draw polypolygons properly in opengl backend

The polygons that make the polypolygon cannot be simply drawn one onto another,
because if they overlap, it's actually xor (as used e.g. for drawing the border
when editing a text box Impress, which without this fix just made it a full
rectangle instead of a frame).

Change-Id: I67c7f6448fb3ee0f9742a2299c612515abff68d8

2 files changed, 28 insertions, 59 deletions

diff --git a/vcl/inc/openglgdiimpl.hxx b/vcl/inc/openglgdiimpl.hxx
index ce49e96c2123..7bb4532a3205 100644
--- a/vcl/inc/openglgdiimpl.hxx
+++ b/vcl/inc/openglgdiimpl.hxx
@@ -89,7 +89,7 @@ public:
     void DrawEdgeAA( double nX1, double nY1, double nX2, double nY2 );
     void DrawConvexPolygon( sal_uInt32 nPoints, const SalPoint* pPtAry, bool blockAA = false );
     void DrawConvexPolygon( const Polygon& rPolygon, bool blockAA = false );
-    void DrawTrapezoid( const basegfx::B2DTrapezoid& trapezoid );
+    void DrawTrapezoid( const basegfx::B2DTrapezoid& trapezoid, bool blockAA = false );
     void DrawRect( long nX, long nY, long nWidth, long nHeight );
     void DrawRect( const Rectangle& rRect );
     void DrawPolygon( sal_uInt32 nPoints, const SalPoint* pPtAry );
diff --git a/vcl/opengl/gdiimpl.cxx b/vcl/opengl/gdiimpl.cxx
index c9b7c0b3a147..50d9ec1d2ae7 100644
--- a/vcl/opengl/gdiimpl.cxx
+++ b/vcl/opengl/gdiimpl.cxx
@@ -718,7 +718,7 @@ void OpenGLSalGraphicsImpl::DrawConvexPolygon( const Polygon& rPolygon, bool blo
     }
 }
 
-void OpenGLSalGraphicsImpl::DrawTrapezoid( const basegfx::B2DTrapezoid& trapezoid )
+void OpenGLSalGraphicsImpl::DrawTrapezoid( const basegfx::B2DTrapezoid& trapezoid, bool blockAA )
 {
     const basegfx::B2DPolygon& rPolygon = trapezoid.getB2DPolygon();
     sal_uInt16 nPoints = rPolygon.count();
@@ -735,7 +735,7 @@ void OpenGLSalGraphicsImpl::DrawTrapezoid( const basegfx::B2DTrapezoid& trapezoi
     mpProgram->SetVertices( &aVertices[0] );
     glDrawArrays( GL_TRIANGLE_FAN, 0, nPoints );
 
-    if( mrParent.getAntiAliasB2DDraw())
+    if( !blockAA && mrParent.getAntiAliasB2DDraw())
     {
         // Make the edges antialiased by drawing the edge lines again with AA.
         // TODO: If transparent drawing is set up, drawing the lines themselves twice
@@ -805,56 +805,15 @@ void OpenGLSalGraphicsImpl::DrawPolygon( sal_uInt32 nPoints, const SalPoint* pPt
 
