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 /****************************************************************************
  *
  * ftimage.h
  *
  *   FreeType glyph image formats and default raster interface
  *   (specification).
  *
  * Copyright (C) 1996-2023 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.
  *
  */
 
   /**************************************************************************
    *
    * Note: A 'raster' is simply a scan-line converter, used to render
    *       `FT_Outline`s into `FT_Bitmap`s.
    *
    */
 
 
 #ifndef FTIMAGE_H_
 #define FTIMAGE_H_
 
 
 FT_BEGIN_HEADER
 
 
   /**************************************************************************
    *
    * @section:
    *   basic_types
    *
    */
 
 
   /**************************************************************************
    *
    * @type:
    *   FT_Pos
    *
    * @description:
    *   The type FT_Pos is used to store vectorial coordinates.  Depending on
    *   the context, these can represent distances in integer font units, or
    *   16.16, or 26.6 fixed-point pixel coordinates.
    */
   typedef signed long  FT_Pos;
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Vector
    *
    * @description:
    *   A simple structure used to store a 2D vector; coordinates are of the
    *   FT_Pos type.
    *
    * @fields:
    *   x ::
    *     The horizontal coordinate.
    *   y ::
    *     The vertical coordinate.
    */
   typedef struct  FT_Vector_
   {
     FT_Pos  x;
     FT_Pos  y;
 
   } FT_Vector;
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_BBox
    *
    * @description:
    *   A structure used to hold an outline's bounding box, i.e., the
    *   coordinates of its extrema in the horizontal and vertical directions.
    *
    * @fields:
    *   xMin ::
    *     The horizontal minimum (left-most).
    *
    *   yMin ::
    *     The vertical minimum (bottom-most).
    *
    *   xMax ::
    *     The horizontal maximum (right-most).
    *
    *   yMax ::
    *     The vertical maximum (top-most).
    *
    * @note:
    *   The bounding box is specified with the coordinates of the lower left
    *   and the upper right corner.  In PostScript, those values are often
    *   called (llx,lly) and (urx,ury), respectively.
    *
    *   If `yMin` is negative, this value gives the glyph's descender.
    *   Otherwise, the glyph doesn't descend below the baseline.  Similarly,
    *   if `ymax` is positive, this value gives the glyph's ascender.
    *
    *   `xMin` gives the horizontal distance from the glyph's origin to the
    *   left edge of the glyph's bounding box.  If `xMin` is negative, the
    *   glyph extends to the left of the origin.
    */
   typedef struct  FT_BBox_
   {
     FT_Pos  xMin, yMin;
     FT_Pos  xMax, yMax;
 
   } FT_BBox;
 
 
   /**************************************************************************
    *
    * @enum:
    *   FT_Pixel_Mode
    *
    * @description:
    *   An enumeration type used to describe the format of pixels in a given
    *   bitmap.  Note that additional formats may be added in the future.
    *
    * @values:
    *   FT_PIXEL_MODE_NONE ::
    *     Value~0 is reserved.
    *
    *   FT_PIXEL_MODE_MONO ::
    *     A monochrome bitmap, using 1~bit per pixel.  Note that pixels are
    *     stored in most-significant order (MSB), which means that the
    *     left-most pixel in a byte has value 128.
    *
    *   FT_PIXEL_MODE_GRAY ::
    *     An 8-bit bitmap, generally used to represent anti-aliased glyph
    *     images.  Each pixel is stored in one byte.  Note that the number of
    *     'gray' levels is stored in the `num_grays` field of the @FT_Bitmap
    *     structure (it generally is 256).
    *
    *   FT_PIXEL_MODE_GRAY2 ::
    *     A 2-bit per pixel bitmap, used to represent embedded anti-aliased
    *     bitmaps in font files according to the OpenType specification.  We
    *     haven't found a single font using this format, however.
    *
    *   FT_PIXEL_MODE_GRAY4 ::
    *     A 4-bit per pixel bitmap, representing embedded anti-aliased bitmaps
    *     in font files according to the OpenType specification.  We haven't
    *     found a single font using this format, however.
    *
    *   FT_PIXEL_MODE_LCD ::
    *     An 8-bit bitmap, representing RGB or BGR decimated glyph images used
    *     for display on LCD displays; the bitmap is three times wider than
    *     the original glyph image.  See also @FT_RENDER_MODE_LCD.
    *
    *   FT_PIXEL_MODE_LCD_V ::
    *     An 8-bit bitmap, representing RGB or BGR decimated glyph images used
    *     for display on rotated LCD displays; the bitmap is three times
    *     taller than the original glyph image.  See also
    *     @FT_RENDER_MODE_LCD_V.
    *
    *   FT_PIXEL_MODE_BGRA ::
    *     [Since 2.5] An image with four 8-bit channels per pixel,
    *     representing a color image (such as emoticons) with alpha channel.
    *     For each pixel, the format is BGRA, which means, the blue channel
    *     comes first in memory.  The color channels are pre-multiplied and in
    *     the sRGB colorspace.  For example, full red at half-translucent
    *     opacity will be represented as '00,00,80,80', not '00,00,FF,80'.
    *     See also @FT_LOAD_COLOR.
    */
   typedef enum  FT_Pixel_Mode_
   {
     FT_PIXEL_MODE_NONE = 0,
     FT_PIXEL_MODE_MONO,
     FT_PIXEL_MODE_GRAY,
     FT_PIXEL_MODE_GRAY2,
     FT_PIXEL_MODE_GRAY4,
     FT_PIXEL_MODE_LCD,
     FT_PIXEL_MODE_LCD_V,
     FT_PIXEL_MODE_BGRA,
 
