omap 0.5.0

Interact with or write new Open Orienteering Mapper omap-files
Documentation 
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use geo_types::Coord;

use super::GeoRef;

/// Coordinate transform between map and projected (CRS) coordinates.
#[derive(Debug, Clone)]
pub struct Transform {
    map_center: Coord,
    proj_center: Coord,
    scale_factor: f64,
    sin: f64,
    cos: f64,
}

impl Transform {
    /// Convert projected (CRS) coordinates to map coordinates.
    pub fn to_map_coords(&self, proj_coord: Coord) -> Coord {
        let (x, mut y) = ((proj_coord - self.proj_center) / self.scale_factor).x_y();

        let x_r = x * self.cos - y * self.sin;
        y = x * self.sin + y * self.cos;

        Coord { x: x_r, y } + self.map_center
    }

    /// Convert map coordinates to projected (CRS) coordinates.
    pub fn to_proj_coords(&self, map_coord: Coord) -> Coord {
        let (x, mut y) = ((map_coord - self.map_center) * self.scale_factor).x_y();

        // we want to rotate other way so flip the signs of the sins
        let x_r = x * self.cos + y * self.sin;
        y = -x * self.sin + y * self.cos;

        Coord { x: x_r, y } + self.proj_center
    }

    pub(super) fn from_geo_ref(geo_ref: &GeoRef) -> Self {
        Self {
            map_center: geo_ref.map_ref_point,
            proj_center: geo_ref.projected_ref_point,
            sin: geo_ref.grivation_deg().to_radians().sin(),
            cos: geo_ref.grivation_deg().to_radians().cos(),
            scale_factor: geo_ref.combined_scale_factor() * geo_ref.scale_denominator as f64
                / 1000.,
        }
    }
}