Restrict PDF output to 1.7

README.md

@@ -17,7 +17,9 @@ For debugging. Similar to [rasterview](https://github.com/michaelrsweet/rastervi
 ## pdf2printable
 Takes a PDF document and makes it suitable for printing, by:
 - rotate and scale to fit as needed to a desired page size
-- convert to PDF 1.5, Postscript 2 or PWG/URF raster
+- convert to PDF 1.7¹, Postscript level 2 or PWG/URF raster
+
+1. PDF 1.5 if using Cairo < 1.18.
 
 ## baselinify
 Takes a JPEG and losslessly repacks it to the baseline ecoding profile, keeping only JFIF and Exif headers.

lib/libfuncs

@@ -11,6 +11,7 @@ FUNC(cairo, cairo_surface_t*, cairo_ps_surface_create_for_stream, cairo_write_fu
 FUNC(cairo, void, cairo_ps_surface_restrict_to_level, cairo_surface_t*, cairo_ps_level_t);
 FUNC(cairo, cairo_surface_t*, cairo_image_surface_create, cairo_format_t, int, int);
 FUNC(cairo, cairo_surface_t*, cairo_pdf_surface_create_for_stream, cairo_write_func_t, void*, double, double);
+FUNC(cairo, void, cairo_pdf_surface_restrict_to_version, cairo_surface_t*, cairo_pdf_version_t);
 FUNC(cairo, void, cairo_pdf_surface_set_metadata, cairo_surface_t*, cairo_pdf_metadata_t, const char*);
 FUNC(cairo, void, cairo_translate, cairo_t*, double, double);
 FUNC(cairo, void, cairo_scale, cairo_t*, double, double);

lib/pdf2printable.cpp

@@ -119,6 +119,12 @@ Error pdf_to_printable(std::string inFile, WriteFun writeFun, const PrintParamet
     surface = cairo_pdf_surface_create_for_stream(bytestream_writer, &outBts,
                                                   params.getPaperSizeWInPoints(),
                                                   params.getPaperSizeHInPoints());
+    #if CAIRO_VERSION < CAIRO_VERSION_ENCODE(1, 18, 0)
+    // Cairo is robust against setting "too new" versions - pretend we know about 1.7 even if we don't
+    #define CAIRO_PDF_VERSION_1_7 (cairo_pdf_version_t)(CAIRO_PDF_VERSION_1_5 + 2)
+    #endif
+    // 1.7 aka ISO32000 is the recommended version according to PWG5100.14
+    cairo_pdf_surface_restrict_to_version(surface, CAIRO_PDF_VERSION_1_7);
     cairo_pdf_surface_set_metadata(surface, CAIRO_PDF_METADATA_CREATOR, PDF_CREATOR);
   }
   else if(params.format == PrintParameters::Postscript)