116 lines
4.5 KiB
Text
116 lines
4.5 KiB
Text
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Troubleshooting GNU FreeFont
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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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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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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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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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glyph substitution
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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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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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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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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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Linux and Unix
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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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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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Just what to do depends on how and where the font was installed.
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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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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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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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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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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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Windows
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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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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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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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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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reporting problems
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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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$Id: troubleshooting.txt,v 1.10 2011-07-16 08:38:06 Stevan_White Exp $
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