ftraster.c

这是一个开放源代码的与WINNT/WIN2K/WIN2003兼容的操作系统

  /*                                                                       */
  /* <Description>                                                         */
  /*    Finalizes the current profile.                                     */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success.  FAILURE in case of overflow or incoherency.   */
  /*                                                                       */
  static Bool
  End_Profile( RAS_ARG )
  {
    Long      h;
    PProfile  oldProfile;


    h = (Long)( ras.top - ras.cProfile->offset );

    if ( h < 0 )
    {
      FT_ERROR(( "End_Profile: negative height encountered!\n" ));
      ras.error = Raster_Err_Neg_Height;
      return FAILURE;
    }

    if ( h > 0 )
    {
      FT_TRACE6(( "Ending profile %lx, start = %ld, height = %ld\n",
                  (long)ras.cProfile, ras.cProfile->start, h ));

      oldProfile           = ras.cProfile;
      ras.cProfile->height = h;
      ras.cProfile         = (PProfile)ras.top;

      ras.top             += AlignProfileSize;

      ras.cProfile->height = 0;
      ras.cProfile->offset = ras.top;
      oldProfile->next     = ras.cProfile;
      ras.num_Profs++;
    }

    if ( ras.top >= ras.maxBuff )
    {
      FT_TRACE1(( "overflow in End_Profile\n" ));
      ras.error = Raster_Err_Overflow;
      return FAILURE;
    }

    ras.joint = FALSE;

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Insert_Y_Turn                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Inserts a salient into the sorted list placed on top of the render */
  /*    pool.                                                              */
  /*                                                                       */
  /* <Input>                                                               */
  /*    New y scanline position.                                           */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success.  FAILURE in case of overflow.                  */
  /*                                                                       */
  static Bool
  Insert_Y_Turn( RAS_ARGS Int  y )
  {
    PLong  y_turns;
    Int    y2, n;


    n       = ras.numTurns - 1;
    y_turns = ras.sizeBuff - ras.numTurns;

    /* look for first y value that is <= */
    while ( n >= 0 && y < y_turns[n] )
      n--;

    /* if it is <, simply insert it, ignore if == */
    if ( n >= 0 && y > y_turns[n] )
      while ( n >= 0 )
      {
        y2 = (Int)y_turns[n];
        y_turns[n] = y;
        y = y2;
        n--;
      }

    if ( n < 0 )
    {
      ras.maxBuff--;
      if ( ras.maxBuff <= ras.top )
      {
        ras.error = Raster_Err_Overflow;
        return FAILURE;
      }
      ras.numTurns++;
      ras.sizeBuff[-ras.numTurns] = y;
    }

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Finalize_Profile_Table                                             */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Adjusts all links in the profiles list.                            */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success.  FAILURE in case of overflow.                  */
  /*                                                                       */
  static Bool
  Finalize_Profile_Table( RAS_ARG )
  {
    Int       bottom, top;
    UShort    n;
    PProfile  p;


    n = ras.num_Profs;

    if ( n > 1 )
    {
      p = ras.fProfile;
      while ( n > 0 )
      {
        if ( n > 1 )
          p->link = (PProfile)( p->offset + p->height );
        else
          p->link = NULL;

        switch ( p->flow )
        {
        case Flow_Down:
          bottom     = (Int)( p->start - p->height + 1 );
          top        = (Int)p->start;
          p->start   = bottom;
          p->offset += p->height - 1;
          break;

        case Flow_Up:
        default:
          bottom = (Int)p->start;
          top    = (Int)( p->start + p->height - 1 );
        }

        if ( Insert_Y_Turn( RAS_VARS bottom )   ||
             Insert_Y_Turn( RAS_VARS top + 1 )  )
          return FAILURE;

        p = p->link;
        n--;
      }
    }
    else
      ras.fProfile = NULL;

    return SUCCESS;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Split_Conic                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Subdivides one conic Bezier into two joint sub-arcs in the Bezier  */
  /*    stack.                                                             */
  /*                                                                       */
  /* <Input>                                                               */
  /*    None (subdivided Bezier is taken from the top of the stack).       */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This routine is the `beef' of this component.  It is  _the_ inner  */
  /*    loop that should be optimized to hell to get the best performance. */
  /*                                                                       */
  static void
  Split_Conic( TPoint*  base )
  {
    Long  a, b;


    base[4].x = base[2].x;
    b = base[1].x;
    a = base[3].x = ( base[2].x + b ) / 2;
    b = base[1].x = ( base[0].x + b ) / 2;
    base[2].x = ( a + b ) / 2;

    base[4].y = base[2].y;
    b = base[1].y;
    a = base[3].y = ( base[2].y + b ) / 2;
    b = base[1].y = ( base[0].y + b ) / 2;
    base[2].y = ( a + b ) / 2;

