Support buffering SystemDependent GraphicData (III)

This change is for speedup of fat line drawing when using
X11. This is a long-term problem which never really progressed,
but is avoided using Cairo in the future. Still - if used,
speedup using current state and buffering possibilities.

Two speedup steps will be used:
(1) The tesselation is no longer done using trapezoids. That
works (but was done wrong leaving artifacts) but is not fast
and done every time. It is even not done with FatLines and
more than 1000 points.
New version will use triangulation. Dspite using the existing
triangulator (that works but is slow) extend the FatLine
geometry creator to directly create triangles.
This is also necessary since for buffering that data a
transformation-invariant version is needed (in device coordinates
the data changes all the time when scrolling). Trapezoids are
by definition *not* transformation-invariant (e.g. rotation)

(2) Buffer that triangulation - with the needed care and watch.
It is e.g. necessary to react on 'hairlines' since these change
their logical LineWidth view-dependent (zoom). In those cases, the
buffered data *has* to be removed due to the base for buffering is
the created FatLine geometry based on one stable logical LineWidth

Also took the time to adapt B2DPolygonTriangulator to use an
own data type (B2DTriangle) and a vector of these for better
understandability and security. Adapted all usages as needed.

Change-Id: Iedb2932b094a8786fd9c32d0d0ab1ca603a1a7b2
Reviewed-on: https://gerrit.libreoffice.org/60818
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@cib.de>

4 files changed, 225 insertions, 76 deletions

diff --git a/vcl/unx/generic/gdi/gdiimpl.cxx b/vcl/unx/generic/gdi/gdiimpl.cxx
index a5fcf86cd3a7..8b0742b4ec68 100644
--- a/vcl/unx/generic/gdi/gdiimpl.cxx
+++ b/vcl/unx/generic/gdi/gdiimpl.cxx
@@ -50,6 +50,7 @@
 #include <basegfx/matrix/b2dhommatrixtools.hxx>
 #include <basegfx/polygon/b2dpolypolygoncutter.hxx>
 #include <basegfx/polygon/b2dtrapezoid.hxx>
+#include <basegfx/utils/systemdependentdata.hxx>
 #include <ControlCacheKey.hxx>
 
 #undef SALGDI2_TESTTRANS
@@ -1569,6 +1570,110 @@ bool X11SalGraphicsImpl::drawFilledTrapezoids( const basegfx::B2DTrapezoid* pB2D
     return true;
 }
 
