t2driver.c

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Hash : f0df85ba
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Date : 2000-06-22T00:17:42

- MAJOR INTERNAL REDESIGN: A lot of internal modifications have been performed lately on the source in order to provide the following enhancements: - more generic module support: The FT_Module type is now defined to represent a handle to a given module. The file <freetype/ftmodule.h> contains the FT_Module_Class definition, as well as the module-loading public API The FT_Driver type is still defined, and still represents a pointer to a font driver. Note that FT_Add_Driver is replaced by FT_Add_Module, FT_Get_Driver by FT_Get_Module, etc.. - support for generic glyph image types: The FT_Renderer type is a pointer to a module used to perform various operations on glyph image. Each renderer is capable of handling images in a single format (e.g. ft_glyph_format_outline). Its functions are used to: - transform an glyph image - render a glyph image into a bitmap - return the control box (dimensions) of a given glyph image The scan converters "ftraster.c" and "ftgrays.c" have been moved to the new directory "src/renderer", and are used to provide two default renderer modules. One corresponds to the "standard" scan-converter, the other to the "smooth" one. The current renderer can be set through the new function FT_Set_Renderer. The old raster-related function FT_Set_Raster, FT_Get_Raster and FT_Set_Raster_Mode have now disappeared, in favor of the new: FT_Get_Renderer FT_Set_Renderer see the file <freetype/ftrender.h> for more details.. These changes were necessary to properly support different scalable formats in the future, like bi-color glyphs, etc.. - glyph loader object: A new internal object, called a 'glyph loader' has been introduced in the base layer. It is used by all scalable format font drivers to load glyphs and composites. This object has been created to reduce the code size of each driver, as each one of them basically re-implemented its functionality. See <freetype/internal/ftobjs.h> and the FT_GlyphLoader type for more information.. - FT_GlyphSlot had new fields: In order to support extended features (see below), the FT_GlyphSlot structure has a few new fields: linearHoriAdvance: this field gives the linearly scaled (i.e. scaled but unhinted) advance width for the glyph, expressed as a 16.16 fixed pixel value. This is useful to perform WYSIWYG text. linearVertAdvance: this field gives the linearly scaled advance height for the glyph (relevant in vertical glyph layouts only). This is useful to perform WYSIWYG text. Note that the two above field replace the removed "metrics2" field in the glyph slot. advance: this field is a vector that gives the transformed advance for the glyph. By default, it corresponds to the advance width, unless FT_LOAD_VERTICAL_LAYOUT was specified when calling FT_Load_Glyph or FT_Load_Char bitmap_left: this field gives the distance in integer pixels from the current pen position to the left-most pixel of a glyph image WHEN IT IS A BITMAP. It is only valid when the "format" field is set to "ft_glyph_format_bitmap", for example, after calling the new function FT_Render_Glyph. bitmap_top: this field gives the distance in integer pixels from the current pen position (located on the baseline) to the top-most pixel of the glyph image WHEN IT IS A BITMAP. Positive values correspond to upwards Y. loader: this is a new private field for the glyph slot. Client applications should not touch it.. - support for transforms and direct rendering in FT_Load_Glyph: Most of the functionality found in <freetype/ftglyph.h> has been moved to the core library. Hence, the following: - a transform can be specified for a face through FT_Set_Transform. this transform is applied by FT_Load_Glyph to scalable glyph images (i.e. NOT TO BITMAPS) before the function returns, unless the bit flag FT_LOAD_IGNORE_TRANSFORM was set in the load flags.. - once a glyph image has been loaded, it can be directly converted to a bitmap by using the new FT_Render_Glyph function. Note that this function takes the glyph image from the glyph slot, and converts it to a bitmap whose properties are returned in "face.glyph.bitmap", "face.glyph.bitmap_left" and "face.glyph.bitmap_top". The original native image might be lost after the conversion. - when using the new bit flag FT_LOAD_RENDER, the FT_Load_Glyph and FT_Load_Char functions will call FT_Render_Glyph automatically when needed.

src/cff/t2driver.c

/***************************************************************************/
/*                                                                         */
/*  t2driver.c                                                             */
/*                                                                         */
/*    OpenType 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/freetype.h>
#include <freetype/internal/ftdebug.h>
#include <freetype/internal/ftstream.h>
#include <freetype/internal/sfnt.h>
#include <freetype/ttnameid.h>

#include <t2driver.h>
#include <t2gload.h>

#include <freetype/internal/t2errors.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_t2driver


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****                          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>                                                              */
  /*    TrueType 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 T2_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 T2_Err_Ok;

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


#undef PAIR_TAG



  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Load_Glyph                                                         */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A driver method used to load a glyph within a given glyph slot.    */
  /*                                                                       */
  /* <Input>                                                               */
  /*    slot        :: A handle to the target slot object where the glyph  */
  /*                   will be loaded.                                     */
  /*                                                                       */
  /*    size        :: A handle to the source face size at which the glyph */
  /*                   must be scaled, loaded, etc.                        */
  /*                                                                       */
  /*    glyph_index :: The index of the glyph in the font file.            */
  /*                                                                       */
  /*    load_flags  :: A flag indicating what to load for this glyph.  The */
  /*                   FTLOAD_??? constants can be used to control the     */
  /*                   glyph loading process (e.g., whether the outline    */
  /*                   should be scaled, whether to load bitmaps or not,   */
  /*                   whether to hint the outline, etc).                  */
  /*                                                                       */
  /* <Return>                                                              */
  /*    TrueType error code.  0 means success.                             */
  /*                                                                       */
  static
  FT_Error  Load_Glyph( T2_GlyphSlot  slot,
                        T2_Size       size,
                        FT_UShort     glyph_index,
                        FT_UInt       load_flags )
  {
    FT_Error  error;


    if ( !slot )
      return T2_Err_Invalid_Glyph_Handle;

