vector
> on the stack, not with new. I think my bad C++ programming skills just
> catched me:-) Can someone help me?
you are trying to use [] on your KisPolygon class. There you haven't defined 
the [] operator.
Trolltech have defined the [] on the QValueVector.

If I were you I would make a function:

KisPoint KisPolygon::getPoint(int i)
{
	return m_data[i];
}

and use that in the cubismfilter
-- 
best regards / venlig hilsen
Casper Boemann