Reorganize FrameBorderPrimitive creation (II)

Step5: Move the view-dependent decomposition from
BorderLinePrimitive2D to SdrFrameBorderPrimitive2D.

It is now possible to use discrete sizes before the
line and edge matching is done what will look much
better. When it was done at BorderLinePrimitive2D
and the matching was already done, that match was
'displaced' with the adapted forced scale to discrete
units.

The space and size used when zooming out for a single
discrete unit (pixel) can heavily vary - it just covers
a much larger logical area than the 'real' line/poly
would do. All this needs to be handled (also for bound
ranges) and can only be in a good way using primitives.

Adapted to no longer do view-dependent changes in
BorderLinePrimitive2D. Adapted to do these now at
SdrFrameBorderPrimitive2D. Currently used to force
the existing border partial lines (up to three) to
not get taller than one logical unit.

Adapted to no longer switch off AntiAliased rendering
in VclPixelProcessor2D for processBorderLinePrimitive2D,
this is problematic with various renderers on various
systems (e.g. vcl still falls back to render multiple
one-pixel-lines when taller than 3.5 pixels which looks
horrible combined with other parts like filled polygons)

All this needs fine balancing on
- all systems
- all renderers
- all apps (which all have their own table implementation)
- all render targets (pixel/PDF/print/slideshow/...)

Done as thorough as possible, but may need additional
finetuning. May also be a motivation to move away from
vcl and implement these urgetly needed system-dependent
primitive renderers...

Adapted UnitTest testDoublePixelProcessing with the needed
comments.

Change-Id: Ie88bb76c2474b6ab3764d45a9cd1669264492acd
Reviewed-on: https://gerrit.libreoffice.org/62344
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@cib.de>

2 files changed, 25 insertions, 84 deletions

diff --git a/drawinglayer/source/primitive2d/borderlineprimitive2d.cxx b/drawinglayer/source/primitive2d/borderlineprimitive2d.cxx
index 4c7bf9743628..e23a48921dc6 100644
--- a/drawinglayer/source/primitive2d/borderlineprimitive2d.cxx
+++ b/drawinglayer/source/primitive2d/borderlineprimitive2d.cxx
@@ -76,18 +76,6 @@ namespace drawinglayer
                 && isGap() == rBorderLine.isGap();
         }
 
-        double BorderLine::getAdaptedWidth(double fMinWidth) const
-        {
-            if(isGap())
-            {
-                return std::max(getLineAttribute().getWidth(), fMinWidth);
-            }
-            else
-            {
-                return getLineAttribute().getWidth();
-            }
-        }
-
         // helper to add a centered, maybe stroked line primitive to rContainer
         static void addPolygonStrokePrimitive2D(
             Primitive2DContainer& rContainer,
@@ -124,7 +112,7 @@ namespace drawinglayer
 
             for(const auto& candidate : maBorderLines)
             {
-                fRetval += candidate.getAdaptedWidth(mfSmallestAllowedDiscreteGapDistance);
+                fRetval += candidate.getLineAttribute().getWidth();
             }
 
             return fRetval;
@@ -143,7 +131,7 @@ namespace drawinglayer
 
                 for(const auto& candidate : maBorderLines)
                 {
-                    const double fWidth(candidate.getAdaptedWidth(mfSmallestAllowedDiscreteGapDistance));
+                    const double fWidth(candidate.getLineAttribute().getWidth());
 
                     if(!candidate.isGap())
                     {
@@ -289,8 +277,7 @@ namespace drawinglayer
             maStart(rStart),
             maEnd(rEnd),
             maBorderLines(rBorderLines),
-            maStrokeAttribute(rStrokeAttribute),
-            mfSmallestAllowedDiscreteGapDistance(0.0)
+            maStrokeAttribute(rStrokeAttribute)
         {
         }
 
@@ -320,71 +307,6 @@ namespace drawinglayer
             return false;
         }
 
