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67 lines
2 KiB
C++
67 lines
2 KiB
C++
#include "Painter.h"
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namespace Upp {
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void Painter::DoArc0(double theta, double th_sweep, const Xform2D& m)
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{
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int nsegs = int(ceil(fabs(th_sweep / (M_PI * 0.5 + 0.001))));
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for(int i = 0; i < nsegs; i++) {
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double th0 = theta + i * th_sweep / nsegs;
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double th1 = theta + (i + 1) * th_sweep / nsegs;
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double thHalf = 0.5 * (th1 - th0);
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double t = (8.0 / 3.0) * sin(thHalf * 0.5) * sin(thHalf * 0.5) / sin(thHalf);
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double x3 = cos(th1);
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double y3 = sin(th1);
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Cubic(m.Transform(cos(th0) - t * sin(th0), sin(th0) + t * cos(th0)),
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m.Transform(x3 + t * sin(th1), y3 - t * cos(th1)),
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m.Transform(x3, y3));
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}
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}
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void Painter::DoArc(const Pointf& c, const Pointf& r, double angle, double sweep, double xangle)
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{
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Xform2D m = Xform2D::Scale(r.x, r.y);
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m = m * Xform2D::Translation(c.x, c.y);
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Line(m.Transform(cos(angle), sin(angle)));
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DoArc0(angle, sweep, m);
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}
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void Painter::DoSvgArc(const Pointf& rr, double xangle, int large, int sweep,
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const Pointf& p1, const Pointf& p0)
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{
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Pointf r(fabs(rr.x), fabs(rr.y));
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Xform2D m = Xform2D::Rotation(-xangle);
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Pointf d1 = m.Transform(0.5 * (p0 - p1));
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Pointf pr = r * r;
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Pointf p = d1 * d1;
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double check = p.x / pr.x + p.y / pr.y;
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if(check > 1)
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r *= sqrt(check);
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m.x /= r.x;
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m.y /= r.y;
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Pointf q0 = m.Transform(p0);
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Pointf q1 = m.Transform(p1);
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double d = SquaredDistance(q0, q1);
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double sfactor_sq = 1.0 / d - 0.25;
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if(sfactor_sq < 0)
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sfactor_sq = 0;
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double sfactor = sqrt(sfactor_sq);
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if(sweep == large)
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sfactor = -sfactor;
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Pointf c(0.5 * (q0.x + q1.x) - sfactor * (q1.y - q0.y),
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0.5 * (q0.y + q1.y) + sfactor * (q1.x - q0.x));
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double theta = Bearing(q0 - c);
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double th_sweep = Bearing(q1 - c) - theta;
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if(th_sweep < 0 && sweep)
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th_sweep += 2 * M_PI;
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else
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if(th_sweep > 0 && !sweep)
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th_sweep -= 2 * M_PI;
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m = Xform2D::Rotation(xangle);
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m.x *= r;
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m.y *= r;
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m = Xform2D::Translation(c.x, c.y) * m;
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DoArc0(theta, th_sweep, m);
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}
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}
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