asfont.h(1)

libAfterImage/asfont.h
 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.
 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()
 Other libAfterImage modules :
     asimage.h, asvisual.h, blender.h, import.h
  Sasha Vasko <sashav at sprintmail dot com>

libAfterImage/MAX_GLYPHS_PER_FONT
 Max value of glyphs per font allowed. We need that so we can detect
 and avoid broken fonts somehow.
    #define MAX_GLYPHS_PER_FONT  2048

libAfterImage/ASFontType
 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.
    typedef enum
    {
        ASF_X11 = 0,
        ASF_Freetype,
        ASF_GuessWho
    }ASFontType;

libAfterImage/CHAR_SIZE
 Convinient macro so we can transparently determine the number of
 bytes that character spans. It assumes UTF-8 encoding when I18N is
 enabled.
    #ifdef I18N
    /* size of the UTF-8 encoded character is based on value of the first byte : */
    #define CHAR_SIZE(c)    (((c)&0x80)?(((c)&0x40)?(((c)&0x20)?(((c)&0x10)?5:4):3):2):1)
    #else
    #define CHAR_SIZE(c)    1
    #endif

libAfterImage/ASGlyph
  ASGlyph

 Stores glyph's image, as well as width, height and other
 characteristics of the glyph.
    typedef struct ASGlyph
    {
        CARD8          *pixmap ;        /* glyph's RLE encoded pixmap */
        unsigned 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 */
        short  ascend, descend ;        /* distance of the top of the
                                         * glyph from the baseline */
    }ASGlyph;

libAfterImage/ASGlyphRange
  ASGlyphRange

 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.
    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
  ASFont

 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.
    typedef struct ASFont
    {
        unsigned long   magic ;

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

        ASFontType      type ;
        ASGlyphRange   *codemap;        /* linked list of glyphsets, each
                                         * representing continuos range of
                                         * available codes */
        ASGlyph         default_glyph;  /* valid glyph to be drawn when
                                         * code is not valid */

        unsigned int    max_height,     /* maximiu height of the character
                                         * glyph */
                        max_ascend,     /* maximum distance from the baseline
                                         * to the top of the character glyph */
                        space_size;     /* fixed width value to be used when
                                         * rendering spaces and tabs */
    #define LEFT_TO_RIGHT    1
    #define RIGHT_TO_LEFT   -1
        int             pen_move_dir ;  /* direction of the text flow */
    #ifdef HAVE_FREETYPE
        FT_Face         ft_face;        /* free type font handle */
    #else
        CARD32         *pad;
    #endif

    }ASFont;

libAfterImage/ASFontManager
  ASFontManager

 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.
    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
 Available types of 3D text to be drawn.
    typedef enum ASText3DType{
        AST_Plain =0,                              /* regular 2D text */
        AST_Embossed,
        AST_Sunken,
        AST_ShadeAbove,
        AST_ShadeBelow,
        AST_EmbossedThick,
        AST_SunkenThick,
        AST_3DTypes
    }ASText3DType;

libAfterImage/asfont/create_font_manager()
 ASFontManager *create_font_manager( Display *dpy,
                                     const char *font_path,
                                     ASFontManager *reusable_memory );
 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
 Pointer to Initialized ASFontManager object on success.
 NULL otherwise.
 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.

libAfterImage/asfont/destroy_font_manager()
 void destroy_font_manager( ASFontManager *fontman,
                            Bool reusable );
 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
            usefull for structures created on stack.
 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.

libAfterImage/asfont/open_freetype_font()
 ASFont *open_freetype_font( ASFontManager *fontman,
                             const char *font_string,
                             int face_no,
                             int size, Bool verbose);
 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.
 pointer to Opened ASFont structure, containing all the glyphs of the
 font, as well as other relevant info. On failure returns NULL.
 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 extention as a face number, and try and
 find the file with extention 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.

libAfterImage/asfont/open_X11_font()
 ASFont *open_X11_font( ASFontManager *fontman,
                        const char *font_string);
 fontman     - pointer to previously created ASFontManager. Needed for
               connection X Server.
 font_string - name of the font as recognized by Xlib.
 pointer to Opened ASFont structure, containing all the glyphs of the
 font, as well as other relevant info. On failure returns NULL.
 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.
 implement proper XFontSet support, when used with I18N enabled.

libAfterImage/asfont/get_asfont()
 ASFont *get_asfont( ASFontManager *fontman,
                     const char *font_string,
                     int face_no, int size,
                     ASFontType type );
 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.
 pointer to Opened ASFont structure, containing all the glyphs of the
 font, as well as other relevant info. On failure returns NULL.
 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.

libAfterImage/asfont/destroy_font()
 void destroy_font( ASFont *font );
 font - pointer to the valid ASFont structure containing loaded font.
 This function will close the font, remove it from ASFontManager's
 list, destroy all the glyphs and generally free everything else used
 by ASFont.

libAfterImage/asfont/print_asfont()
 void    print_asfont( FILE* stream,
                       ASFont* font);
 stream - output file pointer
 font   - pointer to ASFont structure to print.
 prints all the geometry information about font.

libAfterImage/asfont/print_asglyph()
 void   print_asglyph( FILE* stream,
                         ASFont* font, unsigned long c);
 stream - output file pointer
 font   - pointer to ASFont structure to print.
 c      - character code to print glyph for
 prints out contents of the cached glyph for specifyed character code.

libAfterImage/asfont/draw_text()
 ASImage *draw_text( const char *text,
                     ASFont *font, ASText3DType type,
                     int compression );
 Bool get_text_size( const char *text,
                     ASFont *font, ASText3DType type,
                     unsigned int *width, unsigned int *height );
 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.
 Pointer to new ASImage containing rendered text on success.
 NULL on failure.
 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.