+bool X11SalGraphicsImpl::drawFilledTriangles(
+    const basegfx::B2DHomMatrix& rObjectToDevice,
+     const basegfx::triangulator::B2DTriangleVector& rTriangles,
+     double fTransparency,
+     bool bPixelOffset)
+{
+    if(rTriangles.empty())
+        return true;
+
+    Picture aDstPic = GetXRenderPicture();
+    // check xrender support for this drawable
+    if( !aDstPic )
+    {
+        return false;
+    }
+
+    // prepare transformation for ObjectToDevice coordinate system
+    basegfx::B2DHomMatrix aObjectToDevice(rObjectToDevice);
+
+    if(bPixelOffset)
+    {
+        aObjectToDevice = basegfx::utils::createTranslateB2DHomMatrix(0.5, 0.5) * aObjectToDevice;
+    }
+
+     // convert the Triangles into XRender-Triangles
+    std::vector<XTriangle> aTriVector(rTriangles.size());
+    sal_uInt32 nIndex(0);
+
+    for(const auto& rCandidate : rTriangles)
+    {
+        const basegfx::B2DPoint aP1(aObjectToDevice * rCandidate.getA());
+        const basegfx::B2DPoint aP2(aObjectToDevice * rCandidate.getB());
+        const basegfx::B2DPoint aP3(aObjectToDevice * rCandidate.getC());
+        XTriangle& rTri(aTriVector[nIndex++]);
+
+        rTri.p1.x = XDoubleToFixed(aP1.getX());
+        rTri.p1.y = XDoubleToFixed(aP1.getY());
+
+        rTri.p2.x = XDoubleToFixed(aP2.getX());
+        rTri.p2.y = XDoubleToFixed(aP2.getY());
+
+        rTri.p3.x = XDoubleToFixed(aP3.getX());
+        rTri.p3.y = XDoubleToFixed(aP3.getY());
+    }
+
+    // get xrender Picture for polygon foreground
+    // TODO: cache it like the target picture which uses GetXRenderPicture()
+    XRenderPeer& rRenderPeer = XRenderPeer::GetInstance();
+    SalDisplay::RenderEntry& rEntry = mrParent.GetDisplay()->GetRenderEntries( mrParent.m_nXScreen )[ 32 ];
+    if( !rEntry.m_aPicture )
+    {
+        Display* pXDisplay = mrParent.GetXDisplay();
+
+        rEntry.m_aPixmap = limitXCreatePixmap( pXDisplay, mrParent.hDrawable_, 1, 1, 32 );
+        XRenderPictureAttributes aAttr;
+        aAttr.repeat = int(true);
+
+        XRenderPictFormat* pXRPF = rRenderPeer.FindStandardFormat( PictStandardARGB32 );
+        rEntry.m_aPicture = rRenderPeer.CreatePicture( rEntry.m_aPixmap, pXRPF, CPRepeat, &aAttr );
+    }
+
+    // set polygon foreground color and opacity
+    XRenderColor aRenderColor = GetXRenderColor( mnBrushColor , fTransparency );
+    rRenderPeer.FillRectangle( PictOpSrc, rEntry.m_aPicture, &aRenderColor, 0, 0, 1, 1 );
+
+    // set clipping
+    // TODO: move into GetXRenderPicture?
+    if( mrParent.mpClipRegion && !XEmptyRegion( mrParent.mpClipRegion ) )
+        rRenderPeer.SetPictureClipRegion( aDstPic, mrParent.mpClipRegion );
+
+    // render the trapezoids
+    const XRenderPictFormat* pMaskFormat = rRenderPeer.GetStandardFormatA8();
+    rRenderPeer.CompositeTriangles( PictOpOver,
+        rEntry.m_aPicture, aDstPic, pMaskFormat, 0, 0, &aTriVector[0], aTriVector.size() );
+
+    return true;
+}
+
+class SystemDependentData_Triangulation : public basegfx::SystemDependentData
+{
+private:
+    basegfx::triangulator::B2DTriangleVector    maTriangles;
+    basegfx::B2DVector                          maLineWidth;
+
+public:
+    SystemDependentData_Triangulation(
+        basegfx::SystemDependentDataManager& rSystemDependentDataManager,
+        const basegfx::triangulator::B2DTriangleVector& rTriangles,
+        const basegfx::B2DVector& rLineWidth);
+
+    const basegfx::triangulator::B2DTriangleVector& getTriangles() const { return maTriangles; }
+    const basegfx::B2DVector& getLineWidth() const { return maLineWidth; }
+};
+
+SystemDependentData_Triangulation::SystemDependentData_Triangulation(
+    basegfx::SystemDependentDataManager& rSystemDependentDataManager,
+    const basegfx::triangulator::B2DTriangleVector& rTriangles,
+    const basegfx::B2DVector& rLineWidth)
+:   basegfx::SystemDependentData(rSystemDependentDataManager),
+    maTriangles(rTriangles),
+    maLineWidth(rLineWidth)
+{
+}
+
 bool X11SalGraphicsImpl::drawPolyLine(
     const basegfx::B2DHomMatrix& rObjectToDevice,
     const basegfx::B2DPolygon& rPolygon,
@@ -1579,96 +1684,121 @@ bool X11SalGraphicsImpl::drawPolyLine(
     double fMiterMinimumAngle,
     bool bPixelSnapHairline)
 {
-    // Transform to DeviceCoordinates, get DeviceLineWidth, execute PixelSnapHairline
-    const basegfx::B2DVector aLineWidth(rObjectToDevice * rLineWidth);
-    const bool bIsHairline((aLineWidth.getX() == aLineWidth.getY()) && (aLineWidth.getX() <= 1.2));
-
-    // #i101491#
-    if( !bIsHairline && (rPolygon.count() > 1000) )
+    // short circuit if there is nothing to do
+    if(0 == rPolygon.count() || fTransparency < 0.0 || fTransparency >= 1.0)
     {
-        // the used basegfx::utils::createAreaGeometry is simply too
-        // expensive with very big polygons; fallback to caller (who
-        // should use ImplLineConverter normally)
-        // AW: ImplLineConverter had to be removed since it does not even
-        // know LineJoins, so the fallback will now prepare the line geometry
-        // the same way.
-        return false;
+        return true;
     }
 
