moving trunk for module inkscape

(bzr r1)

1 files changed, 66 insertions, 0 deletions

diff --git a/src/libnr/nr-rotate-fns.cpp b/src/libnr/nr-rotate-fns.cpp
new file mode 100644
index 000000000..f2669c20c
--- /dev/null
+++ b/src/libnr/nr-rotate-fns.cpp
@@ -0,0 +1,66 @@
+/** \file
+ * Functions to/from NR::rotate.
+ */
+#include <glib.h>
+#include "libnr/nr-rotate-ops.h"
+#include "libnr/nr-rotate-fns.h"
+
+/**
+ * Returns a rotation matrix corresponding by the specified angle about the origin.
+ *
+ * Angle direction in Inkscape code: If you use the traditional mathematics convention that y
+ * increases upwards, then positive angles are anticlockwise as per the mathematics convention.  If
+ * you take the common non-mathematical convention that y increases downwards, then positive angles
+ * are clockwise, as is common outside of mathematics.
+ */
+NR::rotate
+rotate_degrees(double degrees)
+{
+    if (degrees < 0) {
+        return rotate_degrees(-degrees).inverse();
+    }
+
+    double const degrees0 = degrees;
+    if (degrees >= 360) {
+        degrees = fmod(degrees, 360);
+    }
+
+    NR::rotate ret(1., 0.);
+
+    if (degrees >= 180) {
+        NR::rotate const rot180(-1., 0.);
+        degrees -= 180;
+        ret = rot180;
+    }
+
+    if (degrees >= 90) {
+        NR::rotate const rot90(0., 1.);
+        degrees -= 90;
+        ret *= rot90;
+    }
+
+    if (degrees == 45) {
+        NR::rotate const rot45(M_SQRT1_2, M_SQRT1_2);
+        ret *= rot45;
+    } else {
+        double const radians = M_PI * ( degrees / 180 );
+        ret *= NR::rotate(cos(radians), sin(radians));
+    }
+
+    NR::rotate const raw_ret( M_PI * ( degrees0 / 180 ) );
+    g_return_val_if_fail(rotate_equalp(ret, raw_ret, 1e-8),
+                         raw_ret);
+    return ret;
+}
+
+
+/*
+  Local Variables:
+  mode:c++
+  c-file-style:"stroustrup"
+  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+  indent-tabs-mode:nil
+  fill-column:99
+  End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :