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Benjamin Roth authored on28/03/2023 09:47:26 Showing1 changed files
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+ Troubleshooting GNU FreeFont |
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+ |
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+So your text looks lousy, although you installed FreeFont and you seem to be |
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+using it. What do you do? |
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+ |
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+Before you blame the problem on FreeFont, take the time to double-check that |
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+the text you are looking at is really rendered with FreeFont. |
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+ |
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+Be aware that not all Unicode characters are supported by FreeFont, and |
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+even characters supported by one face, such as Serif, might not be |
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+supported by other faces such as Sans. |
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+ |
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+Also, some systems have settings that strongly affect the rendering |
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+of fonts. It may be worth tweaking these. |
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+ |
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+glyph substitution |
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+================== |
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+ |
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+When given the task of displaying characters in text, modern font rendering |
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+software usually tries to display *something*, even if the font it is |
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+*supposed* to be using does not contain glyphs for all the characters in the |
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+text. The software will snoop through all the fonts on the system to find |
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+one that has a glyph for the one missing in the desired font. So although |
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+you have specified FreeSans-bold, you may be looking at a letter from quite |
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+a different font. |
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+ |
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+First double-check that the font in question really contains the character |
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+in question. If you don't have font development software, this can be |
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+tricky. In the case of FreeFont, you can check if a given character |
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+range is supported: <http://www.gnu.org/software/freefont/coverage.html> |
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+ |
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+Next double-check that your application (web browser, text editor, etc) |
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+has indeed been properly instructed to use the font. |
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+ |
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+Then double-check that the font is really installed in the system. |
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+(This depends on the operating system, of course.) |
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+ |
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+Linux and Unix |
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+============== |
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+ |
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+Modern Linux systems use a system called fontconfig, which maintains a font |
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+cache, for efficiency. |
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+ |
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+The font cache can really complicate font installation and troubleshooting |
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+however. It can happen that when a font is newly installed, what is |
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+displayed is coming out of an old cache entry rather than the new font. |
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+ |
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+Just what to do depends on how and where the font was installed. |
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+ |
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+Fonts installed system-wide are usually put in a directory such as |
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+ /usr/share/fonts/ |
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+the font cache for these might be in |
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+ /var/cache/fontconfig/ |
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+Fonts installed just for one user account will typically be in |
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+ ~/.fonts/ |
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+and the cache will be |
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+ ~/.fontconfig/ |
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+ |
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+You can clean your local cache merely by emptying the directory |
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+ ~/.fontconfig/ |
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+In any case, to clean the cache, you can use the fontconfig command |
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+ fc-cache -vf |
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+If run as root, it will clean the system cache, if run as a normal user, |
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+it cleans only the normal user's cache. |
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+ |
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+The procedure for local fonts is: |
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+ 1) shut off any program using the fonts in question |
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+ 2) clean the cache |
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+ 3) re-start the program |
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+The procedure for system-wide fonts is: |
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+ 1) log out of the X Windows session |
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+ 2) in a console, clean the cache |
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+ 3) log in to an X Windows session |
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+ |
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+LibreOffice / OpenOffice |
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+======================== |
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+These products have their own font rendering libraries, which have |
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+idiosyncratic behavior. |
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+ |
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+It has recently been reported that as of LibreOffice 3.5.1, font features |
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+are disabled for OpenType fonts. If you use FreeFont with these products, |
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+you may want to install the TrueType versions of the fonts. |
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+ |
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+Windows |
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+======= |
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+ |
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+The most common complaint has to do with "blurry text". There are two |
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+causes. |
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+ |
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+The first is that ClearType smoothing is turned off. The best way to check |
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+is to use the native Windows Web browser. Do a search for "ClearType Tuner". |
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+The Microsoft pages install a tuner for ClearType. A security block notice |
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+will appear at the top of the window--you have to allow the installation. |
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+Then check the box "Turn on ClearType". The change happens immediately. |
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+ |
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+The secont cause is that the FreeFont version with cubic spline outlines is |
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+installed. As of the 2012 GNU FreeFont release, the TrueType builds have |
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+quadratic splines, which work best with Windows' rendering software. |
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+ TTF (TrueType) quadratic splines Windows 7, Vista, Windows XP. |
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+ OTF (OpenType) cubic splines Linux, Mac |
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+ |
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+Note also: Firefox has a setting for ClearType: |
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+ gfx.font_rendering.cleartype_params.rendering_mode |
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+A value of 2 sets it to old-style GDI rendering, while -1 is the default. |
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+ |
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+reporting problems |
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+================== |
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+ |
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+If you really think you're seeing a bug in FreeFont, or if you have |
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+a suggestion, consider opening a problem report at |
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+ https://savannah.gnu.org/bugs/?group=freefont |
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+It is best that you make a Savannah account and log in with that, so |
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+you can be e-mailed whenever changes are made to your report. |
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+ |
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+$Id: troubleshooting.txt,v 1.10 2011-07-16 08:38:06 Stevan_White Exp $ |