try fixing CI failures

Author: simeonschaub

Project.toml

@@ -4,12 +4,14 @@ version = "1.2.2"
 
 [deps]
 FileIO = "5789e2e9-d7fb-5bc7-8068-2c6fae9b9549"
+Ghostscript_jll = "61579ee1-b43e-5ca0-a5da-69d92c66a64b"
 ImageCore = "a09fc81d-aa75-5fe9-8630-4744c3626534"
 ImageMagick_jll = "c73af94c-d91f-53ed-93a7-00f77d67a9d7"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
 
 [compat]
 FileIO = "1"
+Ghostscript_jll = "= 9.55.0"
 ImageCore = "0.8.1, 0.9"
 ImageMagick_jll = "= 6.9.10"
 julia = "1.3"

src/ImageMagick.jl

@@ -5,6 +5,7 @@ using InteractiveUtils: subtypes
 using ImageCore
 using ImageMagick_jll
 using Base: convert
+using Ghostscript_jll
 
 Color1{T}           = Color{T,1}
 Color2{T,C<:Color1} = TransparentColor{C,T,2}

src/libmagickwand.jl

@@ -269,25 +269,31 @@ function pingimage(wand::MagickWand, filename::AbstractString)
     nothing
 end
 
-function readimage(wand::MagickWand, filename::AbstractString)
+function readimage(wand::MagickWand, from)
+    withenv("PATH" => "$(Ghostscript_jll.PATH[]):$(ENV["PATH"])") do
+        _readimage(wand, from)
+    end
+end
+
+function _readimage(wand::MagickWand, filename::AbstractString)
     status = ccall((:MagickReadImage, libwand), Cint, (Ptr{Cvoid}, Ptr{UInt8}), wand, filename)
     status == 0 && error(wand)
     nothing
 end
 
-function readimage(wand::MagickWand, stream::IO)
+function _readimage(wand::MagickWand, stream::IO)
     status = ccall((:MagickReadImageFile, libwand), Cint, (Ptr{Cvoid}, Ptr{Cvoid}), wand, Libc.FILE(stream).ptr)
     status == 0 && error(wand)
     nothing
 end
 
-function readimage(wand::MagickWand, stream::Vector{UInt8})
+function _readimage(wand::MagickWand, stream::Vector{UInt8})
     status = ccall((:MagickReadImageBlob, libwand), Cint, (Ptr{Cvoid}, Ptr{Cvoid}, Cint), wand, stream, length(stream)*sizeof(eltype(stream)))
     status == 0 && error(wand)
     nothing
 end
 
-readimage(wand::MagickWand, stream::IOBuffer) = readimage(wand, stream.data)
+_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)