From 75c97380562ad134756e47ac5895b637d7a495c7 Mon Sep 17 00:00:00 2001
From: buliabyak <buliabyak@users.sourceforge.net>
Date: Fri, 30 Jun 2006 03:54:17 +0000
Subject: [PATCH] add methods to identify scales and rotations

---
 src/libnr/nr-matrix.cpp | 20 ++++++++++++++++++++
 src/libnr/nr-matrix.h   | 10 ++++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/libnr/nr-matrix.cpp b/src/libnr/nr-matrix.cpp
index 24fa2e206..12a2f2fcb 100644
--- 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 47196137e..767c2105b 100644
--- 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;
+
 
     /**
      *
-- 
2.30.2