Support reading from an IOBuffer (#180)

Fixes JuliaIO/FileIO.jl#174

Author: Arkoniak

src/libmagickwand.jl

@@ -287,6 +287,8 @@ function readimage(wand::MagickWand, stream::Vector{UInt8})
     nothing
 end
 
+readimage(wand::MagickWand, stream::IOBuffer) = readimage(wand, stream.data)
+
 function writeimage(wand::MagickWand, filename::AbstractString)
     status = ccall((:MagickWriteImages, libwand), Cint, (Ptr{Cvoid}, Ptr{UInt8}, Cint), wand, filename, true)
     status == 0 && error(wand)

test/constructed_images.jl

@@ -229,6 +229,16 @@ mutable struct TestType end
         @test size(img) == (2,2)
     end
 
+    Sys.isunix() && @testset "Reading from an IOBuffer (issue https://github.com/JuliaIO/FileIO.jl/issues/174)" begin
+        fn = joinpath(workdir, "2by2.png")
+        io = open(fn)
+        arr = read(io)
+        close(io)
+        iobuffer = IOBuffer(arr)
+        img = ImageMagick.load(iobuffer)
+        @test size(img) == (2,2)
+    end
+
     @testset "show(MIME)" begin
         Ar = rand(UInt8, 3, 2, 2)
         Ar[1] = typemax(eltype(Ar))