void
_pixman_general_conical_gradient_get_scanline_32 (pixman_image_t *image,
int x,
int y,
int width,
uint32_t * buffer,
const uint32_t *mask,
uint32_t mask_bits)
{
source_image_t *source = (source_image_t *)image;
gradient_t *gradient = (gradient_t *)source;
conical_gradient_t *conical = (conical_gradient_t *)image;
uint32_t *end = buffer + width;
pixman_gradient_walker_t walker;
pixman_bool_t affine = TRUE;
double cx = 1.;
double cy = 0.;
double cz = 0.;
double rx = x + 0.5;
double ry = y + 0.5;
double rz = 1.;
double a = (conical->angle * M_PI) / (180. * 65536);
_pixman_gradient_walker_init (&walker, gradient, source->common.repeat);
if (source->common.transform)
{
pixman_vector_t v;
/* reference point is the center of the pixel */
v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
v.vector[2] = pixman_fixed_1;
if (!pixman_transform_point_3d (source->common.transform, &v))
return;
cx = source->common.transform->matrix[0][0] / 65536.;
cy = source->common.transform->matrix[1][0] / 65536.;
cz = source->common.transform->matrix[2][0] / 65536.;
rx = v.vector[0] / 65536.;
ry = v.vector[1] / 65536.;
rz = v.vector[2] / 65536.;
affine =
source->common.transform->matrix[2][0] == 0 &&
v.vector[2] == pixman_fixed_1;
}
if (affine)
{
rx -= conical->center.x / 65536.;
ry -= conical->center.y / 65536.;
while (buffer < end)
{
double angle;
if (!mask || *mask++ & mask_bits)
{
pixman_fixed_48_16_t t;
angle = atan2 (ry, rx) + a;
t = (pixman_fixed_48_16_t) (angle * (65536. / (2 * M_PI)));
*buffer = _pixman_gradient_walker_pixel (&walker, t);
}
++buffer;
rx += cx;
ry += cy;
}
}
else
{
while (buffer < end)
{
double x, y;
double angle;
if (!mask || *mask++ & mask_bits)
{
pixman_fixed_48_16_t t;
if (rz != 0)
{
x = rx / rz;
y = ry / rz;
}
else
{
x = y = 0.;
}
x -= conical->center.x / 65536.;
y -= conical->center.y / 65536.;
angle = atan2 (y, x) + a;
t = (pixman_fixed_48_16_t) (angle * (65536. / (2 * M_PI)));
*buffer = _pixman_gradient_walker_pixel (&walker, t);
}
++buffer;
rx += cx;
ry += cy;
rz += cz;
}
}
}
static uint32_t *
radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
{
/*
* Implementation of radial gradients following the PDF specification.
* See section 8.7.4.5.4 Type 3 (Radial) Shadings of the PDF Reference
* Manual (PDF 32000-1:2008 at the time of this writing).
*
* In the radial gradient problem we are given two circles (c₁,r₁) and
* (c₂,r₂) that define the gradient itself.
*
* Mathematically the gradient can be defined as the family of circles
*
* ((1-t)·c₁ + t·(c₂), (1-t)·r₁ + t·r₂)
*
* excluding those circles whose radius would be < 0. When a point
* belongs to more than one circle, the one with a bigger t is the only
* one that contributes to its color. When a point does not belong
* to any of the circles, it is transparent black, i.e. RGBA (0, 0, 0, 0).
* Further limitations on the range of values for t are imposed when
* the gradient is not repeated, namely t must belong to [0,1].
*
* The graphical result is the same as drawing the valid (radius > 0)
* circles with increasing t in [-inf, +inf] (or in [0,1] if the gradient
* is not repeated) using SOURCE operator composition.
*
* It looks like a cone pointing towards the viewer if the ending circle
* is smaller than the starting one, a cone pointing inside the page if
* the starting circle is the smaller one and like a cylinder if they
* have the same radius.
