ftraster.c

qt-x11-opensource-src-4.1.4.tar.gz源码

  /*    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_Down( RAS_ARGS Long  x1,
                      Long  y1,
                      Long  x2,
                      Long  y2,
                      Long  miny,
                      Long  maxy )
  {
    Bool  result, fresh;


    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;
  }


  /* A function type describing the functions used to split Bezier arcs */
  typedef void  (*TSplitter)( TPoint*  base );


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Bezier_Up                                                          */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Computes the x-coordinates of an ascending Bezier arc and stores   */
  /*    them in the render pool.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    degree   :: The degree of the Bezier arc (either 2 or 3).          */
  /*                                                                       */
  /*    splitter :: The function to split Bezier arcs.                     */
  /*                                                                       */
  /*    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
  Bezier_Up( RAS_ARGS Int        degree,
                      TSplitter  splitter,
                      Long       miny,
                      Long       maxy )
  {
    Long   y1, y2, e, e2, e0;
    Short  f1;

    TPoint*  arc;
    TPoint*  start_arc;

    PLong top;


    arc = ras.arc;
    y1  = arc[degree].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 = (Short)( FRAC( y1 ) );
      e0 = e;

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

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

        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[degree].y;
        if ( y2 - y1 >= ras.precision_step )
        {
          splitter( arc );
          arc += degree;
        }
        else
        {
          *top++ = arc[degree].x + FMulDiv( arc[0].x-arc[degree].x,
                                            e - y1, y2 - y1 );
          arc -= degree;
          e   += ras.precision;
        }
      }
      else
      {
        if ( y2 == e )
        {
          ras.joint  = TRUE;
          *top++     = arc[0].x;

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

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


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Bezier_Down                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Computes the x-coordinates of an descending Bezier arc and stores  */
  /*    them in the render pool.                                           */
  /*                                                                       */
  /* <Input>                                                               */
  /*    degree   :: The degree of the Bezier arc (either 2 or 3).          */
  /*                                                                       */
  /*    splitter :: The function to split Bezier arcs.                     */
  /*                                                                       */
  /*    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
  Bezier_Down( RAS_ARGS Int        degree,
                        TSplitter  splitter,
                        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;
    if ( degree > 2 )
      arc[3].y = -arc[3].y;

    fresh = ras.fresh;

    result = Bezier_Up( RAS_VARS degree, splitter, -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 :: The x-coordinate of the segment's end point (its start point   */
  /*        is stored in `lastX').                                         */
  /*                                                                       */
  /*   y :: The y-coordinate of the segment's end point (its start point   */
  /*        is stored in `lastY').                                         */
  /*                                                                       */
  /* <Return>                                                              */
  /*   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_State:
      if ( y > ras.lastY )
      {
        if ( New_Profile( RAS_VARS Ascending_State ) )
          return FAILURE;
      }
      else
      {
        if ( y < ras.lastY )
          if ( New_Profile( RAS_VARS Descending_State ) )
            return FAILURE;
      }
      break;

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

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

    default:
      ;
    }

    /* Then compute the lines */

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

    case Descending_State:
      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>                                                            */
  /*    Conic_To                                                           */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Injects a new conic arc and adjusts the profile list.              */
  /*                                                                       */
  /* <Input>                                                               */
  /*   cx :: The x-coordinate of the arc's new control point.              */
  /*                                                                       */
  /*   cy :: The y-coordinate of the arc's new control point.              */
  /*                                                                       */
  /*   x  :: The x-coordinate of the arc's end point (its start point is   */
  /*         stored in `lastX').                                           */
  /*                                                                       */
  /*   y  :: The y-coordinate of the arc's end point (its start point is   */
  /*         stored in `lastY').                                           */
  /*                                                                       */
  /* <Return>                                                              */
  /*   SUCCESS on success, FAILURE on render pool overflow or incorrect    */
  /*   profile.                                                            */
  /*                                                                       */
  static Bool
  Conic_To( RAS_ARGS Long  cx,
                     Long  cy,
                     Long  x,
                     Long  y )
  {
    Long     y1, y2, y3, x3, ymin, ymax;
    TStates  state_bez;


    ras.arc      = ras.arcs;
    ras.arc[2].x = ras.lastX;
    ras.arc[2].y = ras.lastY;
    ras.arc[1].x = cx; ras.arc[1].y = cy;
    ras.arc[0].x = x;  ras.arc[0].y = 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 */