From a8b16be07dfc9fe5899c7a5108a12afc3670adf3 Mon Sep 17 00:00:00 2001
From: Phuntsok Drak-pa <phundrak@phundrak.fr>
Date: Mon, 17 Dec 2018 14:50:01 +0100
Subject: [PATCH] some comments

---
 src/compress.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/compress.c b/src/compress.c
index 32877db..319725c 100644
--- a/src/compress.c
+++ b/src/compress.c
@@ -59,15 +59,18 @@ void addPixelToSelectedZone(Image *t_img, int64_t t_idx, Zone *t_zone) {
   const uint32_t y = (uint32_t)(t_idx / t_img->sizeX);
   int64_t left_limit, right_limit;
   const int64_t xd_limit = (int64_t)t_img->sizeX * (y + 1);
-  if (t_idx >= (int64_t)img_size || t_idx < 0) {
+  if (t_idx >= (int64_t)img_size || t_idx < 0) { /* Pixel in range? */
     return;
   }
   current_pixel = darrayGet(t_img->pixels, (size_t)t_idx);
+
+  /* Pixel already visited or of the right color? */
   if (current_pixel->visited || !sameColor(current_pixel, t_zone)) {
     return;
   }
   (*current_pixel).visited = 1;
 
+  /* right limit */
   for (right_limit = t_idx; right_limit < xd_limit; ++right_limit) {
     current_pixel = darrayGet(t_img->pixels, (size_t)right_limit);
     if (!sameColor(current_pixel, t_zone)) {
@@ -75,6 +78,7 @@ void addPixelToSelectedZone(Image *t_img, int64_t t_idx, Zone *t_zone) {
     }
     current_pixel->visited = 1;
   }
+  /* left limit */
   for (left_limit = t_idx; left_limit - (y - 1) * (int64_t)t_img->sizeX >= 0;
        --left_limit) {
     current_pixel = darrayGet(t_img->pixels, (size_t)left_limit);
@@ -86,9 +90,11 @@ void addPixelToSelectedZone(Image *t_img, int64_t t_idx, Zone *t_zone) {
 
   darrayPushBack(t_zone->segments,
                  newSegment((uint32_t)right_limit, (uint32_t)left_limit));
+  /* for each pixel of the segment, test the pixel above */
   for (; left_limit <= right_limit; ++left_limit) {
     addPixelToSelectedZone(t_img, t_idx + t_img->sizeX, t_zone);
   }
+  /* for each pixel of the segment, test the pixel below */
   for (; left_limit <= right_limit; ++left_limit) {
     addPixelToSelectedZone(t_img, t_idx - t_img->sizeX, t_zone);
   }