ttraster.c

神龙卡开发原代码

    fresh  = ras.fresh;

    result = Line_Up( RAS_VARS x1, -y1, x2, -y2, -maxy, -miny );

    if ( fresh && !ras.fresh )
      ras.cProfile->start = -ras.cProfile->start;

    return result;
  }


/****************************************************************************/
/*                                                                          */
/* Function:    Bezier_Up                                                   */
/*                                                                          */
/* Description: Computes thes x-coordinates of an ascending bezier arc      */
/*              and stores them in the render pool.                         */
/*                                                                          */
/* Input:       None.  The arc is taken from the top of the Bezier stack.   */
/*                                                                          */
/* Returns:     SUCCESS on success.                                         */
/*              FAILURE on Render Pool overflow.                            */
/*                                                                          */
/****************************************************************************/

  static Bool  Bezier_Up( RAS_ARGS Long  miny, Long  maxy )
  {
    Long   y1, y2, e, e2, e0;
    Short  f1;

    TPoint*  arc;
    TPoint*  start_arc;

    PStorage top;


    arc = ras.arc;
    y1  = arc[2].y;
    y2  = arc[0].y;
    top = ras.top;

    if ( y2 < miny || y1 > maxy )
      goto Fin;

    e2 = FLOOR( y2 );

    if ( e2 > maxy )
      e2 = maxy;

    e0 = miny;

    if ( y1 < miny )
      e = miny;
    else
    {
      e  = CEILING( y1 );
      f1 = FRAC( y1 );
      e0 = e;

      if ( f1 == 0 )
      {
        if ( ras.joint )
        {
          top--;
          ras.joint = FALSE;
        }

        *top++ = arc[2].x;

        DEBUG_PSET;

        e += ras.precision;
      }
    }

    if ( ras.fresh )
    {
      ras.cProfile->start = TRUNC( e0 );
      ras.fresh = FALSE;
    }

    if ( e2 < e )
      goto Fin;

    if ( ( top + TRUNC( e2 - e ) + 1 ) >= ras.maxBuff )
    {
      ras.top   = top;
      ras.error = Raster_Err_Overflow;
      return FAILURE;
    }

    start_arc = arc;

    while ( arc >= start_arc && e <= e2 )
    {
      ras.joint = FALSE;

      y2 = arc[0].y;

      if ( y2 > e )
      {
        y1 = arc[2].y;
        if ( y2 - y1 >= ras.precision_step )
        {
          Split_Bezier( arc );
          arc += 2;
        }
        else
        {
          *top++ = arc[2].x + FMulDiv( arc[0].x - arc[2].x,
                                       e - y1,
                                       y2 - y1 );
          DEBUG_PSET;

          arc -= 2;
          e   += ras.precision;
        }
      }
      else
      {
        if ( y2 == e )
        {
          ras.joint  = TRUE;
          *top++     = arc[0].x;

          DEBUG_PSET;

          e += ras.precision;
        }
        arc -= 2;
      }
    }

  Fin:
    ras.top  = top;
    ras.arc -= 2;
    return SUCCESS;
  }


/****************************************************************************/
/*                                                                          */
/* Function:    Bezier_Down                                                 */
/*                                                                          */
/* Description: Computes the x-coordinates of a descending bezier arc       */
/*              and stores them in the render pool.                         */
/*                                                                          */
/* Input:       None.  Arc is taken from the top of the Bezier stack.       */
/*                                                                          */
/* Returns:     SUCCESS on success.                                         */
/*              FAILURE on Render Pool overflow.                            */
/*                                                                          */
/****************************************************************************/

  static Bool  Bezier_Down( RAS_ARGS Long  miny, Long  maxy )
  {
    TPoint*  arc = ras.arc;
    Bool     result, fresh;


    arc[0].y = -arc[0].y;
    arc[1].y = -arc[1].y;
    arc[2].y = -arc[2].y;

    fresh = ras.fresh;

    result = Bezier_Up( RAS_VARS -maxy, -miny );

    if ( fresh && !ras.fresh )
      ras.cProfile->start = -ras.cProfile->start;

    arc[0].y = -arc[0].y;
    return result;
  }


/****************************************************************************/
/*                                                                          */
/* Function:    Line_To                                                     */
/*                                                                          */
/* Description: Injects a new line segment and adjusts Profiles list.       */
/*                                                                          */
/* Input:       x, y : segment endpoint (start point in LastX,LastY)        */
/*                                                                          */
/* Returns:     SUCCESS on success.                                         */
/*              FAILURE on Render Pool overflow or Incorrect Profile.       */
/*                                                                          */
/****************************************************************************/

  static Bool  Line_To( RAS_ARGS Long  x, Long  y )
  {
    /* First, detect a change of direction */

    switch ( ras.state )
    {
    case Unknown:
      if ( y > ras.lastY )
      {
        if ( New_Profile( RAS_VARS  Ascending ) ) return FAILURE;
      }
      else
      {
        if ( y < ras.lastY )
          if ( New_Profile( RAS_VARS  Descending ) ) return FAILURE;
      }
      break;

    case Ascending:
      if ( y < ras.lastY )
      {
        if ( End_Profile( RAS_VAR ) ||
             New_Profile( RAS_VARS  Descending ) ) return FAILURE;
      }
      break;

    case Descending:
      if ( y > ras.lastY )
      {
        if ( End_Profile( RAS_VAR ) ||
             New_Profile( RAS_VARS  Ascending ) ) return FAILURE;
      }
      break;

