CairoMakie: Allow restricting PDF version

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## [Unreleased]
+- CairoMakie: Add argument `pdf_version` to restrict the PDF version when saving a figure as a PDF [#3845](https://github.com/MakieOrg/Makie.jl/pull/3845).
 
 ## [0.21.0] - 2024-05-21
 

CairoMakie/src/cairo-extension.jl

@@ -74,3 +74,23 @@ function get_render_type(surface::Cairo.CairoSurface)
  typ == Cairo.CAIRO_SURFACE_TYPE_IMAGE && return IMAGE
  return IMAGE # By default assume that the render type is IMAGE
 end
+
+const CAIRO_PDF_VERSION_1_4 = 0
+const CAIRO_PDF_VERSION_1_5 = 1
+const CAIRO_PDF_VERSION_1_6 = 2
+const CAIRO_PDF_VERSION_1_7 = 3
+
+function restrict_pdf_version!(surface::Cairo.CairoSurface, pdf_version::String)
+ @assert surface.ptr != C_NULL
+ versions = Dict("1.4" => CAIRO_PDF_VERSION_1_4,
+ "1.5" => CAIRO_PDF_VERSION_1_5,
+ "1.6" => CAIRO_PDF_VERSION_1_6,
+ "1.7" => CAIRO_PDF_VERSION_1_7)
+ if !haskey(versions, pdf_version)
+ versionlist = join(sort(collect(keys(versions))), ", ")
+ throw(ArgumentError("PDF version must be one of $versionlist (received '$pdf_version')"))
+ end
+ cairo_pdf_version = versions[pdf_version]
+ ccall((:cairo_pdf_surface_restrict_to_version, Cairo.libcairo), Nothing,
+ (Ptr{UInt8},Int32), surface.ptr, cairo_pdf_version)
+end

CairoMakie/src/screen.jl

@@ -85,13 +85,15 @@ to_cairo_antialias(aa::Int) = aa
 * `pt_per_unit = 0.75`
 * `antialias::Union{Symbol, Int} = :best`: antialias modus Cairo uses to draw. Applicable options: `[:best => Cairo.ANTIALIAS_BEST, :good => Cairo.ANTIALIAS_GOOD, :subpixel => Cairo.ANTIALIAS_SUBPIXEL, :none => Cairo.ANTIALIAS_NONE]`.
 * `visible::Bool`: if true, a browser/image viewer will open to display rendered output.
+* `pdf_version::String = ""`: the version of output PDFs. Applicable options are `"1.4"`, `"1.5"`, `"1.6"`, `"1.7"`, or the default, `""`, which leaves the PDF version unrestricted.
 """
 struct ScreenConfig
  px_per_unit::Float64
  pt_per_unit::Float64
  antialias::Symbol
  visible::Bool
  start_renderloop::Bool # Only used to satisfy the interface for record using `Screen(...; start_renderloop=false)` for GLMakie
+ pdf_version::String
 end
 
 function device_scaling_factor(rendertype, sc::ScreenConfig)
@@ -213,6 +215,11 @@ function apply_config!(screen::Screen, config::ScreenConfig)
  aa = to_cairo_antialias(config.antialias)
  Cairo.set_antialias(context, aa)
  set_miter_limit(context, 2.0)
+
+ if get_render_type(surface) === PDF && !isempty(config.pdf_version)
+ restrict_pdf_version!(surface, config.pdf_version)
+ end
+
  screen.antialias = aa
  screen.device_scaling_factor = dsf
  screen.config = config
@@ -285,6 +292,11 @@ function Screen(scene::Scene, config::ScreenConfig, surface::Cairo.CairoSurface)
  aa = to_cairo_antialias(config.antialias)
  Cairo.set_antialias(ctx, aa)
  set_miter_limit(ctx, 2.0)
+
+ if get_render_type(surface) === PDF && !isempty(config.pdf_version)
+ restrict_pdf_version!(surface, config.pdf_version)
+ end
+
  return Screen{get_render_type(surface)}(scene, surface, ctx, dsf, aa, config.visible, config)
 end
 

CairoMakie/test/runtests.jl

@@ -198,3 +198,29 @@ functions = [:volume, :volume!, :uv_mesh]
  missing_images, scores = ReferenceTests.record_comparison(recording_dir)
  ReferenceTests.test_comparison(scores; threshold = 0.05)
 end
+
+@testset "restrict PDF version" begin
+ magic_number(filename) = open(filename) do f
+ return String(read(f, sizeof("%PDF-X.Y")))
+ end
+
+ filename = "$(tempname()).pdf"
+
+ try
+ save(filename, Figure(), pdf_version="")
+ @test startswith(magic_number(filename), "%PDF-")
+ finally
+ rm(filename)
+ end
+
+ for version in ["1.4", "1.5", "1.6", "1.7"]
+ try
+ save(filename, Figure(), pdf_version=version)
+ @test magic_number(filename) == "%PDF-$version"
+ finally
+ rm(filename)
+ end
+ end
+
+ @test_throws ArgumentError save(filename, Figure(), pdf_version="foo")
+end

docs/explanations/backends/cairomakie.md

@@ -62,3 +62,13 @@ v = rand(10,2)
 scatter(v[:,1], v[:,2], rasterize = 10, markersize = 30.0)
 ```
 \end{examplefigure}
+
+#### PDF version
+
+The version of output PDFs can be restricted via the `pdf_version` argument of the screen config. Conveniently, it can be also passed as an argument of the `save` function:
+```julia
+using CairoMakie
+fig = Figure()
+# ...
+save("figure.pdf", fig, pdf_version="1.4")
+```

src/theming.jl

@@ -89,7 +89,8 @@ const MAKIE_DEFAULT_THEME = Attributes(
  pt_per_unit = 0.75,
  antialias = :best,
  visible = true,
- start_renderloop = false
+ start_renderloop = false,
+ pdf_version = ""
  ),
 
  GLMakie = Attributes(