add transform method for coordinate transformations (#35)

* add transform method for coordinate transformations

* clean up tests

* actually run the test

* dont flip!

* no flip

* fix the doc

src/GeometryOps.jl

@@ -7,6 +7,7 @@ using GeometryBasics
 import Proj
 using LinearAlgebra
 import ExactPredicates
+import Proj.CoordinateTransformations.StaticArrays
 
 using GeoInterface.Extents: Extents
 
@@ -38,5 +39,6 @@ include("transformations/flip.jl")
 include("transformations/simplify.jl")
 include("transformations/reproject.jl")
 include("transformations/tuples.jl")
+include("transformations/transform.jl")
 
 end

src/transformations/transform.jl

@@ -0,0 +1,56 @@
+
+"""
+    transform(f, obj)
+
+Apply a function `f` to all the points in `obj`.
+
+Points will be passed to `f` as an `SVector` to allow
+using CoordinateTransformations.jl and Rotations.jl 
+without hassle.
+
+`SVector` is also a valid GeoInterface.jl point, so will
+work in all GeoInterface.jl methods.
+
+## Example
+
+```julia
+julia> import GeoInterface as GI
+
+julia> import GeometryOps as GO
+
+julia> geom = GI.Polygon([GI.LinearRing([(1, 2), (3, 4), (5, 6), (1, 2)]), GI.LinearRing([(3, 4), (5, 6), (6, 7), (3, 4)])]);
+
+julia> f = CoordinateTransformations.Translation(3.5, 1.5)
+Translation(3.5, 1.5)
+
+julia> GO.transform(f, geom)
+GeoInterface.Wrappers.Polygon{false, false, Vector{GeoInterface.Wrappers.LinearRing{false, false, Vector{StaticArraysCore.SVector{2, Float64}}, Nothing, Nothing}}, Nothing, Nothing}(GeoInterface.Wrappers.Linea
+rRing{false, false, Vector{StaticArraysCore.SVector{2, Float64}}, Nothing, Nothing}[GeoInterface.Wrappers.LinearRing{false, false, Vector{StaticArraysCore.SVector{2, Float64}}, Nothing, Nothing}(StaticArraysCo
+re.SVector{2, Float64}[[4.5, 3.5], [6.5, 5.5], [8.5, 7.5], [4.5, 3.5]], nothing, nothing), GeoInterface.Wrappers.LinearRing{false, false, Vector{StaticArraysCore.SVector{2, Float64}}, Nothing, Nothing}(StaticA
+rraysCore.SVector{2, Float64}[[6.5, 5.5], [8.5, 7.5], [9.5, 8.5], [6.5, 5.5]], nothing, nothing)], nothing, nothing)
+```
+
+With Rotations.jl you need to actuall multiply the Rotation
+by the `SVector` point, which is easy using an anonymous function.
+
+```julia
+julia> using Rotations
+
+julia> GO.transform(p -> one(RotMatrix{2}) * p, geom)
+GeoInterface.Wrappers.Polygon{false, false, Vector{GeoInterface.Wrappers.LinearRing{false, false, Vector{StaticArraysCore.SVector{2, Int64}}, Nothing, Nothing}}, Nothing, Nothing}(GeoInterface.Wrappers.LinearR
+ing{false, false, Vector{StaticArraysCore.SVector{2, Int64}}, Nothing, Nothing}[GeoInterface.Wrappers.LinearRing{false, false, Vector{StaticArraysCore.SVector{2, Int64}}, Nothing, Nothing}(StaticArraysCore.SVe
+ctor{2, Int64}[[2, 1], [4, 3], [6, 5], [2, 1]], nothing, nothing), GeoInterface.Wrappers.LinearRing{false, false, Vector{StaticArraysCore.SVector{2, Int64}}, Nothing, Nothing}(StaticArraysCore.SVector{2, Int64
+}[[4, 3], [6, 5], [7, 6], [4, 3]], nothing, nothing)], nothing, nothing)
+```
+"""
+function transform(f, geom; kw...) 
+    if _is3d(geom)
+        return apply(PointTrait, geom; kw...) do p
+            f(StaticArrays.SVector{3}((GI.x(p), GI.y(p), GI.z(p))))
+        end
+    else
+        return apply(PointTrait, geom; kw...) do p
+            f(StaticArrays.SVector{2}((GI.x(p), GI.y(p))))
+        end
+    end
+end

test/runtests.jl

@@ -28,4 +28,5 @@ const GO = GeometryOps
     @testset "Reproject" begin include("transformations/reproject.jl") end
     @testset "Flip" begin include("transformations/flip.jl") end
     @testset "Simplify" begin include("transformations/simplify.jl") end
+    @testset "Transform" begin include("transformations/transform.jl") end
 end

test/transformations/transform.jl

@@ -0,0 +1,14 @@
+using Test
+
+import GeoInterface as GI
+import GeometryOps as GO
+using GeometryOps.Proj.CoordinateTransformations
+
+@testset "transform" begin
+    geom = GI.Polygon([GI.LinearRing([(1, 2), (3, 4), (5, 6), (1, 2)]), 
+                       GI.LinearRing([(3, 4), (5, 6), (6, 7), (3, 4)])])
+    translated = GI.Polygon([GI.LinearRing([[4.5, 3.5], [6.5, 5.5], [8.5, 7.5], [4.5, 3.5]]), 
+                             GI.LinearRing([[6.5, 5.5], [8.5, 7.5], [9.5, 8.5], [6.5, 5.5]])])
+    f = CoordinateTransformations.Translation(3.5, 1.5)
+    @test GO.transform(f, geom) == translated
+end