asfont(1)                AfterStep X11 window manager                asfont(1)



NAME
       asfont - text drawing functionality and handling of TTF and X11 fonts
       libAfterImage/asfont.h

NAMEasfont
DESCRIPTION
       Text drawing functionality.  Text is drawn as an ASImage with only
       alpha channel. Since alpha channel is 8 bit widths that allows for 256
       shades to be used in rendered glyphs. That in turn allows for smoothing
       and antialiasing of the drawn text. Such an approcah allows for easy
       manipulation of the drawn text, such as changing color, making it
       transparent, texturizing, rotation, etc.

       libAfterImage supports two types of fonts : Fonts that could be
       rendered using standard Xlib functionality, and fonts rendered by
       FreeType 2 library. That may include TrueType fonts. When fonts are
       obtained via Xlib special processing is performed in order to smooth
       its shape and leverage 256 shades palette available.

       Any font being used is has to be opened first. At that time its
       properties are analysed and glyphs are cached in clients memory.
       Special RLE compression method is used for font glyphs, significantly
       reducing memory utilization without any effect on performance.

       Font management and drawing functionality has been designed with
       internatiolization in mind, althou support for locales is not complete
       yet.

SEE ALSO
       Structures :
                ASFontManager
                ASFont
                ASGlyph
                ASGlyphRange

       Functions :
                create_font_manager(), destroy_font_manager(),
                open_freetype_font(), open_X11_font(), get_asfont(),
                destroy_font(), print_asfont(), print_asglyph(),
                draw_text(),
                get_asfont_glyph_spacing(), set_asfont_glyph_spacing()

       Other libAfterImage modules :
                ascmap.h asfont.h asimage.h asvisual.h blender.h export.h
                import.h transform.h ximage.h

AUTHOR
       Sasha Vasko <sasha at aftercode dot net>

NAMEMAX_GLYPHS_PER_FONT
       - Max value of glyphs per font allowed. We need that so we can detect
       and avoid broken fonts somehow.


SOURCE
           #define MAX_GLYPHS_PER_FONT  2048
       libAfterImage/ASFontType

NAMEASFontType
       - Supported types of fonts - Xlib or FreeType 2 ASF_GuessWho will
       enable autodetection of the font type. It is attempted to be opened as
       FreeType font first, and if that fails - it will be opened as Xlib
       font.


SOURCE
           typedef enum {
               ASF_X11         = 0,
               ASF_Freetype    = (0x01<<0),
               ASF_GuessWho    = (0x01<<1), #define ASF_TypeMask
           (ASF_GuessWho|ASF_Freetype)

               /* flags below should be combined with one of the above values
           */
               ASF_Monospaced  = (0x01<<2),
               ASF_RightToLeft = (0x01<<3),  /* direction of the text flow */
               ASF_HasKerning  = (0x01<<4) }ASFontType;
       libAfterImage/ASGlyph

NAMEASGlyph
DESCRIPTION
       Stores glyph's image, as well as width, height and other
       characteristics of the glyph.

SOURCE
           typedef struct ASGlyph {
               CARD8          *pixmap ;        /* glyph's RLE encoded pixmap
           */
               short   width, height ; /* meaningfull width and height
                                                * of the glyphs pixmap */
               short  lead, step ;             /* distance pen position to
           glyph
                                                * beginning and to the next
           glyph */
                                               /* in XRender it should be used
           as so:
                                                * x = -lead, xOff = step
                                                */
               short  ascend, descend ;        /* distance of the top of the
                                                * glyph from the baseline */
                                               /* in XRender it should be used
           as so:
                                                * y = -ascend, yOff = 0
                                                */
               unsigned int font_gid ;         /* index of the glyph inside
           the font( TTF only ) */
               long         xrender_gid ;      /* Used only with XRender  -
           gid of the glyph in GlyphSet */ }ASGlyph;
       libAfterImage/ASGlyphRange

NAMEASGlyphRange
DESCRIPTION
       Organizes glyphs that belongs to the continuos range of char codes.
       ASGlyphRange structures could be tied together to cover entire codeset
       supported by the font.

