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#include <fitz.h>
static inline void
addspan(unsigned char *list, int x0, int x1, int xofs, int hs)
{
int x0pix, x0sub;
int x1pix, x1sub;
if (x0 == x1)
return;
/* x between 0 and width of bbox */
x0 -= xofs;
x1 -= xofs;
x0pix = x0 / hs;
x0sub = x0 % hs;
x1pix = x1 / hs;
x1sub = x1 % hs;
if (x0pix == x1pix)
{
list[x0pix] += x1sub - x0sub;
list[x0pix+1] += x0sub - x1sub;
}
else
{
list[x0pix] += hs - x0sub;
list[x0pix+1] += x0sub;
list[x1pix] += x1sub - hs;
list[x1pix+1] += -x1sub;
}
}
static inline void
nonzerowinding(fz_ael *ael, unsigned char *list, int xofs, int hs)
{
int winding = 0;
int x = 0;
int i;
for (i = 0; i < ael->len; i++)
{
if (!winding && (winding + ael->edges[i]->ydir))
x = ael->edges[i]->x;
if (winding && !(winding + ael->edges[i]->ydir))
addspan(list, x, ael->edges[i]->x, xofs, hs);
winding += ael->edges[i]->ydir;
}
}
static inline void
evenodd(fz_ael *ael, unsigned char *list, int xofs, int hs)
{
int even = 0;
int x = 0;
int i;
for (i = 0; i < ael->len; i++)
{
if (!even)
x = ael->edges[i]->x;
else
addspan(list, x, ael->edges[i]->x, xofs, hs);
even = !even;
}
}
static void toalpha(unsigned char *list, int n)
{
int d = 0;
while (n--)
{
d += *list;
*list++ = d;
}
}
fz_error *
fz_scanconvert(fz_gel *gel, fz_ael *ael, int eofill, int y0, int y1,
void (*blitfunc)(int,int,int,unsigned char*,void*), void *blitdata)
{
fz_error *error;
unsigned char *deltas;
int y, e;
int yd, yc;
int xmin = fz_idiv(gel->xmin, gel->hs);
int xmax = fz_idiv(gel->xmax, gel->hs) + 1;
int xofs = xmin * gel->hs;
int hs = gel->hs;
int vs = gel->vs;
if (gel->len == 0)
return nil;
deltas = fz_malloc(xmax - xmin + 1);
if (!deltas)
return fz_outofmem;
memset(deltas, 0, xmax - xmin + 1);
e = 0;
y = gel->edges[0].y;
yc = fz_idiv(y, vs);
yd = yc;
while (ael->len > 0 || e < gel->len)
{
yc = fz_idiv(y, vs);
if (yc != yd) {
if (yd >= y0 && yd < y1)
{
toalpha(deltas, xmax - xmin);
blitfunc(yd, xmin, xmax - xmin, deltas, blitdata);
memset(deltas, 0, xmax - xmin + 1);
}
}
yd = yc;
error = fz_insertael(ael, gel, y, &e);
if (error) {
fz_free(deltas);
return error;
}
if (yd >= y0 && yd < y1)
{
if (eofill)
evenodd(ael, deltas, xofs, hs);
else
nonzerowinding(ael, deltas, xofs, hs);
}
fz_advanceael(ael);
if (ael->len > 0)
y ++;
else if (e < gel->len)
y = gel->edges[e].y;
}
if (yd >= y0 && yd < y1)
{
toalpha(deltas, xmax - xmin);
blitfunc(yd, xmin, xmax - xmin, deltas, blitdata);
}
fz_free(deltas);
return nil;
}
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