fix conditional dependencies

docs/src/index.md

@@ -11,8 +11,8 @@ to simplify the creation of complex graphics and serves as the basis of the
 
 ## Package features
 
-- Renders publication quality graphics to SVG, PNG, Postscript, PDF and PGF
-- Intuitive and consistent interface
+- Renders publication quality graphics to PGF and interactive SVG using pure Julia; relies on [cairo](https://cairographics.org/) for PNG, Postscript, PDF and PGF
+- Can handle most text formatting natively; calls out to [pango](https://www.pango.org/) for more advanced notation and [fontconfig](https://www.fontconfig.org/) for a wider choice of fonts
 - Works with [Jupyter](http://jupyter.org/) notebooks via [IJulia](https://github.com/JuliaLang/IJulia.jl) out of the box
 
 ## Installation

docs/src/tutorial.md

@@ -58,6 +58,15 @@ composition2 |> SVG("celery.svg")
 composition3 |> SVG("rutabaga.svg")  # etc...
 ```
 
+To render to PDF, PNG, and postscript, first install, if necessary,
+and load Cairo before instantiating a backend:
+
+```
+Pkg.add("Cairo")
+import Cairo
+composition |> PDF("tomato.pdf")
+```
+
 
 ## The compose function accepts S-expressions
 

src/Compose.jl

@@ -123,9 +123,9 @@ default_fill_color = colorant"black"
 # Use cairo for the PNG, PS, PDF if it's installed.
 macro missing_cairo_error(backend)
     msg1 = """
-    The Cairo and Fontconfig packages are necessary for the $(backend) backend.
-    Add them with the package manager if necessary, then run:
-      import Cairo, Fontconfig
+    The Cairo package is necessary for the $(backend) backend.
+    Add it with the package manager if necessary, then run:
+      import Cairo
     before invoking $(backend).
     """
     string(msg1)
@@ -139,22 +139,25 @@ PDF(args...; kwargs...) = error(@missing_cairo_error "PDF")
 include("svg.jl")
 include("pgf_backend.jl")
 
-# If available, pango and fontconfig are used to compute text extents and match
+# If imported, pango and/or fontconfig are used to compute text extents and match
 # fonts. Otherwise a simplistic pure-julia fallback is used.
 
 include("fontfallback.jl")
 
 function link_fontconfig()
     @info "Loading Fontconfig backend into Compose.jl"
-    pango_cairo_ctx = C_NULL
+    include("fontconfig.jl")
+end
+
+function link_pango()
+    @info "Loading Pango backend into Compose.jl"
+    global pango_cairo_ctx = C_NULL
     include("pango.jl")
 
-    ccall((:g_type_init, libgobject), Cvoid, ())
-    pango_cairo_fm  = ccall((:pango_cairo_font_map_new, libpangocairo),
-                             Ptr{Cvoid}, ())
-    pango_cairo_ctx = ccall((:pango_font_map_create_context, libpango),
-                             Ptr{Cvoid}, (Ptr{Cvoid},), pango_cairo_fm)
-    pangolayout = PangoLayout()
+    #Pango.g_type_init()
+    pango_cairo_fm  = Pango.pango_cairo_font_map_new()
+    pango_cairo_ctx = Pango.pango_font_map_create_context(pango_cairo_fm)
+    pangolayout = Base.invokelatest(PangoLayout)
 end
 
 function link_cairo()
@@ -166,6 +169,7 @@ end
 function __init__()
     @require Cairo="159f3aea-2a34-519c-b102-8c37f9878175" link_cairo()
     @require Fontconfig="186bb1d3-e1f7-5a2c-a377-96d770f13627" link_fontconfig()
+    @require Pango="4071c42e-c4ca-11e8-2c78-e3c1daf35efa" link_pango()
 end
 
 show(io::IO, m::MIME"text/html", ctx::Context) =

src/abandoned.jl

@@ -812,5 +812,11 @@ function draw(img::SVG, prim::PathPrimitive, idx::Int)
