[gegl] workshop/enlarge: add checker alpha removal utility function

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 0693b1c4fe1c5fa23308bc50aa99a094333f08ac
Author: Øyvind Kolås <pippin gimp org>
Date:   Wed Jun 26 19:34:34 2019 +0200

    workshop/enlarge: add checker alpha removal utility function

 operations/workshop/enlarge.c      | 58 ++++++++++++++++++++++++++++++++++++--
 operations/workshop/pixel-duster.h | 20 ++++++-------
 2 files changed, 65 insertions(+), 13 deletions(-)
---
diff --git a/operations/workshop/enlarge.c b/operations/workshop/enlarge.c
index ad240a67e..d6ba55544 100644
--- a/operations/workshop/enlarge.c
+++ b/operations/workshop/enlarge.c
@@ -20,6 +20,7 @@
 #include <stdio.h>
 #include "config.h"
 #include <glib/gi18n-lib.h>
+#include <math.h>
 
 #ifdef GEGL_PROPERTIES
 
@@ -79,12 +80,61 @@ static void scaled_copy (PixelDuster *duster,
       {
         float rgba[4];
         GeglRectangle r = {x, y, 1, 1};
-        gegl_sampler_get (duster->in_sampler_f, x / scale, y / scale, NULL,
+        gegl_sampler_get (duster->in_sampler_f, x / scale+0.5, y / scale+0.5, NULL,
                           &rgba[0], 0);
         gegl_buffer_set (out, &r, 0, format, &rgba[0], 0);
       }
 }
 
+static void remove_checker (GeglBuffer  *out,
+                            int          phase)
+{
+  GeglRectangle rect;
+  const Babl *format = babl_format ("RGBA float");
+  GeglBufferIterator *iterator;
+  rect = *gegl_buffer_get_extent (out);
+  iterator  = gegl_buffer_iterator_new (out, &rect, 0, format, GEGL_BUFFER_READWRITE, GEGL_ABYSS_NONE, 1);
+  while (gegl_buffer_iterator_next (iterator))
+  {
+    int x = iterator->items[0].roi.x;
+    int y = iterator->items[0].roi.y;
+    gfloat *data = iterator->items[0].data;
+
+    int i;
+    for (i = 0; i < iterator->length; i++)
+    {
+
+      if (phase == 0)
+      {
+
+        if ( ((x%2==0) && (y%2==0)) ||
+             ((x%2==1) && (y%2==1)))
+        {
+          data[3]=0.0;
+        }
+      }
+      else
+      {
+        if ( ((x%2==1) && (y%2==1)) ||
+             ((x%2==0) && (y%2==0)))
+        {
+          data[3]=0.0;
+        }
+
+      }
+      data += 4;
+
+      x++;
+      if (x >= iterator->items[0].roi.x + iterator->items[0].roi.width)
+      {
+        x = iterator->items[0].roi.x;
+        y++;
+      }
+    }
+  }
+}
+
+
 static void improve (PixelDuster *duster,
                      GeglBuffer *in,
                      GeglBuffer *out,
@@ -133,7 +183,7 @@ static void improve (PixelDuster *duster,
             }
 
           if (rgba[3] <= 0.01)
-            fprintf (stderr, "eek %i,%i %f %f %f %f\n", probe->source_x[MAX_K/2], probe->source_y[MAX_K/2], 
rgba[0], rgba[1], rgba[2], rgba[3]);
+            fprintf (stderr, "eek %f,%f %f %f %f %f\n", probe->source_x[MAX_K/2], probe->source_y[MAX_K/2], 
rgba[0], rgba[1], rgba[2], rgba[3]);
 
           gegl_buffer_set (duster->output, GEGL_RECTANGLE(probe->target_x, probe->target_y, 1, 1), 0, 
format, &rgba[0], 0);
 #else
@@ -193,8 +243,12 @@ process (GeglOperation       *operation,
                               NULL);
   scaled_copy (duster, input, output, o->scale);
   seed_db (duster);
+
+  remove_checker (output, 0);
   improve (duster, input, output, o->scale);
+  remove_checker (output, 1);
   improve (duster, input, output, o->scale);
+  //improve (duster, input, output, o->scale);
   pixel_duster_destroy (duster);
 
   return TRUE;
diff --git a/operations/workshop/pixel-duster.h b/operations/workshop/pixel-duster.h
index a99ef0924..dd78d7dfe 100644
--- a/operations/workshop/pixel-duster.h
+++ b/operations/workshop/pixel-duster.h
@@ -75,10 +75,10 @@ typedef struct
 } PixelDuster;
 
 
-#define MAX_K               2
+#define MAX_K               1
 #define PIXDUST_REL_DIGEST  0
-#define NEIGHBORHOOD        23
-#define PIXDUST_ORDERED     0
+#define NEIGHBORHOOD        123
+#define PIXDUST_ORDERED     1
 #define MAX_DIR             4
 
 //#define ONLY_DIR            1
@@ -86,15 +86,15 @@ typedef struct
 typedef struct Probe {
   int     target_x;
   int     target_y;
-  /* the only real datamembers are above should be float*/
 
   int     age;
   int     k;
   float   score;
-  int     k_score[MAX_K];
+  float   k_score[MAX_K];
   /* should store sampled coordinates instead */
-  int     source_x[MAX_K];
-  int     source_y[MAX_K];
+  /* the only real datamembers are below and should be float*/
+  float   source_x[MAX_K];
+  float   source_y[MAX_K];
   guchar *hay[MAX_K];
 } Probe;
 
@@ -550,7 +550,6 @@ static int site_subset (guchar *site)
   return a;
 }
 
-
 static void site_subset2 (guchar *site, gint *min, gint *max)
 {
   int v[3] = {(site[4  + 1]/4), (site[8  + 1]/4), (site[12 + 1]/4)};
@@ -700,8 +699,6 @@ static int probe_improve (PixelDuster *duster,
   void *ptr[3] = {duster, probe, &needle[0]};
   float old_score = probe->score;
   static const Babl *format = NULL;
-  int    set_start[3];
-  int    set_end[3];
 
   if (!format)
     format = babl_format ("RGBA float");
@@ -866,8 +863,9 @@ static inline void pixel_duster_fill (PixelDuster *duster)
           }
           for (gint c = 0; c < 4; c++)
             rgba[c] = sum_rgba[c] / probe->k;
+
           if (rgba[3] <= 0.01)
-            fprintf (stderr, "eek %i,%i %f %f %f %f\n", probe->source_x[MAX_K/2], probe->source_y[MAX_K/2], 
rgba[0], rgba[1], rgba[2], rgba[3]);
+            fprintf (stderr, "eek %f,%f %f %f %f %f\n", probe->source_x[MAX_K/2], probe->source_y[MAX_K/2], 
rgba[0], rgba[1], rgba[2], rgba[3]);
           gegl_buffer_set (duster->output, GEGL_RECTANGLE(probe->target_x, probe->target_y, 1, 1), 0, 
format, &rgba[0], 0);
          }
       }