From 4959b86e89db20463925786bcd256b4725e1fefe Mon Sep 17 00:00:00 2001
From: Dustin Carlino <dabreegster@gmail.com>
Date: Mon, 18 Dec 2023 12:04:26 +0900
Subject: [PATCH] Improve Mercator API

---
 backend/src/lib.rs      | 14 ++++----------
 backend/src/mercator.rs | 22 ++++++++++++++++++----
 backend/src/scrape.rs   |  7 +++----
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/backend/src/lib.rs b/backend/src/lib.rs
index dcaa627..c4fcce1 100644
--- a/backend/src/lib.rs
+++ b/backend/src/lib.rs
@@ -4,7 +4,7 @@ extern crate log;
 use std::fmt;
 use std::sync::Once;
 
-use geo::{LineString, MapCoordsInPlace, Point};
+use geo::{LineString, Point};
 use geojson::{Feature, GeoJson, Geometry};
 use wasm_bindgen::prelude::*;
 
@@ -91,18 +91,15 @@ impl MapModel {
 
         let mut nodes = Vec::new();
         for i in &self.intersections {
-            nodes.push(self.mercator.to_wgs84(i.point.into()));
+            nodes.push(self.mercator.to_wgs84(&i.point).into());
         }
 
         let mut edges = Vec::new();
         for r in &self.roads {
-            let mut linestring = r.linestring.clone();
-            linestring.map_coords_in_place(|c| self.mercator.to_wgs84(c));
-
             edges.push(Edge {
                 node1: NodeID(r.src_i.0 as u32),
                 node2: NodeID(r.dst_i.0 as u32),
-                geometry: linestring,
+                geometry: self.mercator.to_wgs84(&r.linestring),
                 // Isn't serialized, doesn't matter
                 length_meters: 0.0,
                 name: r.tags.get("name").cloned(),
@@ -128,10 +125,7 @@ impl MapModel {
 
 impl Road {
     fn to_gj(&self, mercator: &mercator::Mercator) -> Feature {
-        let mut linestring = self.linestring.clone();
-        linestring.map_coords_in_place(|c| mercator.to_wgs84(c));
-
-        let mut f = Feature::from(Geometry::from(&linestring));
+        let mut f = Feature::from(Geometry::from(&mercator.to_wgs84(&self.linestring)));
         f.set_property("id", self.id.0);
         f.set_property("way", self.way.to_string());
         f.set_property("node1", self.node1.to_string());
diff --git a/backend/src/mercator.rs b/backend/src/mercator.rs
index 2461e71..f19f7da 100644
--- a/backend/src/mercator.rs
+++ b/backend/src/mercator.rs
@@ -1,4 +1,4 @@
-use geo::{BoundingRect, Coord, HaversineLength, LineString, Rect};
+use geo::{BoundingRect, Coord, HaversineLength, LineString, MapCoords, MapCoordsInPlace, Rect};
 
 /// Projects WGS84 points onto a Euclidean plane, using a Mercator projection. The top-left is (0,
 /// 0) and grows to the right and down (screen-drawing order, not Cartesian), with units of meters.
@@ -31,7 +31,7 @@ impl Mercator {
         })
     }
 
-    pub fn to_mercator(&self, pt: Coord) -> Coord {
+    pub fn pt_to_mercator(&self, pt: Coord) -> Coord {
         let x = self.width * (pt.x - self.wgs84_bounds.min().x) / self.wgs84_bounds.width();
         // Invert y, so that the northernmost latitude is 0
         let y = self.height
@@ -39,12 +39,26 @@ impl Mercator {
         Coord { x, y }
     }
 
-    pub fn to_wgs84(&self, pt: Coord) -> Coord {
+    pub fn pt_to_wgs84(&self, pt: Coord) -> Coord {
         let x = self.wgs84_bounds.min().x + (pt.x / self.width * self.wgs84_bounds.width());
         let y = self.wgs84_bounds.min().y
             + (self.wgs84_bounds.height() * (self.height - pt.y) / self.height);
         Coord { x, y }
     }
 
-    // TODO Take anything that can do mapcoords
+    pub fn to_mercator<G: MapCoords<f64, f64, Output = G>>(&self, geom: &G) -> G {
+        geom.map_coords(|pt| self.pt_to_mercator(pt))
+    }
+
+    pub fn to_wgs84<G: MapCoords<f64, f64, Output = G>>(&self, geom: &G) -> G {
+        geom.map_coords(|pt| self.pt_to_wgs84(pt))
+    }
+
+    pub fn to_mercator_in_place<G: MapCoordsInPlace<f64>>(&self, geom: &mut G) {
+        geom.map_coords_in_place(|pt| self.pt_to_mercator(pt));
+    }
+
+    pub fn to_wgs84_in_place<G: MapCoordsInPlace<f64>>(&self, geom: &mut G) {
+        geom.map_coords_in_place(|pt| self.pt_to_wgs84(pt));
+    }
 }
diff --git a/backend/src/scrape.rs b/backend/src/scrape.rs
index 01d2255..ac5afcd 100644
--- a/backend/src/scrape.rs
+++ b/backend/src/scrape.rs
@@ -1,7 +1,7 @@
 use std::collections::HashMap;
 
 use anyhow::Result;
-use geo::{Coord, Geometry, GeometryCollection, LineString, MapCoordsInPlace, Point};
+use geo::{Coord, Geometry, GeometryCollection, LineString, Point};
 use osm_reader::{Element, NodeID, WayID};
 
 use crate::mercator::Mercator;
@@ -49,11 +49,10 @@ pub fn scrape_osm(input_bytes: &[u8]) -> Result<MapModel> {
         .into();
     let mercator = Mercator::from(collection).unwrap();
     for r in &mut roads {
-        r.linestring
-            .map_coords_in_place(|pt| mercator.to_mercator(pt));
+        mercator.to_mercator_in_place(&mut r.linestring);
     }
     for i in &mut intersections {
-        i.point.map_coords_in_place(|pt| mercator.to_mercator(pt));
+        mercator.to_mercator_in_place(&mut i.point);
     }
 
     Ok(MapModel {