out_bl2d.c   [plain text]

/* $Xorg: out_bl2d.c,v 1.3 2000/08/17 19:46:26 cpqbld Exp $ */

/*

Copyright 1989-1991, Bitstream Inc., Cambridge, MA.
You are hereby granted permission under all Bitstream propriety rights to
use, copy, modify, sublicense, sell, and redistribute the Bitstream Speedo
software and the Bitstream Charter outline font for any purpose and without
restrictions; provided, that this notice is left intact on all copies of such
software or font and that Bitstream's trademark is acknowledged as shown below
on all unmodified copies of such font.

BITSTREAM CHARTER is a registered trademark of Bitstream Inc.


BITSTREAM INC. DISCLAIMS ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
WITHOUT LIMITATION THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE.  BITSTREAM SHALL NOT BE LIABLE FOR ANY DIRECT OR INDIRECT
DAMAGES, INCLUDING BUT NOT LIMITED TO LOST PROFITS, LOST DATA, OR ANY OTHER
INCIDENTAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF OR IN ANY WAY CONNECTED
WITH THE SPEEDO SOFTWARE OR THE BITSTREAM CHARTER OUTLINE FONT.

*/
/* $XFree86: xc/lib/font/Speedo/out_bl2d.c,v 1.4 2001/01/17 19:43:17 dawes Exp $ */

/*************************** O U T _ B L 2 D . C *****************************
 *                                                                           *
 * This is an output module for screen writer using two dimensional scanning *
 ****************************************************************************/


#include "spdo_prv.h"              /* General definitions for speedo */

#define   CLOCKWISE  1
#define   DEBUG      0
#define   ABS(X)     ( (X < 0) ? -X : X)

#if DEBUG
#include <stdio.h>
#define SHOW(X) printf("X = %d\n", X)
#else
#define SHOW(X)
#endif

/***** GLOBAL VARIABLES *****/

/***** GLOBAL FUNCTIONS *****/

/***** EXTERNAL VARIABLES *****/

/***** EXTERNAL FUNCTIONS *****/

/***** STATIC VARIABLES *****/

/***** STATIC FUNCTIONS *****/

#if INCL_2D
static void sp_draw_vector_to_2d(PROTO_DECL2 fix15 x0,fix15 y0,fix15 x1,fix15 y1,band_t GLOBALFAR *band);
static void sp_add_intercept_2d(PROTO_DECL2 fix15 y,fix15 x);
static void sp_proc_intercepts_2d(PROTO_DECL1);
#endif

#if INCL_2D
FUNCTION boolean init_2d(
GDECL
specs_t GLOBALFAR *specsarg)
/*
 * init_out_2d() is called by sp_set_specs() to initialize the output module.
 * Returns TRUE if output module can accept requested specifications.
 * Returns FALSE otherwise.
 */
{

if (specsarg->flags & CURVES_OUT)
    return FALSE;           /* Curves out, clipping not supported */

#if DEBUG
printf("INIT_OUT__2d()\n");
#endif
return TRUE;
}
#endif

#if INCL_2D
FUNCTION boolean begin_char_2d(
GDECL
point_t Psw,
point_t Pmin,
point_t Pmax)
/* Called once at the start of the character generation process
 * Initializes intercept table, either calculates pixel maxima or
 * decides that they need to be collected
 */
{
#if DEBUG
printf("BEGIN_CHAR__2d(%3.1f, %3.1f, %3.1f, %3.1f, %3.1f, %3.1f\n", 
                    (real)Psw.x / (real)sp_globals.onepix, (real)Psw.y / (real)sp_globals.onepix,
                    (real)Pmin.x / (real)sp_globals.onepix, (real)Pmin.y / (real)sp_globals.onepix,
                    (real)Pmax.x / (real)sp_globals.onepix, (real)Pmax.y / (real)sp_globals.onepix);
#endif
/* Convert PIX.FRAC to 16.16 form */
sp_globals.x_scan_active = TRUE;  /* Assume x-scanning from the start */

init_char_out(Psw,Pmin,Pmax);
return TRUE;
}
#endif


#if INCL_2D
FUNCTION void begin_contour_2d(
GDECL
point_t P1,
boolean outside)
/* Called at the start of each contour
 */
{

