drawinglayer: avoid AA for hairline polygons built from hori/vert lines only

For one, it seems this was the intention already since commit
85c70f37b56299f6fa02312c0fb73cc55af084ef (CWS-TOOLING: integrate CWS
aw063, 2009-03-04): "suppress AntiAliasing for pure horizontal or
vertical lines".

For another, this fixes the TileCacheTests::testTileWireIDHandling()
testcase in online.git, which assumes that the indicators at the corners
of the Writer body frame (paragraph marks hidden / default case) can be
painted multiple times, producing pixel-by-pixel matching results. But
in reality AA breaks that assumption, and we know these indicators are
never diagonal lines.

Change-Id: Ib74f823165799991296b64cee58ec106dbdcedcf
Reviewed-on: https://gerrit.libreoffice.org/72000
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

1 files changed, 18 insertions, 0 deletions

diff --git a/basegfx/source/polygon/b2dpolypolygontools.cxx b/basegfx/source/polygon/b2dpolypolygontools.cxx
index 062e37da9dae..d537531a4600 100644
--- a/basegfx/source/polygon/b2dpolypolygontools.cxx
+++ b/basegfx/source/polygon/b2dpolypolygontools.cxx
@@ -416,6 +416,24 @@ namespace basegfx
             return aRetval;
         }
 
+        bool containsOnlyHorizontalOrVerticalLines(const basegfx::B2DPolygon& rPolygon)
+        {
+            if (rPolygon.count() <= 1)
+                return false;
+
+            for (size_t i = 1; i < rPolygon.count(); ++i)
+            {
+                const basegfx::B2DPoint& rPrevPoint = rPolygon.getB2DPoint(i - 1);
+                const basegfx::B2DPoint& rPoint = rPolygon.getB2DPoint(i);
+                if (rPrevPoint.getX() == rPoint.getX() || rPrevPoint.getY() == rPoint.getY())
+                    continue;
+
+                return false;
+            }
+
+            return true;
+        }
+
         B2DPolyPolygon createSevenSegmentPolyPolygon(sal_Char nNumber, bool bLitSegments)
         {
             // config here