SOURCE
           typedef struct ASGlyphRange {
               unsigned long   min_char, max_char; /* Code range.
                                                    * for some locales that
           would
                                                    * be sufficient to simply
           set
                                                    * range of characteres
                                                    * supported by font */
               ASGlyph *glyphs;                    /* array of glyphs
           belonging to
                                                    * that code range */
               struct ASGlyphRange *below, *above; }ASGlyphRange;
       libAfterImage/ASFont

NAMEASFont
DESCRIPTION
       Structure to contain all the font characteristics, as well as set of
       glyph images. Such structure has to be created/opened prior to being
       able to draw characters with any font.

SOURCE
           typedef struct ASFont {
               unsigned long   magic ;
               int             ref_count ;

               struct ASFontManager *fontman;  /* our owner */
               char                 *name;

               ASFontType      type ;
               ASFlagType      flags ;

               ASGlyphRange   *codemap; /* linked list of glyphsets, each
                                         * representing continuos range of
                                         * available codes - used for ASCII
                                         * codes */
               ASHashTable    *locale_glyphs;  /* hash of locale specific
           glyphs */

               ASGlyph         default_glyph;  /* valid glyph to be drawn when
                                                * code is not valid */

               int             max_height;  /* maximiu height of the character
                                             * glyph */
               int             max_ascend,  /* maximum distance from the
           baseline
                                             * to the top of the character
           glyph */
                               max_descend; /* need both descend and ascend to
           be
                                               able to dynamically recalculate
           font
                                               height while adding new
           characters */
               int             space_size;  /* fixed width value to be used
           when
                                             * rendering spaces and tabs */
               int             spacing_x, spacing_y;
               /* If these are set to anything above 0 then all the glyphs has
           to be
                * padded ( if its smaller then the cell ) or scaled down
                * ( if its bigger then the cell )
                */
               int    cell_width, cell_height ;

           #ifdef HAVE_FREETYPE
               FT_Face         ft_face;        /* free type font handle */
           #else
               CARD32         *pad; #endif

               unsigned long   xrender_glyphset ;  /* GlyphSet is the actuall
           datatype,
                                                    * but for easier
           compilation -
                                                    * we use generic which is
           the same */ }ASFont;
       libAfterImage/ASFontManager

NAMEASFontManager
DESCRIPTION
       Global data identifying connection to external libraries, as well as
       fonts location paths.  This structure has to be created/initialized
       prior to any font being loaded.  It also holds list of fonts that are
       currently open, allowing for easy access to fonts.  When ASFontManagaer
       object is destroyd it automagically closes all the open fonts.

SOURCE
           typedef struct ASFontManager {
               Display    *dpy;
               char       *font_path ;

               ASHashTable *fonts_hash ;

               size_t       unicode_used;
               CARD32      *local_unicode; /* list of unicodes from current
           locale
                                            * - we use it to limit number of
           glyphs
                                            * we load */
               Bool        ft_ok ; #ifdef HAVE_FREETYPE
               FT_Library  ft_library;     /* free type library handle */
           #else
               void       *pad ; #endif }ASFontManager;
       libAfterImage/ASText3DType

NAMEASText3DType
       - Available types of 3D text to be drawn.


SOURCE
           typedef enum ASText3DType{
               AST_Plain =0,                              /* regular 2D text
           */
               AST_Embossed,
               AST_Sunken,
               AST_ShadeAbove,
               AST_ShadeBelow,
               AST_EmbossedThick,
               AST_SunkenThick,
               AST_OutlineAbove,
               AST_OutlineBelow,
               AST_OutlineFull,
               AST_3DTypes }ASText3DType;
       libAfterImage/ASTextAttributes

NAMEASTextAttributes
       - Attributes for text rendering


SOURCE
           typedef struct ASTextAttributes { #define ASTA_UseTabStops
           (0x01<<0)
               unsigned int version ;
                               /* structure version, so we can implement
           future
                                * extensions without breaking binary apps */
               ASFlagType   rendition_flags ;
               ASText3DType type;
               ASCharType   char_type;
               unsigned int tab_size ;   /* tab size in chars  - defaults to 8
           */
               unsigned int origin ;     /* distance from the left margin
                                          * (in pixels) */
               unsigned int *tab_stops ; /* tab stops in pixels where
                                          * left margin is 0 */
               unsigned int tab_stops_num ;

