extend OffsetArrays.centered for AxisArray/Axis (#57)

src/ImageAxes.jl

@@ -11,6 +11,7 @@ export AxisArray, Axis, axisnames, axisvalues, axisdim, atindex, atvalue, collap
 
 @reexport using ImageCore
 using ImageCore.MappedArrays
+using ImageCore.OffsetArrays
 
 
 export # types
@@ -440,4 +441,7 @@ function AxisArrays._summary(io, A::AxisArray{T,N}) where {T<:Union{Fractional,C
     println(io, ",$N,...} with axes:")
 end
 
+# glue codes
+include("offsetarrays.jl")
+
 end # module

src/offsetarrays.jl

@@ -0,0 +1,7 @@
+if isdefined(OffsetArrays, :centered)
+    # Requires OffsetArrays v1.9
+    # https://github.com/JuliaArrays/OffsetArrays.jl/pull/242
+    # Originally from ImageFiltering https://github.com/JuliaImages/ImageFiltering.jl/pull/214
+    OffsetArrays.centered(ax::Axis{name}) where name = Axis{name}(OffsetArrays.centered(ax.val))
+    OffsetArrays.centered(a::AxisArray) = AxisArray(OffsetArrays.centered(a.data), OffsetArrays.centered.(AxisArrays.axes(a)))
+end

test/offsetarrays.jl

@@ -0,0 +1,21 @@
+@testset "centered" begin
+    if isdefined(OffsetArrays, :centered) # OffsetArrays v1.9
+        check_range(r, f, l) = (@test first(r) == f; @test last(r) == l)
+        check_range_axes(r, f, l) = check_range(Base.axes(r)[1], f, l)
+
+        check_range(Base.axes(OffsetArrays.centered(1:3))[1], -1, 1)
+        a = AxisArray(rand(3, 3), Axis{:y}(0.1:0.1:0.3), Axis{:x}(1:3))
+
+        ca = OffsetArrays.centered(a)
+        axs = Base.axes(ca)
+        check_range(axs[1], -1, 1)
+        check_range(axs[2], -1, 1)
+        @test ca[OffsetArrays.center(ca)...] == a[OffsetArrays.center(a)...]
+
+        axs = AxisArrays.axes(ca)
+        check_range(axs[1].val, 0.1, 0.3)
+        check_range(axs[2].val, 1, 3)
+        check_range_axes(axs[1].val, -1, 1)
+        check_range_axes(axs[1].val, -1, 1)
+    end
+end

test/runtests.jl

@@ -1,5 +1,6 @@
 using Test, ImageCore
 using ImageCore.MappedArrays
+using ImageCore.OffsetArrays
 import AxisArrays
 
 ambs = detect_ambiguities(ImageCore,AxisArrays,Base,Core)
@@ -232,4 +233,8 @@ end
     @test ImageAxes.filter_streamed((1,2), S) == (2,)
 end
 
+@testset "OffsetArrays" begin
+    include("offsetarrays.jl")
+end
+
 nothing