    /* check whether we want a scaled outline or bitmap */
    if ( !size )
      load_flags |= FT_LOAD_NO_SCALE | FT_LOAD_NO_HINTING;

    if ( load_flags & FT_LOAD_NO_SCALE )
      size = NULL;

    /* reset the size object if necessary */
    if ( size )
    {
      /* these two object must have the same parent */
      if ( size->face != slot->root.face )
        return T2_Err_Invalid_Face_Handle;
    }

    /* now load the glyph outline if necessary */
    error = T2_Load_Glyph( slot, size, glyph_index, load_flags );

    /* force drop-out mode to 2 - irrelevant now */
    /* slot->outline.dropout_mode = 2; */
    return error;
  }


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****             C H A R A C T E R   M A P P I N G S                 ****/
  /****                                                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/

  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Get_Char_Index                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Uses a charmap to return a given character code's glyph index.     */
  /*                                                                       */
  /* <Input>                                                               */
  /*    charmap  :: A handle to the source charmap object.                 */
  /*    charcode :: The character code.                                    */
  /*                                                                       */
  /* <Return>                                                              */
  /*    Glyph index.  0 means `undefined character code'.                  */
  /*                                                                       */
  static
  FT_UInt  Get_Char_Index( TT_CharMap  charmap,
                           FT_Long     charcode )
  {
    FT_Error       error;
    T2_Face        face;
    TT_CMapTable*  cmap;


    cmap = &charmap->cmap;
    face = (T2_Face)charmap->root.face;

    /* Load table if needed */
    if ( !cmap->loaded )
    {
      SFNT_Interface*  sfnt = (SFNT_Interface*)face->sfnt;


      error = sfnt->load_charmap( face, cmap, face->root.stream );
      if ( error )
        return 0;

      cmap->loaded = TRUE;
    }

    return ( cmap->get_index ? cmap->get_index( cmap, charcode ) : 0 );
  }


  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/
  /****                                                                 ****/
  /****                                                                 ****/
  /****                D R I V E R  I N T E R F A C E                   ****/
  /****                                                                 ****/
  /****                                                                 ****/
  /*************************************************************************/
  /*************************************************************************/
  /*************************************************************************/


  static
  FT_Module_Interface  t2_get_interface( T2_Driver    driver,
                                         const char*  interface )
  {
    FT_Module  sfnt;

    /* we simply pass our request to the "sfnt" module */
    sfnt = FT_Get_Module( driver->root.root.library, "sfnt" );
    return sfnt ? sfnt->clazz->get_interface( sfnt, interface ) : 0;
  }


  /* The FT_DriverInterface structure is defined in ftdriver.h. */

  const FT_Driver_Class   cff_driver_class =
  {
    /* begin with the FT_Module_Class fields */
    {
      ft_module_font_driver | ft_module_driver_scalable,
      sizeof( T2_DriverRec ),
      "cff",
      0x10000,
      0x20000,

      0,   /* module-specific interface */
      
      (FT_Module_Constructor)  T2_Init_Driver,
      (FT_Module_Destructor)   T2_Done_Driver,
      (FT_Module_Requester)    t2_get_interface,
    },
    
    /* now the specific driver fields */
    sizeof( TT_FaceRec ),
    sizeof( FT_SizeRec ),
    sizeof( T2_GlyphSlotRec ),

    (FTDriver_initFace)       T2_Init_Face,
    (FTDriver_doneFace)       T2_Done_Face,
    (FTDriver_initSize)       0,
    (FTDriver_doneSize)       0,
    (FTDriver_initGlyphSlot)  0,
    (FTDriver_doneGlyphSlot)  0,

    (FTDriver_setCharSizes)   0,
    (FTDriver_setPixelSizes)  0,
    
    (FTDriver_loadGlyph)      Load_Glyph,
    (FTDriver_getCharIndex)   Get_Char_Index,

    (FTDriver_getKerning)     Get_Kerning,
    (FTDriver_attachFile)     0,
    (FTDriver_getAdvances)    0
  };


#ifdef FT_CONFIG_OPTION_DYNAMIC_DRIVERS


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    getDriverClass                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    This function is used when compiling the TrueType driver as a      */
  /*    shared library (`.DLL' or `.so').  It will be used by the          */
  /*    high-level library of FreeType to retrieve the address of the      */
  /*    driver's generic interface.                                        */
  /*                                                                       */
  /*    It shouldn't be implemented in a static build, as each driver must */
  /*    have the same function as an exported entry point.                 */
  /*                                                                       */
  /* <Return>                                                              */
  /*    The address of the TrueType's driver generic interface.  The       */
  /*    format-specific interface can then be retrieved through the method */
  /*    interface->get_format_interface.                                   */
  /*                                                                       */
  EXPORT_FUNC( FT_Driver_Class* )  getDriverClass( void )
  {
    return &cff_driver_class;
  }


#endif /* CONFIG_OPTION_DYNAMIC_DRIVERS */


/* END */

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