     FT_PIXEL_MODE_MAX      /* do not remove */
 
   } FT_Pixel_Mode;
 
 
   /* these constants are deprecated; use the corresponding `FT_Pixel_Mode` */
   /* values instead.                                                       */
 #define ft_pixel_mode_none   FT_PIXEL_MODE_NONE
 #define ft_pixel_mode_mono   FT_PIXEL_MODE_MONO
 #define ft_pixel_mode_grays  FT_PIXEL_MODE_GRAY
 #define ft_pixel_mode_pal2   FT_PIXEL_MODE_GRAY2
 #define ft_pixel_mode_pal4   FT_PIXEL_MODE_GRAY4
 
   /* */
 
   /* For debugging, the @FT_Pixel_Mode enumeration must stay in sync */
   /* with the `pixel_modes` array in file `ftobjs.c`.                */
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Bitmap
    *
    * @description:
    *   A structure used to describe a bitmap or pixmap to the raster.  Note
    *   that we now manage pixmaps of various depths through the `pixel_mode`
    *   field.
    *
    * @fields:
    *   rows ::
    *     The number of bitmap rows.
    *
    *   width ::
    *     The number of pixels in bitmap row.
    *
    *   pitch ::
    *     The pitch's absolute value is the number of bytes taken by one
    *     bitmap row, including padding.  However, the pitch is positive when
    *     the bitmap has a 'down' flow, and negative when it has an 'up' flow.
    *     In all cases, the pitch is an offset to add to a bitmap pointer in
    *     order to go down one row.
    *
    *     Note that 'padding' means the alignment of a bitmap to a byte
    *     border, and FreeType functions normally align to the smallest
    *     possible integer value.
    *
    *     For the B/W rasterizer, `pitch` is always an even number.
    *
    *     To change the pitch of a bitmap (say, to make it a multiple of 4),
    *     use @FT_Bitmap_Convert.  Alternatively, you might use callback
    *     functions to directly render to the application's surface; see the
    *     file `example2.cpp` in the tutorial for a demonstration.
    *
    *   buffer ::
    *     A typeless pointer to the bitmap buffer.  This value should be
    *     aligned on 32-bit boundaries in most cases.
    *
    *   num_grays ::
    *     This field is only used with @FT_PIXEL_MODE_GRAY; it gives the
    *     number of gray levels used in the bitmap.
    *
    *   pixel_mode ::
    *     The pixel mode, i.e., how pixel bits are stored.  See @FT_Pixel_Mode
    *     for possible values.
    *
    *   palette_mode ::
    *     This field is intended for paletted pixel modes; it indicates how
    *     the palette is stored.  Not used currently.
    *
    *   palette ::
    *     A typeless pointer to the bitmap palette; this field is intended for
    *     paletted pixel modes.  Not used currently.
    *
    * @note:
    *   `width` and `rows` refer to the *physical* size of the bitmap, not the
    *   *logical* one.  For example, if @FT_Pixel_Mode is set to
    *   `FT_PIXEL_MODE_LCD`, the logical width is a just a third of the
    *   physical one.
    */
   typedef struct  FT_Bitmap_
   {
     unsigned int    rows;
     unsigned int    width;
     int             pitch;
     unsigned char*  buffer;
     unsigned short  num_grays;
     unsigned char   pixel_mode;
     unsigned char   palette_mode;
     void*           palette;
 
   } FT_Bitmap;
 
 
   /**************************************************************************
    *
    * @section:
    *   outline_processing
    *
    */
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Outline
    *
    * @description:
    *   This structure is used to describe an outline to the scan-line
    *   converter.
    *
    * @fields:
    *   n_contours ::
    *     The number of contours in the outline.
    *
    *   n_points ::
    *     The number of points in the outline.
    *
    *   points ::
    *     A pointer to an array of `n_points` @FT_Vector elements, giving the
    *     outline's point coordinates.
    *
    *   tags ::
    *     A pointer to an array of `n_points` chars, giving each outline
    *     point's type.
    *
    *     If bit~0 is unset, the point is 'off' the curve, i.e., a Bezier
    *     control point, while it is 'on' if set.
    *
    *     Bit~1 is meaningful for 'off' points only.  If set, it indicates a
    *     third-order Bezier arc control point; and a second-order control
    *     point if unset.
    *
    *     If bit~2 is set, bits 5-7 contain the drop-out mode (as defined in
    *     the OpenType specification; the value is the same as the argument to
    *     the 'SCANMODE' instruction).
    *
    *     Bits 3 and~4 are reserved for internal purposes.
    *
    *   contours ::
    *     An array of `n_contours` shorts, giving the end point of each
    *     contour within the outline.  For example, the first contour is
    *     defined by the points '0' to `contours[0]`, the second one is
    *     defined by the points `contours[0]+1` to `contours[1]`, etc.
    *
    *   flags ::
    *     A set of bit flags used to characterize the outline and give hints
    *     to the scan-converter and hinter on how to convert/grid-fit it.  See
    *     @FT_OUTLINE_XXX.
    *
    * @note:
    *   The B/W rasterizer only checks bit~2 in the `tags` array for the first
    *   point of each contour.  The drop-out mode as given with
    *   @FT_OUTLINE_IGNORE_DROPOUTS, @FT_OUTLINE_SMART_DROPOUTS, and
    *   @FT_OUTLINE_INCLUDE_STUBS in `flags` is then overridden.
    */
   typedef struct  FT_Outline_
   {
     short       n_contours;      /* number of contours in glyph        */
     short       n_points;        /* number of points in the glyph      */
 
     FT_Vector*  points;          /* the outline's points               */
     char*       tags;            /* the points flags                   */
     short*      contours;        /* the contour end points             */
 
     int         flags;           /* outline masks                      */
 
   } FT_Outline;
 
   /* */
 
   /* Following limits must be consistent with */
   /* FT_Outline.{n_contours,n_points}         */
 #define FT_OUTLINE_CONTOURS_MAX  SHRT_MAX
 #define FT_OUTLINE_POINTS_MAX    SHRT_MAX
 
 
   /**************************************************************************
    *
    * @enum:
    *   FT_OUTLINE_XXX
    *
    * @description:
    *   A list of bit-field constants used for the flags in an outline's
    *   `flags` field.
    *
    * @values:
    *   FT_OUTLINE_NONE ::
    *     Value~0 is reserved.
    *
    *   FT_OUTLINE_OWNER ::
    *     If set, this flag indicates that the outline's field arrays (i.e.,
    *     `points`, `flags`, and `contours`) are 'owned' by the outline
    *     object, and should thus be freed when it is destroyed.
    *
    *   FT_OUTLINE_EVEN_ODD_FILL ::
    *     By default, outlines are filled using the non-zero winding rule.  If
    *     set to 1, the outline will be filled using the even-odd fill rule
    *     (only works with the smooth rasterizer).
    *
    *   FT_OUTLINE_REVERSE_FILL ::
    *     By default, outside contours of an outline are oriented in
    *     clock-wise direction, as defined in the TrueType specification.
    *     This flag is set if the outline uses the opposite direction
    *     (typically for Type~1 fonts).  This flag is ignored by the scan
    *     converter.
    *
    *   FT_OUTLINE_IGNORE_DROPOUTS ::
    *     By default, the scan converter will try to detect drop-outs in an
    *     outline and correct the glyph bitmap to ensure consistent shape
    *     continuity.  If set, this flag hints the scan-line converter to
    *     ignore such cases.  See below for more information.
    *
    *   FT_OUTLINE_SMART_DROPOUTS ::
    *     Select smart dropout control.  If unset, use simple dropout control.
    *     Ignored if @FT_OUTLINE_IGNORE_DROPOUTS is set.  See below for more
    *     information.
    *
    *   FT_OUTLINE_INCLUDE_STUBS ::
    *     If set, turn pixels on for 'stubs', otherwise exclude them.  Ignored
    *     if @FT_OUTLINE_IGNORE_DROPOUTS is set.  See below for more
    *     information.
    *
    *   FT_OUTLINE_OVERLAP ::
    *     [Since 2.10.3] This flag indicates that this outline contains
    *     overlapping contours and the anti-aliased renderer should perform
    *     oversampling to mitigate possible artifacts.  This flag should _not_
    *     be set for well designed glyphs without overlaps because it quadruples
    *     the rendering time.
    *
    *   FT_OUTLINE_HIGH_PRECISION ::
    *     This flag indicates that the scan-line converter should try to
    *     convert this outline to bitmaps with the highest possible quality.
    *     It is typically set for small character sizes.  Note that this is
    *     only a hint that might be completely ignored by a given
    *     scan-converter.
    *
    *   FT_OUTLINE_SINGLE_PASS ::
    *     This flag is set to force a given scan-converter to only use a
    *     single pass over the outline to render a bitmap glyph image.
    *     Normally, it is set for very large character sizes.  It is only a
    *     hint that might be completely ignored by a given scan-converter.
    *
    * @note:
    *   The flags @FT_OUTLINE_IGNORE_DROPOUTS, @FT_OUTLINE_SMART_DROPOUTS, and
    *   @FT_OUTLINE_INCLUDE_STUBS are ignored by the smooth rasterizer.
    *
    *   There exists a second mechanism to pass the drop-out mode to the B/W
    *   rasterizer; see the `tags` field in @FT_Outline.
    *
    *   Please refer to the description of the 'SCANTYPE' instruction in the
    *   OpenType specification (in file `ttinst1.doc`) how simple drop-outs,
    *   smart drop-outs, and stubs are defined.
    */
 #define FT_OUTLINE_NONE             0x0
 #define FT_OUTLINE_OWNER            0x1
 #define FT_OUTLINE_EVEN_ODD_FILL    0x2
 #define FT_OUTLINE_REVERSE_FILL     0x4
 #define FT_OUTLINE_IGNORE_DROPOUTS  0x8
 #define FT_OUTLINE_SMART_DROPOUTS   0x10
 #define FT_OUTLINE_INCLUDE_STUBS    0x20
 #define FT_OUTLINE_OVERLAP          0x40
 
