Font autoconfigure

[dkochmanski]

Refactor CLX fonts and TTF extension

[jorams]

There is another library, clx-truetype, that does antialiased TTF font rendering for CLX. Was this looked at?

Rendering using that library tends to perform terribly, so I wonder how the implementation here compares.

[stacksmith]

dkochmanski:
I may be doing something stupid, but I checked out your branch to take a look. Loading via (ql:quickload :mcclim) craps out (sbcl 1.3.8):

The name "ALEXANDRIA" does not designate any package.
   [Condition of type SB-KERNEL:SIMPLE-PACKAGE-ERROR]

Restarts:
 0: [TRY-RECOMPILING] Recompile package and try loading it again
 1: [RETRY] Retry loading FASL for #<CL-SOURCE-FILE "clim-lisp" "package">.
 2: [ACCEPT] Continue, treating loading FASL for #<CL-SOURCE-FILE "clim-lisp" "package"> as having been successful.
 3: [RETRY] Retry ASDF operation.
 4: [CLEAR-CONFIGURATION-AND-RETRY] Retry ASDF operation after resetting the configuration.
 5: [ABORT] Give up on "mcclim"
 --more--

Backtrace:
  0: (SB-INT:FIND-UNDELETED-PACKAGE-OR-LOSE "ALEXANDRIA")
  1: (SB-IMPL::IMPORT-LIST-SYMBOLS (("ALEXANDRIA" "ENSURE-GETHASH")))
  2: ((FLET SB-IMPL::THUNK :IN SB-IMPL::%DEFPACKAGE))
  3: ((FLET #:WITHOUT-INTERRUPTS-BODY-387 :IN SB-THREAD::CALL-WITH-RECURSIVE-LOCK))
  4: (SB-THREAD::CALL-WITH-RECURSIVE-LOCK #<CLOSURE (FLET SB-THREAD::WITH-RECURSIVE-LOCK-THUNK :IN SB-IMPL::CALL-WITH-PACKAGE-GRAPH) {7FFFE4244B1B}> #<SB-THREAD:MUTEX "Package Graph Lock" owner: #<SB-THREA..
  5: (SB-IMPL::CALL-WITH-PACKAGE-GRAPH #<CLOSURE (FLET SB-IMPL::THUNK :IN SB-IMPL::%DEFPACKAGE) {7FFFE4244B6B}>)
  6: (SB-IMPL::%DEFPACKAGE "CLIM-INTERNALS" ("CLIMI") NIL NIL NIL ("CLIM" "CLIM-SYS" "CLIM-EXTENSIONS" "CLIM-BACKEND" "CLIM-LISP") (("ALEXANDRIA" "ENSURE-GETHASH")) ("LETF") NIL ("CLIM-INTERNALS") NIL NIL ..
  7: (SB-FASL::LOAD-FASL-GROUP #S(SB-FASL::FASL-INPUT :STREAM #<SB-SYS:FD-STREAM for "file /home/stacksmith/.cache/common-lisp/sbcl-1.3.8-linux-x64/home/stacksmith/2016/lisp/McCLIM/package.fasl" {100DDE958..
  8: (SB-FASL::LOAD-AS-FASL #<SB-SYS:FD-STREAM for "file /home/stacksmith/.cache/common-lisp/sbcl-1.3.8-linux-x64/home/stacksmith/2016/lisp/McCLIM/package.fasl" {100DDE9583}> NIL NIL)
  9: ((FLET SB-FASL::LOAD-STREAM :IN LOAD) #<SB-SYS:FD-STREAM for "file /home/stacksmith/.cache/common-lisp/sbcl-1.3.8-linux-x64/home/stacksmith/2016/lisp/McCLIM/package.fasl" {100DDE9583}> T)
 10: (LOAD #P"/home/stacksmith/.cache/common-lisp/sbcl-1.3.8-linux-x64/home/stacksmith/2016/lisp/McCLIM/package.fasl" :VERBOSE NIL :PRINT NIL :IF-DOES-NOT-EXIST T :EXTERNAL-FORMAT :DEFAULT)
 11: (UIOP/UTILITY:CALL-WITH-MUFFLED-CONDITIONS #<CLOSURE (LAMBDA NIL :IN UIOP/LISP-BUILD:LOAD*) {100DDE716B}> ("Overwriting already existing readtable ~S." #(#:FINALIZERS-OFF-WARNING :ASDF-FINALIZERS)))
 12: ((SB-PCL::EMF ASDF/ACTION:PERFORM) #<unavailable argument> #<unavailable argument> #<ASDF/LISP-ACTION:LOAD-OP > #<ASDF/LISP-ACTION:CL-SOURCE-FILE "clim-lisp" "package">)
 13: ((:METHOD ASDF/ACTION:PERFORM-WITH-RESTARTS (ASDF/LISP-ACTION:LOAD-OP ASDF/LISP-ACTION:CL-SOURCE-FILE)) #<ASDF/LISP-ACTION:LOAD-OP > #<ASDF/LISP-ACTION:CL-SOURCE-FILE "clim-lisp" "package">) [fast-met..
 14: ((:METHOD ASDF/ACTION:PERFORM-WITH-RESTARTS :AROUND (T T)) #<ASDF/LISP-ACTION:LOAD-OP > #<ASDF/LISP-ACTION:CL-SOURCE-FILE "clim-lisp" "package">) [fast-method]
 15: ((:METHOD ASDF/PLAN:PERFORM-PLAN (LIST)) ((#1=#<ASDF/LISP-ACTION:PREPARE-OP > . #2=#<ASDF/SYSTEM:SYSTEM #3="trivial-gray-streams">) (#1# . #4=#<ASDF/LISP-ACTION:CL-SOURCE-FILE #3# "package">) (#5=#<AS..
 16: ((FLET SB-C::WITH-IT :IN SB-C::%WITH-COMPILATION-UNIT))
 17: ((:METHOD ASDF/PLAN:PERFORM-PLAN :AROUND (T)) ((#1=#<ASDF/LISP-ACTION:PREPARE-OP > . #2=#<ASDF/SYSTEM:SYSTEM #3="trivial-gray-streams">) (#1# . #4=#<ASDF/LISP-ACTION:CL-SOURCE-FILE #3# "package">) (#5..
 18: ((FLET SB-C::WITH-IT :IN SB-C::%WITH-COMPILATION-UNIT))
 19: ((:METHOD ASDF/PLAN:PERFORM-PLAN :AROUND (T)) #<ASDF/PLAN:SEQUENTIAL-PLAN {100AB45593}> :VERBOSE NIL) [fast-method]
 --more--

