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Thread: QpainterPath - odd fragment at the beginning

  1. #1
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    Default QpainterPath - odd fragment at the beginning

    I created the most simple arc with the following code and paint it with a 50px wide QPen. There are no other elements in the path. Can anyone help me to find the cause of the strange triangle at the start of the arc?

    Screenshot.jpg

    Qt Code:
    1. QRectF rect(pCenter.x() -200.0, pCenter.y() -200.0, 400.0,400.0);
    2. QPainterPath path = QPainterPath(QPointF(881.421,398.579));
    3. path.arcTo(rect,45,45);
    4. painter.drawPath(path);
    5. qDebug() << "pCenter:" << pCenter;
    6. qDebug() << "path:" << path;
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    The debug printout is:
    pCenter: QPointF(740,540)
    path: QPainterPath: Element count=5
    -> MoveTo(x=881.421, y=398.579)
    -> LineTo(x=881.421, y=398.579)
    -> CurveTo(x=845.228, y=362.386)
    -> CurveToData(x=795.228, y=340)
    -> CurveToData(x=740, y=340)

  2. #2
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    Default Re: QpainterPath - odd fragment at the beginning

    Hi, the docs for arcTo() say "Note that this function connects the starting point of the arc to the current position if they are not already connected.". Maybe this creates your extra triangle?

    Ginsengelf

  3. The following user says thank you to Ginsengelf for this useful post:

    derschuhmann (30th June 2021)

  4. #3
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    Default Re: QpainterPath - odd fragment at the beginning

    Hy Ginsengelf, that is a great hint! As in my path there is noting but this arc that could be my problem. Thanks! I'll have a look into that.

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