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c++qtqt5qt4qgraphicsview

How to draw an arc between two known points in Qt?

enter image description here

I want to draw an arc between point B to point D and it should touch to point E. ( I want to draw AND gate symbol )
I tried this way

QPainterPath path;    
path.arcTo(60,30,46,100,30*16,120*16); // ( x,y,width,height, startAngle,spanAngle)

But it is drawing full circle and not in proper place.

Currently it is looking like this

enter image description here

After getting suggestion I tried like this :

path.moveTo(106, 80);
path.arcTo(76.0, 30.0, 60.0, 100.0, 90.0, -180.0);

How to get rid of that vertical line ( inside AND gate ) ?
Why it is appearing ?

Solution

  • I think you misunderstood the parameters for arcTo, especially the bounding rectangle.

    Given your image, you should move path to (106, 80) (center of the bounding rectangle)

    path.moveTo(106, 80);

    The bounding rectangle of the arc should look like this:

    • x: 76
    • y: 30
    • width: 60
    • height: 100

    The arc itsel should have a start angle at 90° and should span 180° in negative direction.

    This results in:

    path.arcTo(76.0, 30.0, 60.0, 100.0, 90.0, -180.0);

    Update

    arcTo

    path.moveTo(106, 30);
path.cubicTo(QPointF(156.0, 30.0), QPointF(156.0, 130.0), QPointF(106.0, 130.0));