QList<KoSubpath *> KarbonSimplifyPath::split( const KoPathShape &path )
{
QList<KoSubpath *> res;
KoSubpath *subpath = new KoSubpath;
res.append( subpath );
for ( int i = 0; i < path.pointCount(); ++i )
{
KoPathPoint *p = path.pointByIndex( KoPathPointIndex(0, i) );
// if the path separates two subpaths
// (if it isn't smooth nor the first or last point)
if ( i != 0 && i != path.pointCount()-1 )
{
KoPathPoint *prev = path.pointByIndex( KoPathPointIndex(0, i-1) );
KoPathPoint *next = path.pointByIndex( KoPathPointIndex(0, i+1) );
if ( ! p->isSmooth(prev, next) )
{
// create a new subpath
subpath->append( new KoPathPoint(*p) );
subpath = new KoSubpath;
res.append( subpath );
}
}
subpath->append( new KoPathPoint(*p) );
}
return res;
}
void RoundCornersCommand::roundPath()
{
/*
* This algorithm is worked out by <kudling AT kde DOT org> to produce similar results as
* the "round corners" algorithms found in other applications. Neither code nor
* algorithms from any 3rd party is used though.
*
* We want to replace all corners with round corners having "radius" m_radius.
* The algorithm doesn't really produce circular arcs, but that's ok since
* the algorithm achieves nice looking results and is generic enough to be applied
* to all kind of paths.
* Note also, that this algorithm doesn't touch smooth joins (in the sense of
* KoPathPoint::isSmooth() ).
*
* We'll manipulate the input path for bookkeeping purposes and construct a new
* temporary path in parallel. We finally replace the input path with the new path.
*
*
* Without restricting generality, let's assume the input path is closed and
* contains segments which build a rectangle.
*
* 2
* O------------O
* | | Numbers reflect the segments' order
* 3| |1 in the path. We neglect the "begin"
* | | segment here.
* O------------O
* 0
*
* There are three unique steps to process. The second step is processed
* many times in a loop.
*
* 1) Begin
* -----
* Split the first segment of the input path (called "path[0]" here)
* at parameter t
*
* t = path[0]->param( m_radius )
*
* and move newPath to this new knot. If current segment is too small
* (smaller than 2 * m_radius), we always set t = 0.5 here and in the further
* steps as well.
*
* path: new path:
*
* 2
* O------------O
* | |
* 3 | | 1 The current segment is marked with "#"s.
* | |
* O##O#########O ...O
* 0 0
*
* 2) Loop
* ----
* The loop step is iterated over all segments. After each appliance the index n
* is incremented and the loop step is reapplied until no untouched segment is left.
*
* Split the current segment path[n] of the input path at parameter t
*
* t = path[n]->param( path[n]->length() - m_radius )
*
* and add the first subsegment of the curent segment to newPath.
*
* path: new path:
*
* 2
* O------------O
* | |
* 3 | | 1
* | |
* O--O######O##O O------O...
* 0 0
*
* Now make the second next segment (the original path[1] segment in our example)
* the current one. Split it at parameter t
*
* t = path[n]->param( m_radius )
*
* path: new path:
*
* 2
* O------------O
* | #
* 3 | O 1
* | #
* O--O------O--O O------O...
* 0 0
*
* Make the first subsegment of the current segment the current one.
*
* path: new path:
*
* 2
* O------------O
* | |
* 3 | O 1 O
* | # /.1
* O--O------O--O O------O...
