Moved distribution map code into own class and added memory optimization.

1 files changed, 123 insertions, 0 deletions

diff --git a/tagstats/geodistribution.hpp b/tagstats/geodistribution.hpp
new file mode 100644
index 0000000..4065b5c
--- /dev/null
+++ b/tagstats/geodistribution.hpp
@@ -0,0 +1,123 @@
+#ifndef TAGSTATS_GEODISTRIBUTION_HPP
+#define TAGSTATS_GEODISTRIBUTION_HPP
+
+#include <bitset>
+
+#include <gd.h>
+
+class GeoDistribution {
+
+public:
+
+    static const int resolution_y = 360;
+    static const int resolution_x = 2 * resolution_y;
+
+    static const int image_size_y = resolution_y;
+    static const int image_size_x = resolution_x;
+
+private:
+
+    std::bitset<resolution_x * resolution_y> *location;
+
+    int cells;
+    int loc;
+
+    static std::bitset<resolution_x * resolution_y> location_all;
+
+public:
+
+    GeoDistribution() : location(NULL), cells(0), loc(-1) {
+    }
+
+    ~GeoDistribution() {
+        delete location;
+    }
+
+    /**
+     * Add the given coordinate to the distribution store.
+     */
+    void add_coordinate(double dx, double dy) {
+        int x =                int(2 * (dx + 180));
+        int y = resolution_y - int(2 * (dy +  90));
+        int n = resolution_x * y + x;
+        if (cells == 0) {
+            loc = n;
+            cells++;
+            location_all[n] = true;
+        } else if (cells == 1) {
+            if (loc != n) {
+                location = new std::bitset<resolution_x * resolution_y>;
+                (*location)[loc] = true;
+                location_all[loc] = true;
+                (*location)[n] = true;
+                cells++;
+            }
+        } else {
+            (*location)[n] = true;
+            location_all[n] = true;
+        }
+    }
+
+    /**
+     * Create PNG image.
+     * You have to call free_png() to free the memory allocated for the
+     * PNG image once you are done with it.
+     *
+     * @param size Pointer to integer thats set to the size of the created
+     *        image.
+     * @returns Pointer to memory area with PNG image.
+     */
+    void *create_png(int *size) {
+        gdImagePtr im = gdImageCreate(image_size_x, image_size_y);
+        int bgColor = gdImageColorAllocate(im, 0, 0, 0);
+        gdImageColorTransparent(im, bgColor);
+        int fgColor = gdImageColorAllocate(im, 180, 0, 0);
+
+        if (location) {
+            int n=0;
+            for (int y=0; y < resolution_y; y++) {
+                for (int x=0; x < resolution_x; x++) {
+                    if ((*location)[n]) {
+                        cells++;
+                        gdImageSetPixel(im, x, y, fgColor);
+                    }
+                    n++;
+                }
+            }
+        } else {
+            int y = loc / resolution_x;
+            int x = loc - y;
+            gdImageSetPixel(im, x, y, fgColor);
+        }
+
+        void *png = gdImagePngPtr(im, size);
+        gdImageDestroy(im);
+
+        return png;
+    }
+
+    /**
+     * Call this to free the pointer returned by create_png().
+     */
+    void free_png(void *png) {
+        gdFree(png);
+    }
+
+    /**
+     * Return the number of cells set. This is only valid after a call to create_png().
+     */
+    int get_cells() const {
+        return cells;
+    }
+
+    /**
+     * Return the number of cells that are set in at least one GeoDistribution
+     * object.
+     */
+    static int count_all_set_cells() {
+        return location_all.count();
+    }
+
+};
+
+#endif // TAGSTATS_GEODISTRIBUTION_HPP