Author: alg
Date: Mon Jul 30 10:40:40 2012
New Revision: 1367054
URL: http://svn.apache.org/viewvc?rev=1367054&view=rev
Log:
#115917# Better conversion of C1 and C2 bezier curve points
Patch by: osnola
Review by: alg
Modified:
incubator/ooo/trunk/main/tools/source/generic/poly.cxx
Modified: incubator/ooo/trunk/main/tools/source/generic/poly.cxx
URL:
http://svn.apache.org/viewvc/incubator/ooo/trunk/main/tools/source/generic/poly.cxx?rev=1367054&r1=1367053&r2=1367054&view=diff
==============================================================================
--- incubator/ooo/trunk/main/tools/source/generic/poly.cxx (original)
+++ incubator/ooo/trunk/main/tools/source/generic/poly.cxx Mon Jul 30 10:40:40
2012
@@ -2106,7 +2106,7 @@ void Polygon::Write( SvStream& rOStream
}
// -----------------------------------------------------------------------
-// #i74631# numerical correction method for B2DPolygon
+// numerical correction method for B2DPolygon
void impCorrectContinuity(basegfx::B2DPolygon& roPolygon, sal_uInt32 nIndex,
sal_uInt8 nCFlag)
{
const sal_uInt32 nPointCount(roPolygon.count());
@@ -2116,21 +2116,49 @@ void impCorrectContinuity(basegfx::B2DPo
{
if(roPolygon.isPrevControlPointUsed(nIndex) &&
roPolygon.isNextControlPointUsed(nIndex))
{
+ // #115917# Patch from osnola (modified, thanks for showing the
porblem)
+ //
+ // The correction is needed because an integer polygon with
control points
+ // is converted to double precision. When C1 or C2 is used the
involved vectors
+ // may not have the same directions/lengths since these come from
integer coordinates
+ // and may have been snapped to different nearest integer
coordinates. The snap error
+ // is in the range of +-1 in y and y, thus 0.0 <= error <=
sqrt(2.0). Nonetheless,
+ // it needs to be corrected to be able to detect the continuity in
this points
+ // correctly.
+ //
+ // We only have the integer data here (already in double precision
form, but no mantisses
+ // used), so the best correction is to use:
+ //
+ // for C1: The longest vector since it potentially has best
preserved the original vector.
+ // Even better the sum of the vectors, weighted by their
length. This gives the
+ // normal vector addition to get the vector itself,
lengths need to be preserved.
+ // for C2: The mediated vector(s) since both should be the same,
but mirrored
+
+ // extract the point and vectors
const basegfx::B2DPoint
aPoint(roPolygon.getB2DPoint(nIndex));
+ const basegfx::B2DVector
aNext(roPolygon.getNextControlPoint(nIndex) - aPoint);
+ const basegfx::B2DVector aPrev(aPoint -
roPolygon.getPrevControlPoint(nIndex));
+
+ // calculate common direction vector, normalize
+ const basegfx::B2DVector aDirection(aNext + aPrev);
if(POLY_SMOOTH == nCFlag)
{
- // C1: apply inverse direction of prev to next,
keep length of next
- const basegfx::B2DVector
aOriginalNext(roPolygon.getNextControlPoint(nIndex) - aPoint);
- basegfx::B2DVector aNewNext(aPoint -
roPolygon.getPrevControlPoint(nIndex));
-
- aNewNext.setLength(aOriginalNext.getLength());
- roPolygon.setNextControlPoint(nIndex,
basegfx::B2DPoint(aPoint + aNewNext));
+ // C1: apply common direction vector, preserve individual
lengths
+ const double fInvDirectionLen(1.0 / aDirection.getLength());
+ roPolygon.setNextControlPoint(nIndex,
basegfx::B2DPoint(aPoint + (aDirection * (aNext.getLength() *
fInvDirectionLen))));
+ roPolygon.setPrevControlPoint(nIndex,
basegfx::B2DPoint(aPoint - (aDirection * (aPrev.getLength() *
fInvDirectionLen))));
}
else // POLY_SYMMTR
{
- // C2: apply inverse control point to next
- roPolygon.setNextControlPoint(nIndex, (2.0 *
aPoint) - roPolygon.getPrevControlPoint(nIndex));
+ // C2: get mediated length. Taking half of the unnormalized
direction would be
+ // an approximation, but not correct.
+ const double fMedLength((aNext.getLength() +
aPrev.getLength()) * (0.5 / aDirection.getLength()));
+ const basegfx::B2DVector aScaledDirection(aDirection *
fMedLength);
+
+ // Bring Direction to correct length and apply
+ roPolygon.setNextControlPoint(nIndex,
basegfx::B2DPoint(aPoint + aScaledDirection));
+ roPolygon.setPrevControlPoint(nIndex,
basegfx::B2DPoint(aPoint - aScaledDirection));
}
}
}
