How to get a list with QPoints from QPainter?

[TomNow99]

Hello,

I would like to draw Ellipse using QPainter. Now I would like to get all QPoints, which were drawn by this function. Of course that can be QVector, QList or something else.

I know that I can use mathematical formula, but maybe is there any simple way to achieve, what I want?

EDIT: I find a solution, but I think it's not perfect.

Now I draw Ellipse using QPainterPath and arcTo() with tle last param = 360. Next for each QPoint in QRect of this ellipse I check using intersects.

My code:

    painterPath.moveTo(80,50);
    
    painterPath.arcTo(20.0, 30.0, 60.0, 40.0, 0.0, 360.0);

    painter.drawPath(painterPath);

    for(int i=20;i<80;i++)
    {
        for(int j=30;j<70;j++)
        {
            qInfo()<<i<<j<<painterPath.intersects(QRect(i,j,1,1));
        }
    }

[Gojir4]

@TomNow99 Hi, I guess you can use QPainterPath::toFillPolygons() to get a list of QPolygonF representing your shape, and QPolygonF inherits from QVector<QPointF> so you can probably iterate on this to get all your points.

Something like this : (not tested)

const auto polygons = painterPath.toFillPolygons();
for (const auto &polygon in polygons){
    for(const auto &point in polygon) {
        qInfo << point;
    }
}

[TomNow99]

@Gojir4

Thank you. I check your code, but I get only this:

( I change qInfo() to painter.drawPoint() )

[Gojir4]

@TomNow99 said in How to get a list with QPoints from QPainter?:

hank you. I check your code, but I get only this:

I thought this was what you wanted. What is missing ?

[TomNow99]

@Gojir4 I would like to get all points from circle border.

[Gojir4]

@TomNow99 That's all the points. the painter will trace lines between these points to draw the ellipsis. If you really want all the points on the circle I guess you will need to calculate this by yourself. So your first solution is probably already correct. But I'm far to be an expert of QPainter so there's probably a better solution IDK.