freetype2/include/freetype/ftglyph.h

/***************************************************************************/
/*                                                                         */
/*  ftglyph.h                                                              */
/*                                                                         */
/*    FreeType convenience functions to handle glyphs (specification).     */
/*                                                                         */
/*  Copyright 1996-2001 by                                                 */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* This file contains the definition of several convenience functions    */
  /* that can be used by client applications to easily retrieve glyph      */
  /* bitmaps and outlines from a given face.                               */
  /*                                                                       */
  /* These functions should be optional if you are writing a font server   */
  /* or text layout engine on top of FreeType.  However, they are pretty   */
  /* handy for many other simple uses of the library.                      */
  /*                                                                       */
  /*************************************************************************/


#ifndef __FTGLYPH_H__
#define __FTGLYPH_H__


#include <ft2build.h>
#include FT_FREETYPE_H


FT_BEGIN_HEADER


  /*************************************************************************/
  /*                                                                       */
  /* <Section>                                                             */
  /*    glyph_management                                                   */
  /*                                                                       */
  /* <Title>                                                               */
  /*    Glyph Management                                                   */
  /*                                                                       */
  /* <Abstract>                                                            */
  /*    Generic interface to manage individual glyph data.                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    This section contains definitions used to manage glyph data        */
  /*    through generic FT_Glyph objects.  Each of them can contain a      */
  /*    bitmap, a vector outline, or even images in other formats.         */
  /*                                                                       */
  /*************************************************************************/


  /* forward declaration to a private type */
  typedef struct FT_Glyph_Class_  FT_Glyph_Class;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Glyph                                                           */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Handle to an object used to model generic glyph images.  It is a   */
  /*    pointer to the @FT_GlyphRec structure and can contain a glyph      */
  /*    bitmap or pointer.                                                 */
  /*                                                                       */
  /* <Note>                                                                */
  /*    Glyph objects are not owned by the library.  You must thus release */
  /*    them manually (through @FT_Done_Glyph) _before_ calling            */
  /*    @FT_Done_FreeType.                                                 */
  /*                                                                       */
  typedef struct FT_GlyphRec_*  FT_Glyph;


  /*************************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FT_GlyphRec                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    The root glyph structure contains a given glyph image plus its     */
  /*    advance width in 16.16 fixed float format.                         */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    library :: A handle to the FreeType library object.                */
  /*                                                                       */
  /*    clazz   :: A pointer to the glyph's class.  Private.               */
  /*                                                                       */
  /*    format  :: The format of the glyph's image.                        */
  /*                                                                       */
  /*    advance :: A 16.16 vector that gives the glyph's advance width.    */
  /*                                                                       */
  typedef struct  FT_GlyphRec_
  {
    FT_Library             library;
    const FT_Glyph_Class*  clazz;
    FT_Glyph_Format        format;
    FT_Vector              advance;

  } FT_GlyphRec;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_BitmapGlyph                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to an object used to model a bitmap glyph image.  This is */
  /*    a sub-class of @FT_Glyph, and a pointer to @FT_BitmapGlyphRec.     */
  /*                                                                       */
  typedef struct FT_BitmapGlyphRec_*  FT_BitmapGlyph;


  /*************************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FT_BitmapGlyphRec                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A structure used for bitmap glyph images.  This really is a        */
  /*    `sub-class' of `FT_GlyphRec'.                                      */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    root   :: The root FT_Glyph fields.                                */
  /*                                                                       */
  /*    left   :: The left-side bearing, i.e., the horizontal distance     */
  /*              from the current pen position to the left border of the  */
  /*              glyph bitmap.                                            */
  /*                                                                       */
  /*    top    :: The top-side bearing, i.e., the vertical distance from   */
  /*              the current pen position to the top border of the glyph  */
  /*              bitmap.  This distance is positive for upwards-y!        */
  /*                                                                       */
  /*    bitmap :: A descriptor for the bitmap.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    You can typecast FT_Glyph to FT_BitmapGlyph if you have            */
  /*    glyph->format == FT_GLYPH_FORMAT_BITMAP.  This lets you access     */
  /*    the bitmap's contents easily.                                      */
  /*                                                                       */
  /*    The corresponding pixel buffer is always owned by the BitmapGlyph  */
  /*    and is thus created and destroyed with it.                         */
  /*                                                                       */
  typedef struct  FT_BitmapGlyphRec_
  {
    FT_GlyphRec  root;
    FT_Int       left;
    FT_Int       top;
    FT_Bitmap    bitmap;

