DocsThe data structure which actually contains the font information has changed significantly since previous releases; it now attempts to hide the actual storage format for the data from the application, providing accessor functions to get at the data. This allows a range of internal details for different font sources. The structure is split into two pieces, so that ListFontsWithInfo can share information from the font when it has been loaded. The FontInfo structure, then, contains only information germane to LFWI.
typedef struct _FontInfo {
unsigned short firstCol; /* range of glyphs for this font */
unsigned short lastCol;
unsigned short firstRow;
unsigned short lastRow;
unsigned short defaultCh; /* default character index */
unsigned int noOverlap:1; /* no combination of glyphs overlap */
unsigned int terminalFont:1; /* Character cell font */
unsigned int constantMetrics:1; /* all metrics are the same */
unsigned int constantWidth:1; /* all character widths are the same*/
unsigned int inkInside:1; /* all ink inside character cell */
unsigned int inkMetrics:1; /* font has ink metrics */
unsigned int allExist:1; /* no missing chars in range */
unsigned int drawDirection:2; /* left-to-right/right-to-left*/
unsigned int cachable:1; /* font needn't be opened each time*/
unsigned int anamorphic:1; /* font is strangely scaled */
short maxOverlap; /* maximum overlap amount */
short pad; /* unused */
xCharInfo maxbounds; /* glyph metrics maximums */
xCharInfo minbounds; /* glyph metrics minimums */
xCharInfo ink_maxbounds; /* ink metrics maximums */
xCharInfo ink_minbounds; /* ink metrics minimums */
short fontAscent; /* font ascent amount */
short fontDescent; /* font descent amount */
int nprops; /* number of font properties */
FontPropPtr props; /* font properties */
char *isStringProp; /* boolean array */
} FontInfoRec, *FontInfoPtr;typedef struct _FontInfo {
unsigned short firstCol; /* range of glyphs for this font */
unsigned short lastCol;
unsigned short firstRow;
unsigned short lastRow;
unsigned short defaultCh; /* default character index */
unsigned int noOverlap:1; /* no combination of glyphs overlap */
unsigned int terminalFont:1; /* Character cell font */
unsigned int constantMetrics:1; /* all metrics are the same */
unsigned int constantWidth:1; /* all character widths are the same*/
unsigned int inkInside:1; /* all ink inside character cell */
unsigned int inkMetrics:1; /* font has ink metrics */
unsigned int allExist:1; /* no missing chars in range */
unsigned int drawDirection:2; /* left-to-right/right-to-left*/
unsigned int cachable:1; /* font needn't be opened each time*/
unsigned int anamorphic:1; /* font is strangely scaled */
short maxOverlap; /* maximum overlap amount */
short pad; /* unused */
xCharInfo maxbounds; /* glyph metrics maximums */
xCharInfo minbounds; /* glyph metrics minimums */
xCharInfo ink_maxbounds; /* ink metrics maximums */
xCharInfo ink_minbounds; /* ink metrics minimums */
short fontAscent; /* font ascent amount */
short fontDescent; /* font descent amount */
int nprops; /* number of font properties */
FontPropPtr props; /* font properties */
char *isStringProp; /* boolean array */
} FontInfoRec, *FontInfoPtr;
The font structure, then, contains a font info record, the format of
the bits in each bitmap and the functions which access the font
records (which are stored in an opaque format hung off of
fontPrivate).
typedef struct _Font {
int refcnt;
FontInfoRec info;
char bit; /* bit order: LSBFirst/MSBFirst */
char byte; /* byte order: LSBFirst/MSBFirst */
char glyph; /* glyph pad: 1, 2, 4 or 8 */
char scan; /* glyph scan unit: 1, 2 or 4 */
fsBitmapFormat format; /* FS-style format (packed) */
int (*get_glyphs) ( /* font, count, chars, encoding, count, glyphs */ );
int (*get_metrics) ( /* font, count, chars, encoding, count, glyphs */ );
int (*get_bitmaps) ( /* client, font, flags, format,
flags, nranges, ranges, data_sizep,
num_glyphsp, offsetsp, glyph_datap,
free_datap */ );
int (*get_extents) ( /* client, font, flags, nranges,
ranges, nextentsp, extentsp */);
void (*unload_font) ( /* font */ );
FontPathElementPtr fpe; /* FPE associated with this font */
pointer svrPrivate; /* X/FS private data */
pointer fontPrivate; /* private to font */
pointer fpePrivate; /* private to FPE */
int maxPrivate; /* devPrivates (see below) */
pointer *devPrivates; /* ... */
} FontRec, *FontPtr;typedef struct _Font {
int refcnt;
FontInfoRec info;
char bit; /* bit order: LSBFirst/MSBFirst */
char byte; /* byte order: LSBFirst/MSBFirst */
char glyph; /* glyph pad: 1, 2, 4 or 8 */
char scan; /* glyph scan unit: 1, 2 or 4 */
fsBitmapFormat format; /* FS-style format (packed) */
int (*get_glyphs) ( /* font, count, chars, encoding, count, glyphs */ );
int (*get_metrics) ( /* font, count, chars, encoding, count, glyphs */ );
int (*get_bitmaps) ( /* client, font, flags, format,
flags, nranges, ranges, data_sizep,
num_glyphsp, offsetsp, glyph_datap,
free_datap */ );
int (*get_extents) ( /* client, font, flags, nranges,
ranges, nextentsp, extentsp */);
void (*unload_font) ( /* font */ );
FontPathElementPtr fpe; /* FPE associated with this font */
pointer svrPrivate; /* X/FS private data */
pointer fontPrivate; /* private to font */
pointer fpePrivate; /* private to FPE */
int maxPrivate; /* devPrivates (see below) */
pointer *devPrivates; /* ... */
} FontRec, *FontPtr;
Yes, there are several different private pointers in the
Font structure; they were added
haphazardly until the devPrivate pointers were added. Future
releases may remove some (or all) of the specific pointers,
leaving only the devPrivatesmechanism.
There are two similar interfaces implemented -
get_glyphs/get_metrics
and
get_bitmaps/get_extents.
Too little time caused the font-server specific interfaces to
be placed in the font library (and portions duplicated in each
renderer) instead of having them integrated into the font server
itself. This may change. The X server uses only
get_glyphs/get_metrics,
and those will not change dramatically. Each of the routines
is described below.
This routine returns CharInfoPtrs for each of the requested characters in the font. If the character does not exist in the font, the default character will be returned, unless no default character exists in which case that character is skipped. Thus, the number of glyphs returned will not always be the same as the number of characters passed in.
This is similar to (*get_glyphs)
except that pointers to xCharInfo
structures are returned, and, if the font has ink metrics,
those are returned instead of the bitmap metrics.
This packs the glyph image data in the requested
format and returns it. The
ranges/nranges
argument specify the set of glyphs from the font to pack together.
This is called from the FPE routine
(*close_font), and so should not ever be
called from the application.