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>

2 files changed, 56 insertions, 26 deletions

diff --git a/vcl/qa/cppunit/pdfexport/pdfexport.cxx b/vcl/qa/cppunit/pdfexport/pdfexport.cxx
index f46f94b10b4c..ff5f877b050b 100644
--- a/vcl/qa/cppunit/pdfexport/pdfexport.cxx
+++ b/vcl/qa/cppunit/pdfexport/pdfexport.cxx
@@ -811,15 +811,17 @@ void PdfExportTest::testTdf99680()
     aZCodec.Decompress(rObjectStream, aUncompressed);
     CPPUNIT_ASSERT(aZCodec.EndCompression());
 
-    // Make sure there are no empty clipping regions.
-    OString aEmptyRegion("0 0 m h W* n");
-    auto pStart = static_cast<const char*>(aUncompressed.GetData());
-    const char* pEnd = pStart + aUncompressed.GetSize();
-    auto it = std::search(pStart, pEnd, aEmptyRegion.getStr(), aEmptyRegion.getStr() + aEmptyRegion.getLength());
-    CPPUNIT_ASSERT_EQUAL_MESSAGE("Empty clipping region detected!", it, pEnd);
+    // tdf#130150 See infos in task - short: tdf#99680 was not the
+    // correct fix, so empty clip regions are valid - allow again in tests
+    //      Make sure there are no empty clipping regions.
+    //      OString aEmptyRegion("0 0 m h W* n");
+    //      auto it = std::search(pStart, pEnd, aEmptyRegion.getStr(), aEmptyRegion.getStr() + aEmptyRegion.getLength());
+    //      CPPUNIT_ASSERT_EQUAL_MESSAGE("Empty clipping region detected!", it, pEnd);
 
     // Count save graphic state (q) and restore (Q) operators
     // and ensure their amount is equal
+    auto pStart = static_cast<const char*>(aUncompressed.GetData());
+    const char* pEnd = pStart + aUncompressed.GetSize();
     size_t nSaveCount = std::count(pStart, pEnd, 'q');
     size_t nRestoreCount = std::count(pStart, pEnd, 'Q');
     CPPUNIT_ASSERT_EQUAL_MESSAGE("Save/restore graphic state operators count mismatch!", nSaveCount, nRestoreCount);
@@ -850,15 +852,17 @@ void PdfExportTest::testTdf99680_2()
         aZCodec.Decompress(rObjectStream, aUncompressed);
         CPPUNIT_ASSERT(aZCodec.EndCompression());
 
-        // Make sure there are no empty clipping regions.
-        OString aEmptyRegion("0 0 m h W* n");
-        auto pStart = static_cast<const char*>(aUncompressed.GetData());
-        const char* pEnd = pStart + aUncompressed.GetSize();
-        auto it = std::search(pStart, pEnd, aEmptyRegion.getStr(), aEmptyRegion.getStr() + aEmptyRegion.getLength());
-        CPPUNIT_ASSERT_EQUAL_MESSAGE("Empty clipping region detected!", it, pEnd);
+        // tdf#130150 See infos in task - short: tdf#99680 was not the
+        // correct fix, so empty clip regions are valid - allow again in tests
+        //      Make sure there are no empty clipping regions.
+        //      OString aEmptyRegion("0 0 m h W* n");
+        //      auto it = std::search(pStart, pEnd, aEmptyRegion.getStr(), aEmptyRegion.getStr() + aEmptyRegion.getLength());
+        //      CPPUNIT_ASSERT_EQUAL_MESSAGE("Empty clipping region detected!", it, pEnd);
 
         // Count save graphic state (q) and restore (Q) operators
         // and ensure their amount is equal
+        auto pStart = static_cast<const char*>(aUncompressed.GetData());
+        const char* pEnd = pStart + aUncompressed.GetSize();
         size_t nSaveCount = std::count(pStart, pEnd, 'q');
         size_t nRestoreCount = std::count(pStart, pEnd, 'Q');
         CPPUNIT_ASSERT_EQUAL_MESSAGE("Save/restore graphic state operators count mismatch!", nSaveCount, nRestoreCount);
diff --git a/vcl/source/gdi/pdfwriter_impl.cxx b/vcl/source/gdi/pdfwriter_impl.cxx
index e1186fa22f32..1a5f772af2e5 100644
--- a/vcl/source/gdi/pdfwriter_impl.cxx
+++ b/vcl/source/gdi/pdfwriter_impl.cxx
@@ -9849,8 +9849,15 @@ void PDFWriterImpl::updateGraphicsState(Mode const mode)
                 if ( rNewState.m_aClipRegion.count() )
                 {
                     m_aPages.back().appendPolyPolygon( rNewState.m_aClipRegion, aLine );
-                    aLine.append( "W* n\n" );
                 }
+                else
+                {
+                    // tdf#130150 Need to revert tdf#99680, that breaks the
+                    // rule that an set but empty clip-region clips everything
+                    // aka draws nothing -> nothing is in an empty clip-region
+                    aLine.append( "0 0 m h " ); // NULL clip, i.e. nothing visible
+                }
+                aLine.append( "W* n\n" );
 