#if DEBUG
printf("BEGIN_CONTOUR__2d(%3.4f, %3.4f, %s)\n", 
    (real)P1.x / (real)sp_globals.onepix, 
    (real)P1.y / (real)sp_globals.onepix, 
    outside? "outside": "inside");
#endif
sp_globals.x0_spxl = P1.x;
sp_globals.y0_spxl = P1.y;
}
#endif

#if INCL_2D
FUNCTION void line_2d(
GDECL
point_t P1)
/*
 * Called for each vector in the transformed character
 *     "draws" vector into intercept table
 */
{

#if DEBUG
printf("LINE_0(%3.4f, %3.4f)\n", 
       (real)P1.x / (real)sp_globals.onepix, 
       (real)P1.y / (real)sp_globals.onepix);
#endif

if (sp_globals.extents_running)
    {
    if (sp_globals.x0_spxl > sp_globals.bmap_xmax)         
        sp_globals.bmap_xmax = sp_globals.x0_spxl;
    if (sp_globals.x0_spxl < sp_globals.bmap_xmin)
        sp_globals.bmap_xmin = sp_globals.x0_spxl;
    if (sp_globals.y0_spxl > sp_globals.bmap_ymax)
        sp_globals.bmap_ymax = sp_globals.y0_spxl;
    if (sp_globals.y0_spxl < sp_globals.bmap_ymin)
        sp_globals.bmap_ymin = sp_globals.y0_spxl;
    }

if (!sp_globals.intercept_oflo)
    {
    sp_draw_vector_to_2d(sp_globals.x0_spxl,
                  sp_globals.y0_spxl,
                  P1.x,
                  P1.y,
                  &sp_globals.y_band); /* y-scan */

    if (sp_globals.x_scan_active)
        sp_draw_vector_to_2d(sp_globals.y0_spxl,
                      sp_globals.x0_spxl,
                      P1.y,
                      P1.x,
                      &sp_globals.x_band); /* x-scan if selected */
    }

sp_globals.x0_spxl = P1.x; 
sp_globals.y0_spxl = P1.y; /* update endpoint */
}

FUNCTION static void sp_draw_vector_to_2d(
GDECL
fix15 x0,                /* X coordinate */
fix15 y0,                /* Y coordinate */
fix15 x1,
fix15 y1,
band_t GLOBALFAR *band)
{
register fix15     how_many_y;       /* # of intercepts at y = n + 1/2  */
register fix15     yc;               /* Current scan-line */
         fix15     temp1;            /* various uses */
         fix15     temp2;            /* various uses */
register fix31     dx_dy;            /* slope of line in 16.16 form */
register fix31     xc;               /* high-precision (16.16) x coordinate */
         fix15     y_pxl;

yc = (y0 + sp_globals.pixrnd) >> sp_globals.pixshift;      /* current scan line = end of last line */
y_pxl = (y1 + sp_globals.pixrnd) >> sp_globals.pixshift;   /* calculate new end-scan line */

if ((how_many_y = y_pxl - yc) == 0) return; /* Don't draw a null line */

if (how_many_y < 0) yc--; /* Predecrment downward lines */

if (yc > band->band_max) /* Is start point above band? */
    {
    if (y_pxl > band->band_max) return; /* line has to go down! */
    how_many_y = y_pxl - (yc = band->band_max) - 1; /* Yes, limit it */
    }

if (yc < band->band_min)   /* Is start point below band? */
    {
    if (y_pxl < band->band_min) return; /* line has to go up! */
    how_many_y = y_pxl - (yc = band->band_min);   /* Yes, limit it */
    }

xc = (fix31)(x0 + sp_globals.pixrnd) << 16; /* Original x coordinate with built in  */
                                 /* rounding. int.16 + pixshift form */

if ( (temp1 = (x1 - x0)) == 0)  /* check for vertical line */
    {
    dx_dy = 0L; /* Zero slope, leave xc alone */
    goto skip_calc;
    }
          
/* calculate dx_dy at 16.16 fixed point */

dx_dy = ( (fix31)temp1 << 16 )/(fix31)(y1 - y0);

