Support custom pdf Metadata entries.

Author: anntzer

CHANGELOG.rst

@@ -5,6 +5,7 @@ next
 - Fixed support for macos backend on Matplotlib≥3.6.
 - Fixed compatibility with wheel≥0.41.
 - Support pdf MaxVersion up to 1.7 (if the underlying cairo supports it).
+- Support custom pdf metadata entries.
 - `set_options` can now be used as a context manager.
 
 v0.5 (2022-08-18)

src/_mplcairo.cpp

@@ -536,9 +536,13 @@ void GraphicsContextRenderer::_set_metadata(std::optional<py::dict> metadata)
           detail::cairo_pdf_surface_set_metadata(
             surface, detail::CAIRO_PDF_METADATA_MOD_DATE,
             it.second.attr("isoformat")().cast<std::string>().c_str());
+        } else if (detail::cairo_pdf_surface_set_custom_metadata) {
+          detail::cairo_pdf_surface_set_custom_metadata(
+            surface, key.c_str(), it.second.cast<std::string>().c_str());
         } else {
           py::module::import("warnings").attr("warn")(
-            "Unsupported PDF metadata entry: " + key);
+            "cairo_pdf_surface_set_custom_metadata requires cairo>=1.17.6; "
+            "unsupported PDF metadata entry: " + key);
         }
       }
       break;

src/_util.h

@@ -51,6 +51,8 @@ extern cairo_surface_t* (*cairo_pdf_surface_create_for_stream)(
   cairo_write_func_t, void*, double, double);
 extern void (*cairo_pdf_surface_restrict_to_version)(
   cairo_surface_t*, cairo_pdf_version_t);
+extern void (*cairo_pdf_surface_set_custom_metadata)(
+  cairo_surface_t*, char const*, char const*);
 extern void (*cairo_pdf_surface_set_metadata)(
   cairo_surface_t*, cairo_pdf_metadata_t, char const*);
 extern void (*cairo_pdf_surface_set_size)(cairo_surface_t*, double, double);
@@ -81,6 +83,7 @@ extern void (*cairo_svg_surface_restrict_to_version)(
   _(cairo_pdf_get_versions) \
   _(cairo_pdf_surface_create_for_stream) \
   _(cairo_pdf_surface_restrict_to_version) \
+  _(cairo_pdf_surface_set_custom_metadata) \
   _(cairo_pdf_surface_set_metadata) \
   _(cairo_pdf_surface_set_size) \
   _(cairo_ps_get_levels) \