plot_pdf_into_makie_figure.jl

using CairoMakie
using Cairo
using Poppler_jll

@recipe(PDF) do scene
    Attributes(
        bbox = BBox(0, 100, 0, 100)
    )
end

Makie.plot!(p::PDF) = p

const poppler = Poppler_jll.libpoppler_glib

mutable struct GError
    domain::Cint
    code::Cint
    message::Cstring
end

const _PopplerDocument = Cvoid
const PopplerDocument = _PopplerDocument
const PopplerPage = Cvoid

function poppler_document_new_from_file(uri, password, error)
    ccall((:poppler_document_new_from_file, poppler), Ptr{PopplerDocument}, (Cstring, Cstring, Ptr{Ptr{GError}}), uri, password, error)
end

function poppler_document_get_n_pages(doc)
    ccall((:poppler_document_get_n_pages, poppler), Cint, (Ptr{PopplerDocument},), doc)
end

function poppler_document_get_page(doc, i)
    ccall((:poppler_document_get_page, poppler), Ptr{PopplerPage}, (Ptr{PopplerDocument}, Cint), doc, i)
end

function poppler_page_render_for_printing(page, cairocontext)
    ccall((:poppler_page_render_for_printing, poppler), Ptr{PopplerPage}, (Ptr{PopplerPage}, Ptr{Nothing}), page, cairocontext)
end

function poppler_page_get_size(page)
    w = Ref{Cdouble}()
    h = Ref{Cdouble}()
    ccall((:poppler_page_get_size, poppler), Cvoid, (Ptr{PopplerPage}, Ptr{Cdouble}, Ptr{Cdouble}), page, w, h)
    return w[], h[]
end
    

function CairoMakie.draw_atomic(s::Makie.Scene, sc::CairoMakie.Screen, x::PDF)
    ctx = sc.context
    r = Ref{Ptr{GError}}(C_NULL)
    uri = "file://" * abspath(x.path[])
    doc = poppler_document_new_from_file(uri, C_NULL, r)
    if (doc == C_NULL)
        m = unsafe_load(r[]).message
        print("poppler fail:", unsafe_string(m))
        return
    end
    sc.context |> typeof
    npages = poppler_document_get_n_pages(doc)
    npages != 1 && error("Can currently only handle single-page pdfs, got $npages pages")
    page = poppler_document_get_page(doc, 0)
    w, h = poppler_page_get_size(page)
    Cairo.translate(sc.context, x.bbox[].origin...)
    ws = x.bbox[].widths
    Cairo.scale(sc.context, (ws ./ (w, h))...)
    poppler_page_render_for_printing(page, ctx.ptr)
    return 
end


##

f = lines(cumsum(randn(100)), color = :red; figure = (resolution = (400, 300)))
CairoMakie.save("f1.pdf", f)
f = lines(cumsum(randn(100)), color = :blue; figure = (resolution = (400, 300)))
CairoMakie.save("f2.pdf", f)

##

f = Figure(resolution = (600, 800))
pdf!(f.scene, path = "f1.pdf", bbox = (BBox(0, 600, 400, 800)))
pdf!(f.scene, path = "f2.pdf", bbox = (BBox(0, 600, 0, 400)))
CairoMakie.save("f1_f2.pdf")