Resolves: #i120596# Optimized grid primitive

added some tooling to basegfx

(cherry picked from commit 97fa4faa)

Conflicts:
	basegfx/inc/basegfx/numeric/ftools.hxx

Change-Id: Ib15c43cf4d5b50605ec596dab498e3a678f3734a

basegfx/source/numeric/ftools.cxx

@@ -18,11 +18,88 @@
  */
 
 #include <basegfx/numeric/ftools.hxx>
+#include <algorithm>
 
 namespace basegfx
 {
     // init static member of class fTools
     double ::basegfx::fTools::mfSmallValue = 0.000000001;
+
+    double snapToNearestMultiple(double v, const double fStep)
+    {
+        if(fTools::equalZero(fStep))
+        {
+            // with a zero step, all snaps to 0.0
+            return 0.0;
+        }
+        else
+        {
+            const double fHalfStep(fStep * 0.5);
+            const double fChange(fHalfStep - fmod(v + fHalfStep, fStep));
+
+            if(basegfx::fTools::equal(fabs(v), fabs(fChange)))
+            {
+                return 0.0;
+            }
+            else
+            {
+                return v + fChange;
+            }
+        }
+    }
+
+    double snapToZeroRange(double v, double fWidth)
+    {
+        if(fTools::equalZero(fWidth))
+        {
+            // with no range all snaps to range bound
+            return 0.0;
+        }
+        else
+        {
+            if(v < 0.0 || v > fWidth)
+            {
+                double fRetval(fmod(v, fWidth));
+
+                if(fRetval < 0.0)
+                {
+                    fRetval += fWidth;
+                }
+
+                return fRetval;
+            }
+            else
+            {
+                return v;
+            }
+        }
+    }
+
+    double snapToRange(double v, double fLow, double fHigh)
+    {
+        if(fTools::equal(fLow, fHigh))
+        {
+            // with no range all snaps to range bound
+            return 0.0;
+        }
+        else
+        {
+            if(fLow > fHigh)
+            {
+                // correct range order. Evtl. assert this (?)
+                std::swap(fLow, fHigh);
+            }
+
+            if(v < fLow || v > fHigh)
+            {
+                return snapToZeroRange(v - fLow, fHigh - fLow) + fLow;
+            }
+            else
+            {
+                return v;
+            }
+        }
+    }
 } // end of namespace basegfx
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

include/basegfx/numeric/ftools.hxx

@@ -136,6 +136,36 @@ namespace basegfx
         return v / M_PI_2 * 90.0;
     }
 
+    /** Snap v to nearest multiple of fStep, from negative and
+        positive side.
+
+        Examples:
+
+        snapToNearestMultiple(-0.1, 0.5) = 0.0
+        snapToNearestMultiple(0.1, 0.5) = 0.0
+        snapToNearestMultiple(0.25, 0.5) = 0.0
+        snapToNearestMultiple(0.26, 0.5) = 0.5
+     */
+    double snapToNearestMultiple(double v, const double fStep);
+
+    /** Snap v to the range [0.0 .. fWidth] using modulo
+     */
+    double snapToZeroRange(double v, double fWidth);
+
+    /** Snap v to the range [fLow .. fHigh] using modulo
+     */
+    double snapToRange(double v, double fLow, double fHigh);
+
+    /** return fValue with the sign of fSignCarrier, thus evtl. changed
+    */
+    inline double copySign(double fValue, double fSignCarrier)
+    {
+#ifdef WNT
+        return _copysign(fValue, fSignCarrier);
+#else
+        return copysign(fValue, fSignCarrier);
+#endif
+    }
 
     class BASEGFX_DLLPUBLIC fTools
     {