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111 lines
3.3 KiB
C++
111 lines
3.3 KiB
C++
#include "Painter.h"
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NAMESPACE_UPP
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//----------------------------------------------------------------------------
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// Anti-Grain Geometry - Version 2.4
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// Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
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//
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// Permission to copy, use, modify, sell and distribute this software
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// is granted provided this copyright notice appears in all coM_PIes.
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// This software is provided "as is" without express or implied
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// warranty, and with no claim as to its suitability for any purpose.
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//
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//----------------------------------------------------------------------------
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// Contact: mcseem@antigrain.com
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// mcseemagg@yahoo.com
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// http://www.antigrain.com
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//----------------------------------------------------------------------------
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//
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// Arc generator. Produces at most 4 consecutive cubic bezier curves, i.e.,
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// 4, 7, 10, or 13 vertices.
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//
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//----------------------------------------------------------------------------
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// Recycled for U++ by Miroslav Fidler 2008
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void sSubArc(double cx, double cy, double rx, double ry,
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double start_angle, double sweep_angle,
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double *px, double *py)
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{
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double x0 = cos(sweep_angle / 2.0);
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double y0 = sin(sweep_angle / 2.0);
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double tx = (1.0 - x0) * 4.0 / 3.0;
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double ty = y0 - tx * x0 / y0;
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double x[4], y[4];
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x[0] = x0;
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y[0] = -y0;
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x[1] = x0 + tx;
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y[1] = -ty;
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x[2] = x0 + tx;
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y[2] = ty;
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x[3] = x0;
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y[3] = y0;
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double sn = sin(start_angle + sweep_angle / 2.0);
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double cs = cos(start_angle + sweep_angle / 2.0);
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unsigned i;
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for(i = 0; i < 4; i++) {
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px[i] = cx + rx * (x[i] * cs - y[i] * sn);
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py[i] = cy + ry * (x[i] * sn + y[i] * cs);
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}
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}
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Painter& Painter::Arc(double x, double y, double rx, double ry,
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double start_angle, double sweep_angle, bool startline)
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{
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const double bezier_arc_angle_epsilon = 0.01;
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start_angle = fmod(start_angle, 2.0 * M_PI);
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if(sweep_angle >= 2.0 * M_PI) sweep_angle = 2.0 * M_PI;
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if(sweep_angle <= -2.0 * M_PI) sweep_angle = -2.0 * M_PI;
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if(fabs(sweep_angle) < 1e-10) {
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double px = x + rx * cos(start_angle);
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double py = y + ry * sin(start_angle);
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if(startline)
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Line(px, py);
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else
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Move(px, py);
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Line(x + rx * cos(start_angle + sweep_angle), y + ry * sin(start_angle + sweep_angle));
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return *this;
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}
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double total_sweep = 0.0;
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double local_sweep = 0.0;
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double prev_sweep;
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bool done = false;
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bool first = true;
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for(int i = 0; !done && i < 4; i++) {
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if(sweep_angle < 0.0) {
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prev_sweep = total_sweep;
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local_sweep = -M_PI * 0.5;
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total_sweep -= M_PI * 0.5;
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if(total_sweep <= sweep_angle + bezier_arc_angle_epsilon) {
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local_sweep = sweep_angle - prev_sweep;
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done = true;
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}
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}
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else {
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prev_sweep = total_sweep;
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local_sweep = M_PI * 0.5;
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total_sweep += M_PI * 0.5;
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if(total_sweep >= sweep_angle - bezier_arc_angle_epsilon) {
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local_sweep = sweep_angle - prev_sweep;
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done = true;
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}
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}
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double px[4];
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double py[4];
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sSubArc(x, y, rx, ry, start_angle, local_sweep, px, py);
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if(first)
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if(startline)
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Line(px[0], py[0]);
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else
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Move(px[0], py[0]);
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first = false;
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Cubic(px[1], py[1], px[2], py[2], px[3], py[3]);
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start_angle += local_sweep;
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}
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return *this;
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}
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END_UPP_NAMESPACE
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