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#include "cru/platform/graphics/Geometry.h"
#include <cmath>
namespace cru::platform::graphics {
constexpr float PI = 3.14159265358979323846f;
using std::abs;
using std::atan2;
using std::ceil;
using std::cos;
using std::sin;
using std::sqrt;
// The following codes are from Qt.
static void pathArcSegment(IGeometryBuilder* path, float xc, float yc,
float th0, float th1, float rx, float ry,
float xAxisRotation) {
float sinTh, cosTh;
float a00, a01, a10, a11;
float x1, y1, x2, y2, x3, y3;
float t;
float thHalf;
sinTh = sin(xAxisRotation * (PI / 180.0));
cosTh = cos(xAxisRotation * (PI / 180.0));
a00 = cosTh * rx;
a01 = -sinTh * ry;
a10 = sinTh * rx;
a11 = cosTh * ry;
thHalf = 0.5 * (th1 - th0);
t = (8.0 / 3.0) * sin(thHalf * 0.5) * sin(thHalf * 0.5) / sin(thHalf);
x1 = xc + cos(th0) - t * sin(th0);
y1 = yc + sin(th0) + t * cos(th0);
x3 = xc + cos(th1);
y3 = yc + sin(th1);
x2 = x3 + t * sin(th1);
y2 = y3 - t * cos(th1);
path->CubicBezierTo({a00 * x1 + a01 * y1, a10 * x1 + a11 * y1},
{a00 * x2 + a01 * y2, a10 * x2 + a11 * y2},
{a00 * x3 + a01 * y3, a10 * x3 + a11 * y3});
}
// the arc handling code underneath is from XSVG (BSD license)
/*
* Copyright 2002 USC/Information Sciences Institute
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies
* and that both that copyright notice and this permission notice
* appear in supporting documentation, and that the name of
* Information Sciences Institute not be used in advertising or
* publicity pertaining to distribution of the software without
* specific, written prior permission. Information Sciences Institute
* makes no representations about the suitability of this software for
* any purpose. It is provided "as is" without express or implied
* warranty.
*
* INFORMATION SCIENCES INSTITUTE DISCLAIMS ALL WARRANTIES WITH REGARD
* TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL INFORMATION SCIENCES
* INSTITUTE BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA
* OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*
*/
static void pathArc(IGeometryBuilder* path, float rx, float ry,
float x_axis_rotation, int large_arc_flag, int sweep_flag,
float x, float y, float curx, float cury) {
const float Pr1 = rx * rx;
const float Pr2 = ry * ry;
if (!Pr1 || !Pr2) return;
float sin_th, cos_th;
float a00, a01, a10, a11;
float x0, y0, x1, y1, xc, yc;
float d, sfactor, sfactor_sq;
float th0, th1, th_arc;
int i, n_segs;
float dx, dy, dx1, dy1, Px, Py, check;
rx = abs(rx);
ry = abs(ry);
sin_th = sin(x_axis_rotation * (PI / 180.0));
cos_th = cos(x_axis_rotation * (PI / 180.0));
dx = (curx - x) / 2.0;
dy = (cury - y) / 2.0;
dx1 = cos_th * dx + sin_th * dy;
dy1 = -sin_th * dx + cos_th * dy;
Px = dx1 * dx1;
Py = dy1 * dy1;
/* Spec : check if radii are large enough */
check = Px / Pr1 + Py / Pr2;
if (check > 1) {
rx = rx * sqrt(check);
ry = ry * sqrt(check);
}
a00 = cos_th / rx;
a01 = sin_th / rx;
a10 = -sin_th / ry;
a11 = cos_th / ry;
x0 = a00 * curx + a01 * cury;
y0 = a10 * curx + a11 * cury;
x1 = a00 * x + a01 * y;
y1 = a10 * x + a11 * y;
/* (x0, y0) is current point in transformed coordinate space.
(x1, y1) is new point in transformed coordinate space.
The arc fits a unit-radius circle in this space.
*/
d = (x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0);
if (!d) return;
sfactor_sq = 1.0 / d - 0.25;
if (sfactor_sq < 0) sfactor_sq = 0;
sfactor = sqrt(sfactor_sq);
if (sweep_flag == large_arc_flag) sfactor = -sfactor;
xc = 0.5 * (x0 + x1) - sfactor * (y1 - y0);
yc = 0.5 * (y0 + y1) + sfactor * (x1 - x0);
/* (xc, yc) is center of the circle. */
th0 = atan2(y0 - yc, x0 - xc);
th1 = atan2(y1 - yc, x1 - xc);
th_arc = th1 - th0;
if (th_arc < 0 && sweep_flag)
th_arc += 2 * PI;
else if (th_arc > 0 && !sweep_flag)
th_arc -= 2 * PI;
n_segs = ceil(abs(th_arc / (PI * 0.5 + 0.001)));
for (i = 0; i < n_segs; i++) {
pathArcSegment(path, xc, yc, th0 + i * th_arc / n_segs,
th0 + (i + 1) * th_arc / n_segs, rx, ry, x_axis_rotation);
}
}
void IGeometryBuilder::ArcTo(const Point& radius, float angle,
bool is_large_arc, bool is_clockwise,
const Point& end_point) {
auto current_position = GetCurrentPosition();
pathArc(this, radius.x, radius.y, angle, is_large_arc, is_clockwise,
end_point.x, end_point.y, current_position.x, current_position.y);
}
} // namespace cru::platform::graphics
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