 #define FT_OUTLINE_HIGH_PRECISION   0x100
 #define FT_OUTLINE_SINGLE_PASS      0x200
 
 
   /* these constants are deprecated; use the corresponding */
   /* `FT_OUTLINE_XXX` values instead                       */
 #define ft_outline_none             FT_OUTLINE_NONE
 #define ft_outline_owner            FT_OUTLINE_OWNER
 #define ft_outline_even_odd_fill    FT_OUTLINE_EVEN_ODD_FILL
 #define ft_outline_reverse_fill     FT_OUTLINE_REVERSE_FILL
 #define ft_outline_ignore_dropouts  FT_OUTLINE_IGNORE_DROPOUTS
 #define ft_outline_high_precision   FT_OUTLINE_HIGH_PRECISION
 #define ft_outline_single_pass      FT_OUTLINE_SINGLE_PASS
 
   /* */
 
 #define FT_CURVE_TAG( flag )  ( flag & 0x03 )
 
   /* see the `tags` field in `FT_Outline` for a description of the values */
 #define FT_CURVE_TAG_ON            0x01
 #define FT_CURVE_TAG_CONIC         0x00
 #define FT_CURVE_TAG_CUBIC         0x02
 
 #define FT_CURVE_TAG_HAS_SCANMODE  0x04
 
 #define FT_CURVE_TAG_TOUCH_X       0x08  /* reserved for TrueType hinter */
 #define FT_CURVE_TAG_TOUCH_Y       0x10  /* reserved for TrueType hinter */
 
 #define FT_CURVE_TAG_TOUCH_BOTH    ( FT_CURVE_TAG_TOUCH_X | \
                                      FT_CURVE_TAG_TOUCH_Y )
   /* values 0x20, 0x40, and 0x80 are reserved */
 
 
   /* these constants are deprecated; use the corresponding */
   /* `FT_CURVE_TAG_XXX` values instead                     */
 #define FT_Curve_Tag_On       FT_CURVE_TAG_ON
 #define FT_Curve_Tag_Conic    FT_CURVE_TAG_CONIC
 #define FT_Curve_Tag_Cubic    FT_CURVE_TAG_CUBIC
 #define FT_Curve_Tag_Touch_X  FT_CURVE_TAG_TOUCH_X
 #define FT_Curve_Tag_Touch_Y  FT_CURVE_TAG_TOUCH_Y
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Outline_MoveToFunc
    *
    * @description:
    *   A function pointer type used to describe the signature of a 'move to'
    *   function during outline walking/decomposition.
    *
    *   A 'move to' is emitted to start a new contour in an outline.
    *
    * @input:
    *   to ::
    *     A pointer to the target point of the 'move to'.
    *
    *   user ::
    *     A typeless pointer, which is passed from the caller of the
    *     decomposition function.
    *
    * @return:
    *   Error code.  0~means success.
    */
   typedef int
   (*FT_Outline_MoveToFunc)( const FT_Vector*  to,
                             void*             user );
 
 #define FT_Outline_MoveTo_Func  FT_Outline_MoveToFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Outline_LineToFunc
    *
    * @description:
    *   A function pointer type used to describe the signature of a 'line to'
    *   function during outline walking/decomposition.
    *
    *   A 'line to' is emitted to indicate a segment in the outline.
    *
    * @input:
    *   to ::
    *     A pointer to the target point of the 'line to'.
    *
    *   user ::
    *     A typeless pointer, which is passed from the caller of the
    *     decomposition function.
    *
    * @return:
    *   Error code.  0~means success.
    */
   typedef int
   (*FT_Outline_LineToFunc)( const FT_Vector*  to,
                             void*             user );
 
 #define FT_Outline_LineTo_Func  FT_Outline_LineToFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Outline_ConicToFunc
    *
    * @description:
    *   A function pointer type used to describe the signature of a 'conic to'
    *   function during outline walking or decomposition.
    *
    *   A 'conic to' is emitted to indicate a second-order Bezier arc in the
    *   outline.
    *
    * @input:
    *   control ::
    *     An intermediate control point between the last position and the new
    *     target in `to`.
    *
    *   to ::
    *     A pointer to the target end point of the conic arc.
    *
    *   user ::
    *     A typeless pointer, which is passed from the caller of the
    *     decomposition function.
    *
    * @return:
    *   Error code.  0~means success.
    */
   typedef int
   (*FT_Outline_ConicToFunc)( const FT_Vector*  control,
                              const FT_Vector*  to,
                              void*             user );
 
 #define FT_Outline_ConicTo_Func  FT_Outline_ConicToFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Outline_CubicToFunc
    *
    * @description:
    *   A function pointer type used to describe the signature of a 'cubic to'
    *   function during outline walking or decomposition.
    *
    *   A 'cubic to' is emitted to indicate a third-order Bezier arc.
    *
    * @input:
    *   control1 ::
    *     A pointer to the first Bezier control point.
    *
    *   control2 ::
    *     A pointer to the second Bezier control point.
    *
    *   to ::
    *     A pointer to the target end point.
    *
    *   user ::
    *     A typeless pointer, which is passed from the caller of the
    *     decomposition function.
    *
    * @return:
    *   Error code.  0~means success.
    */
   typedef int
   (*FT_Outline_CubicToFunc)( const FT_Vector*  control1,
                              const FT_Vector*  control2,
                              const FT_Vector*  to,
                              void*             user );
 