* 0 0
*
* 3) End
* ---
*
* path: new path:
*
* 2 4
* O--O------O--O 5 .O------O. 3
* | | / \
* 3 O O 1 6 O O 2
* | | 7 .\ /
* O--O------O--O ...O------O. 1
* 0 0
*/
// TODO: not sure if we should only touch flat segment joins as the original algorithm
m_path->clear();
int subpathCount = m_copy->subpathCount();
for( int subpathIndex = 0; subpathIndex < subpathCount; ++subpathIndex )
{
int pointCount = m_copy->pointCountSubpath( subpathIndex );
if( ! pointCount )
continue;
// check if we have sufficient number of points
if( pointCount < 3 )
{
// copy the only segment
KoPathSegment s = m_copy->segmentByIndex( KoPathPointIndex( subpathIndex, 0 ) );
m_path->moveTo( m_copy->pointByIndex( KoPathPointIndex( subpathIndex, 0 ) )->point() );
addSegment( m_path, s );
continue;
}
KoPathSegment prevSeg = m_copy->segmentByIndex( KoPathPointIndex( subpathIndex, pointCount-1 ) );
KoPathSegment nextSeg = m_copy->segmentByIndex( KoPathPointIndex( subpathIndex, 0 ) );
KoPathSegment lastSeg;
KoPathPoint * currPoint = nextSeg.first();
KoPathPoint * firstPoint = 0;
KoPathPoint * lastPoint = 0;
// check if first path point is a smooth join with the closing segment
bool firstPointIsCorner = m_copy->isClosedSubpath( subpathIndex )
&& ! currPoint->isSmooth( prevSeg.first(), nextSeg.second() );
// Begin: take care of the first path point
if( firstPointIsCorner )
{
// split the previous segment at length - radius
qreal prevLength = prevSeg.length();
qreal prevSplit = prevLength > m_radius ? prevSeg.paramAtLength( prevLength-m_radius ) : 0.5;
QPair<KoPathSegment,KoPathSegment> prevParts = prevSeg.splitAt( prevSplit );
// split the next segment at radius
qreal nextLength = nextSeg.length();
qreal nextSplit = nextLength > m_radius ? nextSeg.paramAtLength( m_radius ) : 0.5;
QPair<KoPathSegment,KoPathSegment> nextParts = nextSeg.splitAt( nextSplit );
// calculate smooth tangents
QPointF P0 = prevParts.first.second()->point();
QPointF P3 = nextParts.first.second()->point();
qreal tangentLength1 = 0.5 * QLineF( P0, currPoint->point() ).length();
qreal tangentLength2 = 0.5 * QLineF( P3, currPoint->point() ).length();
QPointF P1 = P0 - tangentLength1 * tangentAtEnd( prevParts.first );
QPointF P2 = P3 - tangentLength2 * tangentAtStart( nextParts.second );
// start the subpath
firstPoint = m_path->moveTo( prevParts.second.first()->point() );
// connect the split points with curve
// TODO: shall we create a correct arc?
m_path->curveTo( P1, P2, P3 );
prevSeg = nextParts.second;
lastSeg = prevParts.first;
}
else
{
firstPoint = m_path->moveTo( currPoint->point() );
prevSeg = nextSeg;
}
// Loop:
for( int pointIndex = 1; pointIndex < pointCount; ++pointIndex )
{
nextSeg = m_copy->segmentByIndex( KoPathPointIndex( subpathIndex, pointIndex ) );
if( ! nextSeg.isValid() )
break;
currPoint = nextSeg.first();
if( ! currPoint )
continue;
if( currPoint->isSmooth( prevSeg.first(), nextSeg.second() ) )
{
// the current point has a smooth join, so we can add the previous segment
// to our new path
addSegment( m_path, prevSeg );
prevSeg = nextSeg;
}
else
{
// split the previous segment at length - radius
qreal prevLength = prevSeg.length();
qreal prevSplit = prevLength > m_radius ? prevSeg.paramAtLength( prevLength-m_radius ) : 0.5;
QPair<KoPathSegment,KoPathSegment> prevParts = prevSeg.splitAt( prevSplit );
// add the remaining part up to the split point of the pervious segment
lastPoint = addSegment( m_path, prevParts.first );
// split the next segment at radius
qreal nextLength = nextSeg.length();
qreal nextSplit = nextLength > m_radius ? nextSeg.paramAtLength( m_radius ) : 0.5;
QPair<KoPathSegment,KoPathSegment> nextParts = nextSeg.splitAt( nextSplit );
// calculate smooth tangents
QPointF P0 = prevParts.first.second()->point();
QPointF P3 = nextParts.first.second()->point();
qreal tangentLength1 = 0.5 * QLineF( P0, currPoint->point() ).length();
qreal tangentLength2 = 0.5 * QLineF( P3, currPoint->point() ).length();
QPointF P1 = P0 - tangentLength1 * tangentAtEnd( prevParts.first );
QPointF P2 = P3 - tangentLength2 * tangentAtStart( nextParts.second );
// connect the split points with curve
// TODO: shall we create a correct arc?
lastPoint = m_path->curveTo( P1, P2, P3 );
prevSeg = nextParts.second;
}
}
// End: take care of the last path point
if( firstPointIsCorner )
{
// construct the closing segment
lastPoint->setProperty( KoPathPoint::CloseSubpath );
firstPoint->setProperty( KoPathPoint::CloseSubpath );
switch( lastSeg.degree() )
{
case 1:
lastPoint->removeControlPoint2();
firstPoint->removeControlPoint1();
break;
case 2:
if( lastSeg.first()->activeControlPoint2() )
{
lastPoint->setControlPoint2( lastSeg.first()->controlPoint2() );
firstPoint->removeControlPoint1();
}
else
{
lastPoint->removeControlPoint2();
firstPoint->setControlPoint1( lastSeg.second()->controlPoint1() );
}
break;
case 3:
lastPoint->setControlPoint2( lastSeg.first()->controlPoint2() );
firstPoint->setControlPoint1( lastSeg.second()->controlPoint1() );
break;
}
}
else
{
// add the last remaining segment
addSegment( m_path, prevSeg );
}
}
}