[db,loaders] clarify support for PFB

The current PFB loader, although it is indeed completely independent of
the FF libraries, is not yet feature complete. Only the loading of
vectors is supported which suffices for font rendering given the AFM
information.

According to Hans, we have decent chance of it growing into a
full-fledged reader for 1.0.

2 files changed, 13 insertions, 4 deletions

diff --git a/src/luaotfload-database.lua b/src/luaotfload-database.lua
index f18875c..d59b7c8 100644
--- a/src/luaotfload-database.lua
+++ b/src/luaotfload-database.lua
@@ -207,7 +207,8 @@ local make_luanames = function (path)
 end
 
 local format_precedence = {
-    "otf",  "ttc", "ttf", "afm", "pfb"
+    "otf",  "ttc", "ttf", "afm",
+    -- "pfb" --- may come back before Luatex 1.0
 }
 
 local location_precedence = {
@@ -358,7 +359,7 @@ This is a sketch of the luaotfload db:
         conflicts       : { barename : int; basename : int }; // filename conflict with font at index; happens with subfonts
         familyname      : string;   // sanitized name of the font family the font belongs to, usually from the names table
         fontname        : string;   // sanitized name of the font
-        format          : string;   // "otf" | "ttf" | "afm" | "pfb"
+        format          : string;   // "otf" | "ttf" | "afm" (* | "pfb" *)
         fullname        : string;   // sanitized full name of the font including style modifiers
         fullpath        : string;   // path to font in filesystem
         index           : int;      // index in the mappings table
@@ -1681,7 +1682,7 @@ local loaders = {
     otf     = ot_fullinfo,
     ttc     = ot_fullinfo,
     ttf     = ot_fullinfo,
-    pfb     = t1_fullinfo,
+--- pfb     = t1_fullinfo,
 }
 
 --- not side-effect free!
diff --git a/src/luaotfload-loaders.lua b/src/luaotfload-loaders.lua
index f0c1913..8a29256 100644
--- a/src/luaotfload-loaders.lua
+++ b/src/luaotfload-loaders.lua
@@ -49,6 +49,14 @@ local unsupported_reader = function (format)
   end
 end
 
+local afm_compat_message = function (specification, method)
+  logreport ("both", 0, "loaders",
+             "PFB format only supported with matching \z
+              AFM; redirecting (“%s”, “%s”).",
+             tostring (specification.name), tostring (method))
+  return fonts.readers.afm (specification, method)
+end
+
 local install_formats = function ()
   local fonts = fonts
   if not fonts then return false end
@@ -81,7 +89,7 @@ local install_formats = function ()
   return aux ("evl", eval_reader)
      and aux ("lua", lua_reader)
      and aux ("pfa", unsupported_reader "pfa")
-     and aux ("pfb", unsupported_reader "pfb")
+     and aux ("pfb", afm_compat_message) --- pfb loader is incomplete
      and aux ("ofm", readers.tfm)
      and aux ("dfont", unsupported_reader "dfont")
 end