ftraster.c

qt-embedded-2.3.8.tar.gz源码

  /*   cy1 :: The y-coordinate of the arc's first new control point.       */
  /*                                                                       */
  /*   cx2 :: The x-coordinate of the arc's second new control point.      */
  /*                                                                       */
  /*   cy2 :: The y-coordinate of the arc's second 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  Cubic_To( RAS_ARGS Long  cx1,
                           Long  cy1,
                           Long  cx2,
                           Long  cy2,
                           Long  x,
                           Long  y )
  {
    Long     y1, y2, y3, y4, x4, ymin1, ymax1, ymin2, ymax2;
    TStates  state_bez;


    ras.arc      = ras.arcs;
    ras.arc[3].x = ras.lastX;
    ras.arc[3].y = ras.lastY;
    ras.arc[2].x = cx1; ras.arc[2].y = cy1;
    ras.arc[1].x = cx2; ras.arc[1].y = cy2;
    ras.arc[0].x = x;   ras.arc[0].y = y;

    do
    {
      y1 = ras.arc[3].y;
      y2 = ras.arc[2].y;
      y3 = ras.arc[1].y;
      y4 = ras.arc[0].y;
      x4 = ras.arc[0].x;

      /* first, categorize the Bezier arc */

      if ( y1 <= y4 )
      {
        ymin1 = y1;
        ymax1 = y4;
      }
      else
      {
        ymin1 = y4;
        ymax1 = y1;
      }

      if ( y2 <= y3 )
      {
        ymin2 = y2;
        ymax2 = y3;
      }
      else
      {
        ymin2 = y3;
        ymax2 = y2;
      }

      if ( ymin2 < ymin1 || ymax2 > ymax1 )
      {
        /* this arc has no given direction, split it! */
        Split_Cubic( ras.arc );
        ras.arc += 3;
      }
      else if ( y1 == y4 )
      {
        /* this arc is flat, ignore it and pop it from the Bezier stack */
        ras.arc -= 3;
      }
      else
      {
        state_bez = ( y1 <= y4 ) ? Ascending : Descending;

        /* detect a change of direction */
        if ( ras.state != state_bez )
        {
          if ( ras.state != Unknown   &&
               End_Profile( RAS_VAR ) )
            goto Fail;

          if ( New_Profile( RAS_VARS state_bez ) )
            goto Fail;
        }

        /* compute intersections */
        if ( state_bez == Ascending )
        {
          if ( Bezier_Up( RAS_VARS 3, Split_Cubic, ras.minY, ras.maxY ) )
            goto Fail;
        }
        else
          if ( Bezier_Down( RAS_VARS 3, Split_Cubic, ras.minY, ras.maxY ) )
            goto Fail;
      }

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

    ras.lastX = x4;
    ras.lastY = y4;

    return SUCCESS;

  Fail:
    return FAILURE;
  }


#undef  SWAP_
#define SWAP_( x, y )  do                \
                       {                 \
                         Long  swap = x; \
                                         \
                                         \
                         x = y;          \
                         y = swap;       \
                       } while ( 0 )


  /*************************************************************************/
  /*                                                                       */
  /* <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   :: The index of the first point in the contour.            */
  /*                                                                       */
  /*    last    :: The index of the last point in the contour.             */
  /*                                                                       */
  /*    flipped :: If set, flip the direction of the curve.                */
  /*                                                                       */
  /* <Return>                                                              */
  /*    SUCCESS on success, FAILURE on error.                              */
  /*                                                                       */
  static
  Bool  Decompose_Curve( RAS_ARGS UShort  first,
                                  UShort  last,
                                  int     flipped )
  {
    FT_Vector   v_last;
    FT_Vector   v_control;
    FT_Vector   v_start;

    FT_Vector*  points;
    FT_Vector*  point;
    FT_Vector*  limit;
    char*       tags;

    char        tag;       /* current point's state           */


    points = ras.outline.points;
    limit  = points + last;

    v_start.x = SCALED( points[first].x );
    v_start.y = SCALED( points[first].y );
    v_last.x  = SCALED( points[last].x );
    v_last.y  = SCALED( points[last].y );

    if ( flipped )
    {
      SWAP_( v_start.x, v_start.y );
      SWAP_( v_last.x, v_last.y );
    }

    v_control = v_start;

    point = points + first;
    tags  = ras.outline.tags  + first;
    tag   = FT_CURVE_TAG( tags[0] );

