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Diffstat (limited to 'src/2geom/path-sink.h')
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diff --git a/src/2geom/path-sink.h b/src/2geom/path-sink.h new file mode 100644 index 0000000..3bdb007 --- /dev/null +++ b/src/2geom/path-sink.h @@ -0,0 +1,245 @@ +/** + * \file + * \brief callback interface for SVG path data + *//* + * Copyright 2007 MenTaLguY <mental@rydia.net> + * + * This library is free software; you can redistribute it and/or + * modify it either under the terms of the GNU Lesser General Public + * License version 2.1 as published by the Free Software Foundation + * (the "LGPL") or, at your option, under the terms of the Mozilla + * Public License Version 1.1 (the "MPL"). If you do not alter this + * notice, a recipient may use your version of this file under either + * the MPL or the LGPL. + * + * You should have received a copy of the LGPL along with this library + * in the file COPYING-LGPL-2.1; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * You should have received a copy of the MPL along with this library + * in the file COPYING-MPL-1.1 + * + * The contents of this file are subject to the Mozilla Public License + * Version 1.1 (the "License"); you may not use this file except in + * compliance with the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY + * OF ANY KIND, either express or implied. See the LGPL or the MPL for + * the specific language governing rights and limitations. + * + */ + +#ifndef LIB2GEOM_SEEN_PATH_SINK_H +#define LIB2GEOM_SEEN_PATH_SINK_H + +#include <2geom/forward.h> +#include <2geom/pathvector.h> +#include <2geom/curves.h> +#include <iterator> + +namespace Geom { + + +/** @brief Callback interface for processing path data. + * + * PathSink provides an interface that allows one to easily write + * code which processes path data, for instance when converting + * between path formats used by different graphics libraries. + * It is also useful for writing algorithms which must do something + * for each curve in the path. + * + * To store a path in a new format, implement the virtual methods + * for segments in a derived class and call feed(). + * + * @ingroup Paths + */ +class PathSink { +public: + /** @brief Move to a different point without creating a segment. + * Usually starts a new subpath. */ + virtual void moveTo(Point const &p) = 0; + /// Output a line segment. + virtual void lineTo(Point const &p) = 0; + /// Output a quadratic Bezier segment. + virtual void curveTo(Point const &c0, Point const &c1, Point const &p) = 0; + /// Output a cubic Bezier segment. + virtual void quadTo(Point const &c, Point const &p) = 0; + /** @brief Output an elliptical arc segment. + * See the EllipticalArc class for the documentation of parameters. */ + virtual void arcTo(Coord rx, Coord ry, Coord angle, + bool large_arc, bool sweep, Point const &p) = 0; + + /// Close the current path with a line segment. + virtual void closePath() = 0; + /** @brief Flush any internal state of the generator. + * This call should implicitly finish the current subpath. + * Calling this method should be idempotent, because the default + * implementations of path() and pathvector() will call it + * multiple times in a row. */ + virtual void flush() = 0; + // Get the current point, e.g. where the initial point of the next segment will be. + //virtual Point currentPoint() const = 0; + + /** @brief Undo the last segment. + * This method is optional. + * @return true true if a segment was erased, false otherwise. */ + virtual bool backspace() { return false; } + + // these have a default implementation + virtual void feed(Curve const &c, bool moveto_initial = true); + /** @brief Output a subpath. + * Calls the appropriate segment methods according to the contents + * of the passed subpath. You can override this function. + * NOTE: if you override only some of the feed() functions, + * always write this in the derived class: + * @code + using PathSink::feed; + @endcode + * Otherwise the remaining methods will be hidden. */ + virtual void feed(Path const &p); + /** @brief Output a path. + * Calls feed() on each path in the vector. You can override this function. */ + virtual void feed(PathVector const &v); + /// Output an axis-aligned rectangle, using moveTo, lineTo and closePath. + virtual void feed(Rect const &); + /// Output a circle as two elliptical arcs. + virtual void feed(Circle const &e); + /// Output an ellipse as two elliptical arcs. + virtual void feed(Ellipse const &e); + + virtual ~PathSink() {} +}; + +/** @brief Store paths to an output iterator + * @ingroup Paths */ +template <typename OutputIterator> +class PathIteratorSink : public PathSink { +public: + explicit PathIteratorSink(OutputIterator out) + : _in_path(false), _out(out) {} + + void moveTo(Point const &p) { + flush(); + _path.start(p); + _start_p = p; + _in_path = true; + } +//TODO: what if _in_path = false? + + void lineTo(Point const &p) { + // check for implicit moveto, like in: "M 1,1 L 2,2 z l 2,2 z" + if (!_in_path) { + moveTo(_start_p); + } + _path.template appendNew<LineSegment>(p); + } + + void quadTo(Point const &c, Point const &p) { + // check for implicit moveto, like in: "M 1,1 L 2,2 z l 2,2 z" + if (!_in_path) { + moveTo(_start_p); + } + _path.template appendNew<QuadraticBezier>(c, p); + } + + void curveTo(Point const &c0, Point const &c1, Point const &p) { + // check for implicit moveto, like in: "M 1,1 L 2,2 z l 2,2 z" + if (!_in_path) { + moveTo(_start_p); + } + _path.template appendNew<CubicBezier>(c0, c1, p); + } + + void arcTo(Coord rx, Coord ry, Coord angle, + bool large_arc, bool sweep, Point const &p) + { + // check for implicit moveto, like in: "M 1,1 L 2,2 z l 2,2 z" + if (!_in_path) { + moveTo(_start_p); + } + _path.template appendNew<EllipticalArc>(rx, ry, angle, + large_arc, sweep, p); + } + + bool backspace() + { + if (_in_path && _path.size() > 0) { + _path.erase_last(); + return true; + } + return false; + } + + void append(Path const &other) + { + if (!_in_path) { + moveTo(other.initialPoint()); + } + _path.append(other); + } + + void closePath() { + if (_in_path) { + _path.close(); + flush(); + } + } + + void flush() { + if (_in_path) { + _in_path = false; + *_out++ = _path; + _path.clear(); + } + } + + void setStitching(bool s) { + _path.setStitching(s); + } + + using PathSink::feed; + void feed(Path const &other) + { + flush(); + *_out++ = other; + } + +protected: + bool _in_path; + OutputIterator _out; + Path _path; + Point _start_p; +}; + +typedef std::back_insert_iterator<PathVector> SubpathInserter; + +/** @brief Store paths to a PathVector + * @ingroup Paths */ +class PathBuilder : public PathIteratorSink<SubpathInserter> { +private: + PathVector _pathset; +public: + /// Create a builder that outputs to an internal pathvector. + PathBuilder() : PathIteratorSink<SubpathInserter>(SubpathInserter(_pathset)) {} + /// Create a builder that outputs to pathvector given by reference. + PathBuilder(PathVector &pv) : PathIteratorSink<SubpathInserter>(SubpathInserter(pv)) {} + + /// Retrieve the path + PathVector const &peek() const {return _pathset;} + /// Clear the stored path vector + void clear() { _pathset.clear(); } +}; + +} + +#endif +/* + Local Variables: + mode:c++ + c-file-style:"stroustrup" + c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +)) + indent-tabs-mode:nil + fill-column:99 + End: +*/ +// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 : |