 void OpenGLSalGraphicsImpl::DrawPolyPolygon( const basegfx::B2DPolyPolygon& rPolyPolygon, bool blockAA )
 {
-    ::std::vector< GLfloat > aVertices;
-    GLfloat nWidth = GetWidth();
-    GLfloat nHeight = GetHeight();
     const ::basegfx::B2DPolyPolygon& aSimplePolyPolygon = ::basegfx::tools::solveCrossovers( rPolyPolygon );
-
-    for( sal_uInt32 i = 0; i < aSimplePolyPolygon.count(); i++ )
+    basegfx::B2DTrapezoidVector aB2DTrapVector;
+    basegfx::tools::trapezoidSubdivide( aB2DTrapVector, aSimplePolyPolygon );
+    // draw tesselation result
+    if( aB2DTrapVector.size())
     {
-        const basegfx::B2DPolygon& rPolygon( aSimplePolyPolygon.getB2DPolygon( i ) );
-        const ::basegfx::B2DPolygon& aResult(
-            ::basegfx::triangulator::triangulate( rPolygon ) );
-
-        for( sal_uInt32 j = 0; j < aResult.count(); j++ )
-        {
-            const ::basegfx::B2DPoint& rPt( aResult.getB2DPoint( j ) );
-            aVertices.push_back( 2 * rPt.getX() / nWidth - 1.0f );
-            aVertices.push_back( 1.0f - 2 * rPt.getY() / nHeight );
-        }
+        for( size_t i = 0; i < aB2DTrapVector.size(); ++i )
+            DrawTrapezoid( aB2DTrapVector[ i ], blockAA );
     }
-
-    mpProgram->SetVertices( aVertices.data() );
-    glDrawArrays( GL_TRIANGLES, 0, aVertices.size() / 2 );
-
-    if( !blockAA && mrParent.getAntiAliasB2DDraw())
-    {
-        // Make the edges antialiased by drawing the edge lines again with AA.
-        // TODO: If transparent drawing is set up, drawing the lines themselves twice
-        // may be a problem, if that is a real problem, the polygon areas itself needs to be
-        // masked out for this or something.
-#ifdef DBG_UTIL
-        assert( mProgramIsSolidColor );
-#endif
-        SalColor lastSolidColor = mProgramSolidColor;
-        double lastSolidTransparency = mProgramSolidTransparency;
-        if( UseSolidAA( lastSolidColor, lastSolidTransparency ))
-        {
-            for( sal_uInt32 i = 0; i < aSimplePolyPolygon.count(); i++ )
-            {
-                const basegfx::B2DPolygon& rPolygon( aSimplePolyPolygon.getB2DPolygon( i ) );
-                for( sal_uInt32 j = 0; j < rPolygon.count(); j++ )
-                {
-                    const ::basegfx::B2DPoint& rPt1( rPolygon.getB2DPoint( j ) );
-                    const ::basegfx::B2DPoint& rPt2( rPolygon.getB2DPoint(( j + 1 ) % rPolygon.count()) );
-                    DrawEdgeAA( rPt1.getX(), rPt1.getY(), rPt2.getX(), rPt2.getY());
-                }
-            }
-            UseSolid( lastSolidColor, lastSolidTransparency );
-        }
-    }
-
-    CHECK_GL_ERROR();
 }
 
 void OpenGLSalGraphicsImpl::DrawRegionBand( const RegionBand& rRegion )
@@ -1212,8 +1171,24 @@ void OpenGLSalGraphicsImpl::drawPolyPolygon( sal_uInt32 nPoly, const sal_uInt32*
 
     if( UseSolid( mnFillColor ) )
     {
-        for( sal_uInt32 i = 0; i < nPoly; i++ )
-            DrawPolygon( pPoints[i], pPtAry[i] );
+        if( nPoly == 1 )
+        {
+            for( sal_uInt32 i = 0; i < nPoly; i++ )
+                DrawPolygon( pPoints[i], pPtAry[i] );
+        }
+        else
+        {
+            basegfx::B2DPolyPolygon polyPolygon;
+            for( sal_uInt32 i = 0; i < nPoly; ++i )
+            {
+                basegfx::B2DPolygon polygon;
+                for( sal_uInt32 j = 0; j < pPoints[ i ]; ++j )
+                    polygon.append( basegfx::B2DPoint( pPtAry[i][j].mnX, pPtAry[i][j].mnY ) );
+                polygon.setClosed( true );
+                polyPolygon.append( polygon );
+            }
+            DrawPolyPolygon( polyPolygon );
+        }
     }
 
     if( UseSolidAA( mnLineColor ) )
@@ -1235,13 +1210,7 @@ bool OpenGLSalGraphicsImpl::drawPolyPolygon( const ::basegfx::B2DPolyPolygon& rP
     PreDraw();
 
     if( UseSolid( mnFillColor, fTransparency ) )
-    {
-        for( sal_uInt32 i = 0; i < rPolyPolygon.count(); i++ )
-        {
-            const ::basegfx::B2DPolyPolygon aOnePoly( rPolyPolygon.getB2DPolygon( i ) );
-            DrawPolyPolygon( aOnePoly );
-        }
-    }
+        DrawPolyPolygon( rPolyPolygon );
 
     PostDraw();