ftsynth.c

Go to the documentation of this file.

/***************************************************************************/
/*                                                                         */
/*  ftsynth.c                                                              */
/*                                                                         */
/*    FreeType synthesizing code for emboldening and slanting (body).      */
/*                                                                         */
/*  Copyright 2000-2001, 2002, 2003, 2004, 2005, 2006, 2010 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_SYNTHESIS_H
#include FT_INTERNAL_DEBUG_H
#include FT_INTERNAL_OBJECTS_H
#include FT_OUTLINE_H
#include FT_BITMAP_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_synth

  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****   EXPERIMENTAL OBLIQUING SUPPORT                                ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/

  /* documentation is in ftsynth.h */

  FT_EXPORT_DEF( void )
  FT_GlyphSlot_Oblique( FT_GlyphSlot  slot )
  {
    FT_Matrix    transform;
    FT_Outline*  outline = &slot->outline;


    /* only oblique outline glyphs */
    if ( slot->format != FT_GLYPH_FORMAT_OUTLINE )
      return;

    /* we don't touch the advance width */

    /* For italic, simply apply a shear transform, with an angle */
    /* of about 12 degrees.                                      */

    transform.xx = 0x10000L;
    transform.yx = 0x00000L;

    transform.xy = 0x06000L;
    transform.yy = 0x10000L;

    FT_Outline_Transform( outline, &transform );
  }


  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****   EXPERIMENTAL EMBOLDENING/OUTLINING SUPPORT                    ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/


  /* documentation is in ftsynth.h */

  FT_EXPORT_DEF( void )
  FT_GlyphSlot_Embolden( FT_GlyphSlot  slot )
  {
    FT_Library  library = slot->library;
    FT_Face     face    = slot->face;
    FT_Error    error;
    FT_Pos      xstr, ystr;


    if ( slot->format != FT_GLYPH_FORMAT_OUTLINE &&
         slot->format != FT_GLYPH_FORMAT_BITMAP  )
      return;

    /* some reasonable strength */
    xstr = FT_MulFix( face->units_per_EM,
                      face->size->metrics.y_scale ) / 24;
    ystr = xstr;

    if ( slot->format == FT_GLYPH_FORMAT_OUTLINE )
    {
      /* ignore error */
      (void)FT_Outline_Embolden( &slot->outline, xstr );

      /* this is more than enough for most glyphs; if you need accurate */
      /* values, you have to call FT_Outline_Get_CBox                   */
      xstr = xstr * 2;
      ystr = xstr;
    }
    else /* slot->format == FT_GLYPH_FORMAT_BITMAP */
    {
      /* round to full pixels */
      xstr &= ~63;
      if ( xstr == 0 )
        xstr = 1 << 6;
      ystr &= ~63;

      /*
       * XXX: overflow check for 16-bit system, for compatibility
       *      with FT_GlyphSlot_Embolden() since freetype-2.1.10.
       *      unfortunately, this function return no informations
       *      about the cause of error.
       */
      if ( ( ystr >> 6 ) > FT_INT_MAX || ( ystr >> 6 ) < FT_INT_MIN )
      {
        FT_TRACE1(( "FT_GlyphSlot_Embolden:" ));
        FT_TRACE1(( "too strong embolding parameter ystr=%d\n", ystr ));
        return;
      }
      error = FT_GlyphSlot_Own_Bitmap( slot );
      if ( error )
        return;

      error = FT_Bitmap_Embolden( library, &slot->bitmap, xstr, ystr );
      if ( error )
        return;
    }

    if ( slot->advance.x )
      slot->advance.x += xstr;

    if ( slot->advance.y )
      slot->advance.y += ystr;

    slot->metrics.width        += xstr;
    slot->metrics.height       += ystr;
    slot->metrics.horiBearingY += ystr;
    slot->metrics.horiAdvance  += xstr;
    slot->metrics.vertBearingX -= xstr / 2;
    slot->metrics.vertBearingY += ystr;
    slot->metrics.vertAdvance  += ystr;

    /* XXX: 16-bit overflow case must be excluded before here */
    if ( slot->format == FT_GLYPH_FORMAT_BITMAP )
      slot->bitmap_top += (FT_Int)( ystr >> 6 );
  }


/* END */