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livetrax/libs/evoral/evoral/Range.hpp
Carl Hetherington a6786a6dd2 Hopefully less bad version of Evoral::RangeList::subtract,
with more tests.


git-svn-id: svn://localhost/ardour2/branches/3.0@12514 d708f5d6-7413-0410-9779-e7cbd77b26cf
2012-05-31 20:23:31 +00:00

255 lines
6.1 KiB
C++

/* This file is part of Evoral.
* Copyright (C) 2008 David Robillard <http://drobilla.net>
* Copyright (C) 2000-2008 Paul Davis
*
* Evoral 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.
*
* Evoral 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 details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef EVORAL_RANGE_HPP
#define EVORAL_RANGE_HPP
#include <list>
namespace Evoral {
enum OverlapType {
OverlapNone, // no overlap
OverlapInternal, // the overlap is 100% with the object
OverlapStart, // overlap covers start, but ends within
OverlapEnd, // overlap begins within and covers end
OverlapExternal // overlap extends to (at least) begin+end
};
template<typename T>
OverlapType coverage (T sa, T ea, T sb, T eb) {
/* OverlapType returned reflects how the second (B)
range overlaps the first (A).
The diagrams show various relative placements
of A and B for each OverlapType.
Notes:
Internal: the start points cannot coincide
External: the start and end points can coincide
Start: end points can coincide
End: start points can coincide
XXX Logically, Internal should disallow end
point equality.
*/
/*
|--------------------| A
|------| B
|-----------------| B
"B is internal to A"
*/
if ((sb > sa) && (eb <= ea)) {
return OverlapInternal;
}
/*
|--------------------| A
----| B
-----------------------| B
--| B
"B overlaps the start of A"
*/
if ((eb >= sa) && (eb <= ea)) {
return OverlapStart;
}
/*
|---------------------| A
|----------------- B
|----------------------- B
|- B
"B overlaps the end of A"
*/
if ((sb > sa) && (sb <= ea)) {
return OverlapEnd;
}
/*
|--------------------| A
-------------------------- B
|----------------------- B
----------------------| B
|--------------------| B
"B overlaps all of A"
*/
if ((sa >= sb) && (sa <= eb) && (ea <= eb)) {
return OverlapExternal;
}
return OverlapNone;
}
/** Type to describe a time range */
template<typename T>
struct Range {
Range (T f, T t) : from (f), to (t) {}
T from; ///< start of the range
T to; ///< end of the range
};
template<typename T>
bool operator== (Range<T> a, Range<T> b) {
return a.from == b.from && a.to == b.to;
}
template<typename T>
class RangeList {
public:
RangeList () : _dirty (false) {}
typedef std::list<Range<T> > List;
List const & get () {
coalesce ();
return _list;
}
void add (Range<T> const & range) {
_dirty = true;
_list.push_back (range);
}
bool empty () const {
return _list.empty ();
}
void coalesce () {
if (!_dirty) {
return;
}
restart:
for (typename List::iterator i = _list.begin(); i != _list.end(); ++i) {
for (typename List::iterator j = _list.begin(); j != _list.end(); ++j) {
if (i == j) {
continue;
}
if (coverage (i->from, i->to, j->from, j->to) != OverlapNone) {
i->from = std::min (i->from, j->from);
i->to = std::max (i->to, j->to);
_list.erase (j);
goto restart;
}
}
}
_dirty = false;
}
private:
List _list;
bool _dirty;
};
/** Type to describe the movement of a time range */
template<typename T>
struct RangeMove {
RangeMove (T f, double l, T t) : from (f), length (l), to (t) {}
T from; ///< start of the range
double length; ///< length of the range
T to; ///< new start of the range
};
/** Subtract the ranges in `sub' from that in `range',
* returning the result.
*/
template<typename T>
RangeList<T> subtract (Range<T> range, RangeList<T> sub)
{
/* Start with the input range */
RangeList<T> result;
result.add (range);
if (sub.empty ()) {
return result;
}
typename RangeList<T>::List s = sub.get ();
/* The basic idea here is to keep a list of the result ranges, and subtract
the bits of `sub' from them one by one.
*/
for (typename RangeList<T>::List::const_iterator i = s.begin(); i != s.end(); ++i) {
/* Here's where we'll put the new current result after subtracting *i from it */
RangeList<T> new_result;
typename RangeList<T>::List r = result.get ();
/* Work on all parts of the current result using this range *i */
for (typename RangeList<T>::List::const_iterator j = r.begin(); j != r.end(); ++j) {
switch (coverage (j->from, j->to, i->from, i->to)) {
case OverlapNone:
/* The thing we're subtracting does not overlap this bit of the result,
so pass it through.
*/
new_result.add (*j);
break;
case OverlapInternal:
/* Internal overlap of the thing we're subtracting from this bit of the result,
so we might end up with two bits left over.
*/
if (j->from < (i->from - 1)) {
new_result.add (Range<T> (j->from, i->from - 1));
}
if (j->to != i->to) {
new_result.add (Range<T> (i->to, j->to));
}
break;
case OverlapStart:
/* The bit we're subtracting overlaps the start of the bit of the result */
new_result.add (Range<T> (i->to, j->to - 1));
break;
case OverlapEnd:
/* The bit we're subtracting overlaps the end of the bit of the result */
new_result.add (Range<T> (j->from, i->from - 1));
break;
case OverlapExternal:
/* total overlap of the bit we're subtracting with the result bit, so the
result bit is completely removed; do nothing */
break;
}
}
new_result.coalesce ();
result = new_result;
}
return result;
}
}
#endif