[TeMPOraL]

Looks to me that Alexandria is referenced in package.lisp in an :import-from clause, but it's not loaded anywhere; in particular, it's not present in :depends-on clause in the mcclim.asd file.

[dkochmanski]

yes, that was me being sloppy, thanks! (last commit fixes this)

[dkochmanski]

@jorams I wasn't aware about that, will check it for sure. Thanks.

[stacksmith]

@jorams, @dkochmanski - it seems that neither McCLIM nor clx-truetype render fonts using sub-pixel antialiasing that makes all the difference visually. This compares McCLIM's font selector demo font with my emacs font (Make sure your browser is not zooming - in firefox, C-0)

and magnified

Note the top pixel line of the non-rgb antialiased font makes it look really unfortunate...

I am trying to figure it out... xrender supports it...

OK, CLX-TRUETYPE officially does not support it:

TrueType hints are not supported.
RGB antialiasing is not supported.
Text rendering do not use XRender glyph sets. 

CL-CAIRO2 does not seem to do RGB subpixel, or at least I could not coax it to do so.

[dkochmanski]

XRender is an extension which we use to draw fonts ourself (using cl-vectors etc.).

Excerpt from the McCLIM truetype extension readme:

TODO

• Kerning (we didn't do this with Freetype, either. Oops.)
• Implement fixed-font-width-p for zpb-ttf.
• Boxes for missing glyphs.
• Make certain left/right bearings and text-bounding-rectangle are
  correct. (I doubt they are..)

Wish-list

• Subpixel antialiasing. It would be straightforward to generate the
  glyphs by tripling the width as passed to cl-vectors and compressing
  triplets of pixels together ourselves. I'm not certain how to draw
  the result through xrender. I've seen hints on Google that there is
  subpixel AA support in xrender, which isn't obvious from CLX or the
  spec. Failing that, we could use a 24bpp mask with component-alpha.
  That might even be how you're supposed to do it. I'm skeptical as to
  whether this would be accelerated for most people.
• Subpixel positioning. Not hard in principle - render multiple versions
  of each glyph, offset by fractions of a pixel. Horizontal positioning
  is more important than vertical, so 1/4 pixel horizontal resolution
  and 1 pixel vertical resolution should suffice. Given how ugly most
  CLIM apps are, and the lack of WYSIWYG document editors crying out
  for perfect text spacing in small fonts, we don't really need this.