[Dev-luatex] Font patches

5 Jul 2023

      Hi Luigi,

I've attached a series of font-related patches.

Patch 1:

Even if you set "tounicode = 1" at the top level of a font, "tounicode =
<something>" for each character, and run "pdf.setgentounicode(1)",
LuaTeX will only write out a /ToUnicode entry if the document uses
"\pdfextension glyphtounicode" somewhere. 

A minimal(-ish) example:

   % \pdfextension glyphtounicode{fake!}{0000}

   \newcount\fontid
   \directlua{
       local height = tex.sp("8bp")
       local width = tex.sp("36bp")

       pdf.setgentounicode(1)

       local inner = font.define {
           name = "fake-font-inner",
           parameters = {},
           properties = {},
           encodingbytes = 0,
           psname = "none",
           tounicode = 1,
           characters = {
               [1] = {
                   width = width,
                   height = height,
                   depth = 0,
                   tounicode = { 0x1f986 },
               }
           }
       }

       tex.count.fontid = font.define {
           name = "fake-font-virtual",
           parameters = {},
           properties = {},
           characters = {
               [string.byte"x"] = {
                   width = width,
                   height = height,
                   depth = 0,
                   commands = {
                       { "slot", 1, 1 }
                   }

               }
           },
           type = "virtual",
           fonts = {{ id = inner }},
       }

       callback.register(
           "provide_charproc_data",
           function (mode, font_id, slot)
               if mode == 2 then
                   return pdf.immediateobj("stream", "36 0 d0 0 0 36 8 re f"), 36
               elseif mode == 3 then
                   return 1 / 10
               end
           end
       )
   }

   x{\setfontid\fontid x}x

   \bye

You would expect that copying the black box would give you a duck, but
this only happens if the first line is uncommented. The first patch
should fix this.

Patch 2:

Defining a Type 3 font with a character index greater than 256 can cause
a segfault. Using an index >256 is impossible with a T3 font, but you
shouldn't be able to cause a segfault from Lua code.

Minimal example:

   \directlua{
       local height = tex.sp("8bp")
       local width = tex.sp("36bp")

       local id = font.define {
           name = "fake-font-inner",
           parameters = {},
           properties = {},
           encodingbytes = 0,
           psname = "none",
           tounicode = 1,
           characters = {
               [0x1f986] = {
                   width = width,
                   height = height,
                   depth = 0,
               }
           }
       }

       callback.register(
           "provide_charproc_data",
           function (mode, font_id, slot)
               if mode == 2 then
                   return pdf.immediateobj("stream", "36 0 d0 0 0 36 8 re f"), 36
               elseif mode == 3 then
                   return 1 / 10
               end
           end
       )

       local glyph = node.new("glyph")
       glyph.font = id
       glyph.char = 0x1f986

       tex.forcehmode()
       node.write(glyph)
   }
   \bye

The second patch catches this when the font is initialized, skips the
too-large character, and issues a warning.

Patch 3:

The third patch adds the "provide_charproc_data" callback to the manual.

Thanks,
-- Max

[Dev-luatex] Font patches

Max Chernoff