Provided by: libafterimage-dev_2.2.12-2_amd64 bug

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>
       libAfterImage/MAX_GLYPHS_PER_FONT

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.
       libAfterImage/asfont/destroy_font_manager()

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.
       libAfterImage/asfont/open_freetype_font()

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.
       libAfterImage/asfont/open_X11_font()

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
       transferred  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.
       libAfterImage/asfont/get_asfont()

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.
       libAfterImage/asfont/release_font()

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.
       libAfterImage/asfont/print_asfont()

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.
       libAfterImage/asfont/print_asglyph()

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.
       libAfterImage/asfont/draw_text()

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.
       libAfterImage/asfont/get_asfont_glyph_spacing()

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.
       libAfterImage/asfont/set_asfont_glyph_spacing()

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.