text: /****************************************************************************
   *
   * ftimage.h
   *
   *   FreeType glyph image formats and default raster interface
   *   (specification).
   *
   * Copyright (C) 1996-2021 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_Outlines into FT_Bitmaps.
     *
     */
  
  
  #ifndef FTIMAGE_H_
  #define FTIMAGE_H_
  
  
    /* STANDALONE_ is from ftgrays.c */
  #ifndef STANDALONE_
  #endif
  
  
  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.
     */
    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 ::
     *     This flag indicates that this outline contains overlapping contrours
     *     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 = ( ( (unsigned long)_x1 << 24 ) | \
                      ( (unsigned long)_x2 << 16 ) | \
                      ( (unsigned long)_x3 << 8  ) | \
                        (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.
     */
    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_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,
     *   this 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:             */
  