               ARGB32      fore_color ;   /* used with 3D type of Outlined */
             unsigned int width; #define ASTA_VERSION_1  1

           #define ASTA_VERSION_INTERNAL   ASTA_VERSION_1 }ASTextAttributes;
       libAfterImage/asfont/create_font_manager()

NAMEcreate_font_manager()
SYNOPSIS
       ASFontManager *create_font_manager( Display *dpy,
                                           const char *font_path,
                                           ASFontManager *reusable_memory );

INPUTS
       dpy    - pointer to valid and opened Display.

       font_path
              - string, representing colon separated list of directories to
              search for FreeType fonts.

       reusable_memory
              - optional preallocated memory for the ASFontMagaer object


RETURN VALUE
       Pointer to Initialized ASFontManager object on success.  NULL
       otherwise.

DESCRIPTION
       create_font_manager() will create new ASFontManager structure if
       needed. It wioll then store copy of font_path and supplied pointer to
       Display in it. At that time Hash table of loaded fonts is initialized,
       and if needed FreeType library is initialized as well.  ASFontManager
       object returned by this functions has to be open at all times untill
       text drawing is no longer needed.

NAMEdestroy_font_manager()
SYNOPSIS
       void destroy_font_manager( ASFontManager *fontman,
                                  Bool reusable );

INPUTS
       fontman
              - pointer to valid ASFontManager object to be deallocated.

       reusable
              - If True, then memory holding object itself will not be freed -
              only resources will be deallocated. That is useful for
              structures created on stack.


DESCRIPTION
       destroy_font_manager() closes all the fonts open with this
       ASFontManager. It will also close connection to FreeType library, and
       deallocate all cached data. If reusable is False - then memory used for
       object itself will not be freed.

NAMEopen_freetype_font()
SYNOPSIS
       ASFont *open_freetype_font( ASFontManager *fontman,
                                   const char *font_string,
                                   int face_no,
                                   int size, Bool verbose);

INPUTS
       fontman
              - pointer to previously created ASFontManager. Needed for
              connection to FreeType library, as well as path to search fonts
              in.

       font_string
              - filename of the file containing font's data.

       face_no
              - number of face within the font file

       size   - font size in points. Applicable only to scalable fonts, such
              as TrueType.

       verbose
              - if True, extensive error messages will be printed if problems
              encountered.


RETURN VALUE
       pointer to Opened ASFont structure, containing all the glyphs of the
       font, as well as other relevant info. On failure returns NULL.

DESCRIPTION
       open_freetype_font() will attempt to find font file in any of the
       directories specified in ASFontManager's font_path. If it fails to do
       so - then it will check if filename has alldigit extentions. It will
       then try to interpret that extension as a face number, and try and find
       the file with extension stripped off.  If file was found function will
       atempt to read it using FreeType library. If requested face is not
       available in the font - face 0 will be used.  On success all the font's
       glyphs will be rendered and cached, and needed font geometry info
       collected.  When FreeType Library is not available that function does
       nothing.

NAMEopen_X11_font()
SYNOPSIS
       ASFont *open_X11_font( ASFontManager *fontman,
                              const char *font_string);

INPUTS
       fontman
              - pointer to previously created ASFontManager. Needed for
              connection X Server.

       font_string
              - name of the font as recognized by Xlib.


RETURN VALUE
       pointer to Opened ASFont structure, containing all the glyphs of the
       font, as well as other relevant info. On failure returns NULL.

DESCRIPTION
       open_X11_font() attempts to load and query font using Xlib calls.  On
       success it goes thgroughthe codemap of the font and renders all the
       glyphs available. Glyphs then gets transfered to the client's memory
       and encoded using RLE compression. At this time smoothing filters are
       applied on glyph pixmaps, if its size exceeds threshold.

TODO
       implement proper XFontSet support, when used with I18N enabled.

NAMEget_asfont()
SYNOPSIS
       ASFont *get_asfont( ASFontManager *fontman,
                           const char *font_string,
                           int face_no, int size,
                           ASFontType type );

INPUTS
       fontman
              - pointer to previously created ASFontManager. Needed for
              connection to FreeType library, path to search fonts in, and X
              Server connection.

       font_string
              - font name or filename of the file containing font's data.

       face_no
              - number of face within the font file

       size   - font size in points. Applicable only to scalable fonts, such
              as TrueType.

       type   - specifies the type of the font, or GuessWho for autodetection.