 #define FT_Outline_CubicTo_Func  FT_Outline_CubicToFunc
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Outline_Funcs
    *
    * @description:
    *   A structure to hold various function pointers used during outline
    *   decomposition in order to emit segments, conic, and cubic Beziers.
    *
    * @fields:
    *   move_to ::
    *     The 'move to' emitter.
    *
    *   line_to ::
    *     The segment emitter.
    *
    *   conic_to ::
    *     The second-order Bezier arc emitter.
    *
    *   cubic_to ::
    *     The third-order Bezier arc emitter.
    *
    *   shift ::
    *     The shift that is applied to coordinates before they are sent to the
    *     emitter.
    *
    *   delta ::
    *     The delta that is applied to coordinates before they are sent to the
    *     emitter, but after the shift.
    *
    * @note:
    *   The point coordinates sent to the emitters are the transformed version
    *   of the original coordinates (this is important for high accuracy
    *   during scan-conversion).  The transformation is simple:
    *
    *   ```
    *     x' = (x << shift) - delta
    *     y' = (y << shift) - delta
    *   ```
    *
    *   Set the values of `shift` and `delta` to~0 to get the original point
    *   coordinates.
    */
   typedef struct  FT_Outline_Funcs_
   {
     FT_Outline_MoveToFunc   move_to;
     FT_Outline_LineToFunc   line_to;
     FT_Outline_ConicToFunc  conic_to;
     FT_Outline_CubicToFunc  cubic_to;
 
     int                     shift;
     FT_Pos                  delta;
 
   } FT_Outline_Funcs;
 
 
   /**************************************************************************
    *
    * @section:
    *   basic_types
    *
    */
 
 
   /**************************************************************************
    *
    * @macro:
    *   FT_IMAGE_TAG
    *
    * @description:
    *   This macro converts four-letter tags to an unsigned long type.
    *
    * @note:
    *   Since many 16-bit compilers don't like 32-bit enumerations, you should
    *   redefine this macro in case of problems to something like this:
    *
    *   ```
    *     #define FT_IMAGE_TAG( value, _x1, _x2, _x3, _x4 )  value
    *   ```
    *
    *   to get a simple enumeration without assigning special numbers.
    */
 #ifndef FT_IMAGE_TAG
 
 #define FT_IMAGE_TAG( value, _x1, _x2, _x3, _x4 )                         \
           value = ( ( FT_STATIC_BYTE_CAST( unsigned long, _x1 ) << 24 ) | \
                     ( FT_STATIC_BYTE_CAST( unsigned long, _x2 ) << 16 ) | \
                     ( FT_STATIC_BYTE_CAST( unsigned long, _x3 ) << 8  ) | \
                       FT_STATIC_BYTE_CAST( unsigned long, _x4 )         )
 
 #endif /* FT_IMAGE_TAG */
 
 
   /**************************************************************************
    *
    * @enum:
    *   FT_Glyph_Format
    *
    * @description:
    *   An enumeration type used to describe the format of a given glyph
    *   image.  Note that this version of FreeType only supports two image
    *   formats, even though future font drivers will be able to register
    *   their own format.
    *
    * @values:
    *   FT_GLYPH_FORMAT_NONE ::
    *     The value~0 is reserved.
    *
    *   FT_GLYPH_FORMAT_COMPOSITE ::
    *     The glyph image is a composite of several other images.  This format
    *     is _only_ used with @FT_LOAD_NO_RECURSE, and is used to report
    *     compound glyphs (like accented characters).
    *
    *   FT_GLYPH_FORMAT_BITMAP ::
    *     The glyph image is a bitmap, and can be described as an @FT_Bitmap.
    *     You generally need to access the `bitmap` field of the
    *     @FT_GlyphSlotRec structure to read it.
    *
    *   FT_GLYPH_FORMAT_OUTLINE ::
    *     The glyph image is a vectorial outline made of line segments and
    *     Bezier arcs; it can be described as an @FT_Outline; you generally
    *     want to access the `outline` field of the @FT_GlyphSlotRec structure
    *     to read it.
    *
    *   FT_GLYPH_FORMAT_PLOTTER ::
    *     The glyph image is a vectorial path with no inside and outside
    *     contours.  Some Type~1 fonts, like those in the Hershey family,
    *     contain glyphs in this format.  These are described as @FT_Outline,
    *     but FreeType isn't currently capable of rendering them correctly.
    *
    *   FT_GLYPH_FORMAT_SVG ::
    *     [Since 2.12] The glyph is represented by an SVG document in the
    *     'SVG~' table.
    */
   typedef enum  FT_Glyph_Format_
   {
     FT_IMAGE_TAG( FT_GLYPH_FORMAT_NONE, 0, 0, 0, 0 ),
 
