Get/Set the radius of Path.Circle items

[Endash]

Hi,

How can the radius of a Path.Circle item be "get" and "set" ?

Thanks,

[Christopher Best]

Once you create a circle path, it's just a path, and there is no inherent circle structure.

However, the following would be equivalent to getting and setting the radius:

var circlePath = new Path.Circle(center, radius);

// get

var radius = circlePath.bounds.width / 2;

// set

var circlePath.scale(newRadius / radius);

[Endash]

The problem with the solution you propose is that it gets messed up with the strokeWidth.

For instance:

var circlePath = new Path.Circle(center, 100);

circlePath.strokeWidth = 20;

// get

var radius = circlePath.bounds.width / 2;

>>> radius = 60 = 50 + 10 (because of the strokeWidth);

// set
var scale = 2;

var circlePath.scale(2);

radius = circlePath.bounds.width / 2;

>>> radius = (2*100 + 10 + 10) / 2 = 110, where it would have been more logical to be 120 = 2 * 60.

But by writing the "logical" word, I realize the paperjs team may disagree.

I guess I will have to build my own function to return what I consider the "logical" radius. :-)

[Alex Blackwood]

Since it's a circle, why not just use the vector length between any
segment and the center?

var circlePath = new Path.Circle(view.center,100);
circlePath.strokeColor='black';
circlePath.strokeWidth = 50;
function radGet(circle){
rad = (circle.firstSegment.point-circle.bounds.center).length;
return rad;
}
var test = new PointText(new Point(view.center));
test.content= radGet(circlePath);
test.paragraphStyle.justification= 'center';

[Christopher Best]

Hi Endash,

If you want to include stroke in the calculations, Path has a strokeBounds property which will let you find the radius. Setting the radius is slightly more complicated, but not too much. Below are two functions which should get and set the radius the way you want.

var getRadius = function(path) {

return path.bounds.width / 2 + path.strokeWidth / 2;

// or return path.strokeBounds.width / 2; 

}

var setRadius = function(path, radius) {

// figure out what the new radius should be without the stroke

var newRadiusWithoutStroke = radius - path.strokeWidth / 2;

// figure out what the current radius is without the stroke 

var oldRadiusWithoutStroke = path.bounds.width / 2;

path.scale(newRadiusWithoutStroke / oldRadiusWithoutStroke);

}