    /* A contour cannot start with a cubic control point! */
    if ( tag == FT_Curve_Tag_Cubic )
      goto Invalid_Outline;

    /* check first point to determine origin */
    if ( tag == FT_Curve_Tag_Conic )
    {
      /* first point is conic control.  Yes, this happens. */
      if ( FT_CURVE_TAG( ras.outline.tags[last] ) == FT_Curve_Tag_On )
      {
        /* start at last point if it is on the curve */
        v_start = v_last;
        limit--;
      }
      else
      {
        /* if both first and last points are conic,         */
        /* start at their middle and record its position    */
        /* for closure                                      */
        v_start.x = ( v_start.x + v_last.x ) / 2;
        v_start.y = ( v_start.y + v_last.y ) / 2;

        v_last = v_start;
      }
      point--;
      tags--;
    }

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

    while ( point < limit )
    {
      point++;
      tags++;

      tag = FT_CURVE_TAG( tags[0] );

      switch ( tag )
      {
      case FT_Curve_Tag_On:  /* emit a single line_to */
        {
          Long  x, y;


          x = SCALED( point->x );
          y = SCALED( point->y );
          if ( flipped )
            SWAP_( x, y );

          if ( Line_To( RAS_VARS x, y ) )
            goto Fail;
          continue;
        }

      case FT_Curve_Tag_Conic:  /* consume conic arcs */
        v_control.x = SCALED( point[0].x );
        v_control.y = SCALED( point[0].y );

        if ( flipped )
          SWAP_( v_control.x, v_control.y );

      Do_Conic:
        if ( point < limit )
        {
          FT_Vector  v_middle;
          Long       x, y;


          point++;
          tags++;
          tag = FT_CURVE_TAG( tags[0] );

          x = SCALED( point[0].x );
          y = SCALED( point[0].y );

          if ( flipped )
            SWAP_( x, y );

          if ( tag == FT_Curve_Tag_On )
          {
            if ( Conic_To( RAS_VARS v_control.x, v_control.y, x, y ) )
              goto Fail;
            continue;
          }

          if ( tag != FT_Curve_Tag_Conic )
            goto Invalid_Outline;

          v_middle.x = ( v_control.x + x ) / 2;
          v_middle.y = ( v_control.y + y ) / 2;

          if ( Conic_To( RAS_VARS v_control.x, v_control.y,
                                  v_middle.x,  v_middle.y ) )
            goto Fail;

          v_control.x = x;
          v_control.y = y;

          goto Do_Conic;
        }

        if ( Conic_To( RAS_VARS v_control.x, v_control.y,
                                v_start.x,   v_start.y ) )
          goto Fail;

        goto Close;

      default:  /* FT_Curve_Tag_Cubic */
        {
          Long  x1, y1, x2, y2, x3, y3;


          if ( point + 1 > limit                             ||
               FT_CURVE_TAG( tags[1] ) != FT_Curve_Tag_Cubic )
            goto Invalid_Outline;

          point += 2;
          tags  += 2;

          x1 = SCALED( point[-2].x );
          y1 = SCALED( point[-2].y );
          x2 = SCALED( point[-1].x );
          y2 = SCALED( point[-1].y );
          x3 = SCALED( point[ 0].x );
          y3 = SCALED( point[ 0].y );

          if ( flipped )
          {
            SWAP_( x1, y1 );
            SWAP_( x2, y2 );
            SWAP_( x3, y3 );
          }

          if ( point <= limit )
          {
            if ( Cubic_To( RAS_VARS x1, y1, x2, y2, x3, y3 ) )
              goto Fail;
            continue;
          }

          if ( Cubic_To( RAS_VARS x1, y1, x2, y2, v_start.x, v_start.y ) )
            goto Fail;
          goto Close;
        }
      }
    }

    /* close the contour with a line segment */
    if ( Line_To( RAS_VARS v_start.x, v_start.y ) )
      goto Fail;

  Close:
    return SUCCESS;

  Invalid_Outline:
    ras.error = Raster_Err_Invalid;

  Fail:
    return FAILURE;
  }


  /*************************************************************************/
  /*                                                                       */
  /* <Function>                                                            */
  /*    Convert_Glyph                                                      */
  /*                                                                       */
  /* <Description>                                                         */
  /*    Converts a glyph into a series of segments and arcs and makes a    */
  /*    profiles list with them.                                           */
  /*                                                                       */
  /* <Input>