Simplify pixels sorting in image_sim_channel_equal()

And move it to anonymous namespace.

diff --git a/src/similar.cc b/src/similar.cc
index 74acf68..8802f68 100644 (file)
--- a/src/similar.cc
+++ b/src/similar.cc
@@ -25,6 +25,7 @@
 #include <cmath>
 #include <cstdlib>
 #include <functional>
+#include <vector>
 
 #include "options.h"
 
@@ -59,6 +60,32 @@ namespace
 
 using ImageSimilarityCheckAbort = std::function<bool(gdouble)>;
 
+void image_sim_channel_equal(guint8 *pix, gsize len)
+{
+       struct IndexedPix
+       {
+               gsize index;
+               guint8 pix;
+       };
+
+       std::vector<IndexedPix> buf;
+       buf.reserve(len);
+
+       for (gsize i = 0; i < len; i++)
+               {
+               buf.push_back({i, pix[i]});
+               }
+
+       std::sort(buf.begin(), buf.end(), [](const IndexedPix &a, const IndexedPix &b){ return a.pix < b.pix; });
+
+       for (gsize i = 0; i < len; i++)
+               {
+               gint n = buf[i].index;
+
+               pix[n] = static_cast<guint8>(255 * i / len);
+               }
+}
+
 /*
  * 4 rotations (0, 90, 180, 270) combined with two mirrors (0, H)
  * generate all possible isometric transformations
@@ -120,47 +147,6 @@ void image_sim_free(ImageSimilarityData *sd)
        g_free(sd);
 }
 
-static gint image_sim_channel_eq_sort_cb(gconstpointer a, gconstpointer b)
-{
-       auto pa = static_cast<const gint *>(a);
-       auto pb = static_cast<const gint *>(b);
-       if (pa[1] < pb[1]) return -1;
-       if (pa[1] > pb[1]) return 1;
-       return 0;
-}
-
-static void image_sim_channel_equal(guint8 *pix, gint len)
-{
-       gint *buf;
-       gint i;
-       gint p;
-
-       buf = g_new0(gint, len * 2);
-
-       p = 0;
-       for (i = 0; i < len; i++)
-               {
-               buf[p] = i;
-               p++;
-               buf[p] = static_cast<gint>(pix[i]);
-               p++;
-               }
-
-       qsort(buf, len, sizeof(gint) * 2, image_sim_channel_eq_sort_cb);
-
-       p = 0;
-       for (i = 0; i < len; i++)
-               {
-               gint n;
-
-               n = buf[p];
-               p += 2;
-               pix[n] = static_cast<guint8>(255 * i / len);
-               }
-
-       g_free(buf);
-}
-
 static void image_sim_channel_norm(guint8 *pix, gint len)
 {
        guint8 l;