Fix for the label clipping in the label layout algorithm

[rita-gwen]

No description provided.

[nickshulman]

This looks good to me.
It definitely seems to lay out better than before.
Here are some comments which may be helpful. If they're not helpful then I would say don't worry about it and go ahead and merge to master.

[nickshulman]

This should probably have been:

if (e.PropertyName == nameof(Settings.Default.GroupComparisonAvoidLabelOverlap))

so that "Find References" and other sorts of refactoring would work a little bit better.

[nickshulman]

If I have to write code which removes a listener and adds it back I usually put it inside of a try/finally:

try 
{
    Settings.Default.PropertyChanged -= OnLabelOverlapPropertyChange;
// do other stuff
}
finally
{
    Settings.Default.PropertyChanged += OnLabelOverlapPropertyChange;
}

That way, even if some sort of exception happens, things still get back into an expected state.

For something like this, I would probably just have a field:
private bool _inPropertyChange;
and then in the property change handler:

if (_inPropertyChange) 
{
   return;
}
try 
{
    _inPropertyChange = true;
    if (e.PorpertyName == nameof(Settings.Default.GroupComparisonAvoidLabelOverlap)) 
    {
        // do some stuff
    }
    else if (e.PropertyName == nameof(Settings.Default.GroupComparisonSuspendLabelLayout)) 
    {
        // do other stuff
    }
}
finally 
{
    _inPropertyChange = false;
}

But the way you have this is fine too.

[nickshulman]

I am not sure I understand why labelRect.Width / 2 gets added to the X-coordinate, but a similar sort of thing does not get added to the Y-coordinate.
This code might be correct, but I wanted to point out that it looks suspicious.

[rita-gwen]

This is because label coordinates are top-middle, so Y coordinate is not adjusted.

[rita-gwen]

The most recent commit should fix the label clipping in small-size plots in the DIA tuturials. This is how it looks:
DIATtof tutorial

DIAPacef tutorial:

[brendanx67]

Better, but I guess I wonder about the label placement algorithm not finding a better place for the pictured labels. There seems to be a lot of space above the points, and even down a bit from where it is placed. Instead, the placements shown have it overlapping other points. I wonder if the algorithm is now allowing to to be best placed off screen and then simply forcing it on screen, instead of limiting it to placements where it will not get clipped during the best placement search.