     print(img.out, "/>\n")
 end
 
-
+function current_point(img::Image)
+    x = Array{Float64}(undef, 1)
+    y = Array{Float64}(undef, 1)
+    ccall((:cairo_get_current_point, Cairo._jl_libcairo), Cvoid,
+          (Ptr{Cvoid}, Ptr{Float64}, Ptr{Float64}), img.ctx.ptr, x, y)
+    return ((x[1] / img.ppmm)*mm, (x[2] / img.ppmm)*mm)
+end
 

src/cairo_backends.jl

@@ -457,14 +457,6 @@ apply_property(img::Image, property::SVGAttributePrimitive) = nothing
 # Cairo Wrappers
 # --------------
 
-function current_point(img::Image)
-    x = Array{Float64}(undef, 1)
-    y = Array{Float64}(undef, 1)
-    ccall((:cairo_get_current_point, Cairo._jl_libcairo), Cvoid,
-          (Ptr{Cvoid}, Ptr{Float64}, Ptr{Float64}), img.ctx.ptr, x, y)
-    return ((x[1] / img.ppmm)*mm, (x[2] / img.ppmm)*mm)
-end
-
 move_to(img::Image, point::AbsoluteVec2) = Cairo.move_to(img.ctx,
         absolute_native_units(img, point[1].value),
         absolute_native_units(img, point[2].value))

src/fontconfig.jl

@@ -0,0 +1,30 @@
+# Use the freetype/fontconfig backend to find the best match to a font
+# description.
+#
+# Args:
+#   desc: A string giving the font description. This can
+#         also provide a comma-separated list of families. E.g.,
+#         "Helvetica, Arial 10"
+#
+# Returns:
+#   A pointer to a PangoFontDescription with the closest match.
+#
+let available_font_families = Set{AbstractString}()
+    for font_pattern in Fontconfig.list()
+        push!(available_font_families, lowercase(Fontconfig.format(font_pattern, "%{family}")))
+    end
+
+    meta_families = Set(["serif", "sans", "sans-serif", "monospace", "cursive", "fantasy"])
+
+    global match_font
+    function match_font(families::AbstractString, size::Float64)
+        matched_family = "sans-serif"
+        for family in [lowercase(strip(family, [' ', '"', '\''])) for family in split(families, ',')]
+            if family in available_font_families || family in meta_families
+                matched_family = family
+                break
+            end
+        end
+        Fontconfig.format(match(Fontconfig.Pattern(family=family)), "%{family}")
+    end
+end

src/pango.jl

@@ -1,9 +1,5 @@
 # Estimation of text extents using pango.
 
-const libpangocairo = Cairo._jl_libpangocairo
-const libpango = Cairo._jl_libpango
-const libgobject = Cairo._jl_libgobject
-
 # Cairo text backend
 const CAIRO_FONT_TYPE_TOY = 0
 const CAIRO_FONT_TYPE_FT = 1
@@ -16,58 +12,26 @@ const PANGO_SCALE = 1024.0
 
 pango_fmt_float(x::Float64) = @sprintf("%0.4f", x)
 
-# Use the freetype/fontconfig backend to find the best match to a font
-# description.
-#
-# Args:
-#   desc: A string giving the font description. This can
-#         also provide a comma-separated list of families. E.g.,
-#         "Helvetica, Arial 10"
-#
-# Returns:
-#   A pointer to a PangoFontDescription with the closest match.
-#
-let available_font_families = Set{AbstractString}()
-    for font_pattern in Fontconfig.list()
-        push!(available_font_families, lowercase(Fontconfig.format(font_pattern, "%{family}")))
-    end
-
-    meta_families = Set(["serif", "sans", "sans-serif", "monospace", "cursive", "fantasy"])
-
-    global match_font
-    function match_font(families::AbstractString, size::Float64)
-        matched_family = "sans-serif"