-        bool BorderLinePrimitive2D::getSmallestGap(double& rfSmallestGap) const
-        {
-            bool bGapFound(false);
-
-            for(const auto& candidate : maBorderLines)
-            {
-                if(candidate.isGap())
-                {
-                    if(bGapFound)
-                    {
-                        rfSmallestGap = std::min(rfSmallestGap, candidate.getLineAttribute().getWidth());
-                    }
-                    else
-                    {
-                        bGapFound = true;
-                        rfSmallestGap = candidate.getLineAttribute().getWidth();
-                    }
-                }
-            }
-
-            return bGapFound;
-        }
-
-        void BorderLinePrimitive2D::get2DDecomposition(Primitive2DDecompositionVisitor& rVisitor, const geometry::ViewInformation2D& rViewInformation) const
-        {
-            ::osl::MutexGuard aGuard(m_aMutex);
-
-            if (!getStart().equal(getEnd()) && getBorderLines().size() > 1)
-            {
-                // Line with potential gap. In this case, we want to be view-dependent.
-                // get the smallest gap
-                double fSmallestGap(0.0);
-
-                if(getSmallestGap(fSmallestGap))
-                {
-                    // Get the current DiscreteUnit, look at X and Y and use the maximum
-                    const basegfx::B2DVector aDiscreteVector(rViewInformation.getInverseObjectToViewTransformation() * basegfx::B2DVector(1.0, 1.0));
-                    const double fDiscreteUnit(std::min(fabs(aDiscreteVector.getX()), fabs(aDiscreteVector.getY())));
-
-                    // When discrete unit is bigger than distance (distance is less than one pixel),
-                    // force distance to one pixel. Or expressed different, do not let the distance
-                    // get smaller than one pixel. This is done for screen rendering and compatibility.
-                    // This can also be done using DiscreteMetricDependentPrimitive2D as base class
-                    // for this class, but specialization is better here for later buffering (only
-                    // do this when 'double line with gap')
-                    const double fNewDiscreteDistance(std::max(fDiscreteUnit, fSmallestGap));
-
-                    if (!rtl::math::approxEqual(fNewDiscreteDistance, mfSmallestAllowedDiscreteGapDistance))
-                    {
-                        if (!getBuffered2DDecomposition().empty())
-                        {
-                            // conditions of last local decomposition have changed, delete
-                            const_cast< BorderLinePrimitive2D* >(this)->setBuffered2DDecomposition(Primitive2DContainer());
-                        }
-
-                        // remember value for usage in create2DDecomposition
-                        const_cast< BorderLinePrimitive2D* >(this)->mfSmallestAllowedDiscreteGapDistance = fNewDiscreteDistance;
-                    }
-                }
-            }
-
-            // call base implementation
-            BufferedDecompositionPrimitive2D::get2DDecomposition(rVisitor, rViewInformation);
-        }
-
         // provide unique ID
         ImplPrimitive2DIDBlock(BorderLinePrimitive2D, PRIMITIVE2D_ID_BORDERLINEPRIMITIVE2D)
 
diff --git a/drawinglayer/source/processor2d/vclpixelprocessor2d.cxx b/drawinglayer/source/processor2d/vclpixelprocessor2d.cxx
index 4a891166f295..ad70cec45135 100644
--- a/drawinglayer/source/processor2d/vclpixelprocessor2d.cxx
+++ b/drawinglayer/source/processor2d/vclpixelprocessor2d.cxx
@@ -879,17 +879,36 @@ namespace drawinglayer
 
         void VclPixelProcessor2D::processBorderLinePrimitive2D(const drawinglayer::primitive2d::BorderLinePrimitive2D& rBorder)
         {
-            // process recursively, but switch off AntiAliasing for
+            // Process recursively, but switch off AntiAliasing for
             // horizontal/vertical lines (*not* diagonal lines).
             // Checked using AntialiasingFlags::PixelSnapHairline instead,
             // but with AntiAliasing on the display really is too 'ghosty' when
             // using fine stroking. Correct, but 'ghosty'.
 
-            if (rBorder.isHorizontalOrVertical(getViewInformation2D()))
+            // It has shown that there are quite some problems here:
+            // - vcl OutDev renderer methods stuill use fallbacks to paint
+            //   multiple single lines between discrete sizes of < 3.5 what
+            //   looks bad and does not matzch
+            // - mix of filled Polygons and Lines is bad when AA switched off
+            // - Alignment of AA with non-AA may be bad in diverse different
+            //   renderers
+            //
+            // Due to these reasons I change the strategy: Always draw AAed, but
+            // allow fallback to test/check and if needed. The normal case
+            // where BorderLines will be system-depenently snapped to have at
+            // least a single discrete width per partial line (there may be up to
+            // three) works well nowadays due to most renderers moving the AA stuff
+            // by 0.5 pixels (discrete units) to match well with the non-AAed parts.
+            //
+            // Env-Switch for steering this, default is off.
+            // Enable by setting at all (and to something)
+            static const char* pSwitchOffAntiAliasingForHorVerBorderlines(getenv("SAL_SWITCH_OFF_ANTIALIASING_FOR_HOR_VER_BORTDERLINES"));
+            static bool bSwitchOffAntiAliasingForHorVerBorderlines(nullptr != pSwitchOffAntiAliasingForHorVerBorderlines);
+
+            if (bSwitchOffAntiAliasingForHorVerBorderlines && rBorder.isHorizontalOrVertical(getViewInformation2D()))
             {
                 AntialiasingFlags nAntiAliasing = mpOutputDevice->GetAntialiasing();
                 mpOutputDevice->SetAntialiasing(nAntiAliasing & ~AntialiasingFlags::EnableB2dDraw);
-
                 process(rBorder);
                 mpOutputDevice->SetAntialiasing(nAntiAliasing);
             }