/* We have to check for a @#$%@# possible multiply overflow  */
/* by doing another @#$*& multiply.  In assembly language,   */
/* the program could just check the OVerflow flag or whatever*/
/* works on the particular processor.  This C code is meant  */
/* to be processor independent.                              */

temp1 = (yc << sp_globals.pixshift) - y0 + sp_globals.pixrnd;
/* This sees if the sign bits start at bit 15 */
/* if they do, no overflow has occurred       */

temp2 = (fix15)(MULT16(temp1,(fix15)(dx_dy >> 16)) >> 15);

if (  (temp2 != (fix15)0xFFFF) &&
      (temp2 != 0x0000)   )
    {  /* Overflow. Pick point closest to yc + .5 */
    if (ABS(temp1) < ABS((yc << sp_globals.pixshift) - y1 + sp_globals.pixrnd))
        { /* use x1 instead of x0 */
        xc = (fix31)(x1 + sp_globals.pixrnd) << (16 - sp_globals.pixshift);
        }
    goto skip_calc;
    }
/* calculate new xc at the center of the *current* scan line */
/* due to banding, yc may be several lines away from y0      */
/*  xc += (yc + .5 - y0) * dx_dy */
/* This multiply generates a subpixel delta. */
/* So we leave it as an int.pixshift + 16 delta */

xc += (fix31)temp1 * dx_dy;
dx_dy <<= sp_globals.pixshift;
skip_calc:

yc -= band->band_array_offset; /* yc is now an offset relative to the band */

if (how_many_y < 0)
    {   /* Vector down */
    if ((how_many_y += yc + 1) < band->band_floor) 
        how_many_y = band->band_floor; /* can't go below floor */
    while(yc >= how_many_y)
        {
        temp1 = (fix15)(xc >> 16); 
        sp_add_intercept_2d(yc--,temp1); 
        xc -= dx_dy;
        }
    }
    else
    {   /* Vector up */
     /* check to see that line doesn't extend beyond top of band */
    if ((how_many_y += yc) > band->band_ceiling) 
        how_many_y = band->band_ceiling;
    while(yc < how_many_y)
        {
        temp1 = (fix15)(xc >> 16);
        sp_add_intercept_2d(yc++,temp1); 
        xc += dx_dy;
        }
    }
}

#endif

#if INCL_2D
FUNCTION boolean end_char_2d()
/* Called when all character data has been output
 * Return TRUE if output process is complete
 * Return FALSE to repeat output of the transformed data beginning
 * with the first contour
 */
{

fix31 xorg;
fix31 yorg;
#if INCL_CLIPPING
fix31 em_max, em_min, bmap_max, bmap_min;
#endif

#if DEBUG
printf("END_CHAR__2d()\n");
#endif

if (sp_globals.first_pass)
    {
    if (sp_globals.bmap_xmax >= sp_globals.bmap_xmin)
        {
        sp_globals.xmin = (sp_globals.bmap_xmin + sp_globals.pixrnd + 1) >> sp_globals.pixshift;
        sp_globals.xmax = (sp_globals.bmap_xmax + sp_globals.pixrnd) >> sp_globals.pixshift;
        }
    else
        {
        sp_globals.xmin = sp_globals.xmax = 0;
        }
    if (sp_globals.bmap_ymax >= sp_globals.bmap_ymin)
        {

#if INCL_CLIPPING
    switch(sp_globals.tcb0.xtype)
       {
       case 1: /* 180 degree rotation */
            if (sp_globals.specs.flags & CLIP_TOP)
               {
               sp_globals.clip_ymin = (fix31)((fix31)EM_TOP * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_ymin = sp_globals.clip_ymin >> sp_globals.multshift;
               bmap_min = (sp_globals.bmap_ymin + sp_globals.pixrnd + 1) >> sp_globals.pixshift;
	       sp_globals.clip_ymin = -1 * sp_globals.clip_ymin;
	       if (bmap_min < sp_globals.clip_ymin)
		    sp_globals.ymin = sp_globals.clip_ymin;
               else
                    sp_globals.ymin = bmap_min;
               }
            if (sp_globals.specs.flags & CLIP_BOTTOM)
               {
               sp_globals.clip_ymax = (fix31)((fix31)(-1 * EM_BOT) * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_ymax = sp_globals.clip_ymax >> sp_globals.multshift;
               bmap_max = (sp_globals.bmap_ymax + sp_globals.pixrnd) >> sp_globals.pixshift;
	       if (bmap_max < sp_globals.clip_ymax)
                    sp_globals.ymax = bmap_max;
               else
		    sp_globals.ymax = sp_globals.clip_ymax;
               }
               sp_globals.clip_xmax =  -sp_globals.xmin;
               sp_globals.clip_xmin = ((sp_globals.set_width.x+32768L) >> 16) -
                                      sp_globals.xmin;
               break;
       case 2: /* 90 degree rotation */
            if (sp_globals.specs.flags & CLIP_TOP)
               {
               sp_globals.clip_xmin = (fix31)((fix31)(-1 * EM_BOT) * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_xmin = sp_globals.clip_xmin >> sp_globals.multshift;
               sp_globals.clip_xmin = -1 * sp_globals.clip_xmin;
               bmap_min = (sp_globals.bmap_xmin + sp_globals.pixrnd + 1) >> sp_globals.pixshift;
	       if (bmap_min > sp_globals.clip_xmin)
                    sp_globals.clip_xmin = bmap_min;