-        for family in [lowercase(strip(family, [' ', '"', '\''])) for family in split(families, ',')]
-            if family in available_font_families || family in meta_families
-                matched_family = family
-                break
-            end
-        end
-        family = Fontconfig.format(match(Fontconfig.Pattern(family=family)), "%{family}")
-        desc = @sprintf("%s %fpx", family, size)
-        fd = ccall((:pango_font_description_from_string, libpango), Ptr{Cvoid}, (Ptr{UInt8},), desc)
-        return fd
-    end
-end
-
 # Thin wrapper for a pango_layout object.
 mutable struct PangoLayout
     layout::Ptr{Cvoid}
 end
 
 function PangoLayout()
-    layout = ccall((:pango_layout_new, libpango),
-                   Ptr{Cvoid}, (Ptr{Cvoid},), pango_cairo_ctx)
+    layout = Pango.pango_layout_new(pango_cairo_ctx)
     # TODO: finalizer?
 
     PangoLayout(layout)
 end
 
 # Set the layout's font.
 function pango_set_font(pangolayout::PangoLayout, family::AbstractString, pts::Number)
-    fd = match_font(family, pts)
-    ccall((:pango_layout_set_font_description, libpango),
-          Cvoid, (Ptr{Cvoid}, Ptr{Cvoid}), pangolayout.layout, fd)
+    family = match_font(family, pts)
+
+    desc = @sprintf("%s %fpx", family, size)
+    fd = Pango.pango_font_description_from_string(desc)
+
+    Pango.pango_layout_set_font_description(pangolayout.layout, fd)
 end
 
 # Find the width and height of a string.
@@ -81,14 +45,10 @@ end
 #
 function pango_text_extents(pangolayout::PangoLayout, text::AbstractString)
     textarray = convert(Vector{UInt8}, convert(String, text))
-    ccall((:pango_layout_set_markup, libpango),
-          Cvoid, (Ptr{Cvoid}, Ptr{UInt8}, Int32),
-          pangolayout.layout, textarray, length(textarray))
+    Pango.pango_layout_set_markup(pangolayout.layout, textarray, length(textarray))
 
     extents = Array{Int32}(undef, 4)
-    ccall((:pango_layout_get_extents, libpango),
-          Cvoid, (Ptr{Cvoid}, Ptr{Int32}, Ptr{Int32}),
-          pangolayout.layout, extents, C_NULL)
+    Pango.pango_layout_get_extents(pangolayout.layout, extents, C_NULL)
 
     width, height = (extents[3] / PANGO_SCALE)pt, (extents[4] / PANGO_SCALE)pt
 end
@@ -106,11 +66,11 @@ end
 #   A (width, height) tuple in absolute units.
 #
 function max_text_extents(font_family::AbstractString, pts::Float64, texts::AbstractString...)
-    pango_set_font(pangolayout::PangoLayout, font_family, pts)
+    Pango.pango_set_font(pangolayout::PangoLayout, font_family, pts)
     max_width  = 0mm
     max_height = 0mm
     for text in texts
-        (width, height) = pango_text_extents(pangolayout::PangoLayout, text)
+        (width, height) = Pango.pango_text_extents(pangolayout::PangoLayout, text)
         max_width  = max_width.value  < width.value  ? width  : max_width
         max_height = max_height.value < height.value ? height : max_height
     end
@@ -126,8 +86,8 @@ end
 
 # Return an array with the extents of each element
 function text_extents(font_family::AbstractString, pts::Float64, texts::AbstractString...)
-    pango_set_font(pangolayout::PangoLayout, font_family, pts)
-    return [pango_text_extents(pangolayout::PangoLayout, text) for text in texts]
+    Pango.pango_set_font(pangolayout::PangoLayout, font_family, pts)
+    return [Pango.pango_text_extents(pangolayout::PangoLayout, text) for text in texts]
 end
 
