Provided by: libxft-dev_2.3.2-2_amd64 bug

NAME

        Xft - X FreeType interface library

DESCRIPTION

       Xft is a simple library designed to interface the FreeType rasterizer with the X Rendering
       Extension.  This manual page barely scratches the surface of this library.

HEADER FILE

       #include <X11/Xft/Xft.h>

CONSTANTS

       XFT_MAJOR
              is the major version number of Xft.

       XFT_MINOR
              is the minor version number of Xft.

       XFT_REVISION
              is the revision number of Xft.

       XFT_VERSION
              is  XFT_MAJOR  times  10000  (ten  thousand),  plus  XFT_MINOR  times   100,   plus
              XFT_REVISION.

       XftVersion
              is an alias for XFT_VERSION.

       The following example illustrates how Xft's version constants might be used:
           #if (XFT_VERSION >= 20107)
           (void) puts("Version 2.1.7 or later of the Xft library is in"
                       " use.");
           #else
           (void) printf("Insufficient version of Xft (%d.%d.%d) installed;
                         " need at least version 2.1.7.\n", XFT_MAJOR,
                         XFT_MINOR,
                         XFT_REVISION);
           #endif

DATA TYPES

       XftFont
              typedef struct _XftFont {
                  int         ascent;
                  int         descent;
                  int         height;
                  int         max_advance_width;
                  FcCharSet   *charset;
                  FcPattern   *pattern;
              } XftFont;
              An  XftFont  is the primary data structure of interest to programmers using Xft; it
              contains general font metrics and pointers to  the  Fontconfig  character  set  and
              pattern  associated  with  the  font.   The  FcCharSet and FcPattern data types are
              defined by the Fontconfig library.

              XftFonts   are   populated   with   any   of   XftFontOpen(),    XftFontOpenName(),
              XftFontOpenXlfd(),  XftFontOpenInfo(),  or  XftFontOpenPattern().  XftFontCopy() is
              used to duplicate XftFonts, and XftFontClose()  is  used  to  mark  an  XftFont  as
              unused.   XftFonts  are  internally allocated, reference-counted, and freed by Xft;
              the programmer does not ordinarily need to allocate or free storage for them.

              XftDrawGlyphs(),    the    XftDrawString*()    family,    XftDrawCharSpec(),    and
              XftDrawGlyphSpec()  use  XftFonts  to  render  text to an XftDraw object, which may
              correspond to either a core X drawable or an X Rendering Extension drawable.

              XftGlyphExtents() and the  XftTextExtents*()  family  are  used  to  determine  the
              extents (maximum dimensions) of an XftFont.

              An XftFont's glyph or character coverage can be determined with XftFontCheckGlyph()
              or XftCharExists().  XftCharIndex() returns the  XftFont-specific  character  index
              corresponding to a given Unicode codepoint.

              XftGlyphRender(),     XftGlyphSpecRender(),     XftCharSpecRender(),     and    the
              XftTextRender*() family use XftFonts to draw into  X  Rendering  Extension  Picture
              structures.  Note: XftDrawGlyphs(), the XftDrawString*() family, XftDrawCharSpec(),
              and XftDrawGlyphSpec() provide a means of rendering fonts that  is  independent  of
              the availability of the X Rendering Extension on the X server.

       XftFontInfo
              is  an  opaque object that stores information about a font.  XftFontInfo structures
              are created with XftFontInfoCreate(), freed with XftFontInfoDestroy(), and compared
              with XftFontInfoEqual().  XftFontInfo objects are internally allocated and freed by
              Xft; the programmer does not ordinarily need to allocate or free storage for them.

              Each XftFontInfo structure in use is associated with a unique identifier, which can
              be retrieved with XftFontInfoHash().  An XftFont can be opened based on XftFontInfo
              data with XftFontOpenInfo().

       XftColor
              typedef struct _XftColor {
                  unsigned long   pixel;
                  XRenderColor    color;
              } XftColor;
              An XftColor object permits text and other items to  be  rendered  in  a  particular
              color  (or  the  closest  approximation  offered  by  the  X  visual  in use).  The
              XRenderColor data type is defined by the X Render Extension library.

              XftColorAllocName() and XftColorAllocValue() request a color allocation from the  X
              server  (if  necessary)  and  initialize  the  members of XftColor.  XftColorFree()
              instructs the X server to free the color currently allocated for an XftColor.

              One an XftColor has been  initialized,  XftDrawSrcPicture(),  XftDrawGlyphs(),  the
              XftDrawString*()       family,       XftDrawCharSpec(),      XftDrawCharFontSpec(),
              XftDrawGlyphSpec(), XftDrawGlyphFontSpec(), and XftDrawRect() may be used  to  draw
              various objects using it.

       XftDraw
              is  an  opaque object which holds information used to render to an X drawable using
              either the core protocol or the X Rendering extension.

              XftDraw objects are created  with  any  of  XftDrawCreate()  (which  associates  an
              XftDraw    with    an    existing    X    drawable),    XftDrawCreateBitmap(),   or
              XftDrawCreateAlpha(),  and  destroyed  with  XftDrawDestroy().   The   X   drawable
              associated  with  an  XftDraw  can  be  changed with XftDrawChange().  XftDraws are
              internally allocated and freed by Xft; the programmer does not ordinarily  need  to
              allocate or free storage for them.