  } FT_BitmapGlyphRec;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_OutlineGlyph                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to an object used to model an outline glyph image.  This  */
  /*    is a sub-class of @FT_Glyph, and a pointer to @FT_OutlineGlyphRec. */
  /*                                                                       */
  typedef struct FT_OutlineGlyphRec_*  FT_OutlineGlyph;


  /*************************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FT_OutlineGlyphRec                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A structure used for outline (vectorial) glyph images.  This       */
  /*    really is a `sub-class' of `FT_GlyphRec'.                          */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    root    :: The root FT_Glyph fields.                               */
  /*                                                                       */
  /*    outline :: A descriptor for the outline.                           */
  /*                                                                       */
  /* <Note>                                                                */
  /*    You can typecast FT_Glyph to FT_OutlineGlyph if you have           */
  /*    glyph->format == FT_GLYPH_FORMAT_OUTLINE.  This lets you access    */
  /*    the outline's content easily.                                      */
  /*                                                                       */
  /*    As the outline is extracted from a glyph slot, its coordinates are */
  /*    expressed normally in 26.6 pixels, unless the flag                 */
  /*    FT_LOAD_NO_SCALE was used in FT_Load_Glyph() or FT_Load_Char().    */
  /*                                                                       */
  /*    The outline's tables are always owned by the object and are        */
  /*    destroyed with it.                                                 */
  /*                                                                       */
  typedef struct  FT_OutlineGlyphRec_
  {
    FT_GlyphRec  root;
    FT_Outline   outline;

  } FT_OutlineGlyphRec;


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Get_Glyph                                                       */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A function used to extract a glyph image from a slot.              */
  /*                                                                       */
  /* <Input>                                                               */
  /*    slot   :: A handle to the source glyph slot.                       */
  /*                                                                       */
  /* <Output>                                                              */
  /*    aglyph :: A handle to the glyph object.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Get_Glyph( FT_GlyphSlot  slot,
                FT_Glyph     *aglyph );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Glyph_Copy                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A function used to copy a glyph image.                             */
  /*                                                                       */
  /* <Input>                                                               */
  /*    source :: A handle to the source glyph object.                     */
  /*                                                                       */
  /* <Output>                                                              */
  /*    target :: A handle to the target glyph object.  0 in case of       */
  /*              error.                                                   */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Glyph_Copy( FT_Glyph   source,
                 FT_Glyph  *target );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Glyph_Transform                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Transforms a glyph image if its format is scalable.                */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    glyph  :: A handle to the target glyph object.                     */
  /*                                                                       */
  /* <Input>                                                               */
  /*    matrix :: A pointer to a 2x2 matrix to apply.                      */
  /*                                                                       */
  /*    delta  :: A pointer to a 2d vector to apply.  Coordinates are      */
  /*              expressed in 1/64th of a pixel.                          */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code (the glyph format is not scalable if it is     */
  /*    not zero).                                                         */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The 2x2 transformation matrix is also applied to the glyph's       */
  /*    advance vector.                                                    */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Glyph_Transform( FT_Glyph    glyph,
                      FT_Matrix*  matrix,
                      FT_Vector*  delta );

