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
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.
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.
typedef struct _XftCharSpec {
FcChar32 ucs4;
short x;
short y;
} XftCharSpec;
typedef struct _XftCharFontSpec {
XftFont *font;
FcChar32 ucs4;
short x;
short y;
} XftCharFontSpec;
typedef struct _XftGlyphSpec {
FT_UInt glyph;
short x;
short y;
} XftGlyphSpec;
typedef struct _XftGlyphFontSpec {
XftFont *font;
FT_UInt glyph;
short x;
short y;
} XftGlyphFontSpec;
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.
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.
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.
Xft does provide a compatibility interface to its previous major version, Xft 1.x, described below.