Incrementing the length of a QLineF in the negative direction?

[jh224]

The documentation seems to be spotty on this. Below is how I did it. Is this the correct way?

@
QLineF refLine(100,100, 500,500);
QLineF perpLine = refLine.normalVector(); //create a perpendicular line to the refLine
perpLine.setLength(-1); //this seems to set it in the negative direction and it stays in the negative direction

for(int i = 0; i < 50; i++)
{
perpLine.setLength(perpLine.Length + 1); // this will increment perpLine in a negative direction
}

@

[raven-worx]

i read the docs of QLineF::setLength() pretty clear:
[quote]
Sets the length of the line to the given length. QLineF will move the end point (p2) of the line to give the line its new length
[/quote]

The following code would rotate the line by 180° (around p1):
@
QLineF line(100,100, 500,500);
line.setLength( - line.length() );
@

[jh224]

Thanks for the reply. I always find Qt documentation to be top notch. I'm having trouble inferring from the documentation on this topic to mean negative numbers will invert/rotate the line.