add methods to identify scales and rotations

diff --git a/src/libnr/nr-matrix.cpp b/src/libnr/nr-matrix.cpp
index 24fa2e2064f291967d08c685de9419b2dbb4caf5..12a2f2fcbd7e8f75f3e584ce0f8ac17d8761b8a5 100644 (file)
--- a/src/libnr/nr-matrix.cpp
+++ b/src/libnr/nr-matrix.cpp
@@ -522,6 +522,26 @@ bool Matrix::is_translation(Coord const eps) const {
 }
 
 
+/**
+ *
+ */
+bool Matrix::is_scale(Coord const eps) const {
+    return ( (fabs(_c[0] - 1.0) > eps || fabs(_c[3] - 1.0) > eps) &&
+             fabs(_c[1])       < eps &&
+             fabs(_c[2])       < eps   );
+}
+
+
+/**
+ *
+ */
+bool Matrix::is_rotation(Coord const eps) const {
+    return ( fabs(_c[1]) > eps &&
+             fabs(_c[2]) > eps &&
+             fabs(_c[1] + _c[2]) < 2 * eps);
+}
+
+
 
 
 

diff --git a/src/libnr/nr-matrix.h b/src/libnr/nr-matrix.h
index 47196137ea0838685b77bb9a106b871cc50ce8a9..767c2105b40ccba9569c90b2262b61efffe353ae 100644 (file)
--- a/src/libnr/nr-matrix.h
+++ b/src/libnr/nr-matrix.h
@@ -248,6 +248,16 @@ class Matrix {
      */
     bool is_translation(Coord const eps = 1e-6) const;
 
+    /**
+     *
+     */
+    bool is_scale(Coord const eps = 1e-6) const;
+
+    /**
+     *
+     */
+    bool is_rotation(Coord const eps = 1e-6) const;
+
 
     /**
      *