/*
* Handle the case of a large value or a value with a fraction part.
* See gxmatrix.h for more details.
*/
fixed
fixed_coeff_mult(fixed value, long coeff, const fixed_coeff *pfc, int maxb)
{
int shift = pfc->shift;
/*
* Test if the value is too large for simple long math.
*/
if ((value + (fixed_1 << (maxb - 1))) & (-fixed_1 << maxb)) {
/* The second argument of fixed_mult_quo must be non-negative. */
return
(coeff < 0 ?
-fixed_mult_quo(value, -coeff, fixed_1 << shift) :
fixed_mult_quo(value, coeff, fixed_1 << shift));
} else {
/*
* The construction above guarantees that the multiplications
* won't overflow the capacity of an int.
*/
return (fixed)
arith_rshift(fixed2int_var(value) * coeff
+ fixed2int(fixed_fraction(value) * coeff)
+ pfc->round, shift);
}
}
static fixed
edge_x_at_y(const gs_fixed_edge * edge, fixed y)
{
return fixed_mult_quo(edge->end.x - edge->start.x,
y - edge->start.y,
edge->end.y - edge->start.y) + edge->start.x;
}
/* Compute ldi, ldf, and xf similarly. */
static inline void
compute_ldx(trap_line *tl, fixed ys)
{
int di = tl->di;
fixed df = tl->df;
fixed h = tl->h;
if ( df < YMULT_LIMIT ) {
if ( df == 0 ) /* vertical edge, worth checking for */
tl->ldi = int2fixed(di), tl->ldf = 0, tl->xf = -h;
else {
tl->ldi = int2fixed(di) + int2fixed(df) / h;
tl->ldf = int2fixed(df) % h;
tl->xf =
(ys < fixed_1 ? ys * df % h : fixed_mult_rem(ys, df, h)) - h;
}
}
else {
tl->ldi = int2fixed(di) + fixed_mult_quo(fixed_1, df, h);
tl->ldf = fixed_mult_rem(fixed_1, df, h);
tl->xf = fixed_mult_rem(ys, df, h) - h;
}
}
static inline fixed Y_AT_X(active_line *alp, fixed xp)
{ return alp->start.y + fixed_mult_quo(xp - alp->start.x, alp->diff.y, alp->diff.x);
}
/* We should swap axes to get best accuracy, but we don't. */
int
gx_default_fill_triangle(gx_device * dev,
fixed px, fixed py, fixed ax, fixed ay, fixed bx, fixed by,
const gx_device_color * pdevc, gs_logical_operation_t lop)
{
fixed t;
fixed ym;
dev_proc_fill_trapezoid((*fill_trapezoid)) =
dev_proc(dev, fill_trapezoid);
gs_fixed_edge left, right;
int code;
/* Ensure ay >= 0, by >= 0. */
if (ay < 0)
px += ax, py += ay, bx -= ax, by -= ay, ax = -ax, ay = -ay;
if (by < 0)
px += bx, py += by, ax -= bx, ay -= by, bx = -bx, by = -by;
/* Ensure ay <= by. */
if (ay > by)
SWAP(ax, bx, t), SWAP(ay, by, t);
/*
* Make a special check for a flat bottom or top,
* which we can handle with a single call on fill_trapezoid.
*/
left.start.x = right.start.x = px;
left.start.y = right.start.y = py;
if (ay == 0) {
/* Flat top */
if (ax < 0)
left.start.x = px + ax;
else
right.start.x = px + ax;
left.end.x = right.end.x = px + bx;
left.end.y = right.end.y = py + by;
ym = py;
} else if (ay == by) {
/* Flat bottom */
if (ax < bx)
left.end.x = px + ax, right.end.x = px + bx;
else
left.end.x = px + bx, right.end.x = px + ax;
left.end.y = right.end.y = py + by;
ym = py;
} else {
ym = py + ay;
if (fixed_mult_quo(bx, ay, by) < ax) {
/* The 'b' line is to the left of the 'a' line. */
left.end.x = px + bx, left.end.y = py + by;
right.end.x = px + ax, right.end.y = py + ay;
code = (*fill_trapezoid) (dev, &left, &right, py, ym,
false, pdevc, lop);
right.start = right.end;
right.end = left.end;
} else {
/* The 'a' line is to the left of the 'b' line. */
left.end.x = px + ax, left.end.y = py + ay;
right.end.x = px + bx, right.end.y = py + by;
code = (*fill_trapezoid) (dev, &left, &right, py, ym,
false, pdevc, lop);
left.start = left.end;
left.end = right.end;
}
if (code < 0)
return code;
}
return (*fill_trapezoid) (dev, &left, &right, ym, right.end.y,
false, pdevc, lop);
}
/* Define the 'remainder' analogue of fixed_mult_quo. */
static fixed
fixed_mult_rem(fixed a, fixed b, fixed c)
{
/* All kinds of truncation may happen here, but it's OK. */
return a * b - fixed_mult_quo(a, b, c) * c;
}
