diagrams-lib-0.2: Embedded domain-specific language for declarative graphics





Two-dimensional ellipses (and, as a special case, circles).


Ellipse and circle diagrams

circle :: (Backend b R2, Renderable Ellipse b) => Diagram b R2Source

A circle of radius 1.

ellipse :: (Backend b R2, Renderable Ellipse b) => Double -> Diagram b R2Source

ellipse e constructs an ellipse with eccentricity e by scaling the unit circle in the X direction. The eccentricity must be within the interval [0,1).

Mathematical ellipses


data Ellipse Source

An ellipse is represented by an affine transformation acting on the unit circle.


Ellipse T2 

Extracting attributes

ellipseCenter :: Ellipse -> P2Source

Compute the center of an ellipse.

ellipseAngle :: Ellipse -> RadSource

Compute the angle to the major axis of an ellipse, measured counterclockwise from the positive x axis in radians. The result will be in the range [0, tau/2).

ellipseAxes :: Ellipse -> (R2, R2)Source

Compute the vectors (va, vb) from the center of the ellipse to the edge of the ellipse along the major and minor axes. These vectors can lie in any quadrant, depending on how the ellipse has been transformed.

ellipseScale :: Ellipse -> (Double, Double)Source

Compute the scaling factors of an ellipse, i.e. (a,b) where a and b are half the lengths of the major and minor axes respectively.

ellipseCoeffs :: Ellipse -> (Double, Double, Double, Double, Double, Double)Source

Compute the coefficients of the quadratic form

A x^2 + B x y + C y^2 + D x + E y + F = 0

for an ellipse. Returns A through F (in that order) as a tuple.