[gnome-software/1290-dummy-plugin-s-key-colors-test-unreliable: 17/18] gs-key-colors: Ensure all color clusters are covered

[Milan Crha <mcrha src gnome org>]

commit a995a7ad50504d7e4efab58facdf72e060071739
Author: Milan Crha <mcrha redhat com>
Date:   Thu Jul 29 14:43:13 2021 +0200

    gs-key-colors: Ensure all color clusters are covered
    
    It helps to calculate the colors.

 lib/gs-key-colors.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)
---
diff --git a/lib/gs-key-colors.c b/lib/gs-key-colors.c
index ef2d6d01c..b82af9057 100644
--- a/lib/gs-key-colors.c
+++ b/lib/gs-key-colors.c
@@ -161,6 +161,8 @@ k_means (GArray    *colors,
        const ClusterPixel8 *pixels_end;
        Pixel8 cluster_centres[n_clusters];
        CentroidAccumulator cluster_accumulators[n_clusters];
+       gboolean used_clusters[n_clusters];
+       guint covered_clusters = 0;
        guint n_assignments_changed;
        guint n_iterations = 0;
        guint assignments_termination_limit;
@@ -181,6 +183,7 @@ k_means (GArray    *colors,
        pixels_end = &pixels[height * width];
 
        memset (cluster_centres, 0, sizeof (cluster_centres));
+       memset (used_clusters, 0, sizeof (used_clusters));
 
        /* Initialise the clusters using the Random Partition method: randomly
         * assign a starting cluster to each pixel.
@@ -193,8 +196,17 @@ k_means (GArray    *colors,
        for (ClusterPixel8 *p = pixels; p < pixels_end; p++) {
                if (p->alpha < minimum_alpha)
                        p->cluster = G_N_ELEMENTS (cluster_centres);
-               else
+               else {
                        p->cluster = g_random_int_range (0, G_N_ELEMENTS (cluster_centres));
+
+                       if (covered_clusters < n_clusters) {
+                               while (used_clusters[p->cluster])
+                                       p->cluster = (p->cluster + 1) % n_clusters;
+
+                               used_clusters[p->cluster] = TRUE;
+                               covered_clusters++;
+                       }
+               }
        }
 
        /* Iterate until every cluster is relatively settled. This is determined