*
* What we actually do is, given the point whose color we are interested
* in, compute the t values for that point, solving for t in:
*
* length((1-t)·c₁ + t·(c₂) - p) = (1-t)·r₁ + t·r₂
*
* Let's rewrite it in a simpler way, by defining some auxiliary
* variables:
*
* cd = c₂ - c₁
* pd = p - c₁
* dr = r₂ - r₁
* length(t·cd - pd) = r₁ + t·dr
*
* which actually means
*
* hypot(t·cdx - pdx, t·cdy - pdy) = r₁ + t·dr
*
* or
*
* ⎷((t·cdx - pdx)² + (t·cdy - pdy)²) = r₁ + t·dr.
*
* If we impose (as stated earlier) that r₁ + t·dr >= 0, it becomes:
*
* (t·cdx - pdx)² + (t·cdy - pdy)² = (r₁ + t·dr)²
*
* where we can actually expand the squares and solve for t:
*
* t²cdx² - 2t·cdx·pdx + pdx² + t²cdy² - 2t·cdy·pdy + pdy² =
* = r₁² + 2·r₁·t·dr + t²·dr²
*
* (cdx² + cdy² - dr²)t² - 2(cdx·pdx + cdy·pdy + r₁·dr)t +
* (pdx² + pdy² - r₁²) = 0
*
* A = cdx² + cdy² - dr²
* B = pdx·cdx + pdy·cdy + r₁·dr
* C = pdx² + pdy² - r₁²
* At² - 2Bt + C = 0
*
* The solutions (unless the equation degenerates because of A = 0) are:
*
* t = (B ± ⎷(B² - A·C)) / A
*
* The solution we are going to prefer is the bigger one, unless the
* radius associated to it is negative (or it falls outside the valid t
* range).
*
* Additional observations (useful for optimizations):
* A does not depend on p
*
* A < 0 <=> one of the two circles completely contains the other one
* <=> for every p, the radiuses associated with the two t solutions
* have opposite sign
*/
pixman_image_t *image = iter->image;
int x = iter->x;
int y = iter->y;
int width = iter->width;
uint32_t *buffer = iter->buffer;
gradient_t *gradient = (gradient_t *)image;
radial_gradient_t *radial = (radial_gradient_t *)image;
uint32_t *end = buffer + width;
pixman_gradient_walker_t walker;
pixman_vector_t v, unit;
/* reference point is the center of the pixel */
v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
v.vector[2] = pixman_fixed_1;
_pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
if (image->common.transform)
{
if (!pixman_transform_point_3d (image->common.transform, &v))
return iter->buffer;
unit.vector[0] = image->common.transform->matrix[0][0];
unit.vector[1] = image->common.transform->matrix[1][0];
unit.vector[2] = image->common.transform->matrix[2][0];
}
else
{
unit.vector[0] = pixman_fixed_1;
unit.vector[1] = 0;
unit.vector[2] = 0;
}
if (unit.vector[2] == 0 && v.vector[2] == pixman_fixed_1)
{
/*
* Given:
*
* t = (B ± ⎷(B² - A·C)) / A
*
* where
*
* A = cdx² + cdy² - dr²
* B = pdx·cdx + pdy·cdy + r₁·dr
* C = pdx² + pdy² - r₁²
* det = B² - A·C
*
* Since we have an affine transformation, we know that (pdx, pdy)
* increase linearly with each pixel,
*
* pdx = pdx₀ + n·ux,
* pdy = pdy₀ + n·uy,
*
* we can then express B, C and det through multiple differentiation.
*/
pixman_fixed_32_32_t b, db, c, dc, ddc;
/* warning: this computation may overflow */
v.vector[0] -= radial->c1.x;
v.vector[1] -= radial->c1.y;
/*
* B and C are computed and updated exactly.
* If fdot was used instead of dot, in the worst case it would
* lose 11 bits of precision in each of the multiplication and
* summing up would zero out all the bit that were preserved,
* thus making the result 0 instead of the correct one.