    default:
      ;
    }

    /* Then compute the lines */

    switch ( ras.state )
    {
    case Ascending:
      if ( Line_Up ( RAS_VARS  ras.lastX, ras.lastY,
                     x, y, ras.minY, ras.maxY ) )
        return FAILURE;
      break;

    case Descending:
      if ( Line_Down( RAS_VARS ras.lastX, ras.lastY,
                      x, y, ras.minY, ras.maxY ) )
        return FAILURE;
      break;

    default:
      ;
    }

    ras.lastX = x;
    ras.lastY = y;

    return SUCCESS;
  }


/****************************************************************************/
/*                                                                          */
/* Function:    Bezier_To                                                   */
/*                                                                          */
/* Description: Injects a new bezier arc and adjusts the profile list.      */
/*                                                                          */
/* Input:       x,   y : arc endpoint (start point in LastX, LastY)         */
/*              Cx, Cy : control point                                      */
/*                                                                          */
/* Returns:     SUCCESS on success.                                         */
/*              FAILURE on Render Pool overflow or Incorrect Profile.       */
/*                                                                          */
/****************************************************************************/

  static Bool  Bezier_To( RAS_ARGS Long  x,
                                   Long  y,
                                   Long  cx,
                                   Long  cy )
  {
    Long     y1, y2, y3, x3;
    TStates  state_bez;


    Push_Bezier( RAS_VARS ras.lastX, ras.lastY, cx, cy, x, y );

    do
    {
      y1 = ras.arc[2].y;
      y2 = ras.arc[1].y;
      y3 = ras.arc[0].y;
      x3 = ras.arc[0].x;

      /* first, categorize the bezier arc */

      if ( y1 == y2 )
      {
        if ( y2 == y3 )
          state_bez = Flat;
        else if ( y2 > y3 )
          state_bez = Descending;
        else
          state_bez = Ascending;
      }
      else if ( y1 > y2 )
      {
        if ( y2 >= y3 )
          state_bez = Descending;
        else
          state_bez = Unknown;
      }
      else if ( y2 <= y3 )
        state_bez = Ascending;
      else
        state_bez = Unknown;

      /* split non-monotonic arcs, ignore flat ones, or */
      /* computes the up and down ones                  */

      switch ( state_bez )
      {
      case Flat:
        ras.arc -= 2;
        break;

      case Unknown:
        Split_Bezier( ras.arc );
        ras.arc += 2;
        break;

      default:
        /* detect a change of direction */

        if ( ras.state != state_bez )
        {
          if ( ras.state != Unknown )
            if ( End_Profile( RAS_VAR ) ) return FAILURE;

          if ( New_Profile( RAS_VARS state_bez ) ) return FAILURE;
        }

        /* compute */

        switch ( ras.state )
        {
        case Ascending:
          if ( Bezier_Up ( RAS_VARS ras.minY, ras.maxY ) )
            return FAILURE;
          break;

        case Descending:
          if ( Bezier_Down( RAS_VARS ras.minY, ras.maxY ) )
            return FAILURE;
          break;

        default:
          ;
        }
      }
    } while ( ras.arc >= ras.arcs );

    ras.lastX = x3;
    ras.lastY = y3;

    return SUCCESS;
  }


/****************************************************************************/
/*                                                                          */
/* Function:    Decompose_Curve                                             */
/*                                                                          */
/* Description: Scans the outline arays in order to emit individual         */
/*              segments and beziers by calling Line_To() and Bezier_To().  */
/*              It handles all weird cases, like when the first point       */
/*              is off the curve, or when there are simply no 'on'          */
/*              points in the contour!                                      */
/*                                                                          */
/* Input:       first, last    : indexes of first and last point in         */
/*                               contour.                                   */
/*                                                                          */
/* Returns:     SUCCESS on success.                                         */
/*              FAILURE on error.                                           */
/*                                                                          */
/****************************************************************************/

#undef  SWAP_
#define SWAP_(x,y)  { Long swap = x; x = y; y = swap; }

  static Bool  Decompose_Curve( RAS_ARGS UShort  first,
                                         UShort  last,
                                         Bool    flipped )
  {
    Long   x,  y;   /* current point                */
    Long   cx, cy;  /* current Bezier control point */
    Long   mx, my;  /* current middle point         */

    Long   x_first, y_first;  /* first point's coordinates */
    Long   x_last,  y_last;   /* last point's coordinates  */

    UShort  index;     /* current point's index */
    Bool    on_curve;  /* current point's state */

    x_first = SCALED( ras.coords[first].x );
    y_first = SCALED( ras.coords[first].y );

    if ( flipped ) SWAP_( x_first,y_first );

    x_last  = SCALED( ras.coords[last].x );
    y_last  = SCALED( ras.coords[last].y );

    if ( flipped ) SWAP_( x_last,y_last );

    ras.lastX = cx = x_first;
    ras.lastY = cy = y_first;

    on_curve = (ras.flags[first] & 1);
    index    = first;

    /* check first point to determine origin */
    if ( !on_curve )
    {
      /* first point is off the curve.  Yes, this happens... */
      if ( ras.flags[last] & 1 )
      {
        ras.lastX = x_last;  /* start at last point if it */
        ras.lastY = y_last;  /* is on the curve           */
      }
      else
      {
        /* if both first and last points are off the curve, */
        /* start at their middle and record its position    */
        /* for closure                                      */