ttdriver.c

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/***************************************************************************/
/*                                                                         */
/*  ttdriver.c                                                             */
/*                                                                         */
/*    TrueType font driver implementation (body).                          */
/*                                                                         */
/*  Copyright 1996-2001, 2002, 2003, 2004, 2005 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.                                        */
/*                                                                         */
/***************************************************************************/


#include <ft2build.h>
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_STREAM_H
#include FT_INTERNAL_SFNT_H
#include FT_TRUETYPE_IDS_H
#include FT_SERVICE_XFREE86_NAME_H

#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
#include FT_MULTIPLE_MASTERS_H
#include FT_SERVICE_MULTIPLE_MASTERS_H
#endif

#include "ttdriver.h"
#include "ttgload.h"

#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
#include "ttgxvar.h"
#endif

#include "tterrors.h"


  /*************************************************************************/
  /*                                                                       */
  /* The macro FT_COMPONENT is used in trace mode.  It is an implicit      */
  /* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log  */
  /* messages during execution.                                            */
  /*                                                                       */
#undef  FT_COMPONENT
#define FT_COMPONENT  trace_ttdriver


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****                          F A C E S                              ****/
  /****                                                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


#undef  PAIR_TAG
#define PAIR_TAG( left, right )  ( ( (FT_ULong)left << 16 ) | \
                                     (FT_ULong)right        )


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    tt_get_kerning                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to return the kerning vector between two      */
  /*    glyphs of the same face.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    face        :: A handle to the source face object.                 */
  /*                                                                       */
  /*    left_glyph  :: The index of the left glyph in the kern pair.       */
  /*                                                                       */
  /*    right_glyph :: The index of the right glyph in the kern pair.      */
  /*                                                                       */
  /* <Output>                                                              */
  /*    kerning     :: The kerning vector.  This is in font units for      */
  /*                   scalable formats, and in pixels for fixed-sizes     */
  /*                   formats.                                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  /* <Note>                                                                */
  /*    Only horizontal layouts (left-to-right & right-to-left) are        */
  /*    supported by this function.  Other layouts, or more sophisticated  */
  /*    kernings, are out of scope of this method (the basic driver        */
  /*    interface is meant to be simple).                                  */
  /*                                                                       */
  /*    They can be implemented by format-specific interfaces.             */
  /*                                                                       */
  static FT_Error
  tt_get_kerning( FT_Face     ttface,          /* TT_Face */
                  FT_UInt     left_glyph,
                  FT_UInt     right_glyph,
                  FT_Vector*  kerning )
  {
    TT_Face       face = (TT_Face)ttface;
    SFNT_Service  sfnt = (SFNT_Service)face->sfnt;


    kerning->x = 0;
    kerning->y = 0;

    if ( sfnt )
      kerning->x = sfnt->get_kerning( face, left_glyph, right_glyph );
      
    return 0;
  }


#undef PAIR_TAG


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****                           S I Z E S                             ****/
  /****                                                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Set_Char_Sizes                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to reset a size's character sizes (horizontal */
  /*    and vertical) expressed in fractional points.                      */
  /*                                                                       */
  /* <Input>                                                               */
  /*    char_width      :: The character width expressed in 26.6           */
  /*                       fractional points.                              */
  /*                                                                       */
  /*    char_height     :: The character height expressed in 26.6          */
  /*                       fractional points.                              */
  /*                                                                       */
  /*    horz_resolution :: The horizontal resolution of the output device. */
  /*                                                                       */
  /*    vert_resolution :: The vertical resolution of the output device.   */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    size            :: A handle to the target size object.             */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static FT_Error
  Set_Char_Sizes( FT_Size     ttsize,       /* TT_Size */
                  FT_F26Dot6  char_width,
                  FT_F26Dot6  char_height,
                  FT_UInt     horz_resolution,
                  FT_UInt     vert_resolution )
  {
    TT_Size           size     = (TT_Size)ttsize;
    FT_Size_Metrics*  metrics  = &size->root.metrics;
    FT_Size_Metrics*  metrics2 = &size->metrics;
    TT_Face           face     = (TT_Face)size->root.face;
    FT_Long           dim_x, dim_y;


    *metrics2 = *metrics;

    /* This bit flag, when set, indicates that the pixel size must be */
    /* truncated to an integer.  Nearly all TrueType fonts have this  */
    /* bit set, as hinting won't work really well otherwise.          */
    /*                                                                */
    if ( ( face->header.Flags & 8 ) != 0 )
    {
     /* we need to use rounding in the following computations. Otherwise,
      * the resulting hinted outlines will be very slightly distorted
      */
      dim_x = ( ( char_width  * horz_resolution + (36+32*72) ) / 72 ) & ~63;
      dim_y = ( ( char_height * vert_resolution + (36+32*72) ) / 72 ) & ~63;
    }
    else
    {
      dim_x = ( ( char_width  * horz_resolution + 36 ) / 72 );
      dim_y = ( ( char_height * vert_resolution + 36 ) / 72 );
    }

    /* we only modify "metrics2", not "metrics", so these changes have */
    /* no effect on the result of the auto-hinter when it is used      */
    /*                                                                 */
    metrics2->x_ppem  = (FT_UShort)( dim_x >> 6 );
    metrics2->y_ppem  = (FT_UShort)( dim_y >> 6 );
    metrics2->x_scale = FT_DivFix( dim_x, face->root.units_per_EM );
    metrics2->y_scale = FT_DivFix( dim_y, face->root.units_per_EM );

    size->ttmetrics.valid = FALSE;
#ifdef TT_CONFIG_OPTION_EMBEDDED_BITMAPS
    size->strike_index    = 0xFFFFU;
#endif

    return tt_size_reset( size );
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */