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5>FUNCTIONAL OVERVIEW</TITLE
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69CLASS="SECT1"
70><A
71NAME="AEN19"
72>FUNCTIONAL OVERVIEW</A
73></H1
74><P
75>Fontconfig contains two essential modules, the configuration module which
76builds an internal configuration from XML files and the matching module
77which accepts font patterns and returns the nearest matching font.
78  </P
79><DIV
80CLASS="SECT2"
81><H2
82CLASS="SECT2"
83><A
84NAME="AEN22"
85>FONT CONFIGURATION</A
86></H2
87><P
88>The configuration module consists of the FcConfig datatype, libexpat and
89FcConfigParse which walks over an XML tree and amends a configuration with
90data found within.  From an external perspective, configuration of the
91library consists of generating a valid XML tree and feeding that to
92FcConfigParse.  The only other mechanism provided to applications for
93changing the running configuration is to add fonts and directories to the
94list of application-provided font files.
95    </P
96><P
97>The intent is to make font configurations relatively static, and shared by
98as many applications as possible.  It is hoped that this will lead to more
99stable font selection when passing names from one application to another.
100XML was chosen as a configuration file format because it provides a format
101which is easy for external agents to edit while retaining the correct
102structure and syntax.
103    </P
104><P
105>Font configuration is separate from font matching; applications needing to
106do their own matching can access the available fonts from the library and
107perform private matching.  The intent is to permit applications to pick and
108choose appropriate functionality from the library instead of forcing them to
109choose between this library and a private configuration mechanism.  The hope
110is that this will ensure that configuration of fonts for all applications
111can be centralized in one place.  Centralizing font configuration will
112simplify and regularize font installation and customization.
113    </P
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117><H2
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119><A
120NAME="AEN27"
121>FONT PROPERTIES</A
122></H2
123><P
124>While font patterns may contain essentially any properties, there are some
125well known properties with associated types.  Fontconfig uses some of these
126properties for font matching and font completion.  Others are provided as a
127convenience for the application's rendering mechanism.
128    </P
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135><PRE
136CLASS="PROGRAMLISTING"
137>                 Property Definitions
138
139    Property       C Preprocessor Symbol  Type    Description
140    ----------------------------------------------------
141    family         FC_FAMILY              String  Font family names
142    familylang     FC_FAMILYLANG          String  Language corresponding to
143                                                  each family name
144    style          FC_STYLE               String  Font style. Overrides weight
145                                                  and slant
146    stylelang      FC_STYLELANG           String  Language corresponding to
147                                                  each style name
148    fullname       FC_FULLNAME            String  Font face full name where
149                                                  different from family and
150                                                  family + style
151    fullnamelang   FC_FULLNAMELANG        String  Language corresponding to
152                                                  each fullname
153    slant          FC_SLANT               Int     Italic, oblique or roman
154    weight         FC_WEIGHT              Int     Light, medium, demibold,
155                                                  bold or black
156    width          FC_WIDTH               Int     Condensed, normal or expanded
157    size           FC_SIZE                Double  Point size
158    aspect         FC_ASPECT              Double  Stretches glyphs horizontally
159                                                  before hinting
160    pixelsize      FC_PIXEL_SIZE          Double  Pixel size
161    spacing        FC_SPACING             Int     Proportional, dual-width,
162                                                  monospace or charcell
163    foundry        FC_FOUNDRY             String  Font foundry name
164    antialias      FC_ANTIALIAS           Bool    Whether glyphs can be
165                                                  antialiased
166    hintstyle      FC_HINT_STYLE          Int     Automatic hinting style
167    hinting        FC_HINTING             Bool    Whether the rasterizer should
168                                                  use hinting
169    verticallayout FC_VERTICAL_LAYOUT     Bool    Use vertical layout
170    autohint       FC_AUTOHINT            Bool    Use autohinter instead of
171                                                  normal hinter
172    globaladvance  FC_GLOBAL_ADVANCE      Bool    Use font global advance data (deprecated)
173    file           FC_FILE                String  The filename holding the font
174                                                  relative to the config's sysroot
175    index          FC_INDEX               Int     The index of the font within
176                                                  the file
177    ftface         FC_FT_FACE             FT_Face Use the specified FreeType
178                                                  face object
179    rasterizer     FC_RASTERIZER          String  Which rasterizer is in use (deprecated)
180    outline        FC_OUTLINE             Bool    Whether the glyphs are outlines
181    scalable       FC_SCALABLE            Bool    Whether the glyphs are outlines or have color
182    dpi            FC_DPI                 Double  Target dots per inch
183    rgba           FC_RGBA                Int     unknown, rgb, bgr, vrgb,
184                                                  vbgr, none - subpixel geometry
185    scale          FC_SCALE               Double  Scale factor for point-&#62;pixel
186                                                  conversions (deprecated)
187    minspace       FC_MINSPACE            Bool    Eliminate leading from line
188                                                  spacing
189    matrix         FC_MATRIX              Matrix  Hold an affine transformation
190    charset        FC_CHARSET             CharSet Unicode chars encoded by
191                                                  the font
192    lang           FC_LANG                LangSet Set of RFC-3066-style
193                                                  languages this font supports
194    fontversion    FC_FONTVERSION         Int     Version number of the font
195    capability     FC_CAPABILITY          String  List of layout capabilities in
196                                                  the font
197    fontformat     FC_FONTFORMAT          String  String name of the font format
198    embolden       FC_EMBOLDEN            Bool    Rasterizer should
199                                                  synthetically embolden the font
200    embeddedbitmap FC_EMBEDDED_BITMAP     Bool    Use the embedded bitmap instead
201                                                  of the outline
202    decorative     FC_DECORATIVE          Bool    Whether the style is a decorative
203                                                  variant
204    lcdfilter      FC_LCD_FILTER          Int     Type of LCD filter
205    namelang       FC_NAMELANG            String  Language name to be used for the
206                                                  default value of familylang,
207                                                  stylelang and fullnamelang
208    fontfeatures   FC_FONT_FEATURES       String  List of extra feature tags in
209                                                  OpenType to be enabled
210    prgname        FC_PRGNAME             String  Name of the running program
211    hash           FC_HASH                String  SHA256 hash value of the font data
212                                                  with "sha256:" prefix (deprecated)
213    postscriptname FC_POSTSCRIPT_NAME     String  Font name in PostScript
214    color          FC_COLOR               Bool    Whether any glyphs have color
215    symbol         FC_SYMBOL              Bool    Whether font uses MS symbol-font encoding
216    fontvariations FC_FONT_VARIATIONS     String  comma-separated string of axes in variable font
217    variable       FC_VARIABLE            Bool    Whether font is Variable Font
218    fonthashint    FC_FONT_HAS_HINT       Bool    Whether font has hinting
219    order          FC_ORDER               Int     Order number of the font
220    desktop        FC_DESKTOP_NAME        String  Current desktop name
221    namedinstance  FC_NAMED_INSTANCE      Bool    Whether font is a named instance
222    fontwarapper   FC_FONT_WRAPPER        String  The font wrapper format
223    </PRE
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