* This would mean a worst case of unbound relative error or
* about 2^10 absolute error
*/
b = dot (v.vector[0], v.vector[1], radial->c1.radius,
radial->delta.x, radial->delta.y, radial->delta.radius);
db = dot (unit.vector[0], unit.vector[1], 0,
radial->delta.x, radial->delta.y, 0);
c = dot (v.vector[0], v.vector[1],
-((pixman_fixed_48_16_t) radial->c1.radius),
v.vector[0], v.vector[1], radial->c1.radius);
dc = dot (2 * (pixman_fixed_48_16_t) v.vector[0] + unit.vector[0],
2 * (pixman_fixed_48_16_t) v.vector[1] + unit.vector[1],
0,
unit.vector[0], unit.vector[1], 0);
ddc = 2 * dot (unit.vector[0], unit.vector[1], 0,
unit.vector[0], unit.vector[1], 0);
while (buffer < end)
{
if (!mask || *mask++)
{
*buffer = radial_compute_color (radial->a, b, c,
radial->inva,
radial->delta.radius,
radial->mindr,
&walker,
image->common.repeat);
}
b += db;
c += dc;
dc += ddc;
++buffer;
}
}
else
{
/* projective */
/* Warning:
* error propagation guarantees are much looser than in the affine case
*/
while (buffer < end)
{
if (!mask || *mask++)
{
if (v.vector[2] != 0)
{
double pdx, pdy, invv2, b, c;
invv2 = 1. * pixman_fixed_1 / v.vector[2];
pdx = v.vector[0] * invv2 - radial->c1.x;
/* / pixman_fixed_1 */
pdy = v.vector[1] * invv2 - radial->c1.y;
/* / pixman_fixed_1 */
b = fdot (pdx, pdy, radial->c1.radius,
radial->delta.x, radial->delta.y,
radial->delta.radius);
/* / pixman_fixed_1 / pixman_fixed_1 */
c = fdot (pdx, pdy, -radial->c1.radius,
pdx, pdy, radial->c1.radius);
/* / pixman_fixed_1 / pixman_fixed_1 */
*buffer = radial_compute_color (radial->a, b, c,
radial->inva,
radial->delta.radius,
radial->mindr,
&walker,
image->common.repeat);
}
else
{
*buffer = 0;
}
}
++buffer;
v.vector[0] += unit.vector[0];
v.vector[1] += unit.vector[1];
v.vector[2] += unit.vector[2];
}
}
iter->y++;
return iter->buffer;
}
void
_pixman_general_radial_gradient_get_scanline_32 (pixman_image_t *image,
int x,
int y,
int width,
uint32_t * buffer,
const uint32_t *mask,
uint32_t mask_bits)
{
/*
* In the radial gradient problem we are given two circles (c₁,r₁) and
* (c₂,r₂) that define the gradient itself. Then, for any point p, we
* must compute the value(s) of t within [0.0, 1.0] representing the
* circle(s) that would color the point.
*
* There are potentially two values of t since the point p can be
* colored by both sides of the circle, (which happens whenever one
* circle is not entirely contained within the other).
*
* If we solve for a value of t that is outside of [0.0, 1.0] then we
* use the extend mode (NONE, REPEAT, REFLECT, or PAD) to map to a
* value within [0.0, 1.0].
*
* Here is an illustration of the problem:
*
* p₂
* p •
* • ╲
* · ╲r₂
* p₁ · ╲
* • θ╲
* ╲ ╌╌•
* ╲r₁ · c₂
* θ╲ ·
* ╌╌•
* c₁
*
* Given (c₁,r₁), (c₂,r₂) and p, we must find an angle θ such that two
* points p₁ and p₂ on the two circles are collinear with p. Then, the
* desired value of t is the ratio of the length of p₁p to the length
* of p₁p₂.
*
* So, we have six unknown values: (p₁x, p₁y), (p₂x, p₂y), θ and t.
