tdf#130150 Improve clipping in PDF export

For more info and discusson please have a look
at the task. It reverts the change from tdf#99680
which did a wrong paradigm change in how clip in
Region(s) is defined and tries to fix the
underlying error in a more correct way.
This includes problems noted in tdf#44388 and
tdf#113449.
This is a decent improvement, but - due to dealing
with numerical problems - not yet the whole healing.
Still thinking about how to solve this for good.
Adapted PdfExportTest::testTdf99680() and
PdfExportTest::testTdf99680_2() as needed, empty
clip regions are allowed again. Added comments, too.
Had to change solvePolygonOperationAnd to work
on ranges if both inputs *are* ranges. The AND-case
is then completely solvable. Also increased geometry
for transformations of clip geometries - may help
later.

Change-Id: I2370447597faa6efb81d58ee31c63654e304262e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/89874
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

1 files changed, 36 insertions, 0 deletions

diff --git a/basegfx/source/polygon/b2dpolypolygoncutter.cxx b/basegfx/source/polygon/b2dpolypolygoncutter.cxx
index ad185f47f336..6263c78a1ef5 100644
--- a/basegfx/source/polygon/b2dpolypolygoncutter.cxx
+++ b/basegfx/source/polygon/b2dpolypolygoncutter.cxx
@@ -984,6 +984,42 @@ namespace basegfx::utils
             }
             else
             {
+                // tdf#130150 shortcut & precision: If both are simple ranges,
+                // solve based on ranges
+                if(basegfx::utils::isRectangle(rCandidateA) && basegfx::utils::isRectangle(rCandidateB))
+                {
+                    // *if* both are ranges, AND always can be solved
+                    const basegfx::B2DRange aRangeA(rCandidateA.getB2DRange());
+                    const basegfx::B2DRange aRangeB(rCandidateB.getB2DRange());
+
+                    if(aRangeA.isInside(aRangeB))
+                    {
+                        // 2nd completely inside 1st -> 2nd is result of AND
+                        return rCandidateB;
+                    }
+
+                    if(aRangeB.isInside(aRangeA))
+                    {
+                        // 2nd completely inside 1st -> 2nd is result of AND
+                        return rCandidateA;
+                    }
+
+                    // solve by intersection
+                    basegfx::B2DRange aIntersect(aRangeA);
+                    aIntersect.intersect(aRangeB);
+
+                    if(aIntersect.isEmpty())
+                    {
+                        // no overlap -> empty polygon as result of AND
+                        return B2DPolyPolygon();
+                    }
+
+                    // create polygon result
+                    return B2DPolyPolygon(
+                        basegfx::utils::createPolygonFromRect(
+                            aIntersect));
+                }
+
                 // concatenate polygons, solve crossovers and throw away all sub-polygons
                 // with a depth of < 1. This means to keep all polygons where at least two
                 // polygons do overlap.