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  1. Troubleshooting GNU FreeFont
  2. So your text looks lousy, although you installed FreeFont and you seem to be
  3. using it. What do you do?
  4. Before you blame the problem on FreeFont, take the time to double-check that
  5. the text you are looking at is really rendered with FreeFont.
  6. Be aware that not all Unicode characters are supported by FreeFont, and
  7. even characters supported by one face, such as Serif, might not be
  8. supported by other faces such as Sans.
  9. Also, some systems have settings that strongly affect the rendering
  10. of fonts. It may be worth tweaking these.
  11. glyph substitution
  12. ==================
  13. When given the task of displaying characters in text, modern font rendering
  14. software usually tries to display *something*, even if the font it is
  15. *supposed* to be using does not contain glyphs for all the characters in the
  16. text. The software will snoop through all the fonts on the system to find
  17. one that has a glyph for the one missing in the desired font. So although
  18. you have specified FreeSans-bold, you may be looking at a letter from quite
  19. a different font.
  20. First double-check that the font in question really contains the character
  21. in question. If you don't have font development software, this can be
  22. tricky. In the case of FreeFont, you can check if a given character
  23. range is supported: <http://www.gnu.org/software/freefont/coverage.html>
  24. Next double-check that your application (web browser, text editor, etc)
  25. has indeed been properly instructed to use the font.
  26. Then double-check that the font is really installed in the system.
  27. (This depends on the operating system, of course.)
  28. Linux and Unix
  29. ==============
  30. Modern Linux systems use a system called fontconfig, which maintains a font
  31. cache, for efficiency.
  32. The font cache can really complicate font installation and troubleshooting
  33. however. It can happen that when a font is newly installed, what is
  34. displayed is coming out of an old cache entry rather than the new font.
  35. Just what to do depends on how and where the font was installed.
  36. Fonts installed system-wide are usually put in a directory such as
  37. /usr/share/fonts/
  38. the font cache for these might be in
  39. /var/cache/fontconfig/
  40. Fonts installed just for one user account will typically be in
  41. ~/.fonts/
  42. and the cache will be
  43. ~/.fontconfig/
  44. You can clean your local cache merely by emptying the directory
  45. ~/.fontconfig/
  46. In any case, to clean the cache, you can use the fontconfig command
  47. fc-cache -vf
  48. If run as root, it will clean the system cache, if run as a normal user,
  49. it cleans only the normal user's cache.
  50. The procedure for local fonts is:
  51. 1) shut off any program using the fonts in question
  52. 2) clean the cache
  53. 3) re-start the program
  54. The procedure for system-wide fonts is:
  55. 1) log out of the X Windows session
  56. 2) in a console, clean the cache
  57. 3) log in to an X Windows session
  58. LibreOffice / OpenOffice
  59. ========================
  60. These products have their own font rendering libraries, which have
  61. idiosyncratic behavior.
  62. It has recently been reported that as of LibreOffice 3.5.1, font features
  63. are disabled for OpenType fonts. If you use FreeFont with these products,
  64. you may want to install the TrueType versions of the fonts.
  65. Windows
  66. =======
  67. The most common complaint has to do with "blurry text". There are two
  68. causes.
  69. The first is that ClearType smoothing is turned off. The best way to check
  70. is to use the native Windows Web browser. Do a search for "ClearType Tuner".
  71. The Microsoft pages install a tuner for ClearType. A security block notice
  72. will appear at the top of the window--you have to allow the installation.
  73. Then check the box "Turn on ClearType". The change happens immediately.
  74. The secont cause is that the FreeFont version with cubic spline outlines is
  75. installed. As of the 2012 GNU FreeFont release, the TrueType builds have
  76. quadratic splines, which work best with Windows' rendering software.
  77. TTF (TrueType) quadratic splines Windows 7, Vista, Windows XP.
  78. OTF (OpenType) cubic splines Linux, Mac
  79. Note also: Firefox has a setting for ClearType:
  80. gfx.font_rendering.cleartype_params.rendering_mode
  81. A value of 2 sets it to old-style GDI rendering, while -1 is the default.
  82. reporting problems
  83. ==================
  84. If you really think you're seeing a bug in FreeFont, or if you have
  85. a suggestion, consider opening a problem report at
  86. https://savannah.gnu.org/bugs/?group=freefont
  87. It is best that you make a Savannah account and log in with that, so
  88. you can be e-mailed whenever changes are made to your report.
  89. $Id: troubleshooting.txt,v 1.10 2011-07-16 08:38:06 Stevan_White Exp $