Struct Polyline2View

Non-owning read-only view of an ordered sequence of 2D points.

struct Polyline2View(T)
  
if (isGeoScalar!T);

Supported scalar types are int, long, float, double, and real.

Polyline2View.init is an empty view.

Polyline2View does not allocate or copy point data. The caller retains ownership of the backing storage, which must remain valid for the lifetime of the view.

The view aliases its backing storage. Changes made to mutable backing storage through its owner remain visible through an existing view. Mutation is not exposed through Polyline2View itself.

Empty and singleton polylines are valid.

Constructors

NameDescription
this (points) Constructs a view over contiguous point storage.

Properties

NameTypeDescription
empty[get] boolTrue when the view contains no points.
length[get] size_tNumber of stored points.
segmentCount[get] size_tNumber of consecutive line segments represented by the view.

Methods

NameDescription
opIndex (index) Returns one point by value.
segment (index) Returns the segment beginning at point index.

Example

Example borrowing caller-owned point storage as a polyline. 

import geo;

alias P = Point2!double;
alias S = Segment2!double;
alias V = Polyline2View!double;

P[3] points = [
    P(0.0, 0.0),
    P(2.0, 1.0),
    P(5.0, 1.0)
];

auto polyline =
    V(points[]);

assert(!polyline.empty);
assert(polyline.length == 3);
assert(polyline.segmentCount == 2);

assert(
    polyline[1] ==
    P(2.0, 1.0)
);

assert(
    polyline.segment(1) ==
    S(
        P(2.0, 1.0),
        P(5.0, 1.0)
    )
);

/*
 * The view aliases rather than copies caller-owned storage.
 */
points[1] =
    P(3.0, 2.0);

assert(
    polyline[1] ==
    P(3.0, 2.0)
);