* We can also write six equations that constrain the problem:
*
* Point p₁ is a distance r₁ from c₁ at an angle of θ:
*
* 1. p₁x = c₁x + r₁·cos θ
* 2. p₁y = c₁y + r₁·sin θ
*
* Point p₂ is a distance r₂ from c₂ at an angle of θ:
*
* 3. p₂x = c₂x + r2·cos θ
* 4. p₂y = c₂y + r2·sin θ
*
* Point p lies at a fraction t along the line segment p₁p₂:
*
* 5. px = t·p₂x + (1-t)·p₁x
* 6. py = t·p₂y + (1-t)·p₁y
*
* To solve, first subtitute 1-4 into 5 and 6:
*
* px = t·(c₂x + r₂·cos θ) + (1-t)·(c₁x + r₁·cos θ)
* py = t·(c₂y + r₂·sin θ) + (1-t)·(c₁y + r₁·sin θ)
*
* Then solve each for cos θ and sin θ expressed as a function of t:
*
* cos θ = (-(c₂x - c₁x)·t + (px - c₁x)) / ((r₂-r₁)·t + r₁)
* sin θ = (-(c₂y - c₁y)·t + (py - c₁y)) / ((r₂-r₁)·t + r₁)
*
* To simplify this a bit, we define new variables for several of the
* common terms as shown below:
*
* p₂
* p •
* • ╲
* · ┆ ╲r₂
* p₁ · ┆ ╲
* • pdy┆ ╲
* ╲ ┆ •c₂
* ╲r₁ ┆ · ┆
* ╲ ·┆ ┆cdy
* •╌╌╌╌┴╌╌╌╌╌╌╌┘
* c₁ pdx cdx
*
* cdx = (c₂x - c₁x)
* cdy = (c₂y - c₁y)
* dr = r₂-r₁
* pdx = px - c₁x
* pdy = py - c₁y
*
* Note that cdx, cdy, and dr do not depend on point p at all, so can
* be pre-computed for the entire gradient. The simplifed equations
* are now:
*
* cos θ = (-cdx·t + pdx) / (dr·t + r₁)
* sin θ = (-cdy·t + pdy) / (dr·t + r₁)
*
* Finally, to get a single function of t and eliminate the last
* unknown θ, we use the identity sin²θ + cos²θ = 1. First, square
* each equation, (we knew a quadratic was coming since it must be
* possible to obtain two solutions in some cases):
*
* cos²θ = (cdx²t² - 2·cdx·pdx·t + pdx²) / (dr²·t² + 2·r₁·dr·t + r₁²)
* sin²θ = (cdy²t² - 2·cdy·pdy·t + pdy²) / (dr²·t² + 2·r₁·dr·t + r₁²)
*
* Then add both together, set the result equal to 1, and express as a
* standard quadratic equation in t of the form At² + Bt + C = 0
*
* (cdx² + cdy² - dr²)·t² - 2·(cdx·pdx + cdy·pdy + r₁·dr)·t + (pdx² + pdy² - r₁²) = 0
*
* In other words:
*
* A = cdx² + cdy² - dr²
* B = -2·(pdx·cdx + pdy·cdy + r₁·dr)
* C = pdx² + pdy² - r₁²
*
* And again, notice that A does not depend on p, so can be
* precomputed. From here we just use the quadratic formula to solve
* for t:
*
* t = (-2·B ± ⎷(B² - 4·A·C)) / 2·A
*/
gradient_t *gradient = (gradient_t *)image;
source_image_t *source = (source_image_t *)image;
radial_gradient_t *radial = (radial_gradient_t *)image;
uint32_t *end = buffer + width;
pixman_gradient_walker_t walker;
pixman_bool_t affine = TRUE;
double cx = 1.;
double cy = 0.;
double cz = 0.;
double rx = x + 0.5;
double ry = y + 0.5;
double rz = 1.;
_pixman_gradient_walker_init (&walker, gradient, source->common.repeat);
if (source->common.transform)
{
pixman_vector_t v;
/* reference point is the center of the pixel */
v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
v.vector[2] = pixman_fixed_1;
if (!pixman_transform_point_3d (source->common.transform, &v))
return;
cx = source->common.transform->matrix[0][0] / 65536.;
cy = source->common.transform->matrix[1][0] / 65536.;
cz = source->common.transform->matrix[2][0] / 65536.;
rx = v.vector[0] / 65536.;
ry = v.vector[1] / 65536.;
rz = v.vector[2] / 65536.;
affine =
source->common.transform->matrix[2][0] == 0 &&
v.vector[2] == pixman_fixed_1;
}
if (affine)
{
/* When computing t over a scanline, we notice that some expressions
* are constant so we can compute them just once. Given:
*
* t = (-2·B ± ⎷(B² - 4·A·C)) / 2·A
*
* where
*
* A = cdx² + cdy² - dr² [precomputed as radial->A]
* B = -2·(pdx·cdx + pdy·cdy + r₁·dr)
* C = pdx² + pdy² - r₁²
*
* Since we have an affine transformation, we know that (pdx, pdy)
* increase linearly with each pixel,
*
* pdx = pdx₀ + n·cx,
* pdy = pdy₀ + n·cy,
*
* we can then express B in terms of an linear increment along
* the scanline:
*
* B = B₀ + n·cB, with
* B₀ = -2·(pdx₀·cdx + pdy₀·cdy + r₁·dr) and
* cB = -2·(cx·cdx + cy·cdy)
*
* Thus we can replace the full evaluation of B per-pixel (4 multiplies,
* 2 additions) with a single addition.