	       /* normalize to x origin */
               sp_globals.clip_xmin -= sp_globals.xmin;
               }
            if (sp_globals.specs.flags & CLIP_BOTTOM)
               {
               sp_globals.clip_xmax = (fix31)((fix31)EM_TOP * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_xmax = sp_globals.clip_xmax >> sp_globals.multshift;
               bmap_max = (sp_globals.bmap_xmax + sp_globals.pixrnd) >> sp_globals.pixshift;
	       if (bmap_max < sp_globals.clip_xmax)
                    sp_globals.xmax = bmap_max;
               else
		    sp_globals.xmax = sp_globals.clip_xmax;
	       sp_globals.clip_ymax = 0;
	       if ((sp_globals.specs.flags & CLIP_TOP) && 
                   (sp_globals.ymax > sp_globals.clip_ymax))
		    sp_globals.ymax = sp_globals.clip_ymax;
	       sp_globals.clip_ymin = ((sp_globals.set_width.y+32768L) >> 16);
               if ((sp_globals.specs.flags & CLIP_BOTTOM) && 
                   (sp_globals.ymin < sp_globals.clip_ymin))
                    sp_globals.ymin = sp_globals.clip_ymin;
	       /* normalize to x origin */
               sp_globals.clip_xmax -= sp_globals.xmin;
               }
               break;
       case 3: /* 270 degree rotation */
            if (sp_globals.specs.flags & CLIP_TOP)
               {
               sp_globals.clip_xmin = (fix31)((fix31)EM_TOP * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_xmin = sp_globals.clip_xmin >> sp_globals.multshift;
	       sp_globals.clip_xmin = -1 * sp_globals.clip_xmin;
               bmap_min = (sp_globals.bmap_xmin + sp_globals.pixrnd + 1) >> sp_globals.pixshift;

               /* let the minimum be the larger of these two values */
	       if (bmap_min > sp_globals.clip_xmin)
		    sp_globals.clip_xmin = bmap_min;

	       /* normalize the x value to new xorgin */
               sp_globals.clip_xmin -= sp_globals.xmin;
               }
            if (sp_globals.specs.flags & CLIP_BOTTOM)
               {
               sp_globals.clip_xmax = (fix31)((fix31)(-1 * EM_BOT) * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_xmax = sp_globals.clip_xmax >> sp_globals.multshift;
               bmap_max = (sp_globals.bmap_xmax + sp_globals.pixrnd) >> sp_globals.pixshift;

	       /* let the max be the lesser of these two values */
	       if (bmap_max < sp_globals.clip_xmax)
		    {
		    sp_globals.xmax = bmap_max; 
		    sp_globals.clip_xmax = bmap_max;
		    }
               else
                    sp_globals.xmax = sp_globals.clip_xmax;