RETURN VALUE
       pointer to Opened ASFont structure, containing all the glyphs of the
       font, as well as other relevant info. On failure returns NULL.

DESCRIPTION
       This function provides unified interface to font loading. It performs
       search in ASFontManager's list to see if this specific font has been
       loaded already, and if so - returns pointer to relevant structure.
       Otherwise it tryes to load font as FreeType font first, and then Xlib
       font, unless exact font type is specifyed.

NAMErelease_font()
SYNOPSIS
       void release_font( ASFont *font );

INPUTS
       font   - pointer to the valid ASFont structure containing loaded font.


RETURN VALUE
       returns current reference count. -1 means that object has been
       destroyed.

DESCRIPTION
       This function will decrement reference count on loaded font and if
       reference count will be less then 0 ( meaning that release_font() has
       been called more times then get_asfont() ) it will close the font,
       remove it from ASFontManager's list, destroy all the glyphs and
       generally free everything else used by ASFont.  Otherwise font will
       remain in memory for faster reuse.

NAMEprint_asfont()
SYNOPSIS
       void    print_asfont( FILE* stream,
                             ASFont* font);

INPUTS
       stream - output file pointer

       font   - pointer to ASFont structure to print.


DESCRIPTION
       prints all the geometry information about font.

NAMEprint_asglyph()
SYNOPSIS
       void    print_asglyph( FILE* stream,
                               ASFont* font, unsigned long c);

INPUTS
       stream - output file pointer

       font   - pointer to ASFont structure to print.

       c      - character code to print glyph for


DESCRIPTION
       prints out contents of the cached glyph for specifyed character code.

NAMEdraw_text()
       draw_fancy_text()

       get_text_size()

       get_fancy_text_size();



SYNOPSIS
       ASImage *draw_text( const char *text,
                           ASFont *font, ASText3DType type,
                           int compression ); ASImage *draw_fancy_text( const
       void *text,
                                struct ASFont *font, ASTextAttributes *attr,
                                    int compression,
                                    int length ); Bool get_text_size( const
       char *text,
                           ASFont *font, ASText3DType type,
                           unsigned int *width, unsigned int *height ); Bool
       get_fancy_text_size( const void *text,
                                    struct ASFont *font, ASTextAttributes
       *attr,
                                unsigned int *width, unsigned int *height,
                                    int length,
                                    int *x_positions );

INPUTS
       text   - actuall text to render

       font   - pointer to ASFont to render text with

       type   - one of the few available types of 3D text.

       compression
              - compression level to attempt on resulting ASImage.

       width  - pointer to value to be set to text width.

       height - pointer to value to be set to text height.


RETURN VALUE
       Pointer to new ASImage containing rendered text on success.  NULL on
       failure.

DESCRIPTION
       draw_text() creates new ASImage of the size big enough to contain
       entire text. It then renders the text using supplied font as an alpha
       channel of ASImage.  get_text_size() can be used to determine the size
       of the text about to be drawn, so that appropriate drawable can be
       prepared.

NAMEget_asfont_glyph_spacing()
SYNOPSIS
       Bool get_asfont_glyph_spacing( ASFont* font, int *x, int *y );

INPUTS
       font   - Loaded ASFont structure.

       x      - pointer to the variable to receive horizontal spacing value.

       y      - pointer to the variable to receive vertical spacing value.


RETURN VALUE
       True if meaningfull information has been returned.

DESCRIPTION
       Returns inter-glyph spacing of specified font.

NAMEset_asfont_glyph_spacing()
SYNOPSIS
       Bool set_asfont_glyph_spacing( ASFont* font, int x, int y );

INPUTS
       font   - Loaded ASFont structure.

       x      - new horizontal spacing value.

       y      - new vertical spacing value.


RETURN VALUE
       TRue on success.

DESCRIPTION
       Changes inter-glyph spacing of the specified font.



3rd Berkeley Distribution     AfterStep v.2.2.12                     asfont(1)