                 rNewState.m_aMapMode = aNewMapMode;
                 SetMapMode( rNewState.m_aMapMode );
@@ -9995,8 +10002,12 @@ void PDFWriterImpl::setMapMode( const MapMode& rMapMode )
 
 void PDFWriterImpl::setClipRegion( const basegfx::B2DPolyPolygon& rRegion )
 {
-    basegfx::B2DPolyPolygon aRegion = LogicToPixel( rRegion, m_aGraphicsStack.front().m_aMapMode );
-    aRegion = PixelToLogic( aRegion, m_aMapMode );
+    // tdf#130150 improve coordinate manipulations to double precision transformations
+    const basegfx::B2DHomMatrix aCurrentTransform(
+        GetInverseViewTransformation(m_aMapMode) * GetViewTransformation(m_aGraphicsStack.front().m_aMapMode));
+    basegfx::B2DPolyPolygon aRegion(rRegion);
+
+    aRegion.transform(aCurrentTransform);
     m_aGraphicsStack.front().m_aClipRegion = aRegion;
     m_aGraphicsStack.front().m_bClipRegion = true;
     m_aGraphicsStack.front().m_nUpdateFlags |= GraphicsStateUpdateFlags::ClipRegion;
@@ -10006,16 +10017,26 @@ void PDFWriterImpl::moveClipRegion( sal_Int32 nX, sal_Int32 nY )
 {
     if( m_aGraphicsStack.front().m_bClipRegion && m_aGraphicsStack.front().m_aClipRegion.count() )
     {
-        Point aPoint( lcl_convert( m_aGraphicsStack.front().m_aMapMode,
-                                   m_aMapMode,
-                                   this,
-                                   Point( nX, nY ) ) );
-        aPoint -= lcl_convert( m_aGraphicsStack.front().m_aMapMode,
-                               m_aMapMode,
-                               this,
-                               Point() );
+        // tdf#130150 improve coordinate manipulations to double precision transformations
+        basegfx::B2DHomMatrix aConvertA;
+
+        if(MapUnit::MapPixel == m_aGraphicsStack.front().m_aMapMode.GetMapUnit())
+        {
+            aConvertA = GetInverseViewTransformation(m_aMapMode);
+        }
+        else
+        {
+            aConvertA = LogicToLogic(m_aGraphicsStack.front().m_aMapMode, m_aMapMode);
+        }
+
+        basegfx::B2DPoint aB2DPointA(nX, nY);
+        basegfx::B2DPoint aB2DPointB(0.0, 0.0);
+        aB2DPointA *= aConvertA;
+        aB2DPointB *= aConvertA;
+        aB2DPointA -= aB2DPointB;
         basegfx::B2DHomMatrix aMat;
-        aMat.translate( aPoint.X(), aPoint.Y() );
+
+        aMat.translate(aB2DPointA.getX(), aB2DPointA.getY());
         m_aGraphicsStack.front().m_aClipRegion.transform( aMat );
         m_aGraphicsStack.front().m_nUpdateFlags |= GraphicsStateUpdateFlags::ClipRegion;
     }
@@ -10030,9 +10051,14 @@ void PDFWriterImpl::intersectClipRegion( const tools::Rectangle& rRect )
 
 void PDFWriterImpl::intersectClipRegion( const basegfx::B2DPolyPolygon& rRegion )
 {
-    basegfx::B2DPolyPolygon aRegion( LogicToPixel( rRegion, m_aGraphicsStack.front().m_aMapMode ) );
-    aRegion = PixelToLogic( aRegion, m_aMapMode );
+    // tdf#130150 improve coordinate manipulations to double precision transformations
+    const basegfx::B2DHomMatrix aCurrentTransform(
+        GetInverseViewTransformation(m_aMapMode) * GetViewTransformation(m_aGraphicsStack.front().m_aMapMode));
+    basegfx::B2DPolyPolygon aRegion(rRegion);
+
+    aRegion.transform(aCurrentTransform);
     m_aGraphicsStack.front().m_nUpdateFlags |= GraphicsStateUpdateFlags::ClipRegion;
+
     if( m_aGraphicsStack.front().m_bClipRegion )
     {
         basegfx::B2DPolyPolygon aOld( basegfx::utils::prepareForPolygonOperation( m_aGraphicsStack.front().m_aClipRegion ) );