*/
float r1 = radial->c1.radius / 65536.;
float r1sq = r1 * r1;
float pdx = rx - radial->c1.x / 65536.;
float pdy = ry - radial->c1.y / 65536.;
float A = radial->A;
float invA = -65536. / (2. * A);
float A4 = -4. * A;
float B = -2. * (pdx*radial->cdx + pdy*radial->cdy + r1*radial->dr);
float cB = -2. * (cx*radial->cdx + cy*radial->cdy);
pixman_bool_t invert = A * radial->dr < 0;
while (buffer < end)
{
if (!mask || *mask++ & mask_bits)
{
pixman_fixed_t t;
double det = B * B + A4 * (pdx * pdx + pdy * pdy - r1sq);
if (det <= 0.)
t = (pixman_fixed_t) (B * invA);
else if (invert)
t = (pixman_fixed_t) ((B + sqrt (det)) * invA);
else
t = (pixman_fixed_t) ((B - sqrt (det)) * invA);
*buffer = _pixman_gradient_walker_pixel (&walker, t);
}
++buffer;
pdx += cx;
pdy += cy;
B += cB;
}
}
else
{
/* projective */
while (buffer < end)
{
if (!mask || *mask++ & mask_bits)
{
double pdx, pdy;
double B, C;
double det;
double c1x = radial->c1.x / 65536.0;
double c1y = radial->c1.y / 65536.0;
double r1 = radial->c1.radius / 65536.0;
pixman_fixed_48_16_t t;
double x, y;
if (rz != 0)
{
x = rx / rz;
y = ry / rz;
}
else
{
x = y = 0.;
}
pdx = x - c1x;
pdy = y - c1y;
B = -2 * (pdx * radial->cdx +
pdy * radial->cdy +
r1 * radial->dr);
C = (pdx * pdx + pdy * pdy - r1 * r1);
det = (B * B) - (4 * radial->A * C);
if (det < 0.0)
det = 0.0;
if (radial->A * radial->dr < 0)
t = (pixman_fixed_48_16_t) ((-B - sqrt (det)) / (2.0 * radial->A) * 65536);
else
t = (pixman_fixed_48_16_t) ((-B + sqrt (det)) / (2.0 * radial->A) * 65536);
*buffer = _pixman_gradient_walker_pixel (&walker, t);
}
++buffer;
rx += cx;
ry += cy;
rz += cz;
}
}
}
static uint32_t *
conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
{
pixman_image_t *image = iter->image;
int x = iter->x;
int y = iter->y;
int width = iter->width;
uint32_t *buffer = iter->buffer;
gradient_t *gradient = (gradient_t *)image;
conical_gradient_t *conical = (conical_gradient_t *)image;
uint32_t *end = buffer + width;
pixman_gradient_walker_t walker;
pixman_bool_t affine = TRUE;
double cx = 1.;
double cy = 0.;
double cz = 0.;
double rx = x + 0.5;
double ry = y + 0.5;
double rz = 1.;
_pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
if (image->common.transform)
{
pixman_vector_t v;
/* reference point is the center of the pixel */
v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
v.vector[2] = pixman_fixed_1;
if (!pixman_transform_point_3d (image->common.transform, &v))
return iter->buffer;
cx = image->common.transform->matrix[0][0] / 65536.;
cy = image->common.transform->matrix[1][0] / 65536.;
cz = image->common.transform->matrix[2][0] / 65536.;
rx = v.vector[0] / 65536.;
ry = v.vector[1] / 65536.;
rz = v.vector[2] / 65536.;
affine =
image->common.transform->matrix[2][0] == 0 &&
v.vector[2] == pixman_fixed_1;
}
if (affine)
{
rx -= conical->center.x / 65536.;
ry -= conical->center.y / 65536.;
while (buffer < end)
{
if (!mask || *mask++)
{
double t = coordinates_to_parameter (rx, ry, conical->angle);
*buffer = _pixman_gradient_walker_pixel (