-    // Transform to DeviceCoordinates, get DeviceLineWidth, execute PixelSnapHairline
-    basegfx::B2DPolygon aPolyLine(rPolygon);
-    aPolyLine.transform(rObjectToDevice);
-    if(bPixelSnapHairline) { aPolyLine = basegfx::utils::snapPointsOfHorizontalOrVerticalEdges(aPolyLine); }
+    // need to check/handle LineWidth when ObjectToDevice transformation is used
+    basegfx::B2DVector aLineWidth(rLineWidth);
+    const bool bObjectToDeviceIsIdentity(rObjectToDevice.isIdentity());
+    const basegfx::B2DVector aDeviceLineWidths(bObjectToDeviceIsIdentity ? rLineWidth : rObjectToDevice * rLineWidth);
+    const bool bCorrectLineWidth(!bObjectToDeviceIsIdentity && aDeviceLineWidths.getX() < 1.0 && aLineWidth.getX() >= 1.0);
+    basegfx::B2DHomMatrix aObjectToDeviceInv;
+    basegfx::B2DPolygon aPolygon(rPolygon);
 
-    // temporarily adjust brush color to pen color
-    // since the line is drawn as an area-polygon
-    const Color aKeepBrushColor = mnBrushColor;
-    mnBrushColor = mnPenColor;
+    if(bCorrectLineWidth)
+    {
+        if(aObjectToDeviceInv.isIdentity())
+        {
+            aObjectToDeviceInv = rObjectToDevice;
+            aObjectToDeviceInv.invert();
+        }
 
-    // #i11575#desc5#b adjust B2D tessellation result to raster positions
-    // basegfx::B2DPolygon aPolygon = rPolygon;
-    const double fHalfWidth = 0.5 * aLineWidth.getX();
+        // calculate-back logical LineWidth for a hairline
+        aLineWidth = aObjectToDeviceInv * basegfx::B2DVector(1.0, 1.0);
+    }
 
-    // #i122456# This is probably thought to happen to align hairlines to pixel positions, so
-    // it should be a 0.5 translation, not more. It will definitely go wrong with fat lines
-    aPolyLine.transform( basegfx::utils::createTranslateB2DHomMatrix(0.5, 0.5) );
+    // try to access buffered data
+    std::shared_ptr<SystemDependentData_Triangulation> pSystemDependentData_Triangulation(
+        rPolygon.getSystemDependentData<SystemDependentData_Triangulation>());
 
-    // shortcut for hairline drawing to improve performance
-    bool bDrawnOk = true;
-    if( bIsHairline )
+    if(pSystemDependentData_Triangulation)
     {
-        // hairlines can benefit from a simplified tessellation
-        // e.g. for hairlines the linejoin style can be ignored
-        basegfx::B2DTrapezoidVector aB2DTrapVector;
-        basegfx::utils::createLineTrapezoidFromB2DPolygon( aB2DTrapVector, aPolyLine, aLineWidth.getX() );
-
-        // draw tessellation result
-        const int nTrapCount = aB2DTrapVector.size();
-        if( nTrapCount > 0 )
-            bDrawnOk = drawFilledTrapezoids( &aB2DTrapVector[0], nTrapCount, fTransparency );
-
-        // restore the original brush GC
-        mnBrushColor = aKeepBrushColor;
-        return bDrawnOk;
+        // check data validity
+        if(pSystemDependentData_Triangulation->getLineWidth() != aLineWidth)
+        {
+            // sometimes small inconsistencies, use a percentage tolerance
+            const double fFactorX(basegfx::fTools::equalZero(aLineWidth.getX())
+                ? 0.0
+                : fabs(1.0 - (pSystemDependentData_Triangulation->getLineWidth().getX() / aLineWidth.getX())));
+            const double fFactorY(basegfx::fTools::equalZero(aLineWidth.getY())
+                ? 0.0
+                : fabs(1.0 - (pSystemDependentData_Triangulation->getLineWidth().getY() / aLineWidth.getY())));
+
+            // compare with 5.0% tolerance
+            if(basegfx::fTools::more(fFactorX, 0.05) || basegfx::fTools::more(fFactorY, 0.05))
+            {
+                // data invalid, forget
+                pSystemDependentData_Triangulation.reset();
+            }
+        }
     }
 
