freetype2/include/freetype/ftglyph.h

/****************************************************************************
 *
 * ftglyph.h
 *
 *   FreeType convenience functions to handle glyphs (specification).
 *
 * Copyright 1996-2018 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

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif


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-point 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 an @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 @FT_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 an @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.  Note that
   *   the created @FT_Glyph object must be released with @FT_Done_Glyph.
   *
   * @Input:
   *   slot ::
   *     A handle to the source glyph slot.
   *
   * @Output:
   *   aglyph ::
   *     A handle to the glyph object.
   *
   * @Return:
   *   FreeType error code.  0~means success.
   *
   * @Note:
   *   Because `*aglyph->advance.x' and '*aglyph->advance.y' are 16.16
   *   fixed-point numbers, `slot->advance.x' and `slot->advance.y'
   *   (which are in 26.6 fixed-point format) must be in the range
   *   ]-32768;32768[.
   */
  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.  Note that the created
   *   @FT_Glyph object must be released with @FT_Done_Glyph.
   *
   * @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:
   *   Transform 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 (if not 0, the glyph format is not scalable).
   *
   * @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 );


  /**************************************************************************
   *
   * @Enum:
   *   FT_Glyph_BBox_Mode
   *
   * @Description:
   *   The mode how the values of @FT_Glyph_Get_CBox are returned.
   *
   * @Values:
   *   FT_GLYPH_BBOX_UNSCALED ::
   *     Return unscaled font units.
   *
   *   FT_GLYPH_BBOX_SUBPIXELS ::
   *     Return unfitted 26.6 coordinates.
   *
   *   FT_GLYPH_BBOX_GRIDFIT ::
   *     Return grid-fitted 26.6 coordinates.
   *
   *   FT_GLYPH_BBOX_TRUNCATE ::
   *     Return coordinates in integer pixels.
   *
   *   FT_GLYPH_BBOX_PIXELS ::
   *     Return grid-fitted pixel coordinates.
   */
  typedef enum  FT_Glyph_BBox_Mode_
  {
    FT_GLYPH_BBOX_UNSCALED  = 0,
    FT_GLYPH_BBOX_SUBPIXELS = 0,
    FT_GLYPH_BBOX_GRIDFIT   = 1,
    FT_GLYPH_BBOX_TRUNCATE  = 2,
    FT_GLYPH_BBOX_PIXELS    = 3

  } FT_Glyph_BBox_Mode;


  /* these constants are deprecated; use the corresponding */
  /* `FT_Glyph_BBox_Mode' values instead                   */
#define ft_glyph_bbox_unscaled   FT_GLYPH_BBOX_UNSCALED
#define ft_glyph_bbox_subpixels  FT_GLYPH_BBOX_SUBPIXELS
#define ft_glyph_bbox_gridfit    FT_GLYPH_BBOX_GRIDFIT
#define ft_glyph_bbox_truncate   FT_GLYPH_BBOX_TRUNCATE
#define ft_glyph_bbox_pixels     FT_GLYPH_BBOX_PIXELS


  /**************************************************************************
   *
   * @Function:
   *   FT_Glyph_Get_CBox
   *
   * @Description:
   *   Return 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
   *   that 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 that 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 in 26.6 pixel format.  The value @FT_GLYPH_BBOX_SUBPIXELS
   *   is another name for this constant.
   *
   *   If the font is tricky and the glyph has been loaded with
   *   @FT_LOAD_NO_SCALE, the resulting CBox is meaningless.  To get
   *   reasonable values for the CBox it is necessary to load the glyph
   *   at a large ppem value (so that the hinting instructions can
   *   properly shift and scale the subglyphs), then extracting the CBox,
   *   which can be eventually converted back to font units.
   *
   *   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.
   */
  FT_EXPORT( void )
  FT_Glyph_Get_CBox( FT_Glyph  glyph,
                     FT_UInt   bbox_mode,
                     FT_BBox  *acbox );


  /**************************************************************************
   *
   * @Function:
   *   FT_Glyph_To_Bitmap
   *
   * @Description:
   *   Convert 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 describes 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:
   *   This function does nothing if the glyph format isn't scalable.
   *
   *   The glyph image is translated with the `origin' vector before
   *   rendering.
   *
   *   The first parameter is a pointer to an @FT_Glyph handle, that will
   *   be _replaced_ by this function (with newly allocated data).
   *   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_DEFAULT );
   *
   *       // extract glyph image
   *       error = FT_Get_Glyph( face->glyph, &glyph );
   *
   *       // convert to a bitmap (default render mode + destroying old)
   *       if ( glyph->format != FT_GLYPH_FORMAT_BITMAP )
   *       {
   *         error = FT_Glyph_To_Bitmap( &glyph, FT_RENDER_MODE_NORMAL,
   *                                     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 );
   *     }
   *
   *
   *   Here another example, again without error handling:
   *
   *
   *     {
   *       FT_Glyph  glyphs[MAX_GLYPHS]
   *
   *
   *       ...
   *
   *       for ( idx = 0; i < MAX_GLYPHS; i++ )
   *         error = FT_Load_Glyph( face, idx, FT_LOAD_DEFAULT ) ||
   *                 FT_Get_Glyph ( face->glyph, &glyphs[idx] );
   *
   *       ...
   *
   *       for ( idx = 0; i < MAX_GLYPHS; i++ )
   *       {
   *         FT_Glyph  bitmap = glyphs[idx];
   *
   *
   *         ...
   *
   *         // after this call, `bitmap' no longer points into
   *         // the `glyphs' array (and the old value isn't destroyed)
   *         FT_Glyph_To_Bitmap( &bitmap, FT_RENDER_MODE_MONO, 0, 0 );
   *
   *         ...
   *
   *         FT_Done_Glyph( bitmap );
   *       }
   *
   *       ...
   *
   *       for ( idx = 0; i < MAX_GLYPHS; i++ )
   *         FT_Done_Glyph( glyphs[idx] );
   *     }
   */
  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:
   *   Destroy 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:
   *   Perform 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.
   *
   *   Since the function uses wrap-around arithmetic, results become
   *   meaningless if the arguments are very large.
   */
  FT_EXPORT( void )
  FT_Matrix_Multiply( const FT_Matrix*  a,
                      FT_Matrix*        b );


  /**************************************************************************
   *
   * @Function:
   *   FT_Matrix_Invert
   *
   * @Description:
   *   Invert a 2x2 matrix.  Return 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 */


/* Local Variables: */
/* coding: utf-8    */
/* End:             */