     FT_IMAGE_TAG( FT_GLYPH_FORMAT_COMPOSITE, 'c', 'o', 'm', 'p' ),
     FT_IMAGE_TAG( FT_GLYPH_FORMAT_BITMAP,    'b', 'i', 't', 's' ),
     FT_IMAGE_TAG( FT_GLYPH_FORMAT_OUTLINE,   'o', 'u', 't', 'l' ),
     FT_IMAGE_TAG( FT_GLYPH_FORMAT_PLOTTER,   'p', 'l', 'o', 't' ),
     FT_IMAGE_TAG( FT_GLYPH_FORMAT_SVG,       'S', 'V', 'G', ' ' )
 
   } FT_Glyph_Format;
 
 
   /* these constants are deprecated; use the corresponding */
   /* `FT_Glyph_Format` values instead.                     */
 #define ft_glyph_format_none       FT_GLYPH_FORMAT_NONE
 #define ft_glyph_format_composite  FT_GLYPH_FORMAT_COMPOSITE
 #define ft_glyph_format_bitmap     FT_GLYPH_FORMAT_BITMAP
 #define ft_glyph_format_outline    FT_GLYPH_FORMAT_OUTLINE
 #define ft_glyph_format_plotter    FT_GLYPH_FORMAT_PLOTTER
 
 
   /*************************************************************************/
   /*************************************************************************/
   /*************************************************************************/
   /*****                                                               *****/
   /*****            R A S T E R   D E F I N I T I O N S                *****/
   /*****                                                               *****/
   /*************************************************************************/
   /*************************************************************************/
   /*************************************************************************/
 
 
 
   /**************************************************************************
    *
    * @section:
    *   raster
    *
    * @title:
    *   Scanline Converter
    *
    * @abstract:
    *   How vectorial outlines are converted into bitmaps and pixmaps.
    *
    * @description:
    *   A raster or a rasterizer is a scan converter in charge of producing a
    *   pixel coverage bitmap that can be used as an alpha channel when
    *   compositing a glyph with a background.  FreeType comes with two
    *   rasterizers: bilevel `raster1` and anti-aliased `smooth` are two
    *   separate modules.  They are usually called from the high-level
    *   @FT_Load_Glyph or @FT_Render_Glyph functions and produce the entire
    *   coverage bitmap at once, while staying largely invisible to users.
    *
    *   Instead of working with complete coverage bitmaps, it is also possible
    *   to intercept consecutive pixel runs on the same scanline with the same
    *   coverage, called _spans_, and process them individually.  Only the
    *   `smooth` rasterizer permits this when calling @FT_Outline_Render with
    *   @FT_Raster_Params as described below.
    *
    *   Working with either complete bitmaps or spans it is important to think
    *   of them as colorless coverage objects suitable as alpha channels to
    *   blend arbitrary colors with a background.  For best results, it is
    *   recommended to use gamma correction, too.
    *
    *   This section also describes the public API needed to set up alternative
    *   @FT_Renderer modules.
    *
    * @order:
    *   FT_Span
    *   FT_SpanFunc
    *   FT_Raster_Params
    *   FT_RASTER_FLAG_XXX
    *
    *   FT_Raster
    *   FT_Raster_NewFunc
    *   FT_Raster_DoneFunc
    *   FT_Raster_ResetFunc
    *   FT_Raster_SetModeFunc
    *   FT_Raster_RenderFunc
    *   FT_Raster_Funcs
    *
    */
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Span
    *
    * @description:
    *   A structure to model a single span of consecutive pixels when
    *   rendering an anti-aliased bitmap.
    *
    * @fields:
    *   x ::
    *     The span's horizontal start position.
    *
    *   len ::
    *     The span's length in pixels.
    *
    *   coverage ::
    *     The span color/coverage, ranging from 0 (background) to 255
    *     (foreground).
    *
    * @note:
    *   This structure is used by the span drawing callback type named
    *   @FT_SpanFunc that takes the y~coordinate of the span as a parameter.
    *
    *   The anti-aliased rasterizer produces coverage values from 0 to 255,
    *   that is, from completely transparent to completely opaque.
    */
   typedef struct  FT_Span_
   {
     short           x;
     unsigned short  len;
     unsigned char   coverage;
 
   } FT_Span;
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_SpanFunc
    *
    * @description:
    *   A function used as a call-back by the anti-aliased renderer in order
    *   to let client applications draw themselves the pixel spans on each
    *   scan line.
    *
    * @input:
    *   y ::
    *     The scanline's upward y~coordinate.
    *
    *   count ::
    *     The number of spans to draw on this scanline.
    *
    *   spans ::
    *     A table of `count` spans to draw on the scanline.
    *
    *   user ::
    *     User-supplied data that is passed to the callback.
    *
    * @note:
    *   This callback allows client applications to directly render the spans
    *   of the anti-aliased bitmap to any kind of surfaces.
    *
    *   This can be used to write anti-aliased outlines directly to a given
    *   background bitmap using alpha compositing.  It can also be used for
    *   oversampling and averaging.
    */
   typedef void
   (*FT_SpanFunc)( int             y,
                   int             count,
                   const FT_Span*  spans,
                   void*           user );
 
