text-extents returns invalid values for arabic fonts

[dkochmanski]

I've approached this problem during work on McCLIM clx font part refactoring. It seems, that xlib:text-extents returns invalid values for arabic fonts (#<XLIB:FONT -arabic-newspaper-medium-r-normal--32-246-100-100-p-137-iso10646-1 :0 12583033>).

After digging a bit more, I've found, that local-text-extents returns invalid ascent/descent values for the font (i.e -32767). This is fixed, if we comment out local-text-extents and server-text-extents is always called (hack below).

Steps to reproduce:

1. Install xorg-fonts-misc (or arabic24.pcf.gz font from the preferred source)
2. Run font-selector demo from McCLIM)

(eval-when (:compile-toplevel :load-toplevel :execute)
  (ql:quickload 'clim-examples))
(clim-demo:demodemo)
;; pick font-selector demo

NB Arabic font won't be rendered even if we have sane ascent/descent values, but this seems to be a separate issue which I'm not sure where it belongs to, or if its a bug – it may be that Arabic font can't render ASCII characters – but the system doesn't crash, only text isn't rendered).

Hack correcting behaviour (but we should fix local-text-extents instead):

diff --git a/text.lisp b/text.lisp
index dcac272..743fbaa 100644
--- a/text.lisp
+++ b/text.lisp
@@ -165,7 +165,7 @@
              ((integerp new-font) (incf width (the int32 new-font))))

        (let (w a d l r)
-         (if (or (font-char-infos-internal font) (font-local-only-p font))
+         (if nil ;(or (font-char-infos-internal font) (font-local-only-p font))
              ;; Calculate text extents locally
              (progn
                (multiple-value-setq (w a d l r)
@@ -254,7 +254,7 @@
              ((integerp new-font) (incf width (the int32 new-font))))

        (incf width
-             (if (or (font-char-infos-internal font) (font-local-only-p font))
+             (if nil ;(or (font-char-infos-internal font) (font-local-only-p font))
                  (text-extents-local font wbuf 0 buf-end :width-only)
                (text-width-server font wbuf 0 buf-end)))
        (when (type? new-font 'font)