basegfx: add convenience access. and creator to B2DHomMatrix

In SVG, CSS, HTML Canvas it is usual to define a matrix with
a,b,c,d,e,f attributes, where the values correcpond to the
following:
[a,c,e]
[b,d,f]
[0,0,1]

This change adds accessors and creator to B2DHomMatrix, so it is
easier to deal with other matrices that are defined like that.

Change-Id: I6927513b1a70ad5eb70d7fe14a00de4a767f176a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/91310
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/include/basegfx/matrix/b2dhommatrix.hxx b/include/basegfx/matrix/b2dhommatrix.hxx
index 9f2c8a338412..0015b2a78fce 100644
--- a/include/basegfx/matrix/b2dhommatrix.hxx
+++ b/include/basegfx/matrix/b2dhommatrix.hxx
@@ -47,6 +47,33 @@ namespace basegfx
         B2DHomMatrix(B2DHomMatrix&& rMat);
         ~B2DHomMatrix();
 
+        /** Convenience creator for declaration of the matrix that is commonly
+            used by web standards (SVG, CSS, HTML).
+
+           Values a,b,c,d,e,f represent the following values in the matrix:
+              [a,c,e]      [a,c,e]
+              [b,d,f]  or  [b,d,f]
+                           [0,0,1]
+
+        */
+        static B2DHomMatrix abcdef(double da, double db, double dc, double dd, double de, double df)
+        {
+            return B2DHomMatrix(da, dc, de, db, dd, df);
+        }
+
+        // Convenience accessor for value at 0,0 position in the matrix
+        double a() { return get(0,0); }
+        // Convenience accessor for value at 1,0 position in the matrix
+        double b() { return get(1,0); }
+        // Convenience accessor for value at 0,1 position in the matrix
+        double c() { return get(0,1); }
+        // Convenience accessor for value at 1,1 position in the matrix
+        double d() { return get(1,1); }
+        // Convenience accessor for value at 0,2 position in the matrix
+        double e() { return get(0,2); }
+        // Convenience accessor for value at 1,2 position in the matrix
+        double f() { return get(1,2); }
+
         /** constructor to allow setting all needed values for a 3x2 matrix at once. The
             parameter f_0x1 e.g. is the same as using set(0, 1, f)
          */