 #define FT_Raster_Span_Func  FT_SpanFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_BitTest_Func
    *
    * @description:
    *   Deprecated, unimplemented.
    */
   typedef int
   (*FT_Raster_BitTest_Func)( int    y,
                              int    x,
                              void*  user );
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_BitSet_Func
    *
    * @description:
    *   Deprecated, unimplemented.
    */
   typedef void
   (*FT_Raster_BitSet_Func)( int    y,
                             int    x,
                             void*  user );
 
 
   /**************************************************************************
    *
    * @enum:
    *   FT_RASTER_FLAG_XXX
    *
    * @description:
    *   A list of bit flag constants as used in the `flags` field of a
    *   @FT_Raster_Params structure.
    *
    * @values:
    *   FT_RASTER_FLAG_DEFAULT ::
    *     This value is 0.
    *
    *   FT_RASTER_FLAG_AA ::
    *     This flag is set to indicate that an anti-aliased glyph image should
    *     be generated.  Otherwise, it will be monochrome (1-bit).
    *
    *   FT_RASTER_FLAG_DIRECT ::
    *     This flag is set to indicate direct rendering.  In this mode, client
    *     applications must provide their own span callback.  This lets them
    *     directly draw or compose over an existing bitmap.  If this bit is
    *     _not_ set, the target pixmap's buffer _must_ be zeroed before
    *     rendering and the output will be clipped to its size.
    *
    *     Direct rendering is only possible with anti-aliased glyphs.
    *
    *   FT_RASTER_FLAG_CLIP ::
    *     This flag is only used in direct rendering mode.  If set, the output
    *     will be clipped to a box specified in the `clip_box` field of the
    *     @FT_Raster_Params structure.  Otherwise, the `clip_box` is
    *     effectively set to the bounding box and all spans are generated.
    *
    *   FT_RASTER_FLAG_SDF ::
    *     This flag is set to indicate that a signed distance field glyph
    *     image should be generated.  This is only used while rendering with
    *     the @FT_RENDER_MODE_SDF render mode.
    */
 #define FT_RASTER_FLAG_DEFAULT  0x0
 #define FT_RASTER_FLAG_AA       0x1
 #define FT_RASTER_FLAG_DIRECT   0x2
 #define FT_RASTER_FLAG_CLIP     0x4
 #define FT_RASTER_FLAG_SDF      0x8
 
   /* these constants are deprecated; use the corresponding */
   /* `FT_RASTER_FLAG_XXX` values instead                   */
 #define ft_raster_flag_default  FT_RASTER_FLAG_DEFAULT
 #define ft_raster_flag_aa       FT_RASTER_FLAG_AA
 #define ft_raster_flag_direct   FT_RASTER_FLAG_DIRECT
 #define ft_raster_flag_clip     FT_RASTER_FLAG_CLIP
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Raster_Params
    *
    * @description:
    *   A structure to hold the parameters used by a raster's render function,
    *   passed as an argument to @FT_Outline_Render.
    *
    * @fields:
    *   target ::
    *     The target bitmap.
    *
    *   source ::
    *     A pointer to the source glyph image (e.g., an @FT_Outline).
    *
    *   flags ::
    *     The rendering flags.
    *
    *   gray_spans ::
    *     The gray span drawing callback.
    *
    *   black_spans ::
    *     Unused.
    *
    *   bit_test ::
    *     Unused.
    *
    *   bit_set ::
    *     Unused.
    *
    *   user ::
    *     User-supplied data that is passed to each drawing callback.
    *
    *   clip_box ::
    *     An optional span clipping box expressed in _integer_ pixels
    *     (not in 26.6 fixed-point units).
    *
    * @note:
    *   The @FT_RASTER_FLAG_AA bit flag must be set in the `flags` to
    *   generate an anti-aliased glyph bitmap, otherwise a monochrome bitmap
    *   is generated.  The `target` should have appropriate pixel mode and its
    *   dimensions define the clipping region.
    *
    *   If both @FT_RASTER_FLAG_AA and @FT_RASTER_FLAG_DIRECT bit flags
    *   are set in `flags`, the raster calls an @FT_SpanFunc callback
    *   `gray_spans` with `user` data as an argument ignoring `target`.  This
    *   allows direct composition over a pre-existing user surface to perform
    *   the span drawing and composition.  To optionally clip the spans, set
    *   the @FT_RASTER_FLAG_CLIP flag and `clip_box`.  The monochrome raster
    *   does not support the direct mode.
    *
    *   The gray-level rasterizer always uses 256 gray levels.  If you want
    *   fewer gray levels, you have to use @FT_RASTER_FLAG_DIRECT and reduce
    *   the levels in the callback function.
    */
   typedef struct  FT_Raster_Params_
   {
     const FT_Bitmap*        target;
     const void*             source;
     int                     flags;
     FT_SpanFunc             gray_spans;
     FT_SpanFunc             black_spans;  /* unused */
     FT_Raster_BitTest_Func  bit_test;     /* unused */
     FT_Raster_BitSet_Func   bit_set;      /* unused */
     void*                   user;
     FT_BBox                 clip_box;
 
   } FT_Raster_Params;
 
