Add Concentric Ring Topology (#154)

src/NeoPixelBus.h

@@ -40,6 +40,7 @@ License along with NeoPixel.  If not, see
 
 #include "internal/Layouts.h"
 #include "internal/NeoTopology.h"
+#include "internal/NeoRingTopology.h"
 #include "internal/NeoTiles.h"
 #include "internal/NeoMosaic.h"
 

src/internal/NeoRingTopology.h

@@ -0,0 +1,89 @@
+#pragma once
+
+/*-------------------------------------------------------------------------
+NeoRingTopology provides a mapping feature of a 2d polar cordinate to a 
+linear 1d cordinate.
+It is used to map a series of concentric rings of NeoPixels to a index on 
+the NeoPixelBus.
+
+Written by Michael C. Miller.
+
+I invest time and resources providing this open source code,
+please support me by dontating (see https://github.com/Makuna/NeoPixelBus)
+
+-------------------------------------------------------------------------
+This file is part of the Makuna/NeoPixelBus library.
+
+NeoPixelBus is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation, either version 3 of
+the License, or (at your option) any later version.
+
+NeoPixelBus is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with NeoPixel.  If not, see
+<http://www.gnu.org/licenses/>.
+-------------------------------------------------------------------------*/
+
+template <typename T_LAYOUT> class NeoRingTopology : protected T_LAYOUT
+{
+public:
+    NeoRingTopology()
+    {
+    }
+
+    uint16_t Map(uint8_t ring, uint16_t pixel) const
+    {
+        if (pixel >= getPixelCountAtRing(ring)) 
+        {
+            return 0; // invalid ring and/or pixel argument, always return a valid value, the first one
+        }
+
+        return _map(ring, pixel);
+    }
+
+    uint16_t MapProbe(uint8_t ring, uint16_t pixel) const
+    {
+        if (pixel >= getPixelCountAtRing(ring)) 
+        {
+            return getPixelCount(); // total count, out of bounds
+        }
+
+        return _map(ring, pixel);
+    }
+
+    uint16_t getCountOfRings() const 
+    {
+        return _ringCount() - 1; // minus one as the Rings includes the extra value
+    }
+
+    uint16_t getPixelCountAtRing(uint16_t ring) const 
+    {
+        if (ring >= getCountOfRings())
+        {
+            return 0; // invalid, no pixels
+        }
+
+        return T_LAYOUT::Rings[ring + 1] - T_LAYOUT::Rings[ring]; // using the extra value for count calc
+    }
+
+    uint16_t getPixelCount() const
+    {
+        T_LAYOUT::Rings[_ringCount() - 1]; // the last entry is the total count
+    }
+
+private:
+    uint16_t _map(uint16_t ring, uint16_t pixel)  const
+    {
+        return T_LAYOUT::Rings[ring] + pixel;
+    }
+
+    uint16_t _ringCount() const
+    {
+        return sizeof(T_LAYOUT::Rings) / sizeof(T_LAYOUT::Rings[0]);
+    }
+};