              The  X  Display,  Drawable,  Colormap, and Visual of an XftDraw can be queried with
              XftDrawDisplay(),  XftDrawDrawable(),   XftDrawColormap(),   and   XftDrawVisual(),
              respectively.   The  X  Rendering  Extension  Picture associated with an XftDraw is
              returned by XftDrawPicture().

       XftCharSpec
              typedef struct _XftCharSpec {
                  FcChar32    ucs4;
                  short       x;
                  short       y;
              } XftCharSpec;

              The FcChar32 data type is defined by the Fontconfig library.

       XftCharFontSpec
              typedef struct _XftCharFontSpec {
                  XftFont     *font;
                  FcChar32    ucs4;
                  short       x;
                  short       y;
              } XftCharFontSpec;

              The FcChar32 data type is defined by the Fontconfig library.

       XftGlyphSpec
              typedef struct _XftGlyphSpec {
                  FT_UInt     glyph;
                  short       x;
                  short       y;
              } XftGlyphSpec;

              The FT_UInt data type is defined by the FreeType library.

       XftGlyphFontSpec
              typedef struct _XftGlyphFontSpec {
                  XftFont     *font;
                  FT_UInt     glyph;
                  short       x;
                  short       y;
              } XftGlyphFontSpec;

              The FT_UInt data type is defined by the FreeType library.

FUNCTIONS

   Opening and Matching Fonts
       XftFont *
       XftFontOpen (Display *dpy,
                    int     screen,
                    ...);
       XftFontOpen takes a list of pattern  element  triples  of  the  form  field,  type,  value
       (terminated  with a NULL), matches that pattern against the available fonts, and opens the
       matching font, sizing it correctly for screen number screen on display dpy.   The  Display
       data type is defined by the X11 library.  Returns NULL if no match is found.

       Example:
           font = XftFontOpen (dpy, screen,
                               XFT_FAMILY, XftTypeString, "charter",
                               XFT_SIZE, XftTypeDouble, 12.0,
                               NULL);
       This  opens the “charter” font at 12 points.  The point size is automatically converted to
       the correct pixel size based on the resolution of the monitor.

       XftFont *
       XftFontOpenName (Display       *dpy,
                        int           screen,
                        unsigned char *name);
       XftFontOpenName behaves as XftFontOpen does, except that it  takes  a  Fontconfig  pattern
       string (which is passed to the Fontconfig library's FcNameParse() function).

       XftFont *
       XftFontOpenXlfd (Display       *dpy,
                        int           screen,
                        unsigned char *xlfd)
       XftFontOpenXlfd behaves as XftFontOpen does, except that it takes a string containing an X
       Logical Font Description (XLFD).

       FcPattern *
       XftFontMatch (Display   *dpy,
                     int       screen,
                     FcPattern *pattern,
                     FcResult  *result);
       Also used internally by the XftFontOpen* functions, XftFontMatch can also be used directly
       to  determine  the  Fontconfig  font pattern resulting from an Xft font open request.  The
       FcPattern and FcResult data types are defined by the Fontconfig library.

   Determining the Pixel Extents of a Text String
       void
       XftTextExtents8 (Display    *dpy,
                        XftFont    *font,
                        FcChar8    *string,
                        int        len,
                        XGlyphInfo *extents);
       XftTextExtents8 computes the pixel extents on display dpy of no more than len glyphs of  a
       string  consisting  of eight-bit characters when drawn with font, storing them in extents.
       The FcChar8 data type is defined by the Fontconfig library, and the XGlyphInfo  data  type
       is defined by the X Rendering Extension library.

       void
       XftTextExtents16 (Display    *dpy,
                         XftFont    *font,
                         FcChar16   *string,
                         int        len,
                         XGlyphInfo *extents);
       XftTextExtents16 computes the pixel extents on display dpy of no more than len glyphs of a
       string consisting of sixteen-bit characters when drawn with font, storing them in extents.
       The  FcChar16 data type is defined by the Fontconfig library, and the XGlyphInfo data type
       is defined by the X Rendering Extension library.

       void
       XftTextExtents32 (Display    *dpy,
                         XftFont    *font,
                         FcChar32   *string,
                         int        len,
                         XGlyphInfo *extents);
       XftTextExtents32 computes the pixel extents on display dpy of no more than len glyphs of a
       string  consisting  of  thirty-two-bit  characters  when  drawn with font, storing them in
       extents.  The FcChar32 data type is defined by the Fontconfig library, and the  XGlyphInfo
       data type is defined by the X Rendering Extension library.

       void
       XftTextExtentsUtf8 (Display    *dpy,
                           XftFont    *font,
                           FcChar8    *string,
                           int        len,
                           XGlyphInfo *extents);
       XftTextExtentsUtf8  computes the pixel extents on display dpy of no more than len bytes of
       a UTF-8 encoded string when drawn with font, storing them in extents.  The XGlyphInfo data
       type is defined by the X Rendering Extension library.

