improved B2DHomMatrix

since we know that this is a matrix only used for 2D transforms,
we know that the last row of the matrix is always { 0, 0, 1 }.

Therefore, we don't need to store that information, and
we can simplify some of the computations.

Also remove operations like operator+ which are not legal for
such a matrix.

Change-Id: I482de9a45ebbedf79e3b6033575aab590e61c2d5
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/151909
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 7 insertions, 6 deletions

diff --git a/chart2/source/tools/CommonConverters.cxx b/chart2/source/tools/CommonConverters.cxx
index 50b08397e1d4..293fa7b11ddf 100644
--- a/chart2/source/tools/CommonConverters.cxx
+++ b/chart2/source/tools/CommonConverters.cxx
@@ -92,9 +92,10 @@ drawing::HomogenMatrix B3DHomMatrixToHomogenMatrix( const ::basegfx::B3DHomMatri
     aM.set(1, 0, rM.get(1, 0));
     aM.set(1, 1, rM.get(1, 1));
     aM.set(1, 2, rM.get(1, 3));
-    aM.set(2, 0, rM.get(3, 0));
-    aM.set(2, 1, rM.get(3, 1));
-    aM.set(2, 2, rM.get(3, 3));
+    // For this to be a valid 2D transform matrix, the last row must be [0,0,1]
+    assert( rM.get(3, 0) == 0 );
+    assert( rM.get(3, 1) == 0 );
+    assert( rM.get(3, 3) == 1 );
     return aM;
 }
 
@@ -107,9 +108,9 @@ drawing::HomogenMatrix3 B2DHomMatrixToHomogenMatrix3( const ::basegfx::B2DHomMat
     aHM.Line2.Column1 = rM.get(1, 0);
     aHM.Line2.Column2 = rM.get(1, 1);
     aHM.Line2.Column3 = rM.get(1, 2);
-    aHM.Line3.Column1 = rM.get(2, 0);
-    aHM.Line3.Column2 = rM.get(2, 1);
-    aHM.Line3.Column3 = rM.get(2, 2);
+    aHM.Line3.Column1 = 0;
+    aHM.Line3.Column2 = 0;
+    aHM.Line3.Column3 = 1;
     return aHM;
 }