 
   /**************************************************************************
    *
    * @type:
    *   FT_Raster
    *
    * @description:
    *   An opaque handle (pointer) to a raster object.  Each object can be
    *   used independently to convert an outline into a bitmap or pixmap.
    *
    * @note:
    *   In FreeType 2, all rasters are now encapsulated within specific
    *   @FT_Renderer modules and only used in their context.
    *
    */
   typedef struct FT_RasterRec_*  FT_Raster;
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_NewFunc
    *
    * @description:
    *   A function used to create a new raster object.
    *
    * @input:
    *   memory ::
    *     A handle to the memory allocator.
    *
    * @output:
    *   raster ::
    *     A handle to the new raster object.
    *
    * @return:
    *   Error code.  0~means success.
    *
    * @note:
    *   The `memory` parameter is a typeless pointer in order to avoid
    *   un-wanted dependencies on the rest of the FreeType code.  In practice,
    *   it is an @FT_Memory object, i.e., a handle to the standard FreeType
    *   memory allocator.  However, this field can be completely ignored by a
    *   given raster implementation.
    */
   typedef int
   (*FT_Raster_NewFunc)( void*       memory,
                         FT_Raster*  raster );
 
 #define FT_Raster_New_Func  FT_Raster_NewFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_DoneFunc
    *
    * @description:
    *   A function used to destroy a given raster object.
    *
    * @input:
    *   raster ::
    *     A handle to the raster object.
    */
   typedef void
   (*FT_Raster_DoneFunc)( FT_Raster  raster );
 
 #define FT_Raster_Done_Func  FT_Raster_DoneFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_ResetFunc
    *
    * @description:
    *   FreeType used to provide an area of memory called the 'render pool'
    *   available to all registered rasterizers.  This was not thread safe,
    *   however, and now FreeType never allocates this pool.
    *
    *   This function is called after a new raster object is created.
    *
    * @input:
    *   raster ::
    *     A handle to the new raster object.
    *
    *   pool_base ::
    *     Previously, the address in memory of the render pool.  Set this to
    *     `NULL`.
    *
    *   pool_size ::
    *     Previously, the size in bytes of the render pool.  Set this to 0.
    *
    * @note:
    *   Rasterizers should rely on dynamic or stack allocation if they want to
    *   (a handle to the memory allocator is passed to the rasterizer
    *   constructor).
    */
   typedef void
   (*FT_Raster_ResetFunc)( FT_Raster       raster,
                           unsigned char*  pool_base,
                           unsigned long   pool_size );
 
 #define FT_Raster_Reset_Func  FT_Raster_ResetFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_SetModeFunc
    *
    * @description:
    *   This function is a generic facility to change modes or attributes in a
    *   given raster.  This can be used for debugging purposes, or simply to
    *   allow implementation-specific 'features' in a given raster module.
    *
    * @input:
    *   raster ::
    *     A handle to the new raster object.
    *
    *   mode ::
    *     A 4-byte tag used to name the mode or property.
    *
    *   args ::
    *     A pointer to the new mode/property to use.
    */
   typedef int
   (*FT_Raster_SetModeFunc)( FT_Raster      raster,
                             unsigned long  mode,
                             void*          args );
 
 #define FT_Raster_Set_Mode_Func  FT_Raster_SetModeFunc
 
 
   /**************************************************************************
    *
    * @functype:
    *   FT_Raster_RenderFunc
    *
    * @description:
    *   Invoke a given raster to scan-convert a given glyph image into a
    *   target bitmap.
    *
    * @input:
    *   raster ::
    *     A handle to the raster object.
    *
    *   params ::
    *     A pointer to an @FT_Raster_Params structure used to store the
    *     rendering parameters.
    *
    * @return:
    *   Error code.  0~means success.
    *
    * @note:
    *   The exact format of the source image depends on the raster's glyph
    *   format defined in its @FT_Raster_Funcs structure.  It can be an
    *   @FT_Outline or anything else in order to support a large array of
    *   glyph formats.
    *
    *   Note also that the render function can fail and return a
    *   `FT_Err_Unimplemented_Feature` error code if the raster used does not
    *   support direct composition.
    */
   typedef int
   (*FT_Raster_RenderFunc)( FT_Raster                raster,
                            const FT_Raster_Params*  params );
 
 #define FT_Raster_Render_Func  FT_Raster_RenderFunc
 
 
   /**************************************************************************
    *
    * @struct:
    *   FT_Raster_Funcs
    *
    * @description:
    *  A structure used to describe a given raster class to the library.
    *
    * @fields:
    *   glyph_format ::
    *     The supported glyph format for this raster.
    *
    *   raster_new ::
    *     The raster constructor.
    *
    *   raster_reset ::
    *     Used to reset the render pool within the raster.
    *
    *   raster_render ::
    *     A function to render a glyph into a given bitmap.
    *
    *   raster_done ::
    *     The raster destructor.
    */
   typedef struct  FT_Raster_Funcs_
   {
     FT_Glyph_Format        glyph_format;
 
     FT_Raster_NewFunc      raster_new;
     FT_Raster_ResetFunc    raster_reset;
     FT_Raster_SetModeFunc  raster_set_mode;
     FT_Raster_RenderFunc   raster_render;
     FT_Raster_DoneFunc     raster_done;
 
   } FT_Raster_Funcs;
 
   /* */
 
 
 FT_END_HEADER
 
 #endif /* FTIMAGE_H_ */
 
 
 /* END */
 
 
 /* Local Variables: */
 /* coding: utf-8    */
 /* End:             */

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