	       /* normalize the x value to new x origin */
	       sp_globals.clip_xmax -= sp_globals.xmin;
               }
               /* compute y clip values */
	       sp_globals.clip_ymax = ((sp_globals.set_width.y+32768L) >> 16);
	       if ((sp_globals.specs.flags & CLIP_TOP) && 
                   (sp_globals.ymax > sp_globals.clip_ymax))
		    sp_globals.ymax = sp_globals.clip_ymax;
	       sp_globals.clip_ymin = 0;
               if ((sp_globals.specs.flags & CLIP_BOTTOM) && 
                   (sp_globals.ymin < sp_globals.clip_ymin))
                    sp_globals.ymin = sp_globals.clip_ymin;
               break;
       default: /* this is for zero degree rotation and arbitrary rotation */
            if (sp_globals.specs.flags & CLIP_TOP)
               {
	       sp_globals.clip_ymax = (fix31)((fix31)EM_TOP * sp_globals.tcb0.yppo + ((1<<sp_globals.multshift)/2));
               sp_globals.clip_ymax = sp_globals.clip_ymax >> sp_globals.multshift;
               bmap_max = (sp_globals.bmap_ymax + sp_globals.pixrnd) >> sp_globals.pixshift;
	       if (bmap_max > sp_globals.clip_ymax)
                    sp_globals.ymax = bmap_max;
               else
		    sp_globals.ymax = sp_globals.clip_ymax;
               }
            if (sp_globals.specs.flags & CLIP_BOTTOM)
               {
	       sp_globals.clip_ymin = (fix31)((fix31)(-1 * EM_BOT) * sp_globals.tcb0.yppo +  ((1<<sp_globals.multshift)/2));
               sp_globals.clip_ymin = sp_globals.clip_ymin >> sp_globals.multshift;
	       sp_globals.clip_ymin = - sp_globals.clip_ymin;
               bmap_min = (sp_globals.bmap_ymin + sp_globals.pixrnd + 1) >> sp_globals.pixshift;
	       if (bmap_min < sp_globals.clip_ymin)
		    sp_globals.ymin = sp_globals.clip_ymin;
               else
                    sp_globals.ymin = bmap_min;
               }
               sp_globals.clip_xmin = -sp_globals.xmin;
               sp_globals.clip_xmax = ((sp_globals.set_width.x+32768L) >> 16) -
                                      sp_globals.xmin;
               break;
       }
if ( !(sp_globals.specs.flags & CLIP_TOP))
#endif
            sp_globals.ymax = (sp_globals.bmap_ymax + sp_globals.pixrnd) >> sp_globals.pixshift;

#if INCL_CLIPPING
if ( !(sp_globals.specs.flags & CLIP_BOTTOM))
#endif
        sp_globals.ymin = (sp_globals.bmap_ymin + sp_globals.pixrnd + 1) >> sp_globals.pixshift;
        }
    else
        {
        sp_globals.ymin = sp_globals.ymax = 0;
        }

    /* add in the rounded out part (from xform.) of the left edge */
    if (sp_globals.tcb.xmode == 0)    /* for X pix is function of X orus only add the round */
    	xorg = (((fix31)sp_globals.xmin << 16) + (sp_globals.rnd_xmin << sp_globals.poshift));
    else
        if (sp_globals.tcb.xmode == 1) /* for X pix is function of -X orus only, subtr. round */
        	xorg = (((fix31)sp_globals.xmin << 16) - (sp_globals.rnd_xmin << sp_globals.poshift)) ;
        else
        	xorg = (fix31)sp_globals.xmin << 16;   /* for other cases don't use round on x */
           
    if (sp_globals.tcb.ymode == 2)   /* for Y pix is function of X orus only, add round error */ 
    	yorg = (((fix31)sp_globals.ymin << 16) + (sp_globals.rnd_xmin << sp_globals.poshift));
    else
        if (sp_globals.tcb.ymode == 3) /* for Y pix is function of -X orus only, sub round */
        	yorg = (((fix31)sp_globals.ymin << 16) - (sp_globals.rnd_xmin << sp_globals.poshift));
        else                          /* all other cases have no round error on yorg */
         	yorg = (fix31)sp_globals.ymin << 16;

    open_bitmap(sp_globals.set_width.x, sp_globals.set_width.y, xorg, yorg,
				 sp_globals.xmax - sp_globals.xmin, sp_globals.ymax -  sp_globals.ymin);
    if (sp_globals.intercept_oflo)
        {
        sp_globals.y_band.band_min = sp_globals.ymin;
        sp_globals.y_band.band_max = sp_globals.ymax;
        sp_globals.x_scan_active = FALSE;
        sp_globals.no_x_lists = 0;
        init_intercepts_out();
        sp_globals.first_pass = FALSE;
        sp_globals.extents_running = FALSE;
        return FALSE;
        }
    else
        {
        sp_proc_intercepts_2d();
        close_bitmap();
        return TRUE;
        }
    }
else
    {
    if (sp_globals.intercept_oflo)
        {
        reduce_band_size_out();
        init_intercepts_out();
        return FALSE;
        }
    else
        {
        sp_proc_intercepts_2d();
        if (next_band_out())
            {
            init_intercepts_out();
            return FALSE;
            }
        close_bitmap();
        return TRUE;
        }
    }
}
#endif

