ttdriver.c

qt-embedded-2.3.8.tar.gz源码

/***************************************************************************/
/*                                                                         */
/*  ttdriver.c                                                             */
/*                                                                         */
/*    TrueType font driver implementation (body).                          */
/*                                                                         */
/*  Copyright 1996-2000 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 <freetype/internal/ftdebug.h>
#include <freetype/internal/ftstream.h>
#include <freetype/internal/sfnt.h>
#include <freetype/ttnameid.h>


#ifdef FT_FLAT_COMPILE

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

#else

#include <truetype/ttdriver.h>
#include <truetype/ttgload.h>

#endif


  /*************************************************************************/
  /*                                                                       */
  /* 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>                                                            */
  /*    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  Get_Kerning( TT_Face     face,
                         FT_UInt     left_glyph,
                         FT_UInt     right_glyph,
                         FT_Vector*  kerning )
  {
    TT_Kern_0_Pair*  pair;


    if ( !face )
      return TT_Err_Invalid_Face_Handle;

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

    if ( face->kern_pairs )
    {
      /* there are some kerning pairs in this font file! */
      FT_ULong  search_tag = PAIR_TAG( left_glyph, right_glyph );
      FT_Long   left, right;


      left  = 0;
      right = face->num_kern_pairs - 1;

      while ( left <= right )
      {
        FT_Int    middle = left + ( ( right - left ) >> 1 );
        FT_ULong  cur_pair;


        pair     = face->kern_pairs + middle;
        cur_pair = PAIR_TAG( pair->left, pair->right );

        if ( cur_pair == search_tag )
          goto Found;

        if ( cur_pair < search_tag )
          left = middle + 1;
        else
          right = middle - 1;
      }
    }

  Exit:
    return TT_Err_Ok;

  Found:
    kerning->x = pair->value;
    goto Exit;
  }


#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( TT_Size     size,
                            FT_F26Dot6  char_width,
                            FT_F26Dot6  char_height,
                            FT_UInt     horz_resolution,
                            FT_UInt     vert_resolution )
  {
    FT_Size_Metrics*  metrics = &size->root.metrics;
    TT_Face           face    = (TT_Face)size->root.face;
    FT_Long           dim_x, dim_y;


    /* 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.          */
    /*                                                                */
    /* However, for those rare fonts who do not set it, we override   */
    /* the default computations performed by the base layer.  I       */
    /* really don't know whether this is useful, but hey, that's the  */
    /* spec :-)                                                       */
    /*                                                                */
    if ( ( face->header.Flags & 8 ) == 0 )
    {
      /* Compute pixel sizes in 26.6 units */
      dim_x = ( char_width  * horz_resolution ) / 72;
      dim_y = ( char_height * vert_resolution ) / 72;

      metrics->x_scale = FT_DivFix( dim_x, face->root.units_per_EM );
      metrics->y_scale = FT_DivFix( dim_y, face->root.units_per_EM );

      metrics->x_ppem  = (FT_UShort)( dim_x >> 6 );
      metrics->y_ppem  = (FT_UShort)( dim_y >> 6 );
    }

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

    return TT_Reset_Size( size );
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Set_Pixel_Sizes                                                    */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to reset a size's character sizes (horizontal */
  /*    and vertical) expressed in integer pixels.                         */
  /*                                                                       */
  /* <Input>                                                               */
  /*    pixel_width  :: The character width expressed in integer pixels.   */
  /*                                                                       */
  /*    pixel_height :: The character height expressed in integer pixels.  */
  /*                                                                       */
  /* <InOut>                                                               */
  /*    size         :: A handle to the target size object.                */
  /*                                                                       */
  /* <Return>                                                              */
  /*    FreeType error code.  0 means success.                             */
  /*                                                                       */
  static
  FT_Error  Set_Pixel_Sizes( TT_Size  size,
                             FT_UInt  pixel_width,
                             FT_UInt  pixel_height )
  {