  /* */

  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Glyph_Get_CBox                                                  */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Returns a glyph's `control box'.  The control box encloses all the */
  /*    outline's points, including Bezier control points.  Though it      */
  /*    coincides with the exact bounding box for most glyphs, it can be   */
  /*    slightly larger in some situations (like when rotating an outline  */
  /*    which contains Bezier outside arcs).                               */
  /*                                                                       */
  /*    Computing the control box is very fast, while getting the bounding */
  /*    box can take much more time as it needs to walk over all segments  */
  /*    and arcs in the outline.  To get the latter, you can use the       */
  /*    `ftbbox' component which is dedicated to this single task.         */
  /*                                                                       */
  /* <Input>                                                               */
  /*    glyph :: A handle to the source glyph object.                      */
  /*                                                                       */
  /*    mode  :: The mode which indicates how to interpret the returned    */
  /*             bounding box values.                                      */
  /*                                                                       */
  /* <Output>                                                              */
  /*    acbox :: The glyph coordinate bounding box.  Coordinates are       */
  /*             expressed in 1/64th of pixels if it is grid-fitted.       */
  /*                                                                       */
  /* <Note>                                                                */
  /*    Coordinates are relative to the glyph origin, using the Y-upwards  */
  /*    convention.                                                        */
  /*                                                                       */
  /*    If the glyph has been loaded with FT_LOAD_NO_SCALE, `bbox_mode'    */
  /*    must be set to `ft_glyph_bbox_unscaled' to get unscaled font       */
  /*    units.                                                             */
  /*                                                                       */
  /*    If `bbox_mode' is set to `ft_glyph_bbox_subpixels' the bbox        */
  /*    coordinates are returned in 26.6 pixels (i.e. 1/64th of pixels).   */
  /*                                                                       */
  /*    Note that the maximum coordinates are exclusive, which means that  */
  /*    one can compute the width and height of the glyph image (be it in  */
  /*    integer or 26.6 pixels) as:                                        */
  /*                                                                       */
  /*      width  = bbox.xMax - bbox.xMin;                                  */
  /*      height = bbox.yMax - bbox.yMin;                                  */
  /*                                                                       */
  /*    Note also that for 26.6 coordinates, if `bbox_mode' is set to      */
  /*    `ft_glyph_bbox_gridfit', the coordinates will also be grid-fitted, */
  /*    which corresponds to:                                              */
  /*                                                                       */
  /*      bbox.xMin = FLOOR(bbox.xMin);                                    */
  /*      bbox.yMin = FLOOR(bbox.yMin);                                    */
  /*      bbox.xMax = CEILING(bbox.xMax);                                  */
  /*      bbox.yMax = CEILING(bbox.yMax);                                  */
  /*                                                                       */
  /*    To get the bbox in pixel coordinates, set `bbox_mode' to           */
  /*    `ft_glyph_bbox_truncate'.                                          */
  /*                                                                       */
  /*    To get the bbox in grid-fitted pixel coordinates, set `bbox_mode'  */
  /*    to `ft_glyph_bbox_pixels'.                                         */
  /*                                                                       */
  /*    The default value for `bbox_mode' is `ft_glyph_bbox_pixels'.       */
  /*                                                                       */
  enum
  {
    ft_glyph_bbox_unscaled  = 0, /* return unscaled font units           */
    ft_glyph_bbox_subpixels = 0, /* return unfitted 26.6 coordinates     */
    ft_glyph_bbox_gridfit   = 1, /* return grid-fitted 26.6 coordinates  */
    ft_glyph_bbox_truncate  = 2, /* return coordinates in integer pixels */
    ft_glyph_bbox_pixels    = 3  /* return grid-fitted pixel coordinates */
  };


  FT_EXPORT( void )
  FT_Glyph_Get_CBox( FT_Glyph  glyph,
                     FT_UInt   bbox_mode,
                     FT_BBox  *acbox );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Glyph_To_Bitmap                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Converts a given glyph object to a bitmap glyph object.            */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    the_glyph   :: A pointer to a handle to the target glyph.          */
  /*                                                                       */
  /* <Input>                                                               */
  /*    render_mode :: An enumeration that describe how the data is        */
  /*                   rendered.                                           */
  /*                                                                       */
  /*    origin      :: A pointer to a vector used to translate the glyph   */
  /*                   image before rendering.  Can be 0 (if no            */
  /*                   translation).  The origin is expressed in           */
  /*                   26.6 pixels.                                        */
  /*                                                                       */
  /*    destroy     :: A boolean that indicates that the original glyph    */
  /*                   image should be destroyed by this function.  It is  */
  /*                   never destroyed in case of error.                   */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The glyph image is translated with the `origin' vector before      */
  /*    rendering.  In case of error, it it translated back to its         */
  /*    original position and the glyph is left untouched.                 */
  /*                                                                       */
  /*    The first parameter is a pointer to a FT_Glyph handle, that will   */
  /*    be replaced by this function.  Typically, you would use (omitting  */
  /*    error handling):                                                   */
  /*                                                                       */
  /*                                                                       */
  /*      {                                                                */
  /*        FT_Glyph        glyph;                                         */
  /*        FT_BitmapGlyph  glyph_bitmap;                                  */
  /*                                                                       */
  /*                                                                       */
  /*        // load glyph                                                  */
  /*        error = FT_Load_Char( face, glyph_index, FT_LOAD_DEFAUT );     */
  /*                                                                       */
  /*        // extract glyph image                                         */
  /*        error = FT_Get_Glyph( face->glyph, &glyph );                   */
  /*                                                                       */
  /*        // convert to a bitmap (default render mode + destroy old)     */
  /*        if ( glyph->format != FT_GLYPH_FORMAT_BITMAP )                 */
  /*        {                                                              */
  /*          error = FT_Glyph_To_Bitmap( &glyph, ft_render_mode_default,  */
  /*                                      0, 1 );                          */
  /*          if ( error ) // glyph unchanged                              */
  /*            ...                                                        */
  /*        }                                                              */
  /*                                                                       */
  /*        // access bitmap content by typecasting                        */
  /*        glyph_bitmap = (FT_BitmapGlyph)glyph;                          */
  /*                                                                       */
  /*        // do funny stuff with it, like blitting/drawing               */
  /*        ...                                                            */
  /*                                                                       */
  /*        // discard glyph image (bitmap or not)                         */
  /*        FT_Done_Glyph( glyph );                                        */
  /*      }                                                                */
  /*                                                                       */
  /*                                                                       */
  /*    This function will always fail if the glyph's format isn't         */
  /*    scalable.                                                          */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Glyph_To_Bitmap( FT_Glyph*       the_glyph,
                      FT_Render_Mode  render_mode,
                      FT_Vector*      origin,
                      FT_Bool         destroy );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Done_Glyph                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Destroys a given glyph.                                            */
  /*                                                                       */
  /* <Input>                                                               */
  /*    glyph :: A handle to the target glyph object.                      */
  /*                                                                       */
  FT_EXPORT( void )
  FT_Done_Glyph( FT_Glyph  glyph );


  /* other helpful functions */

  /*************************************************************************/
  /*                                                                       */
  /* <Section>                                                             */
  /*    computations                                                       */
  /*                                                                       */
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Matrix_Multiply                                                 */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Performs the matrix operation `b = a*b'.                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    a :: A pointer to matrix `a'.                                      */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    b :: A pointer to matrix `b'.                                      */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The result is undefined if either `a' or `b' is zero.              */
  /*                                                                       */
  FT_EXPORT( void )
  FT_Matrix_Multiply( FT_Matrix*  a,
                      FT_Matrix*  b );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    FT_Matrix_Invert                                                   */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Inverts a 2x2 matrix.  Returns an error if it can't be inverted.   */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    matrix :: A pointer to the target matrix.  Remains untouched in    */
  /*              case of error.                                           */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  FT_EXPORT( FT_Error )
  FT_Matrix_Invert( FT_Matrix*  matrix );


  /* */


FT_END_HEADER

#endif /* __FTGLYPH_H__ */


/* END */