QPainter drawArc question

[kloopa]

For clockwise / counter-clockwise drawing question solved.
But arcs still incorrect. I think problem when calculating angles. Because angles may be + or -.
My program reading coordinates form TXT file (file generated by other software from DXF format, where 0 degree at 12 o'clock).

Part of my code (Python3):

def arcAngles(self, a, b, c):
        startAngle = 16*atan2(a.y() - c.y(), a.x() - c.x())*180 / pi
        endAngle = 16*atan2(b.y() - c.y(), b.x() - c.x())*180 / pi
 
        spanAngle = abs(endAngle) - abs(startAngle)
 
        #Clocksiwe
        if self.direction == -1:
            if spanAngle > 0:
                spanAngle = -spanAngle
 
        print("START: " + str(startAngle / 16) + "\nEND: " + str(endAngle / 16) + "\nSPAN: " + str(spanAngle / 16))
        angles = {'start': startAngle, 'end': endAngle, 'span': spanAngle}
 
        return angles

def arcAngles(self, a, b, c):
        startAngle = 16*atan2(a.y() - c.y(), a.x() - c.x())*180 / pi
        endAngle = 16*atan2(b.y() - c.y(), b.x() - c.x())*180 / pi
        
        spanAngle = abs(endAngle) - abs(startAngle)

        #Clocksiwe
        if self.direction == -1:
            if spanAngle > 0:
                spanAngle = -spanAngle
                
        print("START: " + str(startAngle / 16) + "\nEND: " + str(endAngle / 16) + "\nSPAN: " + str(spanAngle / 16))
        angles = {'start': startAngle, 'end': endAngle, 'span': spanAngle}

        return angles

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Result:

=====1st Arc====
START: -90.0
END: 180.0
SPAN: -90.0
LastPoint: PyQt5.QtCore.QPointF(13.178, 82.461)
EndPoint: PyQt5.QtCore.QPointF(2.278, 93.361)

=====2nd Arc====
START: 180.0
END: 90.0
SPAN: -90.0
LastPoint: PyQt5.QtCore.QPointF(2.278, 151.361)
EndPoint: PyQt5.QtCore.QPointF(13.178, 162.261)

=====3rd Arc====
START: 90.0
END: 0.0
SPAN: -90.0
LastPoint: PyQt5.QtCore.QPointF(143.178, 162.261)
EndPoint: PyQt5.QtCore.QPointF(154.078, 151.361)

Drawing result:
1.png

I tried to solve this by manipulation with offset (90 degree), but still not solved.

Substracting offset from angles:

offset = 90*16
 
        if startAngle < 0:
            startAngle -= -offset
        else:
            startAngle -= offset
 
        if endAngle < 0:
            endAngle -= -offset
        else:
            endAngle -= offset

offset = 90*16

        if startAngle < 0:
            startAngle -= -offset
        else:
            startAngle -= offset
            
        if endAngle < 0:
            endAngle -= -offset
        else:
            endAngle -= offset

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When substract offset from angles i see:

11.png

Add offset to angles:

offset = 90*16
 
        if startAngle < 0:
            startAngle += -offset
        else:
            startAngle += offset
 
        if endAngle < 0:
            endAngle += -offset
        else:
            endAngle += offset

offset = 90*16

        if startAngle < 0:
            startAngle += -offset
        else:
            startAngle += offset
            
        if endAngle < 0:
            endAngle += -offset
        else:
            endAngle += offset

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When adding offset to angles i see:

22.png