       void
       XftTextExtentsUtf16 (Display    *dpy,
                            XftFont    *font,
                            FcChar8    *string,
                            FcEndian   endian,
                            int        len,
                            XGlyphInfo *extents);
       XftTextExtentsUtf16 computes the pixel extents on display dpy of no more than len bytes of
       a UTF-16LE- or UTF-16BE-encoded string when drawn with font, storing them in extents.  The
       endianness  of  string  must be specified in endian.  The FcEndian data type is defined by
       the Fontconfig library, and the XGlyphInfo  data  type  is  defined  by  the  X  Rendering
       Extension library.

       void
       XftGlyphExtents (Display    *dpy,
                        XftFont    *font,
                        FT_UInt    *glyphs,
                        int        nglyphs,
                        XGlyphInfo *extents);
       Also  used internally by the XftTextExtents* functions, XftGlyphExtents computes the pixel
       extents on display dpy of no more than nglyphs  in  the  array  glyphs  drawn  with  font,
       storing  them  in  extents.  The FT_UInt data type is defined by the FreeType library, and
       the XGlyphInfo data type is defined by the X Rendering Extension library.

   Drawing Strings (and Other Things)
       XftDraw *
       XftDrawCreate (Display  *dpy,
                      Drawable drawable,
                      Visual   *visual,
                      Colormap colormap);
       XftDrawCreate creates a structure that can be used to render text and rectangles using the
       specified  drawable,  visual, and colormap on display.  The Drawable, Visual, and Colormap
       data types are defined by the X11 library.

       XftDraw *
       XftDrawCreateBitmap (Display *dpy,
                            Pixmap  bitmap);
       XftDrawCreateBitmap behaves as XftDrawCreate, except it uses an X pixmap of color depth  1
       instead of an X drawable.  The Pixmap data type is defined by the X11 library.

       XftDraw *
       XftDrawCreateAlpha (Display *dpy,
                           Pixmap  pixmap,
                           int     depth);
       XftDrawCreateAlpha  behaves  as  XftDrawCreate,  except it uses an X pixmap of color depth
       depth instead of an X drawable.  The Pixmap data type is defined by the X11 library.

       void
       XftDrawChange (XftDraw  *draw,
                      Drawable drawable);
       XftDrawChange changes the X drawable association of the existing Xft draw object draw from
       its current value to drawable.

       Display *
       XftDrawDisplay (XftDraw *draw);
       XftDrawDisplay returns a pointer to the display associated with the Xft draw object draw.

       Drawable
       XftDrawDrawable (XftDraw *draw);
       XftDrawDrawable returns the X drawable associated with the Xft draw object draw.

       Colormap
       XftDrawColormap (XftDraw *draw);
       XftDrawColormap returns the colormap associatied with the Xft draw object draw.

       Visual *
       XftDrawVisual (XftDraw *draw);
       XftDrawVisual returns a pointer to the visual associated with the Xft draw object draw.

       Picture
       XftDrawPicture (XftDraw *draw);
       XftDrawPicture returns the picture associated with the Xft draw object draw.  If the the X
       server does not support the X Rendering Extension, 0 is returned.

       Picture
       XftDrawSrcPicture (XftDraw *draw,
                          XftColor *color);
       This function is never called if the X server doesn't support the X  Rendering  Extension;
       instead, XftGlyphCore is used.

       void
       XftDrawDestroy (XftDraw *draw);
       XftDrawDestroy  destroys  draw  (created  by one of the XftCreate functions) and frees the
       memory that was allocated for it.

       void
       XftDrawString8 (XftDraw         *d,
                       XftColor        *color,
                       XftFont         *font,
                       int             x,
                       int             y,
                       unsigned char   *string,
                       int             len);
       XftDrawString8 draws no more than len glyphs of string to Xft drawable  d  using  font  in
       color at position x, y.

       void
       XftDrawRect (XftDraw        *d,
                    XftColor       *color,
                    int            x,
                    int            y,
                    unsigned int   width,
                    unsigned int   height);
       XftDrawRect  draws a solid rectangle of the specified color, width, and height at position
       x, y to Xft drawable d.

COMPATIBILITY

       As of version 2, Xft has become relatively stable and is expected  to  retain  source  and
       binary compatibility in future releases.

       Xft  does  provide  a  compatibility  interface  to  its  previous major version, Xft 1.x,
       described below.

   Xft 1.x Compatibility Header File
       #include <X11/Xft/XftCompat.h>

   Xft 1.x Compatibility Data Types
       XftPattern
              holds a set of names with associated value lists; each name refers to a property of
              a  font.   XftPatterns  are  used as inputs to the matching code as well as holding
              information about specific fonts.

       XftFontSet
              contains a list of XftPatterns.  Internally, Xft uses this data structure  to  hold
              sets  of  fonts.   Externally,  Xft  returns  the  results of listing fonts in this
              format.

       XftObjectSet
              holds a set of names and is used to specify which fields from fonts are  placed  in
              the the list of returned patterns when listing fonts.

AUTHOR

       Keith Packard

SEE ALSO

       Fontconfig Developers Reference
       FreeType API Reference
       Xlib - C Language Interface