    /* hand optimized.  gcc doesn't seem to be too good at common      */
    /* expression substitution and instruction scheduling ;-)          */
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Split_Cubic                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Subdivides a third-order Bezier arc into two joint sub-arcs in the */
  /*    Bezier stack.                                                      */
  /*                                                                       */
  /* <Note>                                                                */
  /*    This routine is the `beef' of the component.  It is one of _the_   */
  /*    inner loops that should be optimized like hell to get the best     */
  /*    performance.                                                       */
  /*                                                                       */
  static void
  Split_Cubic( TPoint*  base )
  {
    Long  a, b, c, d;


    base[6].x = base[3].x;
    c = base[1].x;
    d = base[2].x;
    base[1].x = a = ( base[0].x + c + 1 ) >> 1;
    base[5].x = b = ( base[3].x + d + 1 ) >> 1;
    c = ( c + d + 1 ) >> 1;
    base[2].x = a = ( a + c + 1 ) >> 1;
    base[4].x = b = ( b + c + 1 ) >> 1;
    base[3].x = ( a + b + 1 ) >> 1;

    base[6].y = base[3].y;
    c = base[1].y;
    d = base[2].y;
    base[1].y = a = ( base[0].y + c + 1 ) >> 1;
    base[5].y = b = ( base[3].y + d + 1 ) >> 1;
    c = ( c + d + 1 ) >> 1;
    base[2].y = a = ( a + c + 1 ) >> 1;
    base[4].y = b = ( b + c + 1 ) >> 1;
    base[3].y = ( a + b + 1 ) >> 1;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Line_Up                                                            */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Computes the x-coordinates of an ascending line segment and stores */
  /*    them in the render pool.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    x1   :: The x-coordinate of the segment's start point.             */
  /*                                                                       */
  /*    y1   :: The y-coordinate of the segment's start point.             */
  /*                                                                       */
  /*    x2   :: The x-coordinate of the segment's end point.               */
  /*                                                                       */
  /*    y2   :: The y-coordinate of the segment's end point.               */
  /*                                                                       */
  /*    miny :: A lower vertical clipping bound value.                     */
  /*                                                                       */
  /*    maxy :: An upper vertical clipping bound value.                    */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success, FAILURE on render pool overflow.               */
  /*                                                                       */
  static Bool
  Line_Up( RAS_ARGS Long  x1,
                    Long  y1,
                    Long  x2,
                    Long  y2,
                    Long  miny,
                    Long  maxy )
  {
    Long   Dx, Dy;
    Int    e1, e2, f1, f2, size;     /* XXX: is `Short' sufficient? */
    Long   Ix, Rx, Ax;

    PLong  top;


    Dx = x2 - x1;
    Dy = y2 - y1;

    if ( Dy <= 0 || y2 < miny || y1 > maxy )
      return SUCCESS;

    if ( y1 < miny )
    {
      /* Take care: miny-y1 can be a very large value; we use     */
      /*            a slow MulDiv function to avoid clipping bugs */
      x1 += SMulDiv( Dx, miny - y1, Dy );
      e1  = (Int)TRUNC( miny );
      f1  = 0;
    }
    else
    {
      e1 = (Int)TRUNC( y1 );
      f1 = (Int)FRAC( y1 );
    }

    if ( y2 > maxy )
    {
      /* x2 += FMulDiv( Dx, maxy - y2, Dy );  UNNECESSARY */
      e2  = (Int)TRUNC( maxy );
      f2  = 0;
    }
    else
    {
      e2 = (Int)TRUNC( y2 );
      f2 = (Int)FRAC( y2 );
    }

    if ( f1 > 0 )
    {
      if ( e1 == e2 )
        return SUCCESS;
      else
      {
        x1 += FMulDiv( Dx, ras.precision - f1, Dy );
        e1 += 1;
      }
    }
    else
      if ( ras.joint )
      {
        ras.top--;
        ras.joint = FALSE;
      }

    ras.joint = (char)( f2 == 0 );