#if INCL_2D
FUNCTION static  void sp_add_intercept_2d(
GDECL
fix15 y,                 /* Y coordinate in relative pixel units */
                         /* (0 is lowest sample in band) */
fix15 x)                 /* X coordinate of intercept in subpixel units */

/*  Called by line() to add an intercept to the intercept list structure
 */

{
register fix15 from;   /* Insertion pointers for the linked list sort */
register fix15 to;

#if DEBUG
/* Bounds checking IS done in debug mode */
if ((y >= MAX_INTERCEPTS) || (y < 0))
    {
    printf("Intercept out of table!!!!! (%d)\n",y);
    return;
    }

if (y >= sp_globals.no_y_lists)
    {
    printf("    Add x intercept(%2d, %f)\n", 
        y + sp_globals.x_band.band_min - sp_globals.no_y_lists,
        (real)x/(real)sp_globals.onepix);
    if (y > (sp_globals.no_x_lists + sp_globals.no_y_lists))
        {
        printf(" Intercept too big for band!!!!!\007\n");
        return;
        }
    }
    else
    {
    printf("    Add y intercept(%2d, %f)\n", y + sp_globals.y_band.band_min,(real)x/(real)sp_globals.onepix);
    }

if (y < 0)       /* Y value below bottom of current band? */
    {
    printf(" Intecerpt less than 0!!!\007\n");
    return;
    }
#endif

/* Store new values */

sp_intercepts.car[sp_globals.next_offset] = x;

/* Find slot to insert new element (between from and to) */

from = y; /* Start at list head */

while( (to = sp_intercepts.cdr[from]) >= sp_globals.first_offset) /* Until to == end of list */
    {
    if (x <= sp_intercepts.car[to]) /* If next item is larger than or same as this one... */
        goto insert_element; /* ... drop out and insert here */
    from = to; /* move forward in list */
    }

insert_element: /* insert element "next_offset" between elements "from" */
                /* and "to" */

sp_intercepts.cdr[from] = sp_globals.next_offset;
sp_intercepts.cdr[sp_globals.next_offset] = to;

if (++sp_globals.next_offset >= MAX_INTERCEPTS) /* Intercept buffer full? */
    {
    sp_globals.intercept_oflo = TRUE;
/* There may be a few more calls to "add_intercept" from the current line */
/* To avoid problems, we set next_offset to a safe value. We don't care   */
/* if the intercept table gets trashed at this point                      */
    sp_globals.next_offset = sp_globals.first_offset;
    }
}

#endif

#if INCL_2D
FUNCTION static  void sp_proc_intercepts_2d()
/*  Called by sp_make_char to output accumulated intercept lists
 *  Clips output to xmin, xmax, sp_globals.ymin, ymax boundaries
 */
{
register fix15 i;
register fix15 from, to;          /* Start and end of run in pixel units   
                            relative to left extent of character  */
register fix15 y;
register fix15 scan_line;
         fix15 local_bmap_xmin;
         fix15 local_bmap_xmax;
         fix15 first_y, last_y;
         fix15 j,k;

#if INCL_CLIPPING
if ((sp_globals.specs.flags & CLIP_LEFT) != 0)
    clipleft = TRUE;
else
    clipleft = FALSE;
if ((sp_globals.specs.flags & CLIP_RIGHT) != 0)
    clipright = TRUE;
else
    clipright = FALSE;
if (clipleft || clipright)
        {
        xmax = sp_globals.clip_xmax << sp_globals.pixshift;
        xmin = sp_globals.clip_xmin << sp_globals.pixshift;
        }
if (!clipright)
        xmax = ((sp_globals.set_width.x+32768L) >> 16);
#endif

