tor-browser

ftglyph.h (20912B)

---

/****************************************************************************
*
* ftglyph.h
*
*   FreeType convenience functions to handle glyphs (specification).
*
* Copyright (C) 1996-2025 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 <freetype/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.  These objects are
  *   detached from @FT_Face, contrary to @FT_GlyphSlot.
  *
  */


 /* 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 fields of @FT_Glyph.
  *
  *   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;


 /**************************************************************************
  *
  * @type:
  *   FT_SvgGlyph
  *
  * @description:
  *   A handle to an object used to model an SVG glyph.  This is a
  *   'sub-class' of @FT_Glyph, and a pointer to @FT_SvgGlyphRec.
  *
  * @since:
  *   2.12
  */
 typedef struct FT_SvgGlyphRec_*  FT_SvgGlyph;


 /**************************************************************************
  *
  * @struct:
  *   FT_SvgGlyphRec
  *
  * @description:
  *   A structure used for OT-SVG glyphs.  This is a 'sub-class' of
  *   @FT_GlyphRec.
  *
  * @fields:
  *   root ::
  *     The root @FT_GlyphRec fields.
  *
  *   svg_document ::
  *     A pointer to the SVG document.
  *
  *   svg_document_length ::
  *     The length of `svg_document`.
  *
  *   glyph_index ::
  *     The index of the glyph to be rendered.
  *
  *   metrics ::
  *     A metrics object storing the size information.
  *
  *   units_per_EM ::
  *     The size of the EM square.
  *
  *   start_glyph_id ::
  *     The first glyph ID in the glyph range covered by this document.
  *
  *   end_glyph_id ::
  *     The last glyph ID in the glyph range covered by this document.
  *
  *   transform ::
  *     A 2x2 transformation matrix to apply to the glyph while rendering
  *     it.
  *
  *   delta ::
  *     Translation to apply to the glyph while rendering.
  *
  * @note:
  *   The Glyph Management API requires @FT_Glyph or its 'sub-class' to have
  *   all the information needed to completely define the glyph's rendering.
  *   Outline-based glyphs can directly apply transformations to the outline
  *   but this is not possible for an SVG document that hasn't been parsed.
  *   Therefore, the transformation is stored along with the document.  In
  *   the absence of a 'ViewBox' or 'Width'/'Height' attribute, the size of
  *   the ViewPort should be assumed to be 'units_per_EM'.
  */
 typedef struct  FT_SvgGlyphRec_
 {
   FT_GlyphRec  root;

   FT_Byte*  svg_document;
   FT_ULong  svg_document_length;

   FT_UInt  glyph_index;

   FT_Size_Metrics  metrics;
   FT_UShort        units_per_EM;

   FT_UShort  start_glyph_id;
   FT_UShort  end_glyph_id;

   FT_Matrix  transform;
   FT_Vector  delta;

 } FT_SvgGlyphRec;


 /**************************************************************************
  *
  * @function:
  *   FT_New_Glyph
  *
  * @description:
  *   A function used to create a new empty glyph image.  Note that the
  *   created @FT_Glyph object must be released with @FT_Done_Glyph.
  *
  * @input:
  *   library ::
  *     A handle to the FreeType library object.
  *
  *   format ::
  *     The format of the glyph's image.
  *
  * @output:
  *   aglyph ::
  *     A handle to the glyph object.
  *
  * @return:
  *   FreeType error code.  0~means success.
  *
  * @since:
  *   2.10
  */
 FT_EXPORT( FT_Error )
 FT_New_Glyph( FT_Library       library,
               FT_Glyph_Format  format,
               FT_Glyph         *aglyph );


 /**************************************************************************
  *
  * @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.  `NULL` in case of error.
  *
  * @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.  `NULL` 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
  *     1/64 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,
                     const FT_Matrix*  matrix,
                     const 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
  *     1/64 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 do something like the following (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 is 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,
                     const FT_Vector*  origin,
                     FT_Bool           destroy );


 /**************************************************************************
  *
  * @function:
  *   FT_Done_Glyph
  *
  * @description:
  *   Destroy a given glyph.
  *
  * @input:
  *   glyph ::
  *     A handle to the target glyph object.  Can be `NULL`.
  */
 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 */


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