-    // get the area polygon for the line polygon
-    if( (aLineWidth.getX() != aLineWidth.getY()) && !basegfx::fTools::equalZero( aLineWidth.getY() ) )
+    if(!pSystemDependentData_Triangulation)
     {
-        // prepare for createAreaGeometry() with anisotropic linewidth
-        aPolyLine.transform( basegfx::utils::createScaleB2DHomMatrix(1.0, aLineWidth.getX() / aLineWidth.getY()));
-    }
+        // try to create data
+        if(bPixelSnapHairline)
+        {
+            if(!bObjectToDeviceIsIdentity)
+            {
+                aPolygon.transform(rObjectToDevice);
+            }
 
-    // create the area-polygon for the line
-    const basegfx::B2DPolyPolygon aAreaPolyPoly(
-        basegfx::utils::createAreaGeometry(
-            aPolyLine,
-            fHalfWidth,
-            eLineJoin,
-            eLineCap,
-            fMiterMinimumAngle));
+            aPolygon = basegfx::utils::snapPointsOfHorizontalOrVerticalEdges(aPolygon);
 
-    if( (aLineWidth.getX() != aLineWidth.getY()) && !basegfx::fTools::equalZero( aLineWidth.getX() ) )
-    {
-        // postprocess createAreaGeometry() for anisotropic linewidth
-        aPolyLine.transform(basegfx::utils::createScaleB2DHomMatrix(1.0, aLineWidth.getY() / aLineWidth.getX()));
+            if(!bObjectToDeviceIsIdentity)
+            {
+                if(aObjectToDeviceInv.isIdentity())
+                {
+                    aObjectToDeviceInv = rObjectToDevice;
+                    aObjectToDeviceInv.invert();
+                }
+
+                aPolygon.transform(aObjectToDeviceInv);
+            }
+        }
+
+        basegfx::triangulator::B2DTriangleVector aTriangles;
+        const basegfx::B2DPolyPolygon aAreaPolyPoly(
+            basegfx::utils::createAreaGeometry(
+                aPolygon,
+                0.5 * aLineWidth.getX(),
+                eLineJoin,
+                eLineCap,
+                basegfx::deg2rad(12.5),
+                0.4,
+                fMiterMinimumAngle,
+                &aTriangles));
+
+        if(!aTriangles.empty())
+        {
+            // add to buffering mechanism
+            pSystemDependentData_Triangulation = rPolygon.addOrReplaceSystemDependentData<SystemDependentData_Triangulation>(
+                ImplGetSystemDependentDataManager(),
+                aTriangles,
+                aLineWidth);
+        }
     }
 
-    // draw each area polypolygon component individually
-    // to emulate the polypolygon winding rule "non-zero"
-    const int nPolyCount = aAreaPolyPoly.count();
-    for( int nPolyIdx = 0; nPolyIdx < nPolyCount; ++nPolyIdx )
+    if(!pSystemDependentData_Triangulation)
     {
-        const basegfx::B2DPolyPolygon aOnePoly( aAreaPolyPoly.getB2DPolygon( nPolyIdx ) );
+        return false;
+    }
 
-        bDrawnOk = drawPolyPolygon(
-            basegfx::B2DHomMatrix(),
-            aOnePoly,
-            fTransparency);
+    // temporarily adjust brush color to pen color
+    // since the line is drawn as an area-polygon
+    const Color aKeepBrushColor = mnBrushColor;
+    mnBrushColor = mnPenColor;
 
-        if( !bDrawnOk )
-            break;
-    }
+    // create the area-polygon for the line
+    const bool bDrawnOk(
+        drawFilledTriangles(
+            rObjectToDevice,
+            pSystemDependentData_Triangulation->getTriangles(),
+            fTransparency,
+            true));
 