if (sp_globals.x_scan_active)      /* If xscanning, we need to make sure we don't miss any important pixels */
    {
    first_y = sp_globals.x_band.band_floor;        /* start of x lists */
    last_y = sp_globals.x_band.band_ceiling;                          /* end of x lists   */
    for (y = first_y; y != last_y; y++)             /* scan all xlists  */
        {
        i = sp_intercepts.cdr[y];                            /* Index head of intercept list */
        while (i != 0)         /* Link to next intercept if present */
            {
            from = sp_intercepts.car[i];
            j = i;
            i = sp_intercepts.cdr[i];                   /* Link to next intercept */
            if (i == 0)                   /* End of list? */
                {
#if DEBUG
                printf("****** proc_intercepts: odd number of intercepts in x list\n");
#endif
                break;
                }
            to = sp_intercepts.car[i];
            k = sp_intercepts.cdr[i];
            if (((to >> sp_globals.pixshift) >=  (from >> sp_globals.pixshift)) &&
                 ((to - from) < (sp_globals.onepix + 1)))
                {
                from = ((fix31)to + (fix31)from - (fix31)sp_globals.onepix) >> (sp_globals.pixshift + 1);
                if (from > sp_globals.y_band.band_max) 
					from = sp_globals.y_band.band_max;
                if ((from -= sp_globals.y_band.band_min) < 0) 
					from = 0;
                to = ((y - sp_globals.x_band.band_floor + sp_globals.x_band.band_min) 
                           << sp_globals.pixshift) 
                           + sp_globals.pixrnd;
                sp_intercepts.car[j] = to;
                sp_intercepts.car[i] = to + sp_globals.onepix;
                sp_intercepts.cdr[i] = sp_intercepts.cdr[from];
                sp_intercepts.cdr[from] = j;
                }
	    i = k;
            }
        }
    }
#if DEBUG
printf("\nIntercept lists:\n");
#endif

if ((first_y = sp_globals.y_band.band_max) >= sp_globals.ymax)    
    first_y = sp_globals.ymax - 1;               /* Clip to ymax boundary */

if ((last_y = sp_globals.y_band.band_min) < sp_globals.ymin)      
    last_y = sp_globals.ymin;                    /* Clip to sp_globals.ymin boundary */

last_y  -= sp_globals.y_band.band_array_offset;

local_bmap_xmin = sp_globals.xmin << sp_globals.pixshift;
local_bmap_xmax = (sp_globals.xmax << sp_globals.pixshift) + sp_globals.pixrnd;

#if DEBUG
/* Print out all of the intercept info */
scan_line = sp_globals.ymax - first_y - 1;

for (y = first_y - sp_globals.y_band.band_min; y >= last_y; y--, scan_line++)
    {
    i = y;                            /* Index head of intercept list */
    while ((i = sp_intercepts.cdr[i]) != 0)         /* Link to next intercept if present */
        {
        if ((from = sp_intercepts.car[i] - local_bmap_xmin) < 0)
            from = 0;                 /* Clip to xmin boundary */
        i = sp_intercepts.cdr[i];                   /* Link to next intercept */
        if (i == 0)                   /* End of list? */
            {
            printf("****** proc_intercepts: odd number of intercepts\n");
            break;
            }
        if ((to = sp_intercepts.car[i]) > sp_globals.bmap_xmax)
            to = sp_globals.bmap_xmax - local_bmap_xmin;         /* Clip to xmax boundary */
        else
            to -= local_bmap_xmin;
        printf("    Y = %2d (scanline %2d): %3.4f %3.4f:\n", 
            y + sp_globals.y_band.band_min, 
            scan_line, 
            (real)from / (real)sp_globals.onepix, 
            (real)to / (real)sp_globals.onepix);
        }
    }
#endif

/* Draw the image */
scan_line = sp_globals.ymax - first_y - 1;

for (y = first_y - sp_globals.y_band.band_min; y >= last_y; y--, scan_line++)
    {
    i = y;                            /* Index head of intercept list */
    while ((i = sp_intercepts.cdr[i]) != 0)         /* Link to next intercept if present */
        {
        if ((from = sp_intercepts.car[i] - local_bmap_xmin) < 0)
            from = 0;                 /* Clip to xmin boundary */
        i = sp_intercepts.cdr[i];                   /* Link to next intercept */

        if ((to = sp_intercepts.car[i]) > local_bmap_xmax)
            to = sp_globals.bmap_xmax - local_bmap_xmin;         /* Clip to xmax boundary */
        else
            to -= local_bmap_xmin;
#if INCL_CLIPPING
                if (clipleft)
                        {
                        if (to <= xmin)
                                continue;
                        if (from < xmin)
                                from = xmin;
                        }
        if (clipright)
                        {
                        if (from >= xmax)
                                continue;
                        if (to > xmax)
                                to = xmax;
                        }
#endif
        if ( (to - from) <= sp_globals.onepix)
            {
            from = (to + from - sp_globals.onepix) >> (sp_globals.pixshift + 1);
            set_bitmap_bits(scan_line, from, from + 1);
            }
            else
            {
            set_bitmap_bits(scan_line, from >> sp_globals.pixshift, to >> sp_globals.pixshift);
            }
        }
    }
}

#endif