//---------------------------------------------------------------------------- // Anti-Grain Geometry (AGG) - Version 2.5 // A high quality rendering engine for C++ // Copyright (C) 2002-2006 Maxim Shemanarev // Contact: mcseem@antigrain.com // mcseemagg@yahoo.com // http://antigrain.com // // AGG is free software; you can redistribute it and/or // modify it under the terms of the GNU General Public License // as published by the Free Software Foundation; either version 2 // of the License, or (at your option) any later version. // // AGG is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // // You should have received a copy of the GNU General Public License // along with AGG; if not, write to the Free Software // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, // MA 02110-1301, USA. //---------------------------------------------------------------------------- #ifndef AGG_CONV_CURVE_INCLUDED #define AGG_CONV_CURVE_INCLUDED #include "agg_basics.h" #include "agg_curves.h" namespace agg { //---------------------------------------------------------------conv_curve // Curve converter class. Any path storage can have Bezier curves defined // by their control points. There're two types of curves supported: curve3 // and curve4. Curve3 is a conic Bezier curve with 2 endpoints and 1 control // point. Curve4 has 2 control points (4 points in total) and can be used // to interpolate more complicated curves. Curve4, unlike curve3 can be used // to approximate arcs, both circular and elliptical. Curves are approximated // with straight lines and one of the approaches is just to store the whole // sequence of vertices that approximate our curve. It takes additional // memory, and at the same time the consecutive vertices can be calculated // on demand. // // Initially, path storages are not suppose to keep all the vertices of the // curves (although, nothing prevents us from doing so). Instead, path_storage // keeps only vertices, needed to calculate a curve on demand. Those vertices // are marked with special commands. So, if the path_storage contains curves // (which are not real curves yet), and we render this storage directly, // all we will see is only 2 or 3 straight line segments (for curve3 and // curve4 respectively). If we need to see real curves drawn we need to // include this class into the conversion pipeline. // // Class conv_curve recognizes commands path_cmd_curve3 and path_cmd_curve4 // and converts these vertices into a move_to/line_to sequence. //----------------------------------------------------------------------- template<class VertexSource, class Curve3=curve3, class Curve4=curve4> class conv_curve { public: typedef Curve3 curve3_type; typedef Curve4 curve4_type; typedef conv_curve<VertexSource, Curve3, Curve4> self_type; explicit conv_curve(VertexSource& source) : m_source(&source), m_last_x(0.0), m_last_y(0.0) {} void attach(VertexSource& source) { m_source = &source; } void approximation_method(curve_approximation_method_e v) { m_curve3.approximation_method(v); m_curve4.approximation_method(v); } curve_approximation_method_e approximation_method() const { return m_curve4.approximation_method(); } void approximation_scale(double s) { m_curve3.approximation_scale(s); m_curve4.approximation_scale(s); } double approximation_scale() const { return m_curve4.approximation_scale(); } void angle_tolerance(double v) { m_curve3.angle_tolerance(v); m_curve4.angle_tolerance(v); } double angle_tolerance() const { return m_curve4.angle_tolerance(); } void cusp_limit(double v) { m_curve3.cusp_limit(v); m_curve4.cusp_limit(v); } double cusp_limit() const { return m_curve4.cusp_limit(); } void rewind(unsigned path_id); unsigned vertex(double* x, double* y); private: conv_curve(const self_type&); const self_type& operator = (const self_type&); VertexSource* m_source; double m_last_x; double m_last_y; curve3_type m_curve3; curve4_type m_curve4; }; //------------------------------------------------------------------------ template<class VertexSource, class Curve3, class Curve4> void conv_curve<VertexSource, Curve3, Curve4>::rewind(unsigned path_id) { m_source->rewind(path_id); m_last_x = 0.0; m_last_y = 0.0; m_curve3.reset(); m_curve4.reset(); } //------------------------------------------------------------------------ template<class VertexSource, class Curve3, class Curve4> unsigned conv_curve<VertexSource, Curve3, Curve4>::vertex(double* x, double* y) { if(!is_stop(m_curve3.vertex(x, y))) { m_last_x = *x; m_last_y = *y; return path_cmd_line_to; } if(!is_stop(m_curve4.vertex(x, y))) { m_last_x = *x; m_last_y = *y; return path_cmd_line_to; } double ct2_x; double ct2_y; double end_x; double end_y; unsigned cmd = m_source->vertex(x, y); switch(cmd) { case path_cmd_curve3: m_source->vertex(&end_x, &end_y); m_curve3.init(m_last_x, m_last_y, *x, *y, end_x, end_y); m_curve3.vertex(x, y); // First call returns path_cmd_move_to m_curve3.vertex(x, y); // This is the first vertex of the curve cmd = path_cmd_line_to; break; case path_cmd_curve4: m_source->vertex(&ct2_x, &ct2_y); m_source->vertex(&end_x, &end_y); m_curve4.init(m_last_x, m_last_y, *x, *y, ct2_x, ct2_y, end_x, end_y); m_curve4.vertex(x, y); // First call returns path_cmd_move_to m_curve4.vertex(x, y); // This is the first vertex of the curve cmd = path_cmd_line_to; break; } m_last_x = *x; m_last_y = *y; return cmd; } } #endif |