nusamai-shapefile: MultiLineString, MultiPolygonの変換

[sorami]

#203 （MultiPoint）と同じ形で、nusamai-geometryのMultiLineString, MultiPolygonを、Shapefileの形式へ変換する。

参考

ポリゴンは、複数のOuterリングを持つことができる

https://github.com/tmontaigu/shapefile-rs/blob/cd52bcfde8ce24aeaffec0968f155119e02c5a66/src/record/polygon.rs#L198C1-L204C59

/// # Notes
/// - A Polygon ring is a connected sequence of 4 or more points
///   **(this is not checked)**
/// - Polygon's rings MUST be closed (the first and last points MUST be the same) (p 13/34)
///   **(this is done by the constructors if you do not do it yourself)**
/// - The order of rings is not significant (p 13/34)
/// - A polygon may have multiple [`Outer`] rings (p12/34)

リングのオーダー

https://github.com/tmontaigu/shapefile-rs/blob/cd52bcfde8ce24aeaffec0968f155119e02c5a66/src/record/polygon.rs#L26-L37

/// In shapefile, the point ordering is what is used to know if
/// a ring is an outer or inner one:
/// - **Outer** ring => points in clockwise order
/// - **Inner** ring => points in counter-clockwise order
///
/// # Note
///
/// Rings you get access from a [`GenericPolygon`] will always have its points ordered
/// according to its type (outer, inner).
///
/// But `PolygonRing`s you create won't be reordered until you move them into
/// a [`GenericPolygon`].

https://github.com/tmontaigu/shapefile-rs/blob/cd52bcfde8ce24aeaffec0968f155119e02c5a66/src/record/mod.rs#L118-L134

/// Given the points, check if they represent an outer ring of a polygon
///
/// As per ESRI's Shapefile 1998 whitepaper:
/// `
/// The order of vertices or orientation for a ring indicates which side of the ring
/// is the interior of the polygon.
/// The neighborhood to the right of an observer walking along
/// the ring in vertex order is the neighborhood inside the polygon.
/// Vertices of rings defining holes in polygons are in a counterclockwise direction.
/// Vertices for a single, ringed polygon are, therefore, always in clockwise order.
/// `
///
/// Inner Rings defines holes -> points are in counterclockwise order
/// Outer Rings's points are un clockwise order
///
/// https://stackoverflow.com/questions/1165647/how-to-determine-if-a-list-of-polygon-points-are-in-clockwise-order/1180256#1180256
pub(crate) fn ring_type_from_points_ordering<PointType: HasXY>(points: &[PointType]) -> RingType {

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Additional details and impacted files

Components	Coverage Δ
GUI	∅ <ø> (∅)
Backend	66.91% <ø> (-1.71%)	⬇️
Libraries	92.71% <100.00%> (+0.29%)	⬆️

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[ciscorn]

なるほど
https://docs.rs/shapefile/latest/shapefile/record/polygon/enum.PolygonRing.html#note

Rings you get access from a GenericPolygon will always have its points ordered according to its type (outer, inner).
But PolygonRings you create won’t be reordered until you move them into a GenericPolygon.

[ciscorn]

LGtm!