 text_extents(font_family::AbstractString, size::Measure, texts::AbstractString...) =
@@ -272,23 +232,17 @@ unpack_pango_float(ptr::Ptr{Cvoid}) = unsafe_wrap(Array, convert(Ptr{Float64}, p
 #   should be applied starting at that position.
 #
 function unpack_pango_attr_list(ptr::Ptr{Cvoid})
-    attr_it = ccall((:pango_attr_list_get_iterator, libpango),
-                    Ptr{Cvoid}, (Ptr{Cvoid},), ptr)
+    attr_it = Pango.pango_attr_list_get_iterator(ptr)
 
     # Alias some ugly C calls.
-    attr_it_next = () -> ccall((:pango_attr_iterator_next, libpango),
-                               Int32, (Ptr{Cvoid},), attr_it)
+    attr_it_next = () -> Pango.pango_attr_iterator_next(attr_it)
 
-    attr_it_get = attr_name -> ccall((:pango_attr_iterator_get, libpango),
-                                     Ptr{Cvoid}, (Ptr{Cvoid}, Int32),
-                                     attr_it, eval(attr_name))
+    attr_it_get = attr_name -> Pango.pango_attr_iterator_get(attr_it, eval(attr_name))
 
     attr_it_range = () -> begin
         start_idx = Array{Int32}(undef, 1)
         end_idx = Array{Int32}(undef, 1)
-        ccall((:pango_attr_iterator_range, libpango),
-              Cvoid, (Ptr{Cvoid}, Ptr{Int32}, Ptr{Int32}),
-              attr_it, start_idx, end_idx)
+        Pango.pango_attr_iterator_range(attr_it, start_idx, end_idx)
         (start_idx[1], end_idx[1])
     end
 
@@ -312,28 +266,23 @@ function unpack_pango_attr_list(ptr::Ptr{Cvoid})
         push!(attrs, (start_idx, attr))
     end
 
-    ccall((:pango_attr_iterator_destroy, libpango),
-          Cvoid, (Ptr{Cvoid},), attr_it)
+    Pango.pango_attr_iterator_destroy(attr_it)
 
   attrs
 end
 
 
 function pango_to_svg(text::AbstractString)
-    c_stripped_text = Ref{Ptr{UInt8}}()
+    c_stripped_text = Ref{Cstring}()
     c_attr_list = Ref{Ptr{Cvoid}}()
 
-    ret = ccall((:pango_parse_markup, libpango),
-                Int32, (Cstring, Int32, UInt32, Ptr{Ptr{Cvoid}},
-                        Ptr{Ptr{UInt8}}, Ptr{UInt32}, Ptr{Cvoid}),
-                text, -1, 0, c_attr_list, c_stripped_text,
-                C_NULL, C_NULL)
+    ret = Pango.pango_parse_markup(text, -1, 0, c_attr_list, c_stripped_text, C_NULL, C_NULL)
 
     ret == 0 && error("Could not parse pango markup.")
 
     # TODO: do c_stripped_text and c_attr_list need to be freed?
 
-    text = unsafe_wrap(Array, c_stripped_text[])
+    text = unsafe_string(c_stripped_text[])
 
     last_idx = 1
     open_tag = false
@@ -363,16 +312,16 @@ function pango_to_svg(text::AbstractString)
 
             if !(attr.rise === nothing)
                 bs = -((attr.rise / PANGO_SCALE)pt).value
-                @printf(io, " dy=\"%s\"", pango_fmt_float(bs))
+                @printf(io, " dy=\"%s\"", Pango.pango_fmt_float(bs))
                 baseline_shift = bs
             elseif baseline_shift != 0.0
-                @printf(io, " dy=\"%s\"", pango_fmt_float(-baseline_shift))
+                @printf(io, " dy=\"%s\"", Pango.pango_fmt_float(-baseline_shift))
                 baseline_shift = 0.0
             end
 
             if !(attr.scale === nothing)
                 @printf(io, " font-size=\"%s%%\"",
-                        pango_fmt_float(100.0 * attr.scale))
+                        Pango.pango_fmt_float(100.0 * attr.scale))
                 baseline_shift *= attr.scale
             end