     // restore the original brush GC
     mnBrushColor = aKeepBrushColor;
diff --git a/vcl/unx/generic/gdi/gdiimpl.hxx b/vcl/unx/generic/gdi/gdiimpl.hxx
index ac80ec6f0c40..db13696c4ffc 100644
--- a/vcl/unx/generic/gdi/gdiimpl.hxx
+++ b/vcl/unx/generic/gdi/gdiimpl.hxx
@@ -30,6 +30,7 @@
 #include <salgdiimpl.hxx>
 
 #include <basegfx/polygon/b2dtrapezoid.hxx>
+#include <basegfx/polygon/b2dpolygontriangulator.hxx>
 #include <ControlCacheKey.hxx>
 
 /* From <X11/Intrinsic.h> */
@@ -93,6 +94,11 @@ private:
 
     XID GetXRenderPicture();
     bool drawFilledTrapezoids( const basegfx::B2DTrapezoid*, int nTrapCount, double fTransparency );
+    bool drawFilledTriangles(
+        const basegfx::B2DHomMatrix& rObjectToDevice,
+        const basegfx::triangulator::B2DTriangleVector& rTriangles,
+        double fTransparency,
+        bool bPixelOffset);
 
     long GetGraphicsHeight() const;
 
diff --git a/vcl/unx/generic/gdi/salgdi.cxx b/vcl/unx/generic/gdi/salgdi.cxx
index 632d08d1a35b..fd82c3929c88 100644
--- a/vcl/unx/generic/gdi/salgdi.cxx
+++ b/vcl/unx/generic/gdi/salgdi.cxx
@@ -604,9 +604,10 @@ bool X11SalGraphics::drawPolyPolygon(
         return true;
     }
 
-    static bool bUseCairoForPolygons = false;
+    // enable by setting to something
+    static const char* pUseCairoForPolygons(getenv("SAL_ENABLE_USE_CAIRO_FOR_POLYGONS"));
 
-    if (!m_bOpenGL && bUseCairoForPolygons && SupportsCairo())
+    if (!m_bOpenGL && nullptr != pUseCairoForPolygons && SupportsCairo())
     {
         // snap to raster if requested
         const bool bSnapPoints(!getAntiAliasB2DDraw());
@@ -724,9 +725,10 @@ bool X11SalGraphics::drawPolyLine(
     }
 
 #if ENABLE_CAIRO_CANVAS
-    static bool bUseCairoForFatLines = true;
+    // disable by setting to something
+    static const char* pUseCairoForFatLines(getenv("SAL_DISABLE_USE_CAIRO_FOR_FATLINES"));
 
-    if (!m_bOpenGL && bUseCairoForFatLines && SupportsCairo())
+    if (!m_bOpenGL && nullptr == pUseCairoForFatLines && SupportsCairo())
     {
         cairo_t* cr = getCairoContext();
         clipRegion(cr);
diff --git a/vcl/unx/generic/gdi/xrender_peer.hxx b/vcl/unx/generic/gdi/xrender_peer.hxx
index 492924889595..afe793b248da 100644
--- a/vcl/unx/generic/gdi/xrender_peer.hxx
+++ b/vcl/unx/generic/gdi/xrender_peer.hxx
@@ -62,6 +62,9 @@ public:
     void        CompositeTrapezoids( int nOp, Picture aSrc, Picture aDst,
                     const XRenderPictFormat*, int nXSrc, int nYSrc,
                     const XTrapezoid*, int nCount ) const;
+    void        CompositeTriangles( int nOp, Picture aSrc, Picture aDst,
+                    const XRenderPictFormat*, int nXSrc, int nYSrc,
+                    const XTriangle*, int nCount ) const;
 };
 
 inline XRenderPictFormat* XRenderPeer::GetStandardFormatA8() const
@@ -127,6 +130,14 @@ inline void XRenderPeer::CompositeTrapezoids( int nOp,
         nXSrc, nYSrc, pXT, nCount );
 }
 
+inline void XRenderPeer::CompositeTriangles( int nOp,
+    Picture aSrc, Picture aDst, const XRenderPictFormat* pXRPF,
+    int nXSrc, int nYSrc, const XTriangle* pXT, int nCount ) const
+{
+    XRenderCompositeTriangles( mpDisplay, nOp, aSrc, aDst, pXRPF,
+        nXSrc, nYSrc, pXT, nCount );
+}
+
 inline XRenderColor GetXRenderColor( Color rColor, double fTransparency )
 {
     XRenderColor aRetVal;