diff options
Diffstat (limited to 'src/splivarot.cpp')
| -rw-r--r-- | src/splivarot.cpp | 36 |
1 files changed, 31 insertions, 5 deletions
diff --git a/src/splivarot.cpp b/src/splivarot.cpp index 356cf0161..6423129b9 100644 --- a/src/splivarot.cpp +++ b/src/splivarot.cpp @@ -277,11 +277,37 @@ sp_selected_path_boolop(Inkscape::Selection *selection, SPDesktop *desktop, bool theShapeB->ConvertToShape(theShape, origWind[curOrig]); - if (theShapeA->numberOfEdges() == 0) { - Shape *swap = theShapeB; - theShapeB = theShapeA; - theShapeA = swap; - } else if (theShapeB->numberOfEdges() > 0) { + // Due to quantization of the input shape coordinates, we may end up with A or B being empty. + // If this is a union or symdiff operation, we just use the non-empty shape as the result: + // A=0 => (0 or B) == B + // B=0 => (A or 0) == A + // A=0 => (0 xor B) == B + // B=0 => (A xor 0) == A + // If this is an intersection operation, we just use the empty shape as the result: + // A=0 => (0 and B) == 0 == A + // B=0 => (A and 0) == 0 == B + // If this a difference operation, and the upper shape (A) is empty, we keep B. + // If the lower shape (B) is empty, we still keep B, as it's empty: + // A=0 => (B - 0) == B + // B=0 => (0 - A) == 0 == B + // + // In any case, the output from this operation is stored in shape A, so we may apply + // the above rules simply by judicious use of swapping A and B where necessary. + bool zeroA = theShapeA->numberOfEdges() == 0; + bool zeroB = theShapeB->numberOfEdges() == 0; + if (zeroA || zeroB) { + // We might need to do a swap. Apply the above rules depending on operation type. + bool resultIsB = ((bop == bool_op_union || bop == bool_op_symdiff) && zeroA) + || ((bop == bool_op_inters) && zeroB) + || (bop == bool_op_diff); + if (resultIsB) { + // Swap A and B to use B as the result + Shape *swap = theShapeB; + theShapeB = theShapeA; + theShapeA = swap; + } + } else { + // Just do the Boolean operation as usual // les elements arrivent en ordre inverse dans la liste theShape->Booleen(theShapeB, theShapeA, bop); Shape *swap = theShape; |