&walker, (pixman_fixed_48_16_t)pixman_double_to_fixed (t));
}
++buffer;
rx += cx;
ry += cy;
}
}
else
{
while (buffer < end)
{
double x, y;
if (!mask || *mask++)
{
double t;
if (rz != 0)
{
x = rx / rz;
y = ry / rz;
}
else
{
x = y = 0.;
}
x -= conical->center.x / 65536.;
y -= conical->center.y / 65536.;
t = coordinates_to_parameter (x, y, conical->angle);
*buffer = _pixman_gradient_walker_pixel (
&walker, (pixman_fixed_48_16_t)pixman_double_to_fixed (t));
}
++buffer;
rx += cx;
ry += cy;
rz += cz;
}
}
iter->y++;
return iter->buffer;
}
static uint32_t *
linear_get_scanline_narrow (pixman_iter_t *iter,
const uint32_t *mask)
{
pixman_image_t *image = iter->image;
int x = iter->x;
int y = iter->y;
int width = iter->width;
uint32_t * buffer = iter->buffer;
pixman_vector_t v, unit;
pixman_fixed_32_32_t l;
pixman_fixed_48_16_t dx, dy;
gradient_t *gradient = (gradient_t *)image;
linear_gradient_t *linear = (linear_gradient_t *)image;
uint32_t *end = buffer + width;
pixman_gradient_walker_t walker;
_pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
/* reference point is the center of the pixel */
v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
v.vector[2] = pixman_fixed_1;
if (image->common.transform)
{
if (!pixman_transform_point_3d (image->common.transform, &v))
return iter->buffer;
unit.vector[0] = image->common.transform->matrix[0][0];
unit.vector[1] = image->common.transform->matrix[1][0];
unit.vector[2] = image->common.transform->matrix[2][0];
}
else
{
unit.vector[0] = pixman_fixed_1;
unit.vector[1] = 0;
unit.vector[2] = 0;
}
dx = linear->p2.x - linear->p1.x;
dy = linear->p2.y - linear->p1.y;
l = dx * dx + dy * dy;
if (l == 0 || unit.vector[2] == 0)
{
/* affine transformation only */
pixman_fixed_32_32_t t, next_inc;
double inc;
if (l == 0 || v.vector[2] == 0)
{
t = 0;
inc = 0;
}
else
{
double invden, v2;
invden = pixman_fixed_1 * (double) pixman_fixed_1 /
(l * (double) v.vector[2]);
v2 = v.vector[2] * (1. / pixman_fixed_1);
t = ((dx * v.vector[0] + dy * v.vector[1]) -
(dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
inc = (dx * unit.vector[0] + dy * unit.vector[1]) * invden;
}
next_inc = 0;
if (((pixman_fixed_32_32_t )(inc * width)) == 0)
{
register uint32_t color;
color = _pixman_gradient_walker_pixel (&walker, t);
while (buffer < end)
*buffer++ = color;
}
else
{
int i;
i = 0;
while (buffer < end)
{
if (!mask || *mask++)
{
*buffer = _pixman_gradient_walker_pixel (&walker,
t + next_inc);
}
i++;
next_inc = inc * i;
buffer++;
}
}
}
else
{
/* projective transformation */
double t;
t = 0;
while (buffer < end)
{
if (!mask || *mask++)
{
if (v.vector[2] != 0)
{
double invden, v2;
invden = pixman_fixed_1 * (double) pixman_fixed_1 /
(l * (double) v.vector[2]);
v2 = v.vector[2] * (1. / pixman_fixed_1);
t = ((dx * v.vector[0] + dy * v.vector[1]) -
(dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
}
*buffer = _pixman_gradient_walker_pixel (&walker, t);
}
++buffer;
v.vector[0] += unit.vector[0];
v.vector[1] += unit.vector[1];
v.vector[2] += unit